WO2018016904A1 - Method and device for setting plurality of dmrs structures in wireless cellular communication system - Google Patents

Abstract

Disclosed are a communication technique of merging, with IoT technology, a 5G communication system for supporting a data transmission rate higher than that of a 4G system, and a system therefor. The disclosure can be applied to intelligent services (for example, smart home, smart building, smart city, smart car or connected car, health care, digital education, retailing, security and safety relate services, and the like) on the basis of 5G communication technology and IoT related technology. Disclosed is a method by which a base station sets a plurality of demodulation reference signal (DMRS) structures and determines uplink and downlink transmission timing for reducing delay.

Description

Method and apparatus for setting multiple DMRS structures in wireless cellular communication system

The present invention relates to a wireless communication system, and more particularly, to a method and apparatus for a base station to configure a plurality of modulation reference signal (DMRS) structures, and to determine uplink and downlink transmission timing for delay reduction.

In order to meet the increasing demand for wireless data traffic since the commercialization of 4G communication systems, efforts are being made to develop improved 5G communication systems or pre-5G communication systems. For this reason, a 5G communication system or a pre-5G communication system is called a system after a 4G network (Beyond 4G Network) or a system after an LTE system (Post LTE). In order to achieve high data rates, 5G communication systems are being considered for implementation in the ultra-high frequency (mmWave) band (eg, such as the 60 Gigabit (60 GHz) band). In order to mitigate the path loss of radio waves in the ultra-high frequency band and increase the propagation distance of radio waves, beamforming, massive array multiple input / output (FD-MIMO), and FD-MIMO are used in 5G communication systems. Array antenna, analog beam-forming, and large scale antenna techniques are discussed. In addition, in order to improve the network of the system, 5G communication systems have advanced small cells, advanced small cells, cloud radio access network (cloud RAN), ultra-dense network (ultra-dense network) , Device to Device communication (D2D), wireless backhaul, moving network, cooperative communication, Coordinated Multi-Points (CoMP), and interference cancellation The development of such technology is being done. In addition, in 5G systems, Hybrid FSK and QAM Modulation (FQAM) and Slide Window Superposition Coding (SWSC), Advanced Coding Modulation (ACM), and FBMC (Filter Bank Multi Carrier) and NOMA are advanced access technologies. (non orthogonal multiple access), and sparse code multiple access (SCMA) are being developed.

Meanwhile, the Internet is evolving from a human-centered connection network in which humans create and consume information, and an Internet of Things (IoT) network that exchanges and processes information between distributed components such as things. The Internet of Everything (IoE) technology, which combines big data processing technology through connection with cloud servers and the like, is emerging. In order to implement the IoT, technical elements such as sensing technology, wired / wireless communication and network infrastructure, service interface technology, and security technology are required, and recently, a sensor network and a thing to machine , M2M), Machine Type Communication (MTC), etc. are being studied. In an IoT environment, intelligent Internet technology (IT) services can be provided that collect and analyze data generated from connected objects to create new value in human life. IoT is a field of smart home, smart building, smart city, smart car or connected car, smart grid, health care, smart home appliances, advanced medical services, etc. through convergence and complex of existing information technology (IT) technology and various industries. It can be applied to.

Accordingly, various attempts have been made to apply the 5G communication system to the IoT network. For example, technologies such as sensor network, machine to machine (M2M), machine type communication (MTC), and the like, are implemented by techniques such as beamforming, MIMO, and array antennas. It is. Application of cloud radio access network (cloud RAN) as the big data processing technology described above may be an example of convergence of 5G technology and IoT technology.

In addition, unlike the LTE system, 5G wireless communication is considering a system that operates in the high frequency band of more than 6GHz or less frequency band. Since the channel characteristics vary depending on the frequency band, it is necessary to design a reference signal in consideration of the 5G system. In addition, in 5G wireless communication, low latency support and high mobility support are important considerations, and it is important to minimize overhead of a reference signal.

An object of the present invention is to provide a method for configuring a plurality of DMRS (Demodulation Reference Signal) structure and the base station in the 5G system that operates in the high frequency band of 6GHz or less, as well as the low frequency and high mobility, While minimizing the overhead of the reference signal.

In addition, another object of the present invention is to minimize the overhead of the reference signal by providing a method for configuring and feedback information required by the terminal so that the base station selects a DMRS suitable for the transmission environment among the configuration of a plurality of DMRS.

In addition, another object of the present invention is a method for determining transmission timing such as HARQ ACK / NACK transmission timing or PUSCH transmission timing when the time required for signal processing of a base station and a terminal is reduced in an LTE system using FDD or TDD. By providing, the delay time for data transmission is reduced.

The base station method according to an embodiment of the present invention for solving the above problems, the step of determining the control information including at least one of the symbol position information and the symbol number information on the time axis to which the DMRS (demodulation reference signal) is transmitted The method may include transmitting the control information to the terminal and transmitting a DMRS corresponding to the determined control information to the terminal.

The base station according to an embodiment of the present invention includes a control unit that determines a control unit including at least one of the symbol position information and the symbol number information on the time axis to which the transceiver and the demodulation reference signal (DMRS) is transmitted, the control unit The controller may control the transceiver to transmit the control information to the terminal and transmit the DMRS corresponding to the determined control information to the terminal.

A terminal method according to an embodiment of the present invention, receiving control information including at least one of symbol position information and symbol number information on a time axis to which a DMRS (demodulation reference signal) is transmitted from the base station and the determined control information It may include receiving a corresponding DMRS.

According to an embodiment of the present invention, a terminal includes a transceiver and a control unit for receiving control information including at least one of symbol position information and symbol number information on a time axis through which a demodulation reference signal (DMRS) is transmitted from a base station. It may include a control unit for controlling the transceiver to receive a corresponding DMRS.

According to another embodiment of the present invention, the method of the terminal, receiving the first signal in the nkth subframe from the base station, the subframe to transmit the second signal corresponding to the first signal [Table 3-7a] and transmitting the second signal in the identified subframe.

Table 3-7a

Further, according to another embodiment of the present invention, the step of confirming the subframe to transmit the second signal in the [Table 3-7a], the reception timing of the first signal in the [Table 3-7a] And determining a transmission timing of the second signal corresponding to the received timing of the confirmed first signal.

Further, in another embodiment of the present invention, the first signal may include a physical downlink shared channel (PDSCH), and the second signal may include ACK / NACK information for the PDSCH.

Further, according to another embodiment of the present invention, the base station method, the step of transmitting the first signal in the nkth subframe to the terminal, the subframe to receive the second signal corresponding to the first signal The method may include checking in [Table 3-7a] and receiving the second signal in the identified subframe.

Table 3-7a

Further, according to another embodiment of the present invention, the step of checking the subframe to receive the second signal in the [Table 3-7a], the transmission of the first signal in the [Table 3-7a] The method may include determining a timing and confirming a reception timing of the second signal corresponding to the determined transmission timing of the first signal.

According to an embodiment of the present invention, there is provided a method of constructing a plurality of demodulation reference signals (DMRS) and setting a DMRS structure suitable for a transmission environment by a base station. This enables effective channel estimation based on low latency and high mobility support in the channel environment of 5G wireless communication systems. In addition, DMRS transmission is adaptively performed to minimize overhead of reference signals and to enable efficient transmission of radio resources.

In addition, according to another embodiment of the present invention, a base station provides a method for configuring and feeding back information required by a terminal in order to select a DMRS suitable for a transmission environment from among a plurality of DMRSs. Through the present invention, it is possible to minimize the overhead of the reference signal by performing adaptive transmission of the DMRS.

In addition, according to another embodiment of the present invention to provide a method for determining the HARQ ACK / NACK transmission timing or data transmission timing to reduce the delay time.

1A is a diagram illustrating a downlink time-frequency domain transmission structure of an LTE or LTE-A system.

1B is a diagram illustrating an uplink time-frequency domain transmission structure of an LTE or LTE-A system.

FIG. 1C illustrates a radio resource of 1 RB, which is a minimum unit that can be scheduled in downlink in an LTE or LTE-A system.

1d, 1e, 1faa, 1fab, 1fba, 1fbb, and 1g are diagrams illustrating structures of a plurality of DMRSs according to the first-first embodiment of the present invention.

1ha and 1hb are diagrams showing an example of a method for supporting MU transmission orthogonally between terminals using different DMRS structures according to the embodiment 1-3 of the present invention.

1I is a block diagram illustrating an internal structure of a terminal according to an embodiment of the present invention.

1J is a block diagram showing the internal structure of a base station according to an embodiment of the present invention.

FIG. 1K is a diagram illustrating a position of a front-load DMRS when the slot length is 7 or 14 OFDM symbols.

1la, 1lb, 1lc, 1ld, 1le, and 1lf are diagrams illustrating a case where an extended / additional DMRS is transmitted when a slot length is 7 or 14 OFDM symbols.

1M is a diagram for explaining a DMRS structure according to an embodiment of the present invention.

FIG. 1N is a diagram for describing a method of mapping an antenna port to a unit DMRS structure proposed in FIG. 1M.

FIG. 1O is a diagram for describing a method of mapping a larger number of antenna ports to the Unit DMRS structure proposed in FIG. 1M.

2A, 2B and 2C are diagrams illustrating a radio resource configuration of an LTE system.

2D is an exemplary diagram illustrating feedback timing of information required for selecting a reference signal according to embodiment 2-2 of the present invention.

2E is an exemplary diagram illustrating a method of classifying reference signals based on feedback of information required for selecting a reference signal according to embodiment 2-3 of the present invention.

2F is a block diagram illustrating an internal structure of a terminal according to embodiments of the present invention.

2G is a block diagram illustrating an internal structure of a base station according to embodiments of the present invention.

3A is a diagram illustrating a downlink time-frequency domain transmission structure of an LTE or LTE-A system.

3b is a diagram illustrating an uplink time-frequency domain transmission structure of an LTE or LTE-A system.

Figure 3c is a diagram showing a state in which the data for the eMBB, URLLC, mMTC is allocated in the frequency-time resources in the communication system.

FIG. 3D is a diagram showing how data for eMBB, URLLC, and mMTC are allocated in frequency-time resources in a communication system.

3E illustrates a structure in which one transport block is divided into several code blocks and a CRC is added according to an embodiment.

3F is a diagram illustrating a structure in which an outer code is applied and coded according to an embodiment.

3G is a block diagram illustrating the application of an outer code according to an embodiment.

3H is a diagram illustrating a terminal operation according to Embodiments 3-1, 3-2, 3-3, and 3-4.

3I is a diagram illustrating a terminal operation according to Embodiments 3-5, 3-6, 3-7, and 3-8.

3J is a block diagram illustrating a structure of a terminal according to embodiments.

3K is a block diagram illustrating a structure of a base station according to embodiments.

Hereinafter, embodiments of the present invention will be described in detail with the accompanying drawings. In addition, in describing the present invention, when it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted. Terms to be described later are terms defined in consideration of functions in the present invention, and may be changed according to intentions or customs of users or operators. Therefore, the definition should be made based on the contents throughout the specification.

Advantages and features of the present invention, and methods for achieving them will be apparent with reference to the embodiments described below in detail in conjunction with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but may be implemented in various forms, and only the embodiments of the present invention make the disclosure of the present invention complete and the general knowledge in the technical field to which the present invention belongs. It is provided to fully convey the scope of the invention to those skilled in the art, and the present invention is defined only by the scope of the claims. Like reference numerals refer to like elements throughout.

The wireless communication system has moved away from providing the initial voice-oriented service, for example, 3GPP High Speed Packet Access (HSPA), Long Term Evolution (LTE) or Evolved Universal Terrestrial Radio Access (E-UTRA), LTE-Advanced. Advances in broadband wireless communication systems that provide high-speed, high-quality packet data services such as LTE-A, 3GPP2's High Rate Packet Data (HRPD), UMB (Ultra Mobile Broadband), and IEEE's 802.16e Doing. In addition, 5G or NR (new radio) communication standard is being developed as a 5th generation wireless communication system.

First Embodiment

In order to estimate a channel in a wireless communication system, a base station must transmit a reference signal for this. The terminal may perform channel estimation using the reference signal and demodulate the received signal. In addition, the terminal may be used to determine the channel state through the reference signal and feed it back to the base station.

In general, when transmitting a reference signal, the transmission interval of the reference signal based on frequency and time is determined in consideration of the maximum delay spread and the maximum Doppler spread of the channel. As the transmission interval of the reference signal is narrower, the channel estimation performance can be improved to improve the demodulation performance of the signal. However, this results in an increase in overhead of the reference signal, thereby limiting the data rate.

In the 4G LTE system operating in the frequency band of 2 GHz, reference signals such as a cell-specific reference signal (CRS) and a demodulation reference signal (DMRS) are used in downlink. When the interval of the reference signal in frequency is expressed as the subcarrier interval m of the Orthogonal Frequency Division Multiplexing (OFDM) signal, and the interval of the reference signal in time is represented by the symbol interval n of the OFDM signal, normal cyclic prefix (normal Cyclic Prefix); In case of CRS assuming normal CP), the transmission interval based on the frequency and time of the reference signal corresponding to antenna ports 1 and 2 is (m, n) = (3,4). In case of DMRS assuming normal CP, the transmission interval based on the frequency and time of the reference signal is (m, n) = (5,7).

Unlike LTE systems, 5G wireless communication considers a system that operates in the high frequency band as well as the frequency band of 6GHz or less. Since the channel characteristics vary depending on the frequency band, it is necessary to design a reference signal newly in consideration of 5G systems.

As a representative example of the broadband wireless communication system, an Orthogonal Frequency Division Multiplexing (OFDM) scheme is adopted in downlink (DL) in an LTE / LTE-A system, and SC-FDMA (Single) in an uplink (UL). Carrier Frequency Division Multiple Access) is adopted. Uplink refers to a radio link through which a user equipment (UE) or mobile station (MS) transmits data or control signals to a base station (eNode B or base station (BS)). This refers to a wireless link that transmits data or control signals. In the multiple access scheme as described above, the time-frequency resources for carrying data or control information for each user do not overlap each other, that is, the orthogonality is established so that the time-frequency resources are allocated and operated so that each user's data or Classify control information.

FIG. 1A illustrates a basic structure of a time-frequency domain, which is a radio resource region in which the data or control channel is transmitted in downlink in an LTE / LTE-A system.

In FIG. 1A, the horizontal axis represents the time domain and the vertical axis represents the frequency domain. The minimum transmission unit in the time domain is an OFDM symbol, N _symb (102) OFDM symbols are gathered to form one slot 106, two slots are gathered to form one subframe (105). The length of the slot is 0.5ms and the length of the subframe is 1.0ms.

The radio frame 114 is a time domain section composed of 10 subframes. The minimum transmission unit in the frequency domain is a subcarrier, and the bandwidth of the entire system transmission bandwidth is composed of a total of N _BW 104 subcarriers.

The basic unit of a resource in the time-frequency domain may be represented by an OFDM symbol index and a subcarrier index as a resource element (RE). The resource block 108 (Resource Block; RB or PRB) is defined as N _symb 102 consecutive OFDM symbols in the time domain and N _RB 110 consecutive subcarriers in the frequency domain. Thus, one RB 108 is composed of N _symb x N _RB REs 112.

In general, the minimum transmission unit of data is the RB unit. In the LTE system, the N _symb = 7, N _RB = 12, and N _BW and N _RB are proportional to the bandwidth of the system transmission band. The data rate increases in proportion to the number of RBs scheduled for the terminal. The LTE system defines and operates six transmission bandwidths. In the case of an FDD system in which downlink and uplink are divided into frequencies, the downlink transmission bandwidth and the uplink transmission bandwidth may be different. The channel bandwidth represents an RF bandwidth corresponding to the system transmission bandwidth.

 [Table 1-1] shows a correspondence relationship between a system transmission bandwidth and a channel bandwidth defined in the LTE system. For example, an LTE system with a 10 MHz channel bandwidth consists of 50 RBs in transmission bandwidth.

Table 1-1

FIG. 1B is a diagram illustrating a basic structure of a time-frequency domain, which is a radio resource region in which data or a control channel is transmitted in uplink in an LTE / LTE-A system.

Referring to FIG. 1B, the horizontal axis represents a time domain and the vertical axis represents a frequency domain. The minimum transmission unit in the time domain is an SC-FDMA symbol 202, in which N _symb ^UL SC-FDMA symbols are collected to form one slot 206. Two slots are gathered to form one subframe 205. The minimum transmission unit in the frequency domain is a subcarrier, and the total system transmission bandwidth 204 consists of a total of N _BW subcarriers. N _BW has a value proportional to the system transmission band.

The basic unit of a resource in the time-frequency domain may be defined as a SC-FDMA symbol index and a subcarrier index as a resource element (RE) 212. A resource block pair (208, RB pair) is defined as N _symb ^UL contiguous SC-FDMA symbols in the time domain and N _sc ^RB contiguous subcarriers in the frequency domain. Therefore, one RB is composed of N _symb ^UL x N _sc ^RB _Rs . In general, the minimum transmission unit for data or control information is in RB units. PUCCH is mapped to a frequency domain corresponding to 1 RB and transmitted during one subframe.

FIG. 1C illustrates radio resources of 1 RB, which is a minimum unit that can be scheduled in downlink in an LTE / LTE-A system. A plurality of different types of signals may be transmitted through the radio resource illustrated in FIG. 1C as follows.

1. Cell Specific RS (CRS): A reference signal periodically transmitted for all UEs belonging to one cell and may be commonly used by a plurality of UEs.

2. Demodulation Reference Signal (DMRS): This is a reference signal transmitted for a specific terminal and is transmitted only when data is transmitted to the corresponding terminal. DMRS may consist of a total of eight DMRS ports. In LTE / LTE-A, ports 7 to 14 correspond to DMRS ports, and ports maintain orthogonality so as not to interfere with each other by using code division multiplexing (CDM) or frequency division multiplexing (FDM).

3. Physical Downlink Shared Channel (PDSCH): This is a downlink data channel that is used by a base station to transmit traffic to a user equipment and is transmitted by using an RE not transmitting a reference signal in the data region of FIG.

4. CSI-RS (Channel Status Information Reference Signal): A reference signal transmitted for terminals belonging to one cell and used to measure channel status. A plurality of CSI-RSs can be transmitted in one cell.

5. Other Control Channels (PHICH, PCFICH, PDCCH): The terminal provides control information necessary for receiving a PDSCH or transmits an ACK / NACK for operating a hybrid automatic repeat request (HARQ) for uplink data transmission.

In the signal, CRS and DMRS are reference signals used to demodulate a signal received through channel estimation. Since the channel estimation performance directly affects the demodulation performance, the transmission interval based on the frequency and time of the reference signal is determined in consideration of this. And maintain. For example, if the interval of the reference signal in frequency is represented by the subcarrier interval m of the OFDM signal, and the interval of the reference signal in time is represented by the symbol interval n of the OFDM signal in time, CRS assuming normal CP, antenna port 1 and The transmission interval based on the frequency and time of the reference signal corresponding to 2 is (m, n) = (3,4). In addition, in case of DMRS assuming normal CP, the transmission interval based on the frequency and time of the reference signal is (m, n) = (5,7).

Unlike LTE systems, 5G wireless communication considers a system that operates in the high frequency band as well as the frequency band of 6GHz or less. Since the channel characteristics vary depending on the frequency band, it is necessary to design a reference signal in consideration of this in 5G systems. In addition, in 5G wireless communication, low latency support of radio signal transmission and high mobility support of radio signals are considered important. In addition, in 5G systems, it is important to minimize the overhead of the reference signal. Accordingly, the present invention provides a method of configuring a plurality of demodulation reference signal (DMRS) structures and a method for configuring the base station to solve this problem.

DETAILED DESCRIPTION Hereinafter, embodiments of the present invention will be described in detail with the accompanying drawings. Hereinafter, an embodiment of the present invention will be described using an LTE or LTE-A system as an example, but the embodiment of the present invention may be applied to other communication systems having a similar technical background or channel form. For example, the fifth generation mobile communication technology (5G, new radio, NR) developed after LTE-A may be included in this.

More specifically, the basic structure of the time-frequency domain in which signals are transmitted in downlink and uplink may be different from those shown in FIGS. 1A and 1B. In addition, the types of signals transmitted in downlink and uplink may also be different. Accordingly, embodiments of the present invention may be applied to other communication systems through some modifications without departing from the scope of the present invention by the judgment of those skilled in the art.

In addition, in the following description of the present invention, if it is determined that a detailed description of related functions or configurations may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted. Terms to be described later are terms defined in consideration of functions in the present invention, and may be changed according to intentions or customs of users or operators. Therefore, the definition should be made based on the contents throughout the specification. Hereinafter, the base station is a subject performing resource allocation of the terminal, and may be at least one of an eNode B, a Node B, a base station (BS), a wireless access unit, a base station controller, or a node on a network. The terminal may include a user equipment (UE), a mobile station (MS), a cellular phone, a smart phone, a computer, or a multimedia system capable of performing a communication function. In the present invention, downlink (DL) is a radio transmission path of a signal transmitted from a base station to a terminal, and uplink (UL) is a radio transmission path of a signal transmitted from a terminal to a base station.

Since a UE-specific precoding is applied to a reference signal (DMRS) to be described below, the UE may perform demodulation without additionally receiving precoding information. Refers to a reference signal having a feature that can be, and will be used as the name used in the LTE system. However, the term for the DMRS may be expressed in other terms depending on the intention of the user and the purpose of using the reference signal. More specifically, the term DMRS is only intended to provide a specific example to easily explain the technical contents of the present invention and help the understanding of the present invention, and is not intended to limit the scope of the present invention. That is, it is apparent to those skilled in the art that the present invention can be applied to a reference signal based on the technical idea of the present invention.

Embodiment 1-1 of the present invention to be described below describes various DMRS structures according to a use case. Embodiments 1-2 of the present invention describe a method for a base station to set and transmit a suitable DMRS structure among a plurality of DMRS structures according to a transmission environment. In the embodiments 1-3 of the present invention, when a plurality of DMRS structures are supported, a method of supporting multiple-user (MU) transmissions orthogonally between terminals using different DMRS structures will be described.

[Example 1-1]

Embodiment 1-1 describes a method of variously configuring a structure of a DMRS, which is a reference signal of the present invention, according to a transmission environment.

Referring to FIG. 1C, the LTE system has a fixed DMRS structure. When the number of transport layers is 2 or less, 12 DMRS REs are transmitted per RB. If the number of transport layers exceeds 2, 24 DMRSs are used. Sent to the RE.

As described above, unlike the LTE system, the 5G wireless communication system considers a system that operates not only in the frequency band below 6 GHz but also in the high frequency band above. Since channel characteristics vary according to frequency bands, DMRS in 5G systems needs to be designed differently from LTE's DMRS. In addition, 5G systems consider low latency support and high mobility support. Therefore, a plurality of DMRS structures are required according to the transmission environment.

For example, in order to support low latency, channel estimation needs to be performed quickly. For this purpose, DMRS needs to be forwarded on the transmission time base, and for fast mobility support, tracking of fast changing channels in time is required. This must be possible, and for this purpose, the DMRS needs to be transmitted at a high density based on one transmission time base. Here, the density may mean an amount of resources (eg, the number of REs) in which the DMRS is transmitted in any transmission unit.

Also, for example, a 5G system may not support a reference signal such as CRS. In general, the CRS guarantees channel estimation performance even in a low signal-to-interference plus noise ratio (SINR) region (for example, -10 to 0dB) due to the high density of the reference signal. It can be difficult to ensure channel estimation performance in the region.

Accordingly, the present invention proposes a method of variously configuring the structure of DMRS according to a transmission environment.

In order to configure the structure of the DMRS in various ways, first, a setting for a location where the DMRS can be transmitted is required. When the transmittable DMRS location is set, the base station according to an embodiment of the present invention may determine and transmit a DMRS structure necessary for the set location. And the terminal according to an embodiment of the present invention needs to know the transmission possible position of the DMRS.

Unlike the LTE system, since the 5G wireless communication system can be configured with various frame structures and can be operated with a variable transmission time interval (TTI), the location setting for the DMRS needs to be specified as a terminal separately. In addition, unlike in LTE, in the 5G wireless communication system, the number of OFDM symbols and the number of subcarriers in frequency constituting a subframe may be different. In the present invention, in most drawings, the number of OFDM symbols in time constituting a subframe and the number of frequency subcarriers constituting a resource block are set to be the same as in LTE, but this may be set differently. For example, as shown in FIGS. 1faa, 1fab, 1fba, and 1fb, one resource block may consist of 12 subcarriers in frequency or 16.

More specifically, the setting of the position where the DMRS can be transmitted may be divided into a position in time and a position in frequency, and may be set as a combination of a position in time and a position in frequency.

First, there are two ways to consider the time location where the DMRS can be transmitted. The first method is to set the position in time at which the DMRS is transmitted based on the subframe. This is generally a method considering the location setting for a transmission resource in units of subframes.

For example, when a duration corresponding to one subframe is represented by x, a method in which the position of the DMRS is set in units of y = x / 2 may be considered. More specifically, referring to FIGS. 1faa to 1fba, when x = 14 (OFDM symbol), the position of the DMRS may be set in a unit of y = 7, and the time position of the DMRS that can be set in one subframe may be It may be a 3/6/9 / 12th OFDM symbol.

The second method is to set the time position at which the DMRS is transmitted based on the start point of the allocated data channel (ex, PDSCH). This is a method considering that a section in which a data channel is transmitted in various subframes can be set in a 5G wireless communication system unlike the LTE system. For example, with respect to the start point of the data channel, the configurable DMRS in time can be a 1/4/7 / 10th OFDM symbol.

Next, the position on the frequency at which the DMRS can be transmitted may be set to have a density in consideration of the channel environment of the 5G communication system covering various numerologies. Here, the numerology may mean subcarrier spacing (eg, frequency difference between subcarriers), and the length of the interval of subcarriers on frequency is the length of a symbol on the time axis. Can be inversely proportional to

For example, the transmission location on the frequency of the DMRS may be set such that the DMRS is transmitted on at least two consecutive subcarriers. For example, in FIG. 1fab, as illustrated in FIGS. 1fa-4-1 and 1fa-4-2, the positions on two frequencies where DMRS can be transmitted are illustrated.

As described above, the setting of the position where the DMRS can be transmitted may be set by a combination of the position in time and the position in frequency, and the actual DMRS setting may be set to a subset of possible combinations for convenience. . In addition, the transmitted DMRS structure may be implicitly determined according to the position in time at which the above-described DMRS can be transmitted and the number of DMRS layers transmitted.

More specifically, it will be described based on the DMRS structure proposed in FIGS. 1faa and 1fab.

As shown in FIGS. 1fa-2-1 and 1fa-2-2, when the DMRS is configured for only one OFDM symbol located on the time axis within one subframe for low latency support, the UE may transmit a transmitted layer ( DMRS structure can be classified according to the number of layers). For example, when the number of transmitted layers is 4 or less, as shown in FIG. 1fa-2-2, a reference signal may be allocated more densely on frequency. In contrast, when the number of transmitted layers is greater than 4, as shown in FIG. 1fa-2-1, a reference signal having a low density in frequency may be allocated. However, a reference signal set to have a low density as shown in FIG. 1fa-2-1 may be difficult to guarantee channel estimation performance.

As another example, if the DMRS is configured for two OFDM symbols in time within one subframe as shown in FIGS. 1fa-3-1 and 1fa-3-2, if the number of transmitted layers is 4 or less as described above, FIG. As shown in 3-2, the reference signal can be allocated more densely on the frequency. In addition, when the number of transmitted layers is larger than 4, as shown in FIG. 1fa-3-1, a reference signal having a low density in frequency may be allocated.

As another example, as shown in FIGS. 1fa-4-1 and 1fa-4-2, a DMRS is used for supplementation in an environment having a high degree of Doppler effect (hereinafter, used in combination with the term High Doppler). When four OFDM symbols are configured on the time axis in the subframe, when the number of transmitted layers is 4 or less, reference signals may be allocated as shown in FIG. 1fa-4-2. In this case, if the reference signal is more densely allocated on the frequency, the overhead of the reference signal may be too large. When the number of transmitted layers is greater than 4, reference signals may be allocated as shown in FIGS. 1fa-4-1. However, in high-speed transmission, the probability that the number of transport layers is greater than 4 is very low.

In this case, when the number of transmitted layers is 4 or more, OCC (Orthogonal Cover Code) = 4 may be operated. When the number of transmitted layers is 2 or less, OCC = 2 may be operated. The above example can be similarly applied to other DMRS structures. In addition, the example of the DMRS structure described with reference to FIGS. 1FBA and 1Fbb may be equally applicable to the case where the number of subcarriers in frequency is 16 in one resource block.

Next, we propose a method for performing operations such as Doppler frequency measurement, phase noise compensation, and frequency offset correction using DMRS. In the existing LTE system, it was possible to perform such an operation using CRS. However, in the 5G communication system, when there is no outgoing signal in every subframe in the full band like CRS, the aforementioned Doppler frequency measurement, phase noise compensation, and frequency It may be difficult to perform operations such as offset correction.

In order to perform such an operation, a reference signal having a high density in time is required. For example, when DMRS is set to only one OFDM symbol in time for low latency support, it is impossible to perform the operation using only the DMRS. . Therefore, the on-demand method provided on demand allows the base station to set the DMRS with a high density in time to perform operations such as Doppler frequency measurement, phase noise compensation, and frequency offset correction. More specifically, in order to perform such an operation, the base station performs dynamic signaling, and the terminal performs operations such as Doppler frequency measurement, phase noise compensation, and frequency offset correction using the DMRS configured through the base station. For example, one bit may be added to the dynamic control information (DCI) and signaled. Supporting a plurality of DMRS structures in the first-first embodiment may be differentiated as follows compared to supporting one fixed DMRS structure in the existing LTE system. First, unlike the existing LTE, the number of DMRS REs allocated per antenna port may not be fixed. For example, in the LTE system, the number of DMRS REs allocated per antenna port is fixed to 12. However, when supporting a plurality of DMRS structures, the number of DMRS REs allocated per antenna port is determined among the various DMRS structures. It may vary.

In addition, the number of supported antenna ports may vary depending on which of various DMRS structures is configured. For example, it is difficult to support high rank in an environment where the overhead of the reference signal is to be reduced. In this case, the overhead of the reference signal should be minimized by supporting only a minimum antenna port. Hereinafter, specific examples of the above-described differentiation can be confirmed through various DMRS structures proposed.

According to the above-described reason, embodiment 1-1 of the present invention proposes various DMRS structures according to a transmission environment. 1D is a diagram illustrating a first example of various DMRS structures. FIG. 1D illustrates, for example, a structure in which a DMRS can be transmitted through all subcarriers included in one OFDM symbol. However, the position of the DMRS proposed in the present invention is not limited to that shown in FIG. 1D.

More specifically, as shown in FIG. 1D-1, the DMRS may be located in each of the third OFDM symbol and the eleventh OFDM symbol. For example, for time balance, as in FIG. 1D-1, the position of the DMRS may be transmitted through each of the third and twelfth OFDM symbols in one subframe. However, when the 5G system has a basic structure of a time-frequency domain different from that of the LTE / LTE-A system, the position of the DMRS may vary.

As another example, in the present invention, in order to support low latency, as shown in FIGS. 1D-2, the position of the DMRS may be transmitted only through a third OFDM symbol in one subframe. In this case, the terminal can demodulate the received signal quickly because the channel can be estimated while receiving the signal up to the third OFDM symbol.

As another example, in the present invention, in order to support high mobility, as shown in FIGS. 1D-3, the position of the DMRS may be transmitted through three different OFDM symbols in one subframe.

Meanwhile, generation of a DMRS signal may be generated based on pseudo-random sequence similar to downlink DMRS in LTE, or may be generated based on a Zoff (Cadoff-Chu) sequence similar to uplink DMRS in LTE. have. For example, when the uplink / downlink has the same DMRS structure, DMRS signal generation may also orthogonally support the DMRS port of the uplink / downlink when the uplink / downlink is the same.

In addition, in FIG. 1D, it is possible to support a plurality of DMRS ports by applying an orthogonal cover code (OCC) on a frequency. When applying the OCC in frequency, there is an advantage that does not occur a power imbalance problem that can occur when applying the OCC in time. An example of this is shown in FIG. 1E.

FIG. 1E illustrates an example in which the OCC is applied when the number of subcarriers in frequency is 16 in one resource block. In FIG. 1E, DMRS port numbers are numbered from port 7 to port 14 based on the LTE system, but this is an example for description. For example, the port numbers used in 5G systems may be different.

More specifically, FIG. 1E-1 illustrates an example of an OCC applied when two ports (ports 7, ports 8) are used to transmit DMRS. As shown in FIG. 1E-1, an OCC having an OCC length of 2 may be applied at a position where port 7 and port 8 are marked. Therefore, in FIG. 1E-1, when the DMRS is transmitted using two ports, the DMRS may not be transmitted for all resources included in one OFDM symbol.

는 시퀀스 길이에 따른 시퀀스 값을 나타내며, OCC 크기가 2인 경우는

와

가 사용되며, OCC 크기가 4인 경우에는

가 모두 사용된다. 앞서 설명한 바와 같이 [표 1-2]도 LTE시스템을 기준으로 7번 포트부터 14번 포트로 넘버링을 하였지만, 이는 설명을 위한 예시이다. 예를 들어, 5G 시스템에서 사용되는 포트 넘버는 이와 다를 수 있다. Table 1-2 shows the sequence for OCC. In [Table 1-2]

Represents the sequence value according to the sequence length. When the OCC size is 2,

Wow

Is used, and if the OCC size is 4,

Are all used. As described above, [Table 1-2] also numbered from port 7 to port 14 based on the LTE system, but this is an example for explanation. For example, the port numbers used in 5G systems may be different.

1E-2 illustrates an example of application of an OCC applied when four ports 7/8/9/10 are transmitted. As shown in FIG. 1E-2, an OCC having an OCC length of 2 may be applied at a position where ports 7/8/9/10 are indicated. As illustrated, when four or more ports are transmitted, DMRS may be transmitted for all resources of the OFDM symbol. 1E-3 shows an example of applying OCC when eight ports are transmitted. When more than four ports are used as in FIGS. 1E-3, OCC length 4 is used.

Although FIG. 1E shows an example of OCC application for the case where 2/4/8 ports are transmitted, the application of up to 8 other ports can be easily extended from the example of FIG. 1E. For example, if three ports are transmitted, only port 7/8/9 is transmitted in FIG. 1E-1 and port 7/8 may be transmitted by applying an OCC of length 2 at a corresponding position in FIG. 1E-1. However, since port 9 has no other port in the corresponding position of FIGS. 1E-1, the length 2 OCC is not applied.

TABLE 1-2

1faa, 1fab, 1fba and 1fbb next show a second example of the various DMRS structures proposed. 1faa, 1fab, 1fba and 1fbb are modified structures of the type shown in FIGS. 1d and 1e. In detail, the proposed scheme proposes a structure that can be operated more effectively in consideration of the overhead of the reference signal than the method shown in FIGS. 1D and 1E through the proposed DMRS position configuration and antenna port mapping method.

The generation of a DMRS signal may be generated based on a pseudo-random sequence similar to the downlink DMRS in LTE, or may be generated based on a Zadoff-Chu (ZC) sequence similar to the uplink DMRS in LTE. 1faa and 1fab show a structure when the number of subcarriers in frequency constituting the resource block is 12, and FIGS. 1Fba and 1fbb show a structure when the number of subcarriers in frequency constituting the resource block is 16.

는 시퀀스 길이에 따른 시퀀스 값을 나타내며, OCC길이가 2인 경우는

와

가 사용되며, OCC 길이가 4인 경우에는

가 모두 사용된다. 도 1fa-1-2와 1fa-1-3에서 DMRS 포트 넘버를 LTE시스템을 기준으로 7번 포트부터 14번 포트로 넘버링을 하였지만, 이는 설명을 위한 예시이다. 예를 들어, 5G 시스템에서 사용되는 포트 넘버는 이와 다를 수 있다. First, FIG. 1faa and FIG. 1fab are demonstrated. In the method proposed in FIGS. 1faa and 1fab, the DMRS location shown in FIGS. 1fa-1-1 may be flexibly used according to a transmission situation. The OCC and antenna port mapping method may be performed as shown in FIGS. 1fa-1-2 and 1fa-1-3. In [Table 1-2]

Represents the sequence value according to the sequence length, and if the OCC length is 2,

Wow

Is used, and if the OCC length is 4,

Are all used. In FIG. 1fa-1-2 and 1fa-1-3, DMRS port numbers were numbered from port 7 to port 14 based on the LTE system, but this is an example for description. For example, the port numbers used in 5G systems may be different.

First, referring to FIG. 1fa-1-2, a reference signal may not be transmitted to a portion indicated by a grid pattern, but a reference signal may be transmitted only to a portion indicated by a hatched pattern. In this case, two ports 7/8 may be transmitted by applying OCC = 2, and four ports 7/8/11/13 may be transmitted by applying OCC = 4. In contrast, when eight ports from port 7 to port 14 are transmitted, port 7/8/11/13 is transmitted with OCC = 4 at the hatched position, and port 9 at the grid position. 10/12/14 may be transmitted with OCC = 4 applied.

First, referring to FIG. 1fa-1-3, two ports 7/8 may be transmitted by applying OCC = 2 to the hatched portions, and four ports 7/8/11 to the hatched portions. / 13 may be transmitted with OCC = 4 applied. 1fa-1-2 is a method for minimizing the overhead of the reference signal when the channel condition is good, and FIG. 1fa-1-3 shows the channel estimation performance by further using the reference signal when the channel condition is bad. It is a way to improve. 1fa-1-2 and 1fa-1-3 illustrate how the OCC is applied in frequency, but the method in which the OCC is applied is not limited thereto.

As described above, the method proposed in FIGS. 1faa and 1fab may be flexibly used with the DMRS location shown in FIGS. 1fa-1-1 according to a transmission situation. FIG. 1fa-2-1 / 1fa-2-2 / 1fa-3-1 / 1fa-3-2 / 1fa-4-1 / 1fa-4-2 is a diagram showing examples of DMRS positions configurable according to transmission conditions. An embodiment thereof will be referred to the foregoing description.

As described above, FIGS. 1Fba and 1Fbb show a structure when the number of subcarriers in frequency constituting the resource block is 16. Since the operation method thereof is the same as in FIGS. 1faa and 1fab, a detailed description thereof will be omitted. The OCC and antenna port mapping method may be performed as shown in FIGS. 1fb-1-2 and 1fb-1-3, and more detailed operations are the same as in FIGS. 1fa-1-2 and 1fa-1-3. However, the method in which the OCC is applied in the present invention is not limited thereto.

In the method proposed in FIGS. 1fba and 1fbb, the DMRS location shown in FIG. 1fb-1-1 may be used flexibly according to a transmission situation. FIG. 1fb-2-1 / 1fb-3-1 / 1fb-3-2 / 1fb-4-1 is a diagram illustrating examples of configurable DMRS positions.

Finally, FIG. 1G shows a third example of the various DMRS structures proposed. 1G is a structure in which DMRS has a form similar to that of the current LTE system. Therefore, the OCC and antenna port mapping method applied in the DMRS of LTE may be applied as it is. However, in the present invention, rather than applying the DMRS structure of the existing LTE system as it is, another DMRS structure may be considered according to the channel environment in order to satisfy the next generation communication requirements. That is, the present invention extends the DMRS structure of an existing LTE system and proposes a method of configuring various DMRS structures in OFDM symbol units according to a transmission environment.

FIG. 1G-1 illustrates a location of a DMRS that can be implemented in a general channel state. In addition, FIG. 1G-2 illustrates a structure in which additional DMRSs are mapped on a time axis for high mobility support. 1G-3-1 and 1G-3-2 illustrate a method of reducing the DMRS density on the frequency axis in order to minimize the overhead of the reference signal in an environment having a small channel delay. Finally, DMRS structures such as FIGS. 1G-4-1 and 1G-4-2 may be used to support low latency. As shown in FIG. 1G-4-1, when the position of the DMRS is transmitted only to the front OFDM symbol, only up to 4-layer transmission may be supported.

Various DMRS structures according to a transmission environment are shown in FIGS. 1D, 1Fa, 1fab, 1fba, 1fbb, and 1g. However, the DMRS structure in the present invention is not limited to the structure shown in the embodiment 1-1. Accordingly, a DMRS structure different from those of FIGS. 1D, 1FAA, 1fab, 1Fba, 1Fbb, and 1G may be applied to the following embodiments 1-2 and 1-3.

In addition, although the structure of the DMRS has been described based on the downlink in the first-first embodiment, the same structure of the DMRS may be configured in the uplink in the 5G system. If the uplink / downlink has the same DMRS structure, the DMRS port of the uplink / downlink becomes orthogonal, thus enabling more flexible operation in an environment such as a time division duplex (TDD).

[1-1-1 Example]

Embodiment 1-1-1 proposes another method for setting the structure of the DMRS proposed in Embodiment 1-1 above. In the embodiment 1-1-1, the structure of the configurable DMRS can be classified into a front-loaded DMRS and an extended / additional DMRS. First, front-loaded DMRS can be defined by the following two criteria.

1.the number of OFDM symbols for front-loaded DMRS

Front-loaded DMRS is mapped over 1 or 2 adjacent OFDM symbol

Front-loaded DMRS is mapped on 1 OFDM symbol for low rank transmission.

Front-loaded DMRS is mapped on 2 adjacent OFDM symbols for high rank transmission.

2.the location of time for front-loaded DMRS

● Opt. 1: The first symbol of front-loaded DM-RS is fixed regardless of the first symbol of NR-PDSCH.

● Opt. 2: The first symbol of front-loaded DM-RS is no later than the first symbol of NR-PDSCH.

Specifically, the front-loaded DMRS may be configured in one or two adjacent OFDM symbols according to the number of transport layers (ranks). In addition, the front-loaded DMRS is located in front of the NR-PDSCH on the time axis. The position may be fixed as described above, or the front-loaded RS may be located from the first symbol at which the NR-PDSCH starts.

Referring to the advantages and disadvantages of the Opt. 1 and Opt. 2, it can be assumed that in the case of Opt. 1, since the position of the DMRS is fixed, the DMRS of the next cell is always transmitted at the same position. However, when the control channel region is configured to be configured (configurable) or in case of a subframe in which the control channel is not transmitted, a decoding latency problem may occur because the DMRS of the data channel is not positioned earlier.

On the other hand, Opt.2 has an advantage in terms of decoding latency because the front-loaded DMRS is always located ahead of the data channel on the time axis. However, as the position of the front-loaded DMRS is diversified, that is, the position of the DMRS is not fixed, which may cause problems in inter-cell interference control and improved receiver operation. For this purpose, a method of additionally introducing network signaling may be considered, but in general, a method in which the position of the DMRS is fixed is advantageous in operating the system.

Therefore, we propose a specific method for setting the front-load DMRS to a fixed position for the above reasons. In FIG. 1K, the positions of the front-load DMRSs are shown for the case where the slot length is 7 or 14 OFDM symbols, respectively. Here, the position setting of the front-load DMRS may be determined by the area of the control channel. As an example, when the control channel region consists of up to two OFDM symbols, the front-load DMRS is located in the third OFDM symbol as shown in FIG. As another example, when the control channel region consists of up to three OFDM symbols, the front-load DMRS is located in the fourth OFDM symbol as shown in FIG.

As described above, if the position of the front-load DMRS is determined by the maximum size of the controllable channel region, there may be a loss in reducing decoding latency when some or all of the control channels are not set. Therefore, the present invention proposes another method for setting the position of the front-load DMRS by the extended method of Opt.

For example, when the control channel region consists of up to two OFDM symbols, the front-load DMRS is fixed to the third OFDM symbol as shown in FIG. K-1, and the front-load DMRS as shown in FIG. K-3. The setting fixed to the first OFDM symbol may be set as one option. If these two settings are changed according to circumstances, the disadvantage of Option 1 can be compensated for.

In detail, the location of the plurality of front-load DMRSs can be set in various ways. For example, a method of semi-static configuration through higher layer signaling such as RRC may be considered. In addition, for example, the DMRS location may be set and transmitted in system information such as MIB or SIB. Also, for example, a method of dynamically setting a DMRS location through DCI may be considered. Alternatively, it is also possible to set the position of the DMRS through semi-persistent scheduling (SPS).

Next, Extended / Additional DMRS will be described. The front-loaded DMRS described above has difficulty in accurately estimating the channel since it is impossible to track a channel that changes rapidly in time in a high doppler situation. In addition, it is impossible to perform cross-correlation with respect to frequency offset only with front-loaded DMRS. Therefore, additional DMRS needs to be transmitted on the time axis behind the position where the front-loaded DMRS is transmitted in one slot.

1la to 1lf illustrate positions where extended / additional DMRSs are transmitted for the case where the slot length is 7 or 14 OFDM symbols, respectively. 1la to 1lf illustrate Extended / Additional DMRSs for FIGS. K-1, k-2, and k-3 in which the positions of the front-loaded DMRS are set as described with reference to FIG. 1k, respectively.

Figures 1-1 and 1-2 illustrate an embodiment in which an extended / additional DMRS location is set by avoiding a location where a CRS is transmitted in an LTE system. This has the advantage of reducing the influence of interference in the LTE-NR coexistence situation. However, in the case of FIG. 1-3, as in FIG. 3, the position of the front-loaded DMRS overlaps with the position where the CRS is transmitted in the LTE system.

As shown in FIGS. 1la to 1lf, when the length of the slot is 7 OFDM symbols, the position of the extended / additional DMRS can be set to one, whereas when the length of the slot is 14 OFDM symbols, the length of the extended / additional DMRS is increased. The position needs to be set to two depending on the Doppler situation.

For example, referring to FIG. 1-1, the position of the Extended / Additional DMRS can be set as shown in FIG. 1-1-2 in a rapidly changing channel, and in an environment where the channel changes very fast, Extended / It is necessary to set the position of Additional DMRS as shown in Fig. 1-1-3. In the embodiment, FIGS. 1K and 1LA to 1lf illustrate basic positions at which DMRSs are set. If the DMRS transport layer is increased, the position at which the DMRS is transmitted may be additionally set. This will be described in more detail through a method of DMRS port multiplexing in FIG. 1O below.

In addition, in the case of Extended / Additional DMRS, an overhead problem of DMRS may occur as a plurality of DMRSs are configured on the time axis. Therefore, in this case, it is possible to reduce the overhead of the DMRS by setting the DMRS to have a low density on the frequency axis. Through the proposed unit DMRS structure, the front-load DMRS and the extended / additional DMRS described above can be operated more flexibly.

Specifically, the DMRS structure proposed by the present invention will be described with reference to FIG. 1M. The present invention proposes a Unit DMRS structure based on one OFDM symbol. As described above, the unit DMRS structure based on one OFDM symbol is not only advantageous for setting the position of the reference signal with respect to various transmission time intervals (TTIs), but also a reference signal for low latency support and Ultra-Reliable Low Latency Communication (URLLC). It is also advantageous for positioning, and may also be advantageous in terms of scalability such as antenna port expansion.

As illustrated in FIG. 1M, 12 subcarriers may be included in one OFDM symbol based on a PRB, which is a minimum transmission unit of data. As in identification numbers 3m10, 3m20, and 3m30, the density of a DMRS SC (subcarrier) in one OFDM symbol is configurable. Identification number 3m10 and identification number 3m20 indicate the DMRS structure for the case of 4 and 8 DMRS SCs in 12 subcarriers, respectively, and identification number 3m30 indicates the DMRS structure for the case where DMRS SC consists of all 12 subcarriers. Indicates.

Comprising an even number of DMRS SCs in identification numbers 3m10 and 3m20 may have an advantage that orphan RE does not occur when SFBC (Space Frequency Block Coding) is considered as a transmit diversity technique. For example, when the SFBC is transmitted to two antenna ports, and there is no RE for which DMRS is transmitted in frequency, a single RE (orphan RE) may not be used.

SCs not used as DMRS SCs in identification numbers 3m10 and 3m20 may be mapped to data or other reference signals, or may be emptied for DMRS power boosting. Here, emptying the SC that is not used as the DMRS SC for DMRS power boosting may be used as a method of improving the performance of the DMRS channel estimation in a low signal to noise ratio (SNR) region. The DMRS structure of FIG. 1M can be used for other channels (eg, control channels) as well as data channels.

Some of the subcarriers that are not DMRS-transmitted in the identification numbers 3m10 and 3m20 may be used as direct current (DC) subcarriers. However, in the case of the identification number 3m30, since the DMRS is transmitted in all subcarriers, some of the IDs need to be empty to transmit the DC.

In addition, the DMRS structure of identification number 3m10 may be replaced with the structure of identification number 3m40 in consideration of the DC subcarrier. The DMRS SC illustrated in FIGS. 3M10 to 3M40 may be generated based on a pseudo-random (PN) sequence or may be generated based on a Zadoff-Chu (ZC) sequence. DMRS structures of identification numbers 3m10 (or 3m40) and 3m20, which are examples of more specific application methods, may be used in the CP-OFDM system.

And it can be set and used at the same time-frequency position in the up / down link. If the uplink / downlink has the same DMRS structure, the interference cancellation capability can be improved because the uplink / downlink DMRS port becomes orthogonal, which makes channel estimation better than in a TDD-like environment.

On the contrary, the DMRS structure of ID 3m30 is based on the ZC (Zadoff-Chu) sequence similarly to LTE and can be used in the DFT-s-OFDM system in the uplink. Similar to LTE, this could enable operation for a low peak-to-average power ratio (PAPR). However, the present invention is not limited to the method of utilizing the DMRS structure shown in FIGS. 3m10 to 3m40. For example, a DMRS structure of ID 3m30 may be used for both CP-OFDM / DFT-s-OFDM and uplink / downlink.

In FIG. 1N, an antenna port is mapped to a Unit DMRS structure proposed in FIG. 1M. In FIG. 1N, the antenna ports are represented by p = A, B, C, and D for convenience. Note, however, that the antenna port number can be represented by a different number. In addition, the mapping of the antenna port is to support a plurality of layer transmission and rank. Therefore, the antenna port matching described below may be replaced with the term layer transmission or rank support.

Specifically, identification number 3n10 and identification number 3n20 show a case where two antenna ports are mapped to a DMRS structure of identification number 3m10. Identification number 3n10 illustrates how two antenna ports p = A and B are mapped to frequency division multiplexing (FDM) / code division multiplexing (CDM) by applying an orthogonal cover code (OCC) of length 2. In addition, the identification number 3n20 shows how the antenna ports p = A, B are mapped in the FDM scheme without applying the OCC. As will be described later, 3n40 and 3n60 also show an example of mapping antenna ports by applying the FDD scheme without applying the OCC like 3n20.

Next, the identification number 3n30 and the identification number 3n40 show a case where two antenna ports are mapped to the DMRS structure of the identification number 3m20. DMRS of identification number 3m20 can improve the channel estimation performance by increasing the density of the reference signal compared to identification number 3m10. Identification number 3n30 shows how two antenna ports p = A, B are mapped to FDM / CDM by applying an OCC of length 2, and identification number 3n40 maps p = A, B by FDM without applying OCC Shows how.

Next, an identification number 3n50 and an identification number 3n60 show a case where four antenna ports are mapped to a DMRS structure having an identification number 3m20. In particular, in the case of supporting four antenna ports, in order to improve the channel estimation performance, the DMRS structure of the identification number 3m20 may be used for the purpose of DMRS power boosting by emptying the subcarrier in which the DMRS is not transmitted. Identification number 3n50 shows how four antenna ports p = A, B, C, and D are mapped to FDM / CDM by applying OCC and FDM of length 2, and identification number 3n60 uses p as an FDM method without applying OCC. Illustrates how = A, B, C, and D are mapped.

The application of the OCC on the frequency in the identification numbers 3n10, 3n30, 3n50 has the advantage that the power imbalance problem does not occur. In case of LTE system, when the OCC is applied in time, power imbalance problem occurs, and there is a restriction that OCC is different in every PRB within two PRBs.

Finally, the identification number 3n70 illustrates the DMRS structure of identification number 3m30, and since the identification number 3m30 uses all 12 subcarriers as DMRS, the method of supporting orthogonal DMRS antenna ports using ZC (Zadoff-Chu) should be considered. Can be. At this time, as in LTE, subcarrier spacing may be assumed to be 15 kHz, and eight cyclic shift (CS) fields may be applied to support up to eight orthogonal antenna ports. Another way to utilize the 3m30 DMRS architecture is to FDM four subcarrier intervals to support four orthogonal antenna ports.

In the present invention, the method is not limited to the method of mapping the antenna port to the DMRS structure proposed in FIGS. 3n10 to 3n70. For example, in the case of the identification number 3m30, as shown in FIG. 3n80, the DMRS SC may be FDM and support up to eight orthogonal antenna ports by applying four Cyclic Shift fields. The operating method of FIG. 3N80 uses all subcarriers in one OFDM symbol when supporting a high rank, but uses only some subcarriers in one OFDM symbol as reference signals in a low rank environment. Has the advantage of being available for data transmission. For example, in the case of transmission of rank 4 or less in FIG. 3N80, orthogonality may be supported by four CSs using only reference signals of odd subcarriers, and six remaining even subcarriers may be used as data transmission.

FIG. 1O illustrates a method in which a larger number of antenna ports are mapped to the proposed Unit DMRS structure than in FIG. 1M. For more antenna port mapping than in FIG. 1N, additional TDM, FDM, and CDM may be configured in a unit DMRS structure.

First, referring to FIG. 3m20, as shown in FIG. 3o10, FIG. 3m20 may be TDM in time to map up to eight antenna ports. 3o20 illustrates a case where up to 16 antenna port mapping extensions are possible by TDM using three OFDM symbols in time. When the orthogonal antenna port is extended by using TDM, the RS density on the frequency is maintained as it is, but the DMRS density is increased in the transmission unit. In order to keep the DMRS density low in the transmission unit, the higher rank is extended to orthogonal antenna ports by using FDM or CDM, considering that the channel conditions are very good and that the channel selectivity on the frequency is low. You can consider how.

As shown in FIG. 3O30, FIG. 3M20 is FDM in frequency and shows a method of mapping up to eight antenna ports. In addition, as shown in FIG. 3O40, the maximum 8 antenna ports may be mapped by applying the OCC length 8 to FIG. 3m20.

Next, when all subcarriers are configured as DMRS SC as shown in FIG. 3m30, various antenna ports may be extended according to the antenna port mapping method applied to FIG. 3m30. If the subcarrier spacing is assumed to be 15 kHz in FIG. 3m30 to support eight orthogonal antenna ports by CS ZC sequence, 16 orthogonal antenna ports can be extended by applying TDM as shown in FIG. 3o10.

If FDM is used in four subcarrier intervals in FIG. 3m30, up to four orthogonal antenna ports can be supported. However, if FDM is used in eight subcarrier intervals as shown in FIG. 3o30, up to eight orthogonal antenna ports can be supported. Support is available.

The present invention is not limited to the antenna port extension method shown in FIG. The combination of TDM, FDM, and CDM can be applied, and it is possible to extend the orthogonal antenna port in various ways. For example, as described above, when the number of antenna ports is extended using only TDM as in FIG. 3O10 or FIG. 3O20, a DMRS density increases in a transmission unit. As a method for compensating for the above disadvantages, a TDM based on two consecutive slots as shown in FIG. 3O50 or an OCC length 4 CDM based on two consecutive slots as shown in FIG. 3O60 may be applied.

Although FIGS. 3O50 and 3O60 have been described based on two slots, the time units to which TDM or CDM are applied in FIGS. 3O50 and 3O60 are not limited to slots. In addition, unlike the method of mapping the maximum 8 antenna ports by applying the OCC length 8 as shown in Fig. 3o40, if DMRS is generated in the ZC sequence, it is necessary to support additional antenna ports using CS as shown in Fig. 3o70. It is possible. When using CS instead of OCC as in Figure 3o70 has the advantage that the RS density on the frequency is maintained as it is.

[Example 1-2]

Embodiment 1-2 describes a method in which a base station sets a DMRS structure suitable for a transmission environment among a plurality of DMRS structures. When a plurality of DMRS structures are supported as in the first-first embodiment of the present invention and a DMRS structure suitable for the transmission environment can be set as in the first-second embodiment, the base station changes the DMRS structure according to the transmission environment. By setting this, the overhead of the reference signal can be optimized.

More specifically, in a low SNR or high-speed transmission environment, it is necessary to set a DMRS structure with a high overhead of the reference signal to improve channel estimation performance. On the contrary, in a high SNR or low-speed transmission environment, it is necessary to set a DMRS structure with a low overhead of the reference signal to improve transmission efficiency. As such, when the reference signal is adaptively transmitted to the transmission environment, the overhead of unnecessary reference signals can be minimized to maximize the performance of the system.

The following describes in more detail how the base station configures a DMRS structure suitable for a transmission environment. The DMRS structure configuration suitable for the transmission environment of the base station proposed by the present invention may be set semi-statically or dynamically. In addition, a DMRS structure suitable for a transmission environment may be set implicitly.

First, a method of semi-statically setting a DMRS structure suitable for a transmission environment will be described. The simplest way to set the DMRS structure semi-statically is to set the structure of the DMRS through higher layer signaling.

More specifically, as shown in Table 1-3 below, DMRS-StructureId may be set in RRC to signal information about different DMRS structures. In Table 1-3, maxDMRS-Structure represents the number of DMRS structures that can be set, and each set value can represent a different DMRS structure. As such, the DMRS structure may be semi-statically configured through the RRC, and the terminal according to an embodiment of the present invention may determine the structure of the currently transmitted DMRS based on the value set in the RRC.

Table 1-3

For example, referring to the embodiment 1-1-1, the DMRS structure may be divided into two structures, a front-loaded DMRS and an extended / additional DMRS. In this case, the value of maxDMRS-Structure may be set to 1 in [Table 1-3]. For example, if the value of maxDMRS-Structure is 0, it may indicate a front-loaded DMRS, and if the value of maxDMRS-Structure is 1, it may be set to indicate Extended / Additional DMRS. In Table 1-3, DMRS-sturctureID may be changed to DMRS-configureID or another term.

As another example, when there is more than one structure of Extended / Additional DMRS, the value of maxDMRS-Structure may increase to 1 or more. In addition, when adjusting the DMRS density in frequency in the unit DMRS structure as described in the embodiment 1-1-1, the maxDMRS-Structure value may be set to a larger value.

As another example, in contrast to setting the front-loaded DMRS and the extended / additional DMRS, the time / frequency density of the DMRS may be set through an additional configuration. More specifically, it may be set by a method such as [Table 1-4].

Table 1-4

As another example, a method of dynamically configuring a DMRS structure suitable for a transmission environment will be described. If the DMRS information is set in the MAC CE in a manner similar to the method of setting the DMRS information in the RRC, the information on the DMRS structure can be set more dynamically.

As another example, the simplest method of dynamically configuring a DMRS structure is to transmit information about a DMRS structure in a DCI. In this case, a DCI format to which a field for dynamically operating a DMRS structure is not applied may be defined separately for a basic operation. If the DMRS structure is set using the DCI, the DMRS structure can be dynamically changed, thereby improving transmission efficiency. On the other hand, there is a disadvantage that DCI overhead occurs to operate it.

Hereinafter, a method of setting a DMRS structure using DCI will be described in more detail. As the structure of the various reference signals is supported, the number of bits required for signaling the structures of the various reference signals will increase in DCI, but in general, 1-2 bits as shown in [Table 1-5] or [Table 1-6] below. Information on the structure of the DMRS may be included in the DCI field by using. For example, [Table 1-5] shows an example of operating two structures of a reference signal using 1 bit.

Table 1-5

As another example, [Table 1-6] shows an example of operating four types of reference signal structures using 2 bits. The low density2 field of Table 1-6 may be set to a field not to transmit DMRS as necessary. The use thereof will be described in the first to third embodiments. As described in Example 1-1, the DMRS structure may be determined by a combination of the signaling of [Table 1-5] or [Table 1-6] and the number of used DMRS transmission layers.

Table 1-6

In addition, unlike the method of signaling RS density using [Table 1-5] or [Table 1-6] as described above as a method of transmitting information about a DMRS structure in DCI, the embodiment described in Example 1-1 As described above, a time location at which a DMRS can be transmitted may be specifically signaled.

In the embodiment 1-1, the method of setting the position in time at which the DMRS can be transmitted is set based on the subframe and the starting point of the allocated data channel (ex, PDSCH). A method of setting is proposed. At this time, it is possible to signal information about the position in time when the DMRS is transmitted to the DCI.

For example, if the time position at which the DMRS is transmitted is set based on a subframe, when the value representing the subframe duration is defined as x, the position of the DMRS is set in units of y = x / 2. You can consider. In this case, it is possible to indicate whether the DMRS density is high or low in y units using only 1 to 2 bits.

More specifically, the DMRS density low on the time axis may be a DMRS composed of one OFDM symbol, and the DMRS density high on the time axis may be a DMRS composed of two OFDM symbols. In addition, the DMRS structure may be determined by a combination of the number of DMRS transmission layers used together. For a detailed example thereof, see Example 1-1 described above.

On the other hand, since it may be inefficient to include a field indicating the DMRS structure in the DCI at every transmission, the field indicating the DMRS structure may be transmitted through the DCI based on a preset time interval. You may want to consider. However, in this case, since the structure of the reference signal can be changed only when the field indicating the DMRS structure is transmitted, it may be difficult to operate the DMRS structure more dynamically than the method of indicating the DMRS structure every transmission.

Finally, another example of how the base station implicitly configures a DMRS structure suitable for a transmission environment will be described. The first method is to set different DMRS structures according to transmission mode (TM).

More specifically, TM A may be set as a reference signal having a high density, TM B may be set as a reference signal having an average density on the time axis, and TM C may be set as a reference signal having a low density on the time axis. In this case, TM A may be configured as TM to support high mobility and TM C may be configured as TM for low latency support.

Another method is to define two DCI formats in one TM. One of the two formats is set to the structure of the reference signal for transmitting the characteristics of the TM, the other is a reference signal having a high density by operating in the fallback mode (fallback mode) similar to DCI format 1A in LTE It can be set to. In this case, the UE may determine which DMRS structure is applied from the currently set TM mode or DCI format information.

The second method is to change the structure of the reference signal applied according to the modulation and coding scheme (MCS). More specifically, in a region where a low MCS is set, a reference signal having a high density may be mapped to improve channel estimation performance, and a reference signal having a low density may be mapped in a region where a high MCS is set. In this case, the terminal may implicitly know the structure of the reference signal transmitted from the received MCS information.

The third method is a method in which different DMRS structures are set according to the frame structure. More specifically, the self-contained frame structure is set to one OFDM symbol in time forward as in FIG. 1fa-2-1 / FIG. 1fa-2-2, and in the general frame structure, FIG. 1fa-3-1 / FIG. 1fa. As in -3-2, it can be assumed that the DMRS is set to two OFDM symbols in time.

As another configuration method, when the PDCCH in the common search space is identified based on the LTE system, the structure of the reference signal for the PDSCH connected thereto may be mapped to have a high density. Similarly, when identifying a PDCCH in a UE-specific search space, the reference signal for the PDSCH connected thereto may be mapped to a reference signal having a lower density than the PDCCH connected to the common search space. have. This is to improve channel estimation performance for the common search space because it contains important information that all terminals should see. In this case, the UE can know the structure of the reference signal implicitly from the search space.

[Example 1-3]

Unlike the existing LTE system, in the case of the present embodiment 1-3, when multiple DMRS structures are supported, multiple-user transmissions using different DMRS structures may be supported and each of the UEs MU transmitted may be supported. We propose a method by which DMRSs maintain orthogonality with each other. In the 5G system, the UEs performing MU transmission may use a specific reference signal structure so that the problem does not occur. However, in this case, the flexibility of MU transmission may be limited. Accordingly, two methods for maintaining orthogonality between terminals that are MUs when MUs are transmitted between terminals using different DMRS structures are proposed.

The first method is rate matching for overlapping parts to maintain orthogonality when different DMRS structures overlap. This method is described in detail with reference to FIG. 1H. 1H-1 and 1H-2 illustrate a method in which a base station performs rate matching on a region A portion of FIG. 1H-1 when a UE using different DMRS structures is MU-transmitted. .

This method has a disadvantage in that the base station additionally signals information on rate matching to the terminal. In this case, the number of bits required for signaling may differ depending on the number of supported DMRS structures. Basically, if a plurality of DMRS structures are supported, the number of signaling bits required to inform the DMRS structure of another UE to be MU is increased. However, as described in [Table 1-4] and [Table 1-5] of the embodiment 1-2, when the DMRS structure is simplified and operated in 2-4 types, other MUs are transmitted to the terminal through 1-2 bits of signaling. It can inform the DMRS structure of the terminal. At the same time, there is an advantage that power boosting can be performed for the reference signal of this part in consideration of rate matching between different terminals in the reference signal region where different DMRS structures overlap. However, this method, unlike the LTE system, the MU operation is no longer transparent to the UE.

The second method is a method of transmitting an additional reference signal in a reference signal region where the DMRS structures overlap to maintain orthogonality when different DMRS structures overlap. In other words, the second method is to set and transmit the same DMRS structure.

In detail, this method will be described with reference to FIG. 1H when a UE using different DMRS structures of FIGS. 1H-1 and 1H-2 is MU-transmitted. The base station includes a reference signal in the area A of FIG. 1H-1. Send it. In this case, it means that the base station using the DMRS structure of FIG. 1H-1 transmits using the DMRS structure of FIG. 1H-2. When using this method, unlike the first method, there is an advantage that additional signaling is not required for the UE using FIG. 1H-1.

Meanwhile, whether the UE additionally uses the reference signal included in the region A based on FIG. 1H-1 for channel estimation may vary depending on implementation. If the terminal using FIG. 1H-1 is a terminal requiring low latency, for fast signal processing, the reference signal for the area A portion may not be used. In this case, however, additional signaling may be required to indicate this. For example, the base station transmits information on ACK / NACK timing through the DCI to the terminal, so that the terminal estimates whether to use the channel reference signal for the area A based on FIG. 1H-1. You can decide.

1H-3, 1H-4, and 1H-5 illustrate a method of changing the DMRS density when a variable TTI (Transmission Time Interval) is applied. In addition, the present invention proposes a method for maintaining the orthogonality of the DMRS of the UEs to be MU with each other.

More specifically, FIG. 1H-3 illustrates a case where a plurality of TTIs are combined and transmitted. In this case, it may be assumed that the same precoding is applied to the DMRS while multiple TTIs are transmitted. In particular, when the TTI duration is short, transmitting the DMRS with the same density on the frequency may be inefficient in terms of overhead of the reference signal as shown in FIGS. 1H-3. Therefore, an example of changing the DMRS density in FIGS. 1H-4 and 1H-5 is shown as a method of reducing the overhead of the reference signal.

First, a method of setting a DMRS for reducing overhead of a reference signal in TTI-1 and TTI-2 of FIGS. 1H-4 is possible. In another method, there may be a method of not transmitting DMRS in TTI-2 as shown in FIG. 1H-5. As described above, when the TI transmission is performed in the TTI in which the DMRS density is changed, a situation may occur in which orthogonality is not maintained because different terminals use different DMRS structures. In this case, as described above, both methods for maintaining orthogonality may be applied when different DMRS structures overlap.

More specifically, when applying a method for rate matching, the base station uses the DCI to signal information about rate matching before every TTI to the terminal. In contrast, in the case of applying the second method, for example, when MU transmission is performed in TTI-2 of FIGS. 1H-4 and 1H-5, the base station is configured to different terminals in TTI-2 without additional signaling. The same DMRS structure can be set and transmitted. For example, the DMRS structure in TTI-1 may be transmitted in TTI-2.

In addition, a method for efficiently performing MU support between terminals using different OCC lengths is proposed. For example, the case where the terminals using the OCC of length 2 and the OCC of length 4 are transmitted to MU is demonstrated. For example, when 2-layer transmission is performed using an OCC of length 4 based on [Table 1-2], 2-layer transmission is performed through ports 7 and 11, or 2-layer transmission is performed through ports 8 and 13. Can be. This enables more orthogonal MU pairing compared to the 2-layer transmission using ports 7 and 8 or the 2-layer transmission through ports 11 and 13.

As described above, the numbering from port 7 to port 14 is based on the LTE system in [Table 1-2], but this is an example for explanation. For example, the port numbers used in 5G systems may be different. Therefore, the proposed method can be applied based on the sequence of OCC corresponding to each port in [Table 1-2].

In order to carry out the above embodiments of the present invention, a transmitter, a receiver, and a processor of the terminal and the base station are shown in FIGS. 1I and 1J, respectively. In order to configure and provide a method for setting the base station, there is shown a method of transmitting and receiving a base station and a terminal, and in order to perform this, the receiving unit, the processing unit, and the transmitting unit of the base station and the terminal should operate according to the embodiments.

Specifically, FIG. 1I is a block diagram illustrating an internal structure of a terminal according to an embodiment of the present invention. As shown in FIG. 1H, the terminal of the present invention may include a terminal receiver 1800, a terminal transmitter 1804, and a terminal processor 1802. The terminal receiver 1800 and the terminal may collectively be referred to as a transmitter / receiver in the embodiment of the present invention.

The transceiver of the terminal may transmit and receive signals with the base station. The signal may include control information and data. To this end, the transmitting and receiving unit of the terminal may be composed of an RF (Radio Frequency) transmitter for up-converting and amplifying the frequency of the transmitted signal, and an RF receiver for low noise amplifying the received signal and down-converting the frequency of the received signal. Also, the transceiver of the terminal may receive a signal through a wireless channel, output the signal to the terminal processor 1802, and transmit a signal output from the terminal processor 1802 through the wireless channel.

The terminal processor 1802 may control a series of processes to operate the terminal according to the above-described embodiment of the present invention. For example, when the terminal receiver 1800 receives a reference signal from the base station, the terminal processor 1802 may control to interpret a method of applying the reference signal. The terminal transmitter 1804 can also transmit the reference signal in this manner.

1J is a block diagram showing the internal structure of a base station according to an embodiment of the present invention. As shown in FIG. 1I, the base station of the present invention may include a base station receiving unit 1901, a base station transmitting unit 1905, and a base station processing unit 1901. The base station receiver 1901 and the base station transmitter 1905 may be collectively referred to as a transmitter / receiver.

The transceiver of the base station may transmit and receive signals with the terminal. The signal may include control information and data. To this end, the transceiver unit of the base station may be configured with an RF transmitter for up-converting and amplifying the frequency of the transmitted signal, and an RF receiver for low-noise amplifying and down-converting the received signal.

In addition, the transceiver unit of the base station may receive a signal through a wireless channel and output the signal to the base station processing unit 1901, and transmit the signal output from the base station processing unit 1901 through the wireless channel. The base station processing unit 1903 may control a series of processes to operate the base station according to the embodiment of the present invention described above. For example, the base station processor 1903 may determine the structure of the reference signal and control to generate configuration information of the reference signal to be transmitted to the terminal. Thereafter, the reference signal and the configuration information are transmitted to the terminal using the base station transmitter 1905, and the base station receiver 1901 may receive the reference signal.

In addition, according to an embodiment of the present invention, the base station processing unit 1901 may control a process for supporting MU transmission orthogonally between terminals using different DMRS structures. In addition, the information necessary for the control may be transmitted to the terminal using the base station transmitter 1905.

On the other hand, the embodiments of the present invention disclosed in the specification and drawings are merely presented specific examples to easily explain the technical contents of the present invention and help the understanding of the present invention, and are not intended to limit the scope of the present invention. That is, it will be apparent to those skilled in the art that other modifications based on the technical idea of the present invention can be implemented. In addition, each of the above embodiments can be combined with each other if necessary to operate. For example, a portion of the embodiments 1-1, 1-2, and 1-3 of the present invention may be combined with each other to operate the base station and the terminal. In addition, although the above embodiments are presented based on the FDD LTE system, other modifications based on the technical spirit of the above embodiment may be implemented in other systems such as a TDD LTE system, a 5G, or an NR system.

Second Embodiment

In order to estimate a channel in a wireless communication system, a base station must transmit a reference signal for this. The terminal may perform channel estimation using the reference signal and demodulate the received signal. In addition, the terminal may be used to determine the channel state through the reference signal and feed it back to the base station. In general, when transmitting a reference signal, the transmission interval of the reference signal is determined based on the frequency and time of the reference signal in consideration of the maximum delay spread and the maximum Doppler spread of the channel. As the transmission interval of the reference signal is narrower, the channel estimation performance can be improved to improve the demodulation performance of the signal. However, this results in an increase in overhead of the reference signal, thereby limiting the data rate.

In the 4G LTE system operating in the frequency band of 2 GHz, reference signals such as a cell-specific reference signal (CRS) and a demodulation reference signal (DMRS) are used in downlink. When the interval of the reference signal in frequency is expressed as the subcarrier interval m of the Orthogonal Frequency Division Multiplexing (OFDM) signal, and the interval of the reference signal in time is represented by the symbol interval n of the OFDM signal, normal cyclic prefix (normal Cyclic Prefix); In case of CRS assuming normal CP), the transmission interval based on the frequency and time of the reference signal corresponding to antenna ports 1 and 2 is (m, n) = (3,4). In case of DMRS assuming normal CP, the transmission interval based on the frequency and time of the reference signal is (m, n) = (5,7).

Unlike LTE systems, 5G wireless communication considers a system that operates in the high frequency band as well as the frequency band of 6GHz or less. Since the channel characteristics vary depending on the frequency band, it is necessary to design a reference signal newly in consideration of 5G systems. In 5G wireless communication, low latency support and high mobility support are important considerations. In addition, in 5G systems, it is important to minimize the overhead of the reference signal.

In a wireless communication system, a base station must transmit a reference signal to a terminal in order to measure a downlink channel state. In the Long Term Evolution Advanced (LTE-A) system of 3GPP, the terminal uses the CRS or Channel Status Information Reference Signal (CSI-RS) transmitted by the base station to determine the channel state between the base station and the terminal. Measure

Several factors must be considered for the channel state. For example, the amount of interference in downlink may be considered. The amount of interference in the downlink includes interference signals and thermal noise generated by antennas included in each of the adjacent base stations, and plays an important role in determining the channel state of the downlink.

For example, when one transmission antenna included in one base station transmits a signal to one reception antenna included in one terminal, the terminal uses a reference signal received from the base station, per symbol that can be received through downlink. After determining the energy and the amount of interference to be received with the symbol during the period of receiving the symbol, Es / Io should be determined. The determined Es / Io is converted into a data transmission rate or a corresponding value and notified to the base station in the form of a channel quality indicator (CQI), so that the base station transmits data to the terminal at downlink at what transmission rate. Make judgment.

In the LTE-A system, the terminal feeds back information on the channel state of the downlink to the base station so that the base station can utilize the downlink scheduling. That is, the terminal measures the channel state using the reference signal transmitted by the base station through the downlink, and feeds back the measured channel state information to the base station in the form defined in the LTE / LTE-A standard.

There are three channel state information (CSI) fed back by the UE in LTE / LTE-A.

Rank indicator (RI): the number of spatial layers that the terminal can receive in the current channel state

Precoder Matrix Indicator (PMI): Indicator for the precoding matrix preferred by the UE in the current channel state.

Channel Quality Indicator (CQI): The maximum data rate that the terminal can receive in the current channel state. CQI may be replaced with SINR, maximum error correction code rate and modulation scheme, and data efficiency per frequency, which may be utilized similarly to the maximum data rate.

The RI, PMI, and CQI are associated with each other and have meanings. For example, the precoding matrix supported by LTE / LTE-A is defined differently for each rank. Therefore, the PMI value when the RI has a value of 1 and the PMI value when the RI has a value of 2 are interpreted differently even if the values are the same.

In addition, the UE determines the CQI on the assumption that the rank value and the PMI value informed by the UE of the base station are applied by the base station. For example, when the terminal informs the base station of RI_X, PMI_Y, and CQI_Z, when the rank is RI_X and the precoding is PMI_Y, it means that the terminal may receive data according to the data rate corresponding to CQI_Z. As such, the UE assumes a transmission method to the base station when calculating the CQI, so that the base station can obtain optimized performance when the base station actually transmits the transmission method.

In LTE / LTE-A, the periodic feedback of the UE is set to one of the following feedback modes or reporting modes depending on what information is included:

1.Reporting mode 1-0: RI, wideband CQI (wCQI)

2.Reporting mode 1-1: RI, wCQI, PMI

3.Reporting mode 2-0: RI, wCQI, subband CQI (sCQI)

4.Reporting mode 2-1: RI, wCQI, sCQI, PMI

서브프레임이며, 오프셋은 N_OFFSET,CQI + N_OFFSET,RI이다.The feedback timing of each information for the four feedback modes is determined by values of N _pd , N _{OFFSET, CQI} , M _RI , and N _{OFFSET, RI,} etc., which are transmitted as a higher layer signal. In feedback mode 1-0, the transmission period of wCQI is N _pd It is a subframe, and the feedback timing is determined with subframe offset values of N _{OFFSET and CQI} . In addition, the transmission period of RI is

Subframe, offset is N _{OFFSET, CQI} + N _{OFFSET, RI} .

2A is a diagram showing feedback timings of RI and wCQI in the case of N _pd = 2, M _RI = 2, N _{OFFSET, CQI} = 1, and N _{OFFSET, RI} = -1. In FIG. 2A, each timing represents a subframe index.

Feedback mode 1-1 has the same feedback timing as mode 1-0, but the difference that wCQI and PMI are transmitted together in wCQI transmission timing for any one of one antenna port, two antenna ports, or four antenna ports. Has

서브프레임이며, 오프셋 값은 sCQI의 오프셋 값과 같이 N_OFFSET,CQI이다. 여기서,

로 정의되는데 K는 상위신호로 전달되며, J는 시스템 대역폭(bandwidth)에 따라 결정되는 값이다. 예를 들어, 10MHz 시스템에 대한 J 값은 3으로 정의된다. 결국, wCQI는 H번의 sCQI 전송마다 한번씩 이에 대체하여 전송된다. 그리고 RI의 주기는

서브프레임이며 오프셋은 N_OFFSET,CQI + N_OFFSET,RI이다. In feedback mode 2-0, the feedback period for sCQI is N _pd It is a subframe, and the offset values are N _{OFFSET and CQI} . And the feedback period for wCQI

It is a subframe, and the offset value is N _{OFFSET and CQI} like the offset value of sCQI. here,

K is transmitted as an upper signal, and J is a value determined according to a system bandwidth. For example, the J value for a 10 MHz system is defined as 3. As a result, wCQI is alternately transmitted once every H sCQI transmissions. And the cycle of RI

Subframe with offset N _{OFFSET, CQI} + N _{OFFSET, RI} .

Figure 2b shows the RI, sCQI, wCQI feedback timings for the case of N _pd = 2, M _RI = 2, J = 3 (10 MHz), K = 1, N _{OFFSET, CQI} = 1, N _{OFFSET, RI} = -1. It is a figure which shows. Feedback mode 2-1 has the same feedback timing as mode 2-0, but for the situation of one antenna port, two antenna ports or four antenna ports, the difference is that the PMI is transmitted together in the wCQI transmission timing. Have

The feedback timing described above is a case in which the number of CSI-RS antenna ports is one, two, or four. As another example, the CSI-RS for any one of four antenna ports or eight antenna ports may be used. In case of the allocated UE, two kinds of PMI information are fed back differently from the feedback timing. In this case, that is, when the UE is assigned CSI-RS for any one of four antenna ports or eight antenna ports, feedback mode 1-1 may be divided into two submodes.

와 N_OFFSET,CQI + N_OFFSET,RI로 정의된다. For example, in the first submode, the RI is transmitted with the first PMI information and the second PMI information with the wCQI. Here, the period and offset of the feedback for wCQI and the second PMI are defined as N _pd , N _{OFFSET, CQI} , and the feedback period and offset values for RI and the first PMI information are respectively.

And N _{OFFSET, CQI} + N is defined as _{OFFSET, RI} .

When both the first PMI (i1) and the second PMI (i2) are reported from the terminal to the base station, the terminal and the base station correspond to the combination of the first PMI and the second PMI in a set of precoding matrices shared by each other. The precoding matrix W (i1, i2) is identified as a precoding matrix preferred by the terminal.

In other words, when the precoding matrix corresponding to the first PMI is called W1 and the precoding matrix corresponding to the second PMI is called W2, the UE and the BS determine that W1W2, which is the product of the two preferred matrixes, is determined by W1W2. Share the information.

서브프레임이며 오프셋은 N_OFFSET,CQI + N_OFFSET,RI로 정의된다. When the feedback mode for the eight CSI-RS antenna ports is 2-1, precoding type indicator (PTI) information is added to the feedback information. At this time, the PTI is fed back with the RI and the period is

Subframe with offset N _{OFFSET, CQI} + N is defined as _{OFFSET, RI} .

이며 오프셋은 N_OFFSET,CQI이다. 여기서 H'은 상위신호로 전달된다. In detail, when the PTI is 0, the first PMI, the second PMI, and the wCQI are all fed back. At this time, wCQI and the second PMI are transmitted together at the same timing, the period is N _pd and the offset is given as N _{OFFSET, CQI} . The cycle of the first PMI

Offset is N _{OFFSET, CQI} . Where H 'is transmitted as a higher signal.

의 주기와 N_OFFSET,CQI의 오프셋을 가지고 피드백되며 H는 CSI-RS 안테나 포트 개수가 2인 경우와 같이 정의된다. On the other hand, if the PTI is 1, wCQI is transmitted with the wideband second PMI and sCQI is fed back with the narrowband second PMI at a separate timing. At this time, the first PMI is not transmitted, but is reported after the second PMI and the CQI are calculated assuming the first PMI most recently reported when the PTI is 0. The period and offset of PTI and RI are the same as when PTI is zero. The period of sCQI is defined as N _pd subframe, and the offset is defined as N _{OFFSET, CQI} . wCQI and the second PMI

It is fed back with the period of N _{offset and} offset of _CQI , and H is defined as if the number of CSI-RS antenna ports is two.

2C-1 and 2C-1 show N _pd = 2, M _RI = 2, J = 3 (10 MHz), K = 1, H '= 3, N _{OFFSET, CQI} = 1, N _{OFFSET, RI} = -1 Is a diagram showing feedback timing when PTI = 0 and PTI = 1, respectively.

LTE / LTE-A supports aperiodic feedback as well as periodic feedback of the terminal. When the base station wants to obtain aperiodic feedback information of a specific terminal, the base station performs specific aperiodic feedback of the aperiodic feedback indicator included in downlink control information (DCI) for uplink data scheduling of the terminal. By configuring so as to perform uplink data scheduling of the corresponding terminal.

In this case, when the UE receives an indicator configured to perform aperiodic feedback in the nth subframe, the UE performs uplink transmission by including aperiodic feedback information in data transmission in the n + kth subframe. Here, k is a parameter defined in the 3GPP LTE Release 11 standard and is 4 in frequency division duplexing (FDD) and is defined in Table 2-1 in time division duplexing (TDD). [Table 2-1] shows k values for each subframe number n in the TDD UL / DL configuration.

TABLE 2-1

When the aperiodic feedback is set, the feedback information includes RI, PMI, and CQI as in the case of periodic feedback, and the RI and PMI may not be fed back according to the feedback setting. In addition, the CQI may include both wCQI and sCQI or may include only wCQI information.

As described above, unlike the LTE system, 5G wireless communication considers a system that operates not only in the frequency band below 6GHz but also in the high frequency band above. In addition, 5G wireless communication is considering low latency support and high mobility support. In addition, in 5G systems, it is important to minimize the overhead of the reference signal. Therefore, in the 5G system, unlike the LTE system, a plurality of reference signals suitable for a transmission environment may be supported.

As such, when a plurality of reference signals are supported, the UE may need additional feedback information for selecting a reference signal suitable for a transmission environment as well as RI, PMI, and CQI. Accordingly, the present invention provides a method for the terminal to feed back information required for selection of the reference signal to the base station so that the adaptive transmission of the reference signal is possible.

DETAILED DESCRIPTION Hereinafter, embodiments of the present invention will be described in detail with the accompanying drawings. Hereinafter, an embodiment of the present invention will be described using an LTE or LTE-A system as an example, but the embodiment of the present invention may be applied to other communication systems having a similar technical background or channel form. For example, the fifth generation mobile communication technology (5G, new radio, NR) developed after LTE-A may be included in this. More specifically, the method for periodically or aperiodic feedback of channel information may be different from the method described in LTE. Although the present invention has been described with reference to the DMRS, it can be applied to other reference signals. Accordingly, embodiments of the present invention may be applied to other communication systems through some modifications without departing from the scope of the present invention by the judgment of those skilled in the art.

In addition, in describing the present invention, when it is determined that a detailed description of a related function or configuration may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted. Terms to be described later are terms defined in consideration of functions in the present invention, and may be changed according to intentions or customs of users or operators. Therefore, the definition should be made based on the contents throughout the specification. Hereinafter, the base station is a subject performing resource allocation of the terminal, and may be at least one of an eNode B, a Node B, a base station (BS), a wireless access unit, a base station controller, or a node on a network. The terminal may include a user equipment (UE), a mobile station (MS), a cellular phone, a smart phone, a computer, or a multimedia system capable of performing a communication function. In the present invention, downlink (DL) is a radio transmission path of a signal transmitted from a base station to a terminal, and uplink (UL) is a radio transmission path of a signal transmitted from a terminal to a base station.

Feedback information for selecting a reference signal suitable for a transmission environment described below is represented by the term PDI (Pilot density indicator). However, the term for PDI may be expressed in other terms depending on the intention of the user and the purpose of using the reference signal. For example, terms such as reference-signal density indicator (RDI), Doppler frequency indicator (DFI), delay spread indicator (DSI), or SINR indicator (SI) may be substituted. The abbreviation defined as PDI is merely for describing a technical example of the present invention and for providing a specific example to help understanding of the present invention, and is not intended to limit the scope of the present invention. That is, it is apparent to those skilled in the art that the present invention can be applied to a reference signal based on the technical idea of the present invention.

Embodiment 2-1 of the present invention to be described below describes feedback information that may be included in a PDI. Embodiment 2-2 of the present invention describes a method of feeding back a PDI. In Embodiment 2-3 of the present invention, a method of operating a base station using PDI will be described.

[Example 2-1]

Embodiment 2-1 describes information that may be included in PDI, which is feedback information proposed by the present invention. As described above, the structure of the reference signal required according to the transmission environment can be supported in a number.

More specifically, in an environment having a high degree of Doppler effect, it is necessary to increase the channel estimation performance by increasing the density of the reference signal on the transmission time axis. On the other hand, in an environment where the degree of Doppler effect is small (hereinafter, it will be used interchangeably with the term Low Doppler), it is necessary to reduce the overhead of the reference signal by lowering the density of the reference signal on the transmission time axis. In the high delay environment, it is necessary to increase the channel estimation performance by increasing the density of the reference signal on the transmission frequency axis. On the other hand, in a low delay environment, it is necessary to reduce the overhead of the reference signal by lowering the density of the reference signal on the transmission frequency axis. In addition, a low signal-to-interference plus noise ratio (SNR) environment requires a structure of a reference signal having a high density to ensure channel estimation performance, while in a high SNR environment, the reference signal overhead is reduced by reducing the density of the reference signal. Need to be reduced.

As such, the Doppler information, the channel delay information, and the SINR information that determine the structure of the reference signal are information that can be grasped by the UE through measurement. Therefore, PDI, which is feedback information proposed by the present invention, may include Doppler information, channel delay information, and SINR information. However, the information that may be included in the PDI of the present invention is not limited to the information.

The terminal may feed back the measured Doppler information, the channel delay information, and the SINR information to inform the information about the reference signal structure preferred for the channel environment. In the present invention, the PDI may include all Doppler information, channel delay information, and SINR information, or may include only some information.

More specifically, it will be described below which structure of the reference signal is appropriate depending on the situation, based on the information included in the PDI.

First, when Doppler information is included in the PDI, the UE may determine the structure of the reference signal suitable for the channel environment through Doppler frequency measurement. For example, the terminal may measure the Doppler frequency by performing correlation in time on the basis of the reference signal. As shown in Equation 1 below, when the Doppler frequency (Hz) is greater than X, it may indicate that transmission of a reference signal having a high density is required on the transmission time axis.

[Equation 1]

Doppler frequency> X

를 나타낸다. 따라서, Doppler frequency는 캐리어 주파수(carrier frequency)와 단말 속도에 영향을 받음을 알 수 있다. In Equation 1, X (Hz) represents a threshold for the Doppler frequency. The Doppler frequency may be expressed as Doppler frequency = f * v / c. Where f is the carrier frequency (Hz), v (m / s) is the terminal speed, c is the speed of light

Indicates. Therefore, it can be seen that the Doppler frequency is affected by the carrier frequency and the terminal speed.

For example, when f = 2.5 GHz and v = 350 km / h, the Doppler frequency is 810 Hz. As an example, when the Doppler frequency is higher than 800 Hz, when the high Doppler environment is considered, the threshold X for the Doppler frequency may be set to 800 Hz.

Unlike the LTE system, since the 5G system considers the terminal speed up to 500 km / h, the method of adaptively changing the structure of the reference signal in consideration of the terminal speed may be very effective. In the present invention, when the Doppler frequency is greater than X, as shown in Equation 1, a one bit indicator may be fed back to indicate that transmission of a reference signal having a high density on the time axis is required.

Next, when the channel delay information is included in the PDI, the terminal may determine the structure of the reference signal suitable for the channel environment through the channel delay measurement. For example, the terminal may measure channel delay information through various methods based on the reference signal.

For example, the UE may measure a power delay profile (PDP) by performing correlation on frequency based on a reference signal. Delay spread information such as root mean square (RMS) delay and maximum delay spread may be obtained from the PDP information. As shown in Equation 2 below, when the delay spread (sec) is greater than Y, it may indicate that a reference signal having a high density on the transmission frequency axis is required.

[Equation 2]

Delay spread> Y

In Equation 2, Y (sec) represents a threshold for delay spread. The delay spread can be an RMS delay spread or a maximum delay spread. If based on the RMS delay spread, Y is set based on the RMS delay spread value, and may be set differently based on the Maximum delay spread value.

In general, the reference signal in the existing LTE system is designed assuming a worst case for the channel delay, so in a low channel delay environment, a transmission signal may be improved by using a reference signal having a lower density in frequency. Can be.

In addition, the 5G system considers the system not only in the frequency band below 6 GHz but also in the higher frequency band, and accordingly, various subcarrier spacings are considered. Therefore, unlike the existing LTE system, the density of the reference signal in frequency is newly updated. You need to design.

In the present invention, when the delay spread is greater than Y, as shown in Equation 2, one bit indicator may be fed back to indicate that transmission of a reference signal having a high density on the frequency axis is required. However, even in 5G systems, if the reference signal is designed assuming worst case for channel delay, no additional indication of delay information may be needed.

Finally, when the channel SINR information is included in the PDI, the UE may determine the structure of the reference signal suitable for the channel environment through the SINR measurement. For example, the terminal may measure the SINR through various methods based on the received signal. As shown in Equation 3 below, when the SINR is greater than Z, the structure of the reference signal having a high density may be indicated.

[Equation 3]

SINR> Z

In Equation 3, Z represents a threshold for SNR. In general, in the low SINR region (-10 to 0 dB), it is important to maintain the system performance by improving the channel estimation performance by using a reference signal having a high density. As an example, the threshold Z = 0 dB for SINR may be set.

In the present invention, when SINR is greater than Z as in Equation 3, one bit indicator may be fed back to indicate that a reference signal having a high density is preferred. However, in Equation 3, the SINR may be replaced by the CQI index defined in Table 7.2.3-1 of 3GPP LTE standard TS.36.213, the maximum error correction code rate and modulation scheme, and the data efficiency per frequency. It may be.

If the SINR is replaced with the CQI index in [Equation 3], there is an advantage that the structure information of the implicitly preferred reference signal can be fed back implicitly through CQI feedback without using an additional bit. . According to an embodiment, when feeding back the lowest CQI index, it may indicate that a reference signal having a high density is preferred.

From the embodiment 2-1, what reference signal structure the UE prefers through the information that may be included in the PDI, which is the feedback information proposed by the present invention, and information included in the PDI, that is, what reference signal structure is present in the current situation The method of determining whether the transmission is required has been described through Equations 1 to 3 above. According to the above situation, the information necessary for the terminal to feed back to the base station may be set to 1 ~ 3bits.

However, when a plurality of threshold values are set in Equation 1 to 3 as needed, the structure of the reference signal preferred by the terminal may be further divided according to the threshold values. In this case, the number of bits of information required for the terminal to feed back to the base station may increase.

For example, as shown in Equation 4, if two thresholds X1 and X2 are set for the Doppler frequency, the structure of the reference signal preferred by the UE can be divided into three types.

[Equation 4]

Doppler frequency> X1 (4-1)

 X2 ≤ Doppler frequency ≤ X1 (4-2)

Doppler frequency <X2 (4-3)

In Equation 4, when there are three reference signals according to the density on the transmission time axis, Equation 4-1 indicates that the reference signal having the highest density is preferred on the transmission time axis, and Equation 4-2 indicates the transmission time axis. In the above example, the reference signal having a medium density is preferred, and Equation 4-3 may indicate that the reference signal having a low density is preferred on the transmission time axis. The same method can be applied to equations (2) and (3).

Example 2-2

Embodiment 2-2 describes a method for the UE to feed back a pilot density indicator (PDI), which is feedback information proposed by the present invention, to a base station. As described above, the case in which the UE feeds back the PDI together with RI, PMI, and CQI, which are channel state information fed back to the base station by LTE / LTE-A, is considered.

First, in case of using aperiodic feedback, the base station sets the aperiodic feedback indicator included in the downlink control information for uplink data scheduling of the corresponding terminal to perform PDI feedback, thereby providing PDI information to the uplink data of the corresponding terminal. Can be transmitted.

Next, consider the use of aperiodic feedback. In the case of aperiodic feedback, since the number of bits available for feedback may be limited, information necessary for feedback may be limited to 1 to 3 bits using Equations 1 to 3 of the second embodiment. The PDI feedback method proposed in the present invention may be classified as follows based on the CQI feedback of the LTE system.

1. Feedback based on wideband CQI (wCQI)

2. When fed back based on subband CQI (sCQI)

3. Feedback to wCQI and sCQI separately

Based on the assumption of FIG. 2A, FIG. 2D-1 is a diagram illustrating a case where a feedback is performed based on wCQI among the PDI feedback methods. 2D-1 shows that PDI is transmitted together whenever wCQI is fed back. In this case, a reference signal suitable for the channel state may be determined based on the entire band.

Based on the assumption of FIG. 2B, FIG. 2D-2 is a diagram illustrating a case where feedback is performed based on sCQI among the PDI feedback methods. In this case, a reference signal suitable for the channel state may be determined based on the narrow band.

Based on the assumption of FIG. 2B, FIGS. 2D-3 illustrate a case in which the PDI feedback is separately fed back to wCQI and sCQI. In this case, a reference signal suitable for the channel state of the base station may be determined based on a wideband or narrowband.

[Example 2-3]

Embodiment 2-3 describes the operation of a base station when PDI, which is feedback information proposed in the present invention, is fed back from a terminal to a base station. The base station can distinguish which environment the supportable reference signal is suitable for, as shown in [Table 2-2] or [Table 2-3] below.

[Table 2-2] shows an example of operating the structure of the reference signal in two, [Table 2-3] shows an example of the case of operating the structure of the reference signal in four. For example, when two structures of supportable reference signals are provided, it is possible to distinguish which environment each of the two reference signals is suitable for through [Table 2-2].

Table 2-2

As another example, when the structure of the supportable reference signal is four different, it is possible to distinguish which environment each reference signal is suitable for through [Table 2-3].

TABLE 2-3

More specifically, the structure of the reference signal for [Table 2-3] is shown in Figure 2e. When the transmission environment requires low latency or in a low doppler environment, it is possible to use a structure of a reference signal having a low density on the time axis as shown in FIG. 2e-1. In contrast, in a low delay environment, a structure of a reference signal having a low density on frequency can be used as shown in FIG. 2E-2. In contrast, in the high delay environment, it is possible to use the structure of the reference signal having a high density on the frequency as shown in FIG. In the high Doppler environment or the low SINR environment, it is possible to use the structure of the reference signal having a high density as shown in FIGS. 2E-4.

In other words, it is possible to interpret as follows. 2E-1 illustrates a structure of a reference signal corresponding to low latency / Low Doppler. 2E-2 illustrates a structure of a reference signal corresponding to low delay / high SINR. 2E-3 illustrates a structure of a reference signal corresponding to high delay / high SINR. 2E-4 illustrates a structure of a reference signal corresponding to High Doppler / Low SINR.

When the base station receives the PDI, which is the feedback information proposed in the present invention, from the terminal, the method of determining the structure of the reference signal suitable for the current environment is described by way of example 2-3. However, as described above, the method of determining the structure of the reference signal suitable for the transmission environment through PDI reception may vary according to the structure of the reference signal supported by the base station.

2-4 Example

In the present invention, when a plurality of reference signals are supported, a method for feeding back information on a reference signal preferred by the terminal has been proposed. Embodiment 2-4 proposes a method of setting the type or number of reference signals that can be supported to a specific terminal as UE capability when a plurality of reference signals are supported.

More specifically, the base station can inform the terminal of the type of the reference signal that can be set through the UE capability signaling, the terminal can feed back information on the reference signal preferred by the terminal within the type of the reference signal that can be set through this. . The fact that the base station informs the terminal of the type of reference signal that can be set through the UE capability signaling has an advantage in that the terminal selects the reference signal preferred by the terminal within the type of the reference signal.

For example, the type or number of configurable reference signal structures may vary depending on the slot structure. More specifically, the structure using 14 symbols as one slot and the structure using 7 symbols as one slot may use different types of reference signals. In the structure of the mini slot, the structure and type of the reference signal different from the above slot structure can be used.

In addition, in the terminal side, the type of reference signals that can be used may be limited according to the terminal implementation. Specifically, since a specific terminal has a limited method of implementing channel estimation for a reference signal, all reference signal structures may not be supported.

Accordingly, as in the proposed method, the base station informs the terminal of the types of reference signals that can be set through the UE capability signaling, and the method of selecting the reference signals preferred by the terminal within the types of the available reference signals may include various reference signals. Required in a supported environment. In this case, the UE capability signaling may be configured in RRC (Radio Resource Control) signaling, which is a higher layer signal.

In order to carry out the above embodiments of the present invention, a transmitter, a receiver, and a processor of the terminal and the base station are illustrated in FIGS. 2F and 2G, respectively. In order to perform an operation of transmitting and receiving PDI (Pilot Density Indicator), which is feedback information proposed by the present invention, from the embodiment 2-1 to the embodiment 2-3, a method of transmitting and receiving a base station and a terminal is shown. The receiver, the processor, and the transmitter of the base station and the terminal should operate according to the embodiment.

Specifically, FIG. 2F is a block diagram illustrating an internal structure of a terminal according to an embodiment of the present invention. As shown in FIG. 2F, the terminal of the present invention may include a terminal receiver 1800, a terminal transmitter 1804, and a terminal processor 1802.

The terminal receiver 1800 and the terminal transmitter 1804 may be collectively referred to as a transmitter / receiver in an embodiment of the present invention. The transceiver of the terminal may transmit and receive signals with the base station. The signal may include control information and data. To this end, the transmitting and receiving unit of the terminal may be composed of an RF (Radio Frequency) transmitter for up-converting and amplifying the frequency of the transmitted signal, and an RF receiver for low noise amplifying the received signal and down-converting the frequency of the received signal.

Also, the transceiver of the terminal may receive a signal through a wireless channel, output the signal to the terminal processor 1802, and transmit a signal output from the terminal processor 1802 through the wireless channel.

The terminal processor 1802 may control a series of processes to operate the terminal according to the above-described embodiment of the present invention. For example, the terminal processor 1802 measures and interprets information that may be included in the PDI. In addition, the terminal processing unit 1802 may control the terminal transmitter 1804 to transmit the PDI information to the base station. In addition, according to an embodiment of the present invention, the terminal processing unit 1802 may determine and control the transmission timing of the PDI periodically or aperiodically.

2G is a block diagram illustrating an internal structure of a base station according to an embodiment of the present invention. As shown in FIG. 2G, the base station of the present invention may include a base station receiving unit 1901, a base station transmitting unit 1905, and a base station processing unit 1901. The base station receiver 1901 and the base station transmitter 1905 may be collectively referred to as a transmitter / receiver.

The transceiver of the base station may transmit and receive signals with the terminal. The signal may include control information and data. To this end, the transmission and reception unit may be composed of an RF transmitter for up-converting and amplifying the frequency of the transmitted signal, and an RF receiver for low noise amplifying and down-converting the received signal.

In addition, the transceiver unit of the base station may receive a signal through a wireless channel and output the signal to the base station processing unit 1901, and transmit the signal output from the base station processing unit 1901 through the wireless channel.

The base station processing unit 1903 may control a series of processes to operate the base station according to the embodiment of the present invention described above. For example, the base station receiver 1901 receives a PDI fed back by the terminal. The base station processor 1903 may interpret the PDI information received from the terminal and determine which structure of the reference signal is suitable for the transmission environment. Thereafter, the base station processor 1903 controls the base station transmitter 1905 to transmit the corresponding reference signal based on the structure of the reference signal selected based on the PDI. In addition, according to an embodiment of the present invention, the base station processor 1903 may perform a setting for receiving PDI periodically or aperiodically and control it.

On the other hand, the embodiments of the present invention disclosed in the specification and drawings are merely presented specific examples to easily explain the technical contents of the present invention and help the understanding of the present invention, and are not intended to limit the scope of the present invention. That is, it will be apparent to those skilled in the art that other modifications based on the technical idea of the present invention can be implemented.

In addition, the above embodiments may be combined and operated as necessary. For example, some of the embodiments 2-1, 2-2, and 2-3 of the present invention may be combined with each other and operated through the base station and the terminal. In addition, although the above embodiments are presented based on the FDD LTE system, other modifications based on the technical spirit of the above embodiment may be implemented in other systems such as a TDD LTE system, a 5G, or an NR system.

Third Embodiment

In a wireless communication system, especially in a conventional LTE system, HARQ (Hybrid Automatic Repeat reQuest) acknowledgment (ACK) or NACK (Negative Acknowledgement) information indicating whether data transmission is successful uplink after 3ms after receiving downlink data is transmitted. Transmit to base station. For example, HARQ ACK / NACK information of a physical downlink shared channel (PDSCH) received from a base station in a subframe n is transmitted from a base station to a physical uplink control channel (PUCCH) or a physical uplink shared channel (PUSCH) in subframe n + 4. Is transmitted to the base station.

In addition, in a frequency division duplex (FDD) LTE system, a base station may transmit downlink control information (DCI) including uplink resource allocation information to a terminal or request retransmission through a physical hybrid ARQ indicator channel (PHICH). When the uplink data transmission scheduling is received in subframe n, the terminal performs uplink data transmission in subframe n + 4. That is, PUSCH transmission is performed in subframe n + 4. The above example is a description of an LTE system using FDD. In an LTE system using a time division duplex (TDD), the HARQ ACK / NACK transmission timing or the PUSCH transmission timing depends on uplink-downlink subframe configuration. This is done according to a predetermined rule.

In the LTE system using the FDD or TDD, the HARQ ACK / NACK transmission timing or the PUSCH transmission timing are predetermined timings when the time required for signal processing between the base station and the terminal is about 3 ms. However, if the LTE base station and the terminal reduces the signal processing time by about 1 ms or 2 ms, it will be possible to reduce the delay time for data transmission. Reducing the signal processing time to 1 ms or 2 ms may be achieved by limiting the number of allocated physical resource blocks (PRBs), a modulation and coding scheme (MCS), a transport block size (TBS), and the like.

In order to meet the increasing demand for wireless data traffic since the commercialization of 4G communication systems, efforts are being made to develop improved 5G communication systems or pre-5G communication systems. For this reason, a 5G communication system or a pre-5G communication system is called a system after a 4G network (Beyond 4G Network) or a system after an LTE system (Post LTE).

In order to achieve high data rates, 5G communication systems are being considered for implementation in the ultra-high frequency (mmWave) band (eg, such as the 60 Gigabit (60 GHz) band). In order to mitigate the path loss of radio waves in the ultra-high frequency band and increase the propagation distance of radio waves, beamforming, massive array multiple input / output (FD-MIMO), and FD-MIMO are used in 5G communication systems. Array antenna, analog beam-forming, and large scale antenna techniques are discussed.

In addition, in order to improve the network of the system, in the 5G communication system, advanced small cells, advanced small cells, cloud radio access network (cloud RAN), ultra-dense network (ultra-dense network) ), Device to Device communication (D2D), wireless backhaul, moving network, cooperative communication, Coordinated Multi-Points (CoMP), and interference cancellation The development of such technology is being done.

In addition, in 5G systems, Hybrid FSK and QAM Modulation (FQAM) and Sliding Window Superposition Coding (SWSC), Advanced Coding Modulation (ACM), and FBMC (Filter Bank Multi Carrier) and NOMA are advanced access technologies. Non-orthogonal multiple access and sparse code multiple access are being developed.

Meanwhile, the Internet is evolving from a human-centered connection network where humans create and consume information, and an Internet of Things (IoT) network that exchanges and processes information among distributed components such as things. The Internet of Everything (IoE) technology, which combines big data processing technology through connection with cloud servers and the like, is emerging. In order to implement the IoT, technical elements such as sensing technology, wired / wireless communication and network infrastructure, service interface technology, and security technology are required, and recently, a sensor network for connection between things, a machine to machine , M2M), Machine Type Communication (MTC), etc. are being studied.

In an IoT environment, intelligent Internet technology (IT) services can be provided that collect and analyze data generated from connected objects to create new value in human life. IoT is a field of smart home, smart building, smart city, smart car or connected car, smart grid, health care, smart home appliances, advanced medical services, etc. through convergence and complex of existing information technology (IT) technology and various industries. It can be applied to.

Accordingly, various attempts have been made to apply the 5G communication system to the IoT network. For example, technologies such as sensor network, machine to machine (M2M) and machine type communication (MTC) are implemented by techniques such as beamforming, MIMO, and array antenna, which are 5G communication technologies. will be. Application of cloud radio access network (cloud RAN) as the big data processing technology described above may be an example of convergence of 5G technology and IoT technology.

As such, a plurality of services may be provided to a user in a communication system, and in order to provide the plurality of services to a user, a method and an apparatus using the same are required to provide each service within a same time period according to characteristics. .

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

In this specification, it will be understood that each block of the flowchart illustrations and combinations of flowchart illustrations may be performed by computer program instructions. Since these computer program instructions may be mounted on a processor of a general purpose computer, special purpose computer, or other programmable data processing equipment, those instructions executed through the processor of the computer or other programmable data processing equipment may be described in flow chart block (s). It creates a means to perform the functions. These computer program instructions may be stored in a computer usable or computer readable memory that can be directed to a computer or other programmable data processing equipment to implement functionality in a particular manner, and thus the computer usable or computer readable memory. It is also possible for the instructions stored in to produce an article of manufacture containing instruction means for performing the functions described in the flowchart block (s). Computer program instructions may also be mounted on a computer or other programmable data processing equipment, such that a series of operating steps may be performed on the computer or other programmable data processing equipment to create a computer-implemented process to create a computer or other programmable data. Instructions for performing the processing equipment may also provide steps for performing the functions described in the flowchart block (s).

In addition, each block may represent a portion of a module, segment, or code that includes one or more executable instructions for executing a specified logical function (s). It should also be noted that in some alternative implementations, the functions noted in the blocks may occur out of order. For example, the two blocks shown in succession may in fact be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending on the corresponding function.

In this case, the term '~ part' used in the present embodiment refers to software or a hardware component such as an FPGA or an ASIC, and '~ part' performs certain roles. However, '~' is not meant to be limited to software or hardware. '~ Portion' may be configured to be in an addressable storage medium or may be configured to play one or more processors. Thus, as an example, '~' means components such as software components, object-oriented software components, class components, and task components, and processes, functions, properties, procedures, and the like. Subroutines, segments of program code, drivers, firmware, microcode, circuits, data, databases, data structures, tables, arrays, and variables. The functionality provided within the components and the 'parts' may be combined into a smaller number of components and the 'parts' or further separated into additional components and the 'parts'. In addition, the components and '~' may be implemented to play one or more CPUs in the device or secure multimedia card. In addition, in an embodiment, “~ unit” may include one or more processors.

In a wireless communication system including a fifth generation, at least one service of Enhanced Mobile Broadband (eMBB), Massive Machine Type Communications (MMTC), and Ultra-Reliable and Low-latency Communications (URLLC) may be provided to a terminal. The services may be provided to the same terminal during the same time period. In an embodiment, the eMBB may be a high speed data transmission, the mMTC may be a service aimed at minimizing the terminal power and accessing multiple terminals, and the URLLC may be a high reliability and a low latency. The three services may be major scenarios in an LTE system or a system such as 5G / NR (new radio, next radio) after LTE. In the embodiment, a coexistence method of eMBB and URLLC, a coexistence method of mMTC and URLLC, and a device using the same will be described.

When a base station schedules data corresponding to an eMBB service to a terminal in a specific transmission time interval (TTI), when a situation occurs in which the URLLC data should be transmitted in the TTI, the eMBB data is scheduled and transmitted. In the present frequency band, the generated URLLC data may be transmitted without transmitting a part of the eMBB data. Here, the terminal scheduled for the eMBB and the terminal scheduled for URLLC may be the same terminal or may be different terminals.

In such a case, since a portion of the eMBB data that has already been scheduled and transmitted is not generated, the possibility of damage to the eMBB data increases. In this case, it is necessary to determine a method for processing a signal received from a terminal scheduled for eMBB or a terminal scheduled for URLLC and a method for receiving a signal.

Therefore, in the embodiment of the present invention, when information according to eMBB and URLLC is scheduled by sharing a part or all frequency bands, when information according to mMTC and URLLC are scheduled at the same time, or information according to mMTC and eMBB is scheduled at the same time. This paper describes how to coexist between heterogeneous services that can transmit information according to each service when the information according to eMBB, URLLC and mMTC is scheduled at the same time.

Hereinafter, the base station is a subject performing resource allocation of the terminal, and may be at least one of an eNode B, a Node B, a base station (BS), a radio access unit, a base station controller, or a node on a network. The terminal may include a user equipment (UE), a mobile station (MS), a cellular phone, a smartphone, a computer, or a multimedia system capable of performing a communication function.

In the present invention, downlink (DL) is a radio transmission path of a signal transmitted from a base station to a terminal, and uplink (UL) is a radio transmission path of a signal transmitted from a terminal to a base station. In addition, the following describes an embodiment of the present invention using an LTE or LTE-A system as an example, but the embodiment of the present invention may be applied to other communication systems having a similar technical background or channel form. For example, the fifth generation mobile communication technology (5G, new radio, NR) developed after LTE-A may be included in this. In addition, the embodiment of the present invention may be applied to other communication systems through some modifications within the scope of the present invention without departing from the scope of the present invention by the judgment of those skilled in the art.

As a representative example of the broadband wireless communication system, an LTE system employs an orthogonal frequency division multiplexing (OFDM) scheme in downlink (DL), and a single carrier frequency division multiple (SC-FDMA) in uplink (UL). Access) method is adopted.

The uplink refers to a radio link through which a terminal or user equipment (UE) or a mobile station (MS) transmits data or control signals to an eNode B or a base station (BS), and the downlink refers to a base station The above-described multiple access scheme is generally designed such that orthogonality does not overlap the time-frequency resources for carrying data or control information for each user. By assigning and operating to establish, the data or control information of each user can be distinguished.

The LTE system employs a hybrid automatic repeat request (HARQ) scheme in which the data is retransmitted in the physical layer when a decoding failure occurs in the initial transmission. In the HARQ scheme, when the receiver does not correctly decode (decode) the data, the receiver transmits NACK (Negative Acknowledgement) informing the transmitter of the decoding failure so that the transmitter can retransmit the corresponding data in the physical layer. The receiver combines the data retransmitted by the transmitter with previously decoded data to improve data reception performance. In addition, when the receiver correctly decodes the data, the transmitter may transmit an acknowledgment (ACK) indicating the decoding success to the transmitter so that the transmitter may transmit new data.

FIG. 3a illustrates a basic structure of a time-frequency domain, which is a radio resource region in which the data or control channel is transmitted in downlink in an LTE system or a similar system.

Referring to FIG. 3A, the horizontal axis represents the time domain and the vertical axis represents the frequency domain. The minimum transmission unit in the time domain is an OFDM symbol, N _symb (102) OFDM symbols are gathered to form one slot 106, two slots are gathered to form one subframe 105. The length of the slot is 0.5ms and the length of the subframe is 1.0ms. The radio frame 114 is a time domain section composed of 10 subframes. The minimum transmission unit in the frequency domain is a subcarrier, and the bandwidth of the entire system transmission bandwidth is composed of a total of N _BW 104 subcarriers. However, such specific numerical values may be applied variably.

The basic unit of a resource in the time-frequency domain may be represented by an OFDM symbol index and a subcarrier index as a resource element (RE). The resource block 108 (Resource Block; RB or PRB) may be defined as N _symb 102 consecutive OFDM symbols in the time domain and N _RB 110 consecutive subcarriers in the frequency domain. Accordingly, one RB 108 in one slot may include N _symb x N _RB REs 112.

In general, the frequency-domain minimum allocation unit of data is the RB. In the LTE system, N _symb = 7, N _RB = 12, and N _BW and N _RB may be proportional to a bandwidth of a system transmission band. The data rate increases in proportion to the number of RBs scheduled to the UE. The LTE system can define and operate six transmission bandwidths. In the case of an FDD system in which downlink and uplink are divided into frequencies, the downlink transmission bandwidth and the uplink transmission bandwidth may be different. The channel bandwidth represents a radio frequency (RF) bandwidth corresponding to the system transmission bandwidth.

[Table 3-1] below shows a correspondence relationship between a system transmission bandwidth and a channel bandwidth defined in an LTE system. For example, an LTE system having a 10 MHz channel bandwidth may have a transmission bandwidth of 50 RBs.

Table 3-1

The downlink control information may be transmitted within the first N OFDM symbols in the subframe. In the examples generally N = {1, 2, 3}. Therefore, the N value may be variably applied to each subframe according to the amount of control information to be transmitted in the subframe. The transmitted control information may include a control channel transmission interval indicator indicating how many control information is transmitted over OFDM symbols, scheduling information for downlink data or uplink data, and information about HARQ ACK / NACK.

In the LTE system, scheduling information on downlink data or uplink data is transmitted from the base station to the terminal through downlink control information (DCI). DCI is defined according to various formats, and according to each format, whether or not scheduling information (UL grant) for uplink data or scheduling information (DL grant) for downlink data, and whether the size of control information is compact DCI. It may indicate whether to apply spatial multiplexing using multiple antennas, whether to use DCI for power control. For example, DCI format 1, which is scheduling control information (DL grant) for downlink data, may include at least one of the following control information.

Resource allocation type 0/1 flag: Indicates whether the resource allocation method is type 0 or type 1. Type 0 uses a bitmap scheme to allocate resources in resource block group (RBG) units. In the LTE system, the basic unit of scheduling is an RB represented by time and frequency domain resources, and the RBG is composed of a plurality of RBs to become a basic unit of scheduling in a type 0 scheme. Type 1 allows allocating a specific RB within the RBG.

Resource block assignment: indicates an RB allocated for data transmission. The resource to be expressed is determined by the system bandwidth and the resource allocation method.

Modulation and coding scheme (MCS): indicates the modulation scheme used for data transmission and the size of a transport block, which is data to be transmitted.

HARQ process number: indicates a process number of HARQ.

New data indicator: indicates whether HARQ initial transmission or retransmission.

-Redundancy version: indicates a redundant version of HARQ.

Transmit Power Control (TPC) command for PUCCH (Physical Uplink Control CHannel): PUCCH indicates a transmit power control command for PUCCH, which is an uplink control channel.

The DCI is a physical downlink control channel (PDCCH) (or control information, hereinafter referred to as used interchangeably) or an enhanced PDCCH (EPDCCH) (or enhanced control information), which is a downlink physical control channel through channel coding and modulation processes. Can be used interchangeably).

In general, the DCI is scrambled with a specific Radio Network Temporary Identifier (RNTI) (or UE ID) independently for each UE, cyclic redundancy check (CRC) is added, channel coded, and configured as independent PDCCHs. Is sent. In the time domain, the PDCCH is mapped and transmitted during the control channel transmission period. The frequency domain mapping position of the PDCCH is determined by an identifier (ID) of each terminal, and can be transmitted by being spread over the entire system transmission band.

The downlink data may be transmitted on a physical downlink shared channel (PDSCH) which is a physical channel for downlink data transmission. PDSCH may be transmitted after the control channel transmission interval, and scheduling information such as specific mapping positions and modulation schemes in the frequency domain is determined based on the DCI transmitted through the PDCCH.

The base station notifies the PDSCH to be transmitted to the terminal through the MCS of the control information constituting the DCI, the applied modulation scheme and the transport block size (TBS) of the data to be transmitted. In an embodiment, the MCS may consist of 5 bits or more or fewer bits. The TBS corresponds to a size before channel coding for error correction is applied to data (transport block, TB) that the base station intends to transmit.

Modulation schemes supported by the LTE system are Quadrature Phase Shift Keying (QPSK), Quadrature Amplitude Modulation (16QAM), and 64QAM. Each modulation order (Qm) corresponds to 2, 4, and 6. That is, 2 bits per symbol for QPSK modulation, 4 bits per symbol for 16QAM modulation, and 6 bits per symbol for 64QAM modulation. In addition, modulation schemes of 256QAM or more may be used depending on system modifications.

3b is a diagram illustrating a basic structure of a time-frequency domain, which is a radio resource region in which data or a control channel is transmitted in uplink in an LTE-A system.

Referring to FIG. 3B, the horizontal axis represents the time domain and the vertical axis represents the frequency domain. The minimum transmission unit in the time domain is an SC-FDMA symbol 202, and N _symb ^UL SC-FDMA symbols may be combined to form one slot 206. Two slots are gathered to form one subframe 205. The minimum transmission unit in the frequency domain is a subcarrier, and the total system transmission bandwidth 204 consists of a total of N _BW subcarriers. N _BW may have a value proportional to the system transmission band.

The basic unit of a resource in the time-frequency domain may be defined as a SC-FDMA symbol index and a subcarrier index as a resource element (RE) 212. A resource block pair 208 may be defined as N _symb ^UL contiguous SC-FDMA symbols in the time domain and N _sc ^RB contiguous subcarriers in the frequency domain. Therefore, one RB is composed of N _symb ^UL x N _sc ^RB _Rs . In general, the minimum transmission unit for data or control information is in RB units. PUCCH is mapped to a frequency domain corresponding to 1 RB and transmitted during one subframe.

In the LTE system, PUCCH or PUSCH, which is an uplink physical channel for transmitting HARQ ACK / NACK corresponding to a PDCCH / EPDDCH including a PDSCH or a semi-persistent scheduling release (SPS release), which is a physical channel for downlink data transmission. The timing relationship of can be defined. For example, in an LTE system operating with frequency division duplex (FDD), HARQ ACK / NACK corresponding to a PDCCH / EPDCCH including a PDSCH or an SPS release transmitted in an n-4th subframe is a PUCCH or PUSCH in an nth subframe. Can be sent to.

In the LTE system, downlink HARQ adopts an asynchronous HARQ scheme in which data retransmission time is not fixed. That is, when the HARQ NACK is fed back from the terminal to the initial transmission data transmitted by the base station, the base station freely determines the transmission time of the retransmission data by the scheduling operation. The UE may buffer the data determined to be an error as a result of decoding the received data for the HARQ operation, and then perform combining with the next retransmission data.

HARQ ACK / NACK information of the PDSCH transmitted in the subframe nk is transmitted from the UE to the base station through the PUCCH or the PUSCH in the subframe n, where k is the FDD or time division duplex (TDD) of the LTE system and its sub It may be defined differently according to the frame setting.

For example, in the case of an FDD LTE system, k is fixed to 4. Meanwhile, in the TDD LTE system, k may be changed according to the subframe configuration and the subframe number. In addition, the value of k may be differently applied according to the TDD setting of each carrier when transmitting data through a plurality of carriers. In the case of the TDD, the k value is determined according to the TDD UL / DL configuration as shown in Table 3-2 below.

Table 3-2

Unlike the downlink HARQ in the LTE system, the uplink HARQ adopts a synchronous HARQ scheme with a fixed data transmission time point. That is, a Physical Hybrid (Physical Uplink Shared Channel), which is a physical channel for transmitting uplink data, a PDCCH, which is a preceding downlink control channel, and a PHICH (Physical Hybrid), which is a physical channel through which downlink HARQ ACK / NACK is transmitted. The uplink / downlink timing relationship of the indicator channel) may be transmitted and received according to the following rule.

When the UE receives the PDCCH including the uplink scheduling control information transmitted from the base station or the PHICH in which downlink HARQ ACK / NACK is transmitted in subframe n, the UE transmits uplink data corresponding to the control information in subframe n + k. Transmit through PUSCH. In this case, k may be defined differently according to FDD or time division duplex (TDD) of LTE system and its configuration. For example, in the case of an FDD LTE system, k may be fixed to four. Meanwhile, in the TDD LTE system, k may be changed according to the subframe configuration and the subframe number. In addition, the value of k may be differently applied according to the TDD setting of each carrier when transmitting data through a plurality of carriers. In the case of the TDD, the k value is determined according to the TDD UL / DL configuration as shown in Table 3-3 below.

Table 3-3

Meanwhile, HARQ-ACK information of the PHICH transmitted in subframe i is related to the PUSCH transmitted in subframe i-k. For an FDD system, k is given by 4. That is, HARQ-ACK information of the PHICH transmitted in subframe i in the FDD system is related to the PUSCH transmitted in subframe i-4. In the case of the TDD system, when a terminal without Enhanced Interference Mitigation and Traffica Adaptation (EIMTA) is configured with only one serving cell or the same TDD UL / DL configuration, the TDD UL / DL configuration 1 to 6 In accordance with Table 3-4, k may be given.

Table 3-4

That is, for example, in the TDD UL / DL configuration 1, the PHICH transmitted in subframe 6 may be HARQ-ACK information of the PUSCH transmitted in subframe 2 that is 4 subframes before.

If, when TDD UL / DL configuration 0, HARQ-ACK is received with a PHICH resource corresponding to I _PHICH = 0, the PUSCH indicated by the HARQ-ACK information is transmitted in subframe ik and the k value is [ Given in Table 3-4]. In the case of TDD UL / DL configuration 0, if HARQ-ACK is received as a PHICH resource corresponding to I _PHICH = 1, the PUSCH indicated by the HARQ-ACK information is transmitted in subframe i-6.

The description of the wireless communication system has been described with reference to the LTE system, and the present invention is not limited to the LTE system but can be applied to various wireless communication systems such as NR and 5G. In addition, in the embodiment, when applied to another wireless communication system, the k value may be changed and applied to a system using a modulation scheme corresponding to FDD.

3C and 3D show how data for eMBB, URLLC, and mMTC, which are services considered in a 5G or NR system, are allocated in frequency-time resources.

3C and 3D, it can be seen how frequency and time resources are allocated for information transmission in each system.

First, in FIG. 3C, data for eMBB, URLLC, and mMTC is allocated in the entire system frequency band 300. If the URLLC data 303, 305, 307 is generated while the eMBB 301 and the mMTC 309 are allocated and transmitted in a specific frequency band and transmission is necessary, the eMBB 301 and the mMTC 309 are already allocated for the eMBB 301 and the mMTC 309. URLLC data 303, 305, 307 may be transmitted without emptying the portion or transmitting the eMBB 301 and mMTC 309.

Since URLLC needs to reduce latency among the services, URLLC data may be allocated 303, 305, and 307 to a portion of the resource 301 to which the eMBB is allocated, and thus may be transmitted. Of course, when URLLC is additionally allocated and transmitted in the resource to which the eMBB is allocated, the eMBB data may not be transmitted in the overlapping frequency-time resource, and thus, transmission performance of the eMBB data may be lowered. That is, in the above case, eMBB data transmission failure due to URLLC allocation may occur.

In FIG. 3D, the entire system frequency band 400 is divided into subbands 402, 404, and 406, and each subband 402, 404, and 406 can be used for transmitting services and data. Information related to the subband configuration may be predetermined, and this information may be transmitted by the base station to the terminal through higher signaling.

Alternatively, the information related to the subbands may be arbitrarily divided by the base station or the network node to provide services to the terminal without transmitting subband configuration information. In FIG. 3D, the subband 402 is used for eMBB data transmission, the subband 404 is URLLC data transmission, and the subband 406 is used for mMTC data transmission.

In the overall embodiment, the length of a transmission time interval (TTI) used for URLLC transmission may be shorter than the length of TTI used for eMBB or mMTC transmission. In addition, the response of the information related to the URLLC can be transmitted faster than eMBB or mMTC, thereby transmitting and receiving information with a low delay.

3E illustrates a process in which one transport block is divided into several code blocks and a CRC is added.

Referring to FIG. 3E, a cyclic redundancy check (CRC) 503 may be added to one or more transport blocks 501 to be transmitted in uplink or downlink. The CRC may have 16 bits or 24 bits or a fixed number of bits, or may have a variable number of bits depending on channel conditions, and may be used to determine whether channel coding is successful.

Blocks 501 and 503 added with TB and CRC may be divided into a plurality of codeblocks (CBs) 507, 509, 511 and 513 (505). The code block may be divided based on a preset maximum size. In this case, the last code block 513 is smaller in size than other code blocks, or 0, a random value, or 1 is added to length the other code blocks. Can be tailored to be the same.

CRCs 517, 519, 521, and 523 may be added to the divided code blocks, respectively (515). The CRC may have 16 bits or 24 bits or a fixed number of bits, and may be used to determine whether channel coding is successful. However, the CRC 503 added to the TB and the CRCs 517, 519, 521, and 523 added to the code block may be omitted according to the type of channel code to be applied to the code block. For example, if a Low Density Parity-Check (LDPC) code is applied to the code block instead of the turbo code, the CRCs 517, 519, 521, and 523 to be inserted for each code block may be omitted. However, even when LDPC is applied, the CRCs 517, 519, 521, and 523 may be added to the code block as it is. In addition, CRC may be added or omitted even when a polar code is used.

FIG. 3F is a diagram illustrating a method of transmitting and using an outer code, and FIG. 3G is a block diagram showing a structure of a communication system using the outer code.

3F and 3G, a method of transmitting a signal using an outer code may be described.

In FIG. 3F, after one transport block is divided into several code blocks, bits or symbols 604 located at the same position in each code block are encoded in a second channel code to generate parity bits or symbols 606. It may be 602. Thereafter, CRCs may be added to the respective code blocks and the parity code blocks generated by the second channel code encoding, respectively (608 and 610). The addition of the CRC may vary depending on the type of channel code. For example, when the turbo code is used as the first channel code, the CRCs 608 and 610 are added, but the respective code blocks and parity code blocks may be encoded by the first channel code encoding.

When the outer code is used, the data to transmit passes through the second channel coding encoder 709. As the channel code used for the second channel coding, for example, a Reed-solomon code, a Bose-Chaudhuri-Hocquenghem (BCH) code, a Raptor code, a parity bit generation code, or the like may be used. The bits or symbols passing through the second channel coding encoder 709 pass through the first channel coding encoder 711. Channel codes used for the first channel coding include convolutional code, LDPC code, Turbo code, and polar code.

When the channel coded symbols are received by the receiver through the channel 713, the receiver may sequentially operate the first channel coding decoder 715 and the second channel coding decoder 717 based on the received signals. . The first channel coding decoder 715 and the second channel coding decoder 717 may perform operations corresponding to the first channel coding encoder 711 and the second channel coding encoder 709, respectively.

On the other hand, in the channel coding block diagram in which the outer code is not used, only the first channel coding encoder 711 and the first channel coding decoder 705 are used in the transceiver, and the second channel coding encoder and the second channel coding decoder are used. It doesn't work. Even when the outer code is not used, the first channel coding encoder 711 and the first channel coding decoder 705 may be configured in the same manner as when the outer code is used.

The eMBB service described below is called a first type service, and the eMBB data is called first type data. The first type of service or the first type of data is not limited to the eMBB but may also be applicable to a case where high-speed data transmission is required or broadband transmission is required. In addition, the URLLC service is referred to as a second type service, and the URLLC data is referred to as second type data. The second type service or the second type data is not limited to URLLC, but may also correspond to a case where low latency or high reliability transmission is required or other systems requiring low latency and high reliability at the same time.

In addition, the mMTC service is referred to as type 3 service, and the data for mMTC is referred to as type 3 data. The third type service or the third type data is not limited to the mMTC and may correspond to a case where a low speed, wide coverage, or low power is required. In addition, when describing an embodiment, it may be understood that the first type service includes or does not include the third type service.

The structure of the physical layer channel used for each type to transmit the three types of services or data may be different. For example, at least one of a length of a transmission time interval (TTI), an allocation unit of frequency resources, a structure of a control channel, and a data mapping method may be different.

In the above description, three types of services and three types of data are described, but more types of services and corresponding data may exist, and in this case, the contents of the present invention may be applied.

The terms physical channel and signal in the conventional LTE or LTE-A system may be used to describe the method and apparatus proposed by the embodiment. However, the contents of the present invention can be applied in a wireless communication system other than the LTE and LTE-A systems.

As described above, the embodiment defines the transmission and reception operations of the terminal and the base station for the first type, the second type, the third type of service or data transmission, and the terminals receiving different types of service or data scheduling in the same system. Suggests specific ways to work together. In the present invention, the first type, the second type, and the third type terminal refer to terminals which have received one type, second type, third type service or data scheduling, respectively. In an embodiment, the first type terminal, the second type terminal, and the third type terminal may be the same terminal or may be different terminals.

Hereinafter, at least one of a PHICH, an uplink scheduling grant signal, and a downlink data signal is referred to as a first signal. In the present invention, at least one of an uplink data signal for the uplink scheduling grant and a HARQ ACK / NACK for the downlink data signal is called a second signal. According to the embodiment, the signal transmitted from the base station to the terminal may be a first signal if a signal is expected from the terminal, and the response signal of the terminal corresponding to the first signal may be a second signal. In an embodiment, the service type of the first signal may be at least one of eMBB, URLLC, and mMTC, and the second signal may also correspond to at least one of the services.

For example, in LTE and LTE-A systems, PUCCH format 0 or 4 and PHICH may be a first signal, and a second signal corresponding thereto may be a PUSCH. In addition, for example, in LTE and LTE-A systems, a PDSCH may be a first signal, and a PUCCH or PUSCH including HARQ ACK / NACK information of the PDSCH may be a second signal.

In the following embodiment, the TTI length of the first signal may indicate the length of time that the first signal is transmitted as a time value associated with the first signal transmission. Also, in the present invention, the TTI length of the second signal may indicate a length of time that the second signal is transmitted as a time value associated with the second signal transmission, and the TTI length of the third signal may be related to the third signal transmission. The time value may indicate the length of time that the third signal is transmitted. In addition, in the present invention, the second signal transmission timing is information on when the terminal transmits the second signal and when the base station receives the second signal, and may be referred to as a second signal transmission timing.

In addition, in the following embodiment, assuming that the terminal transmits the second signal in the n + k th TTI when the base station transmits the first signal in the n-th TTI, the base station informs the terminal when to transmit the second signal Is the same as telling k. Alternatively, when the base station transmits the first signal in the n th TTI, assuming that the terminal transmits the second signal in the n + 4 + a th TTI, the base station to inform the terminal when to transmit the second signal is offset Equivalent to giving the value a. The offset may be defined by various methods such as n + 3 + a and n + 5 + a instead of n + 4 + a, and the n + 4 + a value referred to in the present invention below may also be offset in various ways. It can be defined.

The content of the present invention is applicable to FDD and TDD systems.

In the present invention, the upper signaling is a signal transmission method transmitted from a base station to a terminal using a downlink data channel of a physical layer, or from a terminal to a base station using an uplink data channel of a physical layer, and radio resource control (RRC). Signaling, or Packet Data Convergence Protocol (PDCP) signaling, or Medium Access Control (MAC) control element (MAC CE) may be referred to.

Although the present invention describes a method of determining a timing for transmitting a second signal after receiving a first signal by a terminal or a base station, a method of sending a second signal may be possible in various ways. For example, after the UE receives the PDSCH which is downlink data, the timing of transmitting HARQ ACK / NACK information corresponding to the PDSCH to the base station follows the method described in the present invention, but the PUCCH format is selected and the PUCCH resource is selected. Alternatively, the method of mapping HARQ ACK / NACK information to the PUSCH may follow a method determined in another manner. For example, the selection of the PUCCH format to be used, the selection of the PUCCH resources, or the method of mapping HARQ ACK / NACK information to the PUSCH may be determined based on the contents of the LTE standard.

In the present invention, a delay reducing terminal, a terminal having a delay reduction, a terminal having a reduced processing time, or a terminal having a reduced processing time may be used interchangeably.

[Example 3-1]

Embodiment 3-1 describes a method of determining a timing for performing PUSCH transmission associated with a PDCCH / EPDCCH when a UE receives a PHICH or a DCI carrying uplink scheduling information. If the delay reduction is transmitted to the terminal configured to delay the PHICH may not be used, this case may be applied when a DCI for transmitting uplink scheduling information is received. In this case, since HARQ ACK-NACK information for uplink transmission transmitted with delay reduction is not received in PHICH, the UE may omit PHICH decoding in the corresponding subframe.

When the TDD UL / DL configuration is one of 1 to 6, when the UE receives the PDCCH / EPDCCH including the DCI transmitting the PHICH or uplink scheduling information in subframe n, the PUSCH associated with the subframe n + k is received. Is transmitted by the terminal, and k is given in Table 3-5 below.

Table 3-5

When the TDD UL / DL configuration is 0, a PDCCH / EPDCCH having a Most Significant Bit (MSB) of an UL index of an uplink DCI format is 1 is received, or a PHICH is received in subframes 1 or 6, When the PHICH is received in the subframe 0 or 5 where the I _PHICH resource is 0, the k value may be determined according to Table 3-5. When the TDD UL / DL configuration is 0, a PDCCH / EPDCCH having a LSB (Least Signigicant Bit) of an UL index of an uplink DCI format is 1 or a PHICH is received in a subframe 0 or 5 where the I _PHICH resource is 1 When received, the k value may be determined as 7. If both the MSB and LSB of the UL index of the uplink DCI format are 1, PUSCH may be transmitted both in k and 7 and in subframe n + k when k follows Table 3-5. .

When the TDD UL / DL configuration is 0, the method is not only possible, but may be applied through a slight modification. For example, when the TDD UL / DL configuration is 0, a PDCCH / EPDCCH in which the MSB of the UL index of the uplink DCI format is 1 is received, a PHICH is received in subframes 1 or 6, or a PHICH is subframe 0 or 5 When the I _PHICH resource is received at 1, the k value may be determined according to [Table 3-5].

When the TDD UL / DL configuration is 0, when the PDCCH / EPDCCH with the LSB of the UL index of the uplink DCI format is 1 or when the PHICH is received in the subframe 0 or 5 where the I _PHICH resource is 0, the k The value can be determined as 7. As another example, when the TDD UL / DL configuration is 0, a PDCCH / EPDCCH in which the MSB of the UL index of the uplink DCI format is 1 is received, a PHICH is received in subframes 0 or 5, or a PHICH is subframe 1 or When the I _PHICH resource is received at 1 in 6, the k value may be determined according to [Table 3-5].

When the TDD UL / DL configuration is 0, when the PDCCH / EPDCCH having the LSB of the UL index of the uplink DCI format is 1 or the PHICH is received in the subframe 1 or 6 where the I _PHICH resource is 0, the k The value can be determined as 6.

Example 3-2

Embodiment 2-2 describes a method of determining a timing for performing PUSCH transmission associated with a PDCCH / EPDCCH when a UE receives a PHICH or a DCI carrying uplink scheduling information. If the delay reduction is transmitted to the terminal configured to delay the PHICH may not be used, this case may be applied when a DCI for transmitting uplink scheduling information is received. In this case, since HARQ ACK-NACK information for uplink transmission transmitted with delay reduction is not received in PHICH, the UE may omit PHICH decoding in the corresponding subframe.

When the UE receives the PDCCH / EPDCCH including the PHI or the DCI for transmitting the uplink scheduling information in the subframe n, when the subframe of n + k is a subframe capable of uplink transmission among k greater than 2, The UE transmits the PUSCH in subframe n + k. For example, a terminal receiving an uplink DCI in subframe n transmits a PUSCH in a subframe capable of uplink transmission from n + 3. If n + 3 is a downlink subframe and n + 4 is capable of uplink transmission, the PUSCH is transmitted in subframe n + 4.

[Example 3-3]

Embodiment 3-3 describes a method of determining a timing for performing PUSCH transmission associated with a UE when receiving a PDCCH / EPDCCH including a DCI carrying PHICH or uplink scheduling information. If the delay reduction is transmitted to the terminal configured to delay the PHICH may not be used, this case may be applied when a DCI for transmitting uplink scheduling information is received. In this case, since HARQ ACK-NACK information for uplink transmission transmitted with delay reduction is not received in PHICH, the UE may omit PHICH decoding in the corresponding subframe.

When the TDD UL / DL configuration is one of 1 to 6, when the UE receives the PDCCH / EPDCCH including the DCI transmitting the PHICH or uplink scheduling information in subframe n, the PUSCH associated with the subframe n + k is received. Is transmitted by the terminal, k is given in Table 3-6 below.

Table 3-6

When the TDD UL / DL configuration is 0, a PDCCH / EPDCCH in which the MSB of the UL index of the uplink DCI format is 1 is received, a PHICH is received in subframes 0 or 5, or a PHICH is I _PHICH in subframes 1 or 6 When the resource is received at 0, the value of k can be determined according to [Table 3-6].

When the TDD UL / DL configuration is 0, when the PDCCH / EPDCCH having the LSB of the UL index of the uplink DCI format is 1 or the PHICH is received where the I _PHICH resource is 1 in subframe 1 or 6, k is received. The value can be determined as 3. If both the MSB and LSB of the UL index of the uplink DCI format are 1, the PUSCH may be transmitted in both k when 3 and in subframe n + k when k follows Table 3-5. .

When the TDD UL / DL configuration is 0, the method is not only possible, but may be applied through a slight modification.

[Example 3-4]

Embodiment 3-4 describes a method of determining a timing for performing PUSCH transmission associated with a UE when receiving a PDCCH / EPDCCH including a DCI carrying PHICH or uplink scheduling information. If the delay reduction is transmitted to the terminal configured to delay the PHICH may not be used, this case may be applied when a DCI for transmitting uplink scheduling information is received. In this case, since HARQ ACK-NACK information for uplink transmission transmitted with delay reduction is not received in PHICH, the UE may omit PHICH decoding in the corresponding subframe.

When the UE receives the PDCCH / EPDCCH including the PHI or the DCI for transmitting the uplink scheduling information in the subframe n, when the subframe of n + k is a subframe capable of uplink transmission among k greater than 1 The UE transmits the PUSCH in subframe n + k. For example, a terminal receiving an uplink DCI in subframe n transmits a PUSCH in a subframe capable of uplink transmission from n + 2. If n + 2 is a downlink subframe and n + 3 is capable of uplink transmission, a PUSCH is transmitted in subframe n + 3.

Embodiments 3-1 and 3-3 may be used according to the configuration of the base station to the terminal, or may be used according to information transmitted from the DCI. In addition, the embodiments 3-2 and 3-4 may be used according to the configuration of the base station to the terminal, or may be used according to the information transmitted from the DCI. In addition, in the embodiments 3-1 to 3-4, the base station may try to decode the PUSCH in the subframe in which the UE transmits the PUSCH.

3H illustrates the operation of the terminal. When the terminal receives the PICHCH or EPDCCH containing the PHICH or uplink scheduling information, the UE checks at least one of higher signaling configuration, PHICH resource location, DCI information, etc. (804). In FIG. 3H, the first timing setup 806 may indicate a case where the minimum signal processing time of the UE is about 3 ms including a TA value by using a PUSCH transmission timing in the conventional LTE / LTE-A. . Accordingly, when the UE checks the first timing setup 806, the UE performs the same PUSCH transmission timing in the conventional LTE / LTE-A. For example, if the uplink scheduling information is received on the PDCCH in subframe n in the FDD, The PUSCH is transmitted in the frame n + 4 (808).

In FIG. 3H, the second timing setting 810 may refer to a case where the minimum signal processing time of the UE is about 2 ms including a TA value. Accordingly, when the UE checks the second timing setting 810, timing is determined according to the embodiment 3-1 or embodiment 3-2. For example, in FDD, uplink scheduling information is transmitted from the subframe n to the PDCCH. If so, the PUSCH is transmitted in subframe n + 3 (812).

In FIG. 3H, the third timing setting 814 may indicate a case where the minimum signal processing time of the UE is about 1 ms including the TA value. Accordingly, when the UE checks the third timing setting 814, timing is determined according to the third embodiment or the third embodiment. For example, in FDD, uplink scheduling information is transmitted from the subframe n to the PDCCH. If so, the PUSCH is transmitted in subframe n + 2 (816). According to the terminal or the base station, it may be possible to support only one of the second timing setting 810 and the third timing setting 814.

In addition, it will be possible to implement the combination of the embodiment 3-1 and the embodiment 3-3. For example, when the UE receives a DCI in which PDCCH / EPDCCH transfers uplink scheduling information, the transmission timing of the PUSCH is determined as in the embodiment 3-1, and the UE receives the PHICH and accordingly the PUSCH The transmission timing of may be determined as in the third embodiment. That is, when uplink scheduling is performed in subframe n using DCI, the UE transmits a PUSCH after subframe n + 3 or later, and when the UE instructs uplink retransmission using PHICH, the UE subframe n. PUSCH can be transmitted after +2 or later.

In the embodiments 3-1 to 3-4, the PHICH means information corresponding to HARQ NACK for uplink transmission. Therefore, receiving the PHICH may be interpreted to mean that the UE needs to retransmit.

[Example 3-5]

Embodiment 3-5 describes a method of determining a timing at which a UE receives a downlink data PDSCH transmission and transmits HARQ ACK / NACK for the PDSCH to an uplink channel such as a PUCCH or a PUSCH.

HARQ ACK / NACK information of the PDSCH transmitted in subframe n-k is transmitted in subframe n, and k may vary according to TDD UL / DL configuration and subframe position as shown in Table 3-7 below. In the present embodiment, the PDSCH may be a PDSCH scheduled by PDCCH / EPDCCH or a PDSCH configured PDSCH.

Table 3-7

The order of the numbers written in each column of the table may be changed and applied differently.

In the case of multiple k values in [Table 3-7], it means that HARQ ACK / NACK information for one or more PDSCHs may be transmitted together in subframe n. For example, in UL / DL configuration 1, in subframe 2, HARQ ACK / NACK information corresponding to PDSCHs transmitted before 6 subframes and before 3 subframes is transmitted.

Table 3-7 will be modified to [Table 3-7a] to be used.

Table 3-7a

The order of the numbers written in each column of the table may be changed and applied differently.

[Example 3-6]

Embodiments 3-6 describe a method of determining a timing at which a UE receives a downlink data PDSCH transmission and transmits HARQ ACK / NACK for the PDSCH to an uplink channel such as a PUCCH or a PUSCH.

If the base station transmits the PDSCH to the UE in subframe n, the UE transmits HARQ ACK / NACK information related to the PDSCH when a subframe of n + k is a subframe capable of uplink transmission. The UE transmits the PUCCH or the PUSCH in the subframe n + k. For example, the UE that receives the PDSCH in subframe n transmits HARQ ACK / NACK information on the PDSCH to the base station in PUCCH or PUSCH in a subframe capable of uplink transmission from n + 3. If n + 3 is a downlink subframe and n + 4 is capable of uplink transmission, HARQ ACK / NACK information is transmitted on PUCCH or PUSCH in subframe n + 4.

[Example 3-7]

Embodiments 3-7 describe a method of determining a timing at which a UE receives a downlink data PDSCH transmission and transmits HARQ ACK / NACK for the PDSCH to an uplink channel such as a PUCCH or a PUSCH.

HARQ ACK / NACK information of the PDSCH transmitted in subframe n-k is transmitted in subframe n, and k may vary according to TDD UL / DL configuration and subframe position as shown in Table 3-8 below. In the present embodiment, the PDSCH may be a PDSCH scheduled by PDCCH / EPDCCH or a PDSCH configured PDSCH.

Table 3-8

The order of the numbers written in each column of the table may be changed and applied differently.

In the case of multiple k values in Table 3-8, HARQ ACK / NACK information for one or more PDSCHs may be transmitted together in subframe n. For example, in UL / DL configuration 1, in subframe 2, HARQ ACK / NACK information corresponding to PDSCHs transmitted before 3 subframes and before 2 subframes is transmitted.

Table 3-8 may be modified to the following Table 3-8a.

Table 3-8a

The order of the numbers written in each column of the table may be changed and applied differently.

[Example 3-8]

Embodiments 3-8 describe a method of determining a timing at which a UE receives a downlink data PDSCH transmission and transmits HARQ ACK / NACK for the PDSCH to an uplink channel such as a PUCCH or a PUSCH.

If the base station transmits the PDSCH to the UE in subframe n, the UE transmits HARQ ACK / NACK information related to the PDSCH when a subframe of n + k is a subframe capable of uplink transmission. The UE transmits the PUCCH or the PUSCH in the subframe n + k. For example, the UE that receives the PDSCH in subframe n transmits HARQ ACK / NACK information on the PDSCH to the base station in PUCCH or PUSCH in a subframe capable of uplink transmission from n + 2. If n + 2 is a downlink subframe and n + 3 is capable of uplink transmission, HARQ ACK / NACK information is transmitted on PUCCH or PUSCH in subframe n + 3.

The 3-5th embodiment and the 3-7th embodiment may be used according to the configuration of the base station to the terminal, or may be used according to the information transmitted from the DCI. In addition, embodiments 3-6 and 3-8 may be used according to the configuration of the base station to the terminal, or may be used according to the information transmitted from the DCI. In addition, in the embodiments 3-5 and 3-8, the base station may attempt to decode the PUCCH or the PUSCH in the subframe in which the UE transmits the PUCCH or the PUSCH including the HARQ ACK / NACK information for the PDSCH. There will be.

3i illustrates the operation of the terminal. When the terminal receives the PDSCH, the terminal checks at least one or more of the higher signaling configuration, DCI information, etc. (903). In FIG. 3I, the first timing setup 905 is a timing of HARQ ACK / NACK information transmission using PUCCH or PUSCH in LTE / LTE-A. The minimum signal processing time of the UE is about 3ms including the TA value. This can be the case when Accordingly, when the UE checks the first timing setting 905, the timing of transmitting HARQ ACK / NACK information is the same as that of the conventional LTE / LTE-A. For example, if the PDSCH is received in subframe n in the FDD, the subframe HARQ ACK / NACK information is transmitted through PUCCH or PUSCH at n + 4 (907).

In FIG. 3I, the second timing setting 909 may indicate a case where the minimum signal processing time of the UE is about 2 ms including a TA value. Accordingly, when the UE checks the second timing setting 909, timing is determined according to Embodiments 3-5 or 3-6. For example, if the PDSCH is received in subframe n in the FDD, the subframe is determined. HARQ ACK / NACK information is transmitted over PUCCH or PUSCH at n + 3 (911).

In FIG. 3I, the third timing setting 913 may indicate a case where the minimum signal processing time of the UE is about 1 ms including the TA value. Accordingly, when the UE checks the third timing setting 913, the timing is determined according to Embodiments 3-7 or 3-8. For example, if the PDSCH is received in subframe n in the FDD, the subframe is determined. HARQ ACK / NACK information is transmitted over PUCCH or PUSCH at n + 2 (915). According to the terminal or the base station, it may be possible to support only one of the second timing setting 909 and the third timing setting 913.

[Example 3-9]

Embodiments 3-9 describe timing for controlling power used by the UE for uplink transmission.

A terminal that cannot simultaneously transmit a PUCCH and a PUSCH may calculate a power P _{PUSCH, c} (i) used to transmit a PUSCH to be transmitted to a subframe i in a specific serving cell c as follows.

A terminal capable of simultaneously transmitting a PUCCH and a PUSCH may calculate a power P _{PUSCH, c} (i) used to transmit a PUSCH to be transmitted to a subframe i in a specific serving cell c as follows.

는 P_CMAX,c(i)의 선형 변화된 값이며,

는 PUCCH 전송 전력인 P_PUCCH(i)의 선형변화된 값이다. M_PUSCH,c(i)는 서빙셀 c에서 서브프레임 i에 PUSCH 전송에 사용하도록 할당된 PRB 수이다.

는 상위 시그널링으로 전달된 파라미터들로 만들어지는 값이다. α_c는

값들 중에 하나로 상위에서 전달될 수 있다. P_Lc는 하향링크 패스로스(pathloss) 추정값으로 단말이 계산할 수 있다. In the above equations, P _{CMAX, c} (i) is a set power that the terminal can transmit to subframe i in the serving cell c.

Is the linearly changed value of P _{CMAX, c} (i),

Is a linearly changed value of P _PUCCH (i), which is a PUCCH transmission power. M _{PUSCH, c} (i) is the number of PRBs allocated to use for PUSCH transmission in subframe i in the serving cell c.

Is a value made of parameters passed to higher signaling. α _c is

Can be passed from the parent to one of the values. P _Lc may be calculated by the UE as a downlink pathloss estimate.

는 PUSCH에서 전송되는 제어신호 부분에 따라 결정될 수 있는 값이다. δ_PUSCH.c는 PDCCH 또는 EPDCCH의 DCI 포맷 0/4 혹은 DCI 포맷 3/3A에 포함된 TPC(Transmission Power Control) 명령에 따라 설정될 수 있는 값이며, 이는 하기와 같은 수식에 따라 적용될 수 있다. 누적 전력 계산이 가능하도록 설정된다면

, 누적 설정이 되어있지 않다면

와 같이 계산한다.

Is a value that can be determined according to the control signal portion transmitted in the PUSCH. δ _PUSCH.c is a value that can be set according to a Transmission Power Control (TPC) command included in DCI format 0/4 or DCI format 3 / 3A of PDCCH or EPDCCH, and it can be applied according to the following equation. If the cumulative power calculation is set to be possible

, If the cumulative setting is not

Calculate as

The K _PUSCH determining the timing may be delivered by higher signaling. For example, if the delay reduction terminal is configured to have a minimum signal processing time of 1 ms, the terminal may assume that the K _PUSCH is 2. The K _PUSCH of 2 means that the power of the PUSCH to be transmitted in subframe i is determined according to the power control command transmitted in i-2.

Alternatively, an indicator indicating a K _PUSCH value may be included in a DCI format through which a power control command is transmitted. For example, it can be assumed that K _PUSCH is 2 when the indicator is 0, and K _PUSCH is 3 when the indicator is 1. Information of the K _PUSCH value indicated by the indicator of the DCI format may be mapped in various ways.

Although the above example is based on the FDD system, the value indicated by the TDD may be provided in the following [Table 3-9].

Table 3-9

In TDD UL / DL configuration 1 to 6, K _PUSCH may be determined according to subframe i based on the table. In the case of the TDD UL / DL configuration 0, a method of determining a K _PUSCH value may vary according to embodiments 3-1 to 3-4.

For example, when the TDD UL / DL configuration is 0 in the embodiment 3-1, a PDCCH / EPDCCH in which the MSB of the UL index of the uplink DCI format is 1 is received or a PHICH is received in subframes 1 or 6, When the PHICH is received in the subframe 0 or 5 where the I _PHICH resource is 0, the k value may be determined according to Table 3-5. In addition, when the PDCCH / EPDCCH having the LSB of the UL index of the uplink DCI format is received 1 or the PHICH is received at the position where the I _PHICH resource is 1 in subframe 0 or 5, the k value may be determined as 7. In addition, if the MSB and LSB of the UL index of the uplink DCI format are both 1, in the method of transmitting PUSCH in subframe n + k when k is 7 and when k follows [Table 3-5]. Determination of the K _PUSCH value may be as follows.

In an example of the embodiment 3-1, DCI information for scheduling a PUSCH that can be transmitted in subframes 3 and 8 may be transmitted in subframes 0 or 5 of the corresponding frame, or in subframe 5 or May be passed in zero. Therefore, for power control, it is necessary to specify in which subframe a PUSCH that can be transmitted in subframes 3 and 8 is scheduled.

In the above example, when i is subframe 3 or 8, that is, when PUSCH transmission is transmitted in subframe 3 or 8, the LSB of the UL index portion of DCI format 0 or 4 or other DCI format provided by PDCCH or EPDCCH is If 1, it may be determined as 7.

[Example 3-10]

Embodiment 3-10 describes at what timing a PHICH including HARQ-ACK information according to PUSCH transmission is transmitted. Alternatively, it may be described when the PHICH including HARQ-ACK information received by the UE is associated with the transmitted PUSCH.

The terminal having the delay reduction set may determine that HARQ-ACK information of the PHICH transmitted in the subframe i is related to the PUSCH transmitted in the subframe i-k. For an FDD system, k is given by 3. That is, HARQ-ACK information of the PHICH transmitted in subframe i in the FDD system is related to the PUSCH transmitted in subframe i-3. In the case of the TDD system, when the UE without EIMTA is configured, when only one serving cell is configured or the same TDD UL / DL configuration is used, when the TDD UL / DL configuration 1 is 6, the following [Table 3-10] K can be given.

Table 3-10

That is, for example, in the TDD UL / DL configuration 1, the PHICH transmitted in subframe 6 may be HARQ-ACK information of the PUSCH transmitted in subframe 2 that is 4 subframes before.

If, when TDD UL / DL configuration 0, HARQ-ACK is received with a PHICH resource corresponding to I _PHICH = 0, the PUSCH indicated by the HARQ-ACK information is transmitted in subframe ik and the k value is [ Given in Table 3-4]. In the case of TDD UL / DL configuration 0, if HARQ-ACK is received as a PHICH resource corresponding to I _PHICH = 1, the PUSCH indicated by the HARQ-ACK information is transmitted in subframe i-6. The above-described method will be used as a method of applying a delay reduction terminal capable of n + 3.

Or it may be modified as follows.

The terminal having the delay reduction set may determine that HARQ-ACK information of the PHICH transmitted in the subframe i is related to the PUSCH transmitted in the subframe i-k. For an FDD system, k is given by 2. That is, HARQ-ACK information of the PHICH transmitted in subframe i in the FDD system is related to the PUSCH transmitted in subframe i-2. In the case of the TDD system, when the UE without EIMTA is configured, when only one serving cell or all the same TDD UL / DL configurations are set, when the TDD UL / DL configurations 1 to 6 are as follows, [Table 3-11] K can be given.

Table 3-11

That is, for example, in the TDD UL / DL configuration 1, the PHICH transmitted in subframe 6 may be HARQ-ACK information of the PUSCH transmitted in subframe 3 that is before 3 subframes.

If, when TDD UL / DL configuration 0, HARQ-ACK is received with a PHICH resource corresponding to I _PHICH = 0, the PUSCH indicated by the HARQ-ACK information is transmitted in subframe ik, and the k value is represented in the table above. Is given according to 4. When TDD UL / DL configuration 0, if HARQ-ACK is received as a PHICH resource corresponding to I _PHICH = 1, the PUSCH indicated by the HARQ-ACK information is transmitted in subframe i-3.

Operation methods corresponding to Tables 3-10 and 3-11 may be selectively operated according to higher signaling from a base station.

In the present invention, when referring to the subframe i-k or n-k, when i-k or n-k is less than 0, the subframe i-k or n-k may mean a subframe 10 + i-k or 10 + n-k of the previous radio frame.

In the above, the third to tenth embodiments are configured and used as in the third to third embodiments, the third to second embodiments, the third to third embodiments, or the third to fourth embodiments, and thus are used for uplink data transmission. Can be used to reduce retransmission latency.

[Example 3-11]

Embodiments 3-11 describe a method of determining a timing at which a UE receives a downlink data PDSCH transmission and transmits HARQ ACK / NACK for the PDSCH to an uplink channel such as a PUCCH or a PUSCH. This embodiment may be applied to a case of carrier aggregation, in particular, when a primary cell (Pcell) is a TDD system and a secondary cell (Scell) is FDD. The FDD may correspond to frame structure 1 of LTE, and the TDD may correspond to frame structure 2 of LTE.

HARQ ACK / NACK information of the PDSCH transmitted in subframe n-k is transmitted in subframe n, where k may vary according to TDD UL / DL configuration and subframe position as shown in Table 3-12 below. In the present embodiment, the PDSCH may be a PDSCH scheduled by PDCCH / EPDCCH or a PDSCH configured PDSCH.

Table 3-12

The order of the numbers written in each column of the table may be changed and applied differently.

In the above [Table 3-12], when k values are multiple, it means that HARQ ACK / NACK information for one or more PDSCHs may be transmitted together in subframe n.

Instead of using [Table 3-12], the following [Table 3-13] or [Table 3-14] can be applied.

Table 3-13

Table 3-14

[Table 3-13] can be applied for the purpose of minimizing the delay time, and [Table 3-14] can maintain the number of HARQ-ACK bits transmitted in one subframe similarly. [Table 3-13] and [Table 3-14] can be mixed and applied according to the UL-DL configuration that is a reference, in the UL-DL configuration 6 [Table 3-15] and [Table 3-16] Can be modified and applied in the manner provided.

Table 3-15

Table 3-16

In order to carry out the above embodiments of the present invention, a transmitter, a receiver, and a processor of the terminal and the base station are illustrated in FIGS. 3J and 3K, respectively. The method of transmitting and receiving the base station and the terminal to determine the transmission and reception timing of the second signal and the terminal transmission power and perform the operation according to the embodiment 3-1 to 3-9, and the base station and the The receiver, the processor, and the transmitter of the terminal should operate according to the embodiments.

Specifically, FIG. 3J is a block diagram illustrating an internal structure of a terminal according to an embodiment of the present invention. As shown in FIG. 3J, the terminal of the present invention may include a terminal receiver 1200, a terminal transmitter 1204, and a terminal processor 1202. The terminal receiver 1200 and the terminal collectively referred to as the transmitter 1204 may be referred to as a transceiver in the embodiment of the present invention.

The transceiver of the terminal may transmit and receive signals with the base station. The signal may include control information and data. To this end, the transmitting and receiving unit of the terminal may be composed of an RF transmitter for up-converting and amplifying the frequency of the transmitted signal, and an RF receiver for low-noise amplifying and down-converting the received signal.

Also, the transceiver of the terminal may receive a signal through a wireless channel, output the signal to the terminal processor 1202, and transmit a signal output from the terminal processor 1202 through the wireless channel. The terminal processing unit 1202 may control a series of processes so that the terminal may operate according to the above-described embodiment of the present invention. For example, the terminal receiving unit 1200 may receive a signal including the second signal transmission timing information from the base station, and the terminal processing unit 1202 may control to interpret the second signal transmission timing. Thereafter, the terminal transmitter 1204 transmits the second signal according to the timing.

3K is a block diagram illustrating an internal structure of a base station according to an embodiment of the present invention. As shown in FIG. 3K, the base station of the present invention may include a base station receiver 1301, a base station transmitter 1305, and a base station processor 1303. The base station receiver 1301 and the base station transmitter 1305 may be collectively referred to as a transmitter / receiver.

The transceiver of the base station may transmit and receive signals with the terminal. The signal may include control information and data. To this end, the transceiver unit of the base station may be configured with an RF transmitter for up-converting and amplifying the frequency of the transmitted signal, and an RF receiver for low-noise amplifying and down-converting the received signal.

Also, the transceiver of the base station may receive a signal through a wireless channel, output the signal to the base station processor 1303, and transmit a signal output from the terminal processor 1303 through a wireless channel. The base station processor 1303 may control a series of processes to operate the base station according to the above-described embodiment of the present invention. For example, the base station processor 1303 may determine the second signal transmission timing and control to generate the second signal transmission timing information to be transmitted to the terminal. Thereafter, the base station transmitter 1305 transmits the timing information to the terminal, and the base station receiver 1301 receives a second signal based on the timing.

In addition, according to an embodiment of the present invention, the base station processor 1303 may control to generate downlink control information (DCI) including the second signal transmission timing information. In this case, the DCI may indicate that the second signal transmission timing information.

On the other hand, the embodiments of the present invention disclosed in the specification and drawings are merely presented specific examples to easily explain the technical contents of the present invention and help the understanding of the present invention, and are not intended to limit the scope of the present invention. That is, it will be apparent to those skilled in the art that other modifications based on the technical idea of the present invention can be implemented. In addition, each of the above embodiments can be combined with each other if necessary to operate. For example, a portion of the embodiments 3-1, 3-2, and 3-3 of the present invention may be combined with each other to operate the base station and the terminal. In addition, although the above embodiments are presented based on the LTE / LTE-A system, other modifications based on the technical spirit of the above embodiments may be implemented in other systems such as 5G and NR systems.

Claims (15)

A base station method in a wireless communication system, Determining control information including at least one of symbol position information and symbol number information on a time axis on which a demodulation reference signal (DMRS) is transmitted; Transmitting the control information to a terminal; And And transmitting the DMRS corresponding to the determined control information to the terminal. The method of claim 1, The symbol position information on the time axis includes information on the maximum size of the control channel region set in the transmission unit or information on the start point of the data channel region. The method of claim 1, The symbol number information is one or two, In the case where the symbol number information is two, two symbols are continuous with each other. The method of claim 1, The control information is a base station method, characterized in that included in a Radio Resource Control (RRC) message or Downlink Control Information (DCI). The method of claim 1, When it is determined that the DMRS for the first terminal and the DMRS for the second terminal are transmitted through the same symbol, rate matching is performed on the same symbol among the DMRSs for the first terminal. Base station method. In a base station of a wireless communication system, A transceiver; And A control unit for determining control information including at least one of symbol position information and symbol number information on a time axis on which a DMRS (demodulation reference signal) is transmitted, The control unit, the base station, characterized in that for controlling the transceiver to transmit to the terminal and the DMRS corresponding to the determined control information to the terminal. The method of claim 6, And the symbol position information on the time axis includes information on the maximum size of the control channel region or information about the start point of the data channel region set in the transmission unit. The method of claim 6, The symbol number information is one or two, In the case where the symbol number information is two, the two symbols are continuous with each other. The method of claim 6, The control information base station, characterized in that included in the Radio Resource Control (RRC) message or Downlink Control Information (DCI). The method of claim 6, If the control unit determines that the DMRS for the first terminal and the DMRS for the second terminal transmit through the same symbol, the controller performs rate matching on the same symbol among the DMRSs for the first terminal. A base station characterized in that. A terminal method in a wireless communication system, Receiving control information including at least one of symbol position information and symbol number information on a time axis through which a demodulation reference signal (DMRS) is transmitted from a base station; And And receiving a DMRS corresponding to the determined control information. The method of claim 11, The symbol position information on the time axis includes information on the maximum size of the control channel region set in the transmission unit or information on the start point of the data channel region. The method of claim 11, The symbol number information is one or two, If the symbol number information is two, the terminal method characterized in that the two symbols are continuous with each other. In a terminal of a wireless communication system, A transceiver for receiving control information including at least one of symbol position information and symbol number information on a time axis on which a DMRS (demodulation reference signal) is transmitted from a base station; And And a control unit controlling the transceiver to receive the DMRS corresponding to the determined control information. The method of claim 14, The symbol position information on the time axis includes information about the maximum size of the control channel region or information about the start point of the data channel region set in the transmission unit, The symbol number information is one or two, If the symbol number information is two, the terminal characterized in that the two symbols are continuous with each other.

Images