WO2018070767A1 - Signal transmission method for removing phase noise in wireless communication system and device therefor - Google Patents

Abstract

According to one embodiment of the present specification, a method by which a base station transmits a signal for removing phase noise in an mmWave communication system can be provided, wherein the method for removing phase noise can comprise the steps of: generating a shared PTRS for phase noise of a downlink signal; transmitting, to a terminal, shared PTRS pattern information on the shared PTRS through downlink signaling; and transmitting, to the terminal, the shared PTRS on the basis of the shared PTRS pattern information transmitted to the terminal.

Description

Signal transmission method and apparatus for removing phase noise in wireless communication system

The present disclosure relates to a wireless communication system, and more particularly, to a signal transmission method and apparatus for removing phase noise in a system.

Ultra-high frequency wireless communication systems using millimeter wave (mmWave) are configured such that the center frequency operates at a few GHz to several tens of GHz. Due to the characteristics of the center frequency, path loss may be prominent in the shadow area in the mmWave communication system. Considering that the synchronization signal should be stably transmitted to all terminals located within the coverage of the base station, the mmWave communication system designs and transmits the synchronization signal in consideration of the potential deep-null phenomenon that may occur due to the characteristics of the ultra-high frequency band described above. Should be.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to enable accurate decoding of a received signal by improving a phase noise cancellation process of a terminal in a wireless communication system.

Another object of the present invention is to provide a method for improving the efficiency of signal transmission for phase noise removal.

Another object of the present invention is to provide information on signal transmission for phase noise removal and to improve reception operation.

Another object of the present invention is to provide a method for transmitting a signal for phase noise removal in consideration of the compensation for phase noise and the overhead of a reference signal.

According to one embodiment of the present specification, a method for transmitting a signal for removing phase noise by a base station in an mmWave communication system may be provided. In this case, the method for transmitting a signal for removing phase noise may include generating a shared phase tracking reference signal (PTRS) for the phase noise of the downlink signal, and sharing the shared PTRS pattern information on the shared PTRS through downlink signaling. And transmitting the shared PTRS to the terminal based on the shared PTRS pattern information transmitted to the terminal.

According to one embodiment of the present specification, a base station for transmitting a signal for removing phase noise in an mmWave communication system may be provided. In this case, the base station may include a receiver that receives a signal from an external device, a transmitter that transmits a signal to an external device, and a process of controlling the receiver and the transmitter. In this case, the processor generates a shared PTRS for the phase noise of the downlink signal, transmits the shared PTRS pattern information for the shared PTRS to the terminal through downlink signaling, and based on the shared PTRS pattern information transmitted to the terminal. The shared PTRS can be transmitted to the terminal.

In addition, the following may be commonly applied to a method and apparatus for transmitting a signal for removing phase noise in an mmWave communication system.

According to an embodiment of the present disclosure, further generates a UE-specific PTRS for the phase noise of the downlink signal, further transmits the UE-specific PTRS pattern information for the UE-specific PTRS to the terminal through the downlink signaling, and transmits to the terminal The terminal specific PTRS may be further transmitted to the terminal based on the terminal specific PTRS pattern information.

In this case, according to an embodiment of the present specification, the shared PTRS may be a PTRS shared with another terminal, and the terminal specific PTRS may be a PTRS used only by a specific terminal.

In addition, according to an embodiment of the present specification, the shared PTRS may be set to have different frequency axis and time axis resource positions for each cell.

In this case, according to an embodiment of the present specification, the frequency axis and time axis resource positions may be determined by at least one of radio resource control (RRC) and cell ID (Cell ID).

In this case, according to one embodiment of the present specification, the shared PTRS may have the same precoding as the DeModulation Reference Signal (DMRS) located on the same frequency axis.

In this case, according to one embodiment of the present specification, the shared PTRS may be set to one OFDM symbol on the time axis.

In addition, according to one embodiment of the present specification, the shared PTRS may have different precoding from the DMRS located on the same frequency axis.

In this case, according to an embodiment of the present specification, the shared PTRS may be set to two OFDM symbols on a time axis.

In addition, according to an embodiment of the present disclosure, a plurality of shared PTRS patterns are set in the terminal based on at least one of Radio Resource Control (RRC) and Downlink Control Information (DCI), and the plurality of shared PTRS patterns configured in the terminal Information for selecting any one of these may be additionally set through at least one of RRC and DCI.

[Effects of the Invention]

The present specification may enable accurate decoding of a received signal by improving a phase noise removing process of a terminal in a wireless communication system.

The present disclosure may provide a method for improving the efficiency of signal transmission for phase noise cancellation.

The present specification can improve the reception side operation by providing information on signal transmission for phase noise cancellation.

The present specification may provide a method for transmitting a signal for phase noise removal in consideration of compensation for phase noise and overhead of a reference signal.

Effects obtained in the present specification are not limited to the above-mentioned effects, and other effects not mentioned above may be clearly understood by those skilled in the art from the following description. will be.

1 is a diagram illustrating phase distortion caused by phase noise.

FIG. 2 is a diagram illustrating Block Error Rate (BLER) Performance based on PTRS density in the frequency domain.

3 shows BLER performance based on PTRS density in the time domain.

4 is a diagram showing the spectral efficiency for the PTRS density based on the TRB size of each other.

5 is a diagram illustrating BLER performance based on a carrier frequency offset (CFO).

6 illustrates BLER performance based on the time domain and frequency domain mapping order of PTRS.

7 is a diagram illustrating a pattern to which PTRS is assigned.

8 is a diagram measuring BLER performance based on PTRS.

9 is a diagram measuring BLER performance based on PTRS.

10 is a diagram measuring BLER performance based on PTRS.

11 is a diagram measuring BLER performance based on PTRS.

12 is a diagram illustrating a method of arranging PTRS.

13 is a diagram illustrating different PTRS patterns according to MCS and PRB.

14 is a diagram illustrating a method of allocating PTRS resources.

15 is a diagram illustrating a method of applying precoding of PTRS.

16 illustrates a method of applying precoding of PTRS.

17 illustrates a non-precoding application method of PTRS.

18 is a diagram illustrating performance according to PTRS compensation based on CFO based on MCS.

19 illustrates shared PTRSs set to different types.

20 is a diagram illustrating a method for allocating a terminal specific PTRS.

21 is a diagram illustrating a method for defining and indicating whether a shared PTRS is transmitted as one type.

FIG. 22 is a diagram illustrating a method for arranging a shared PTRS and a terminal specific PTRS. FIG.

23 is a diagram illustrating a shared PTRS allocation method for different cells.

24 is a diagram illustrating a PTRS allocation method based on multi-cell transmission.

25 may be used by all of the shared PTRSs defined on the time axis.

FIG. 26 is a diagram illustrating a method for allocating a shared PTRS only in an OFDM symbol immediately after a DMRS.

27 is a diagram illustrating a method for further allocating a shared PTRS.

28 illustrates a method of allocating a shared PTRS to a DMRS location.

29 is a diagram illustrating a PTRS pattern.

30 is a flowchart illustrating a method for transmitting a signal for removing phase noise by a base station in a communication system.

31 is a diagram illustrating a method of transmitting a shared PTRS and a terminal specific PTRS.

32 is a diagram illustrating a configuration of a terminal and a base station according to an embodiment of the present invention.

The terms used in the present invention have been selected as widely used general terms as possible in consideration of the functions in the present invention, but this may vary according to the intention or precedent of the person skilled in the art, the emergence of new technologies and the like. In addition, in certain cases, there is also a term arbitrarily selected by the applicant, in which case the meaning will be described in detail in the description of the invention. Therefore, the terms used in the present invention should be defined based on the meanings of the terms and the contents throughout the present invention, rather than the names of the simple terms.

The following embodiments combine the components and features of the present invention in a predetermined form. Each component or feature may be considered to be optional unless otherwise stated. Each component or feature may be embodied in a form that is not combined with other components or features. In addition, some of the components and / or features may be combined to form an embodiment of the present invention. The order of the operations described in the embodiments of the present invention may be changed. Some components or features of one embodiment may be included in another embodiment, or may be replaced with corresponding components or features of another embodiment.

In the description of the drawings, procedures or steps, which may obscure the gist of the present invention, are not described, and procedures or steps that can be understood by those skilled in the art are not described.

Throughout the specification, when a portion is said to "comprising" (or including) a component, this means that it may further include other components, except to exclude other components unless otherwise stated. do. In addition, the “…” described in the specification. Wealth ”,“… The term “unit”, “module”, etc. refer to a unit that processes at least one function or operation, which may be implemented by hardware, software, or a combination of hardware and software. Also, “a” or “one”, “the” and similar related terms are not intended to be altered herein in the context of describing the present invention (particularly in the context of the following claims). Unless otherwise indicated or clearly contradicted by context, it may be used in the sense including both the singular and the plural.

In the present specification, embodiments of the present invention have been described based on data transmission / reception relations between a base station and a mobile station. Here, the base station is meant as a terminal node of a network that directly communicates with a mobile station. The specific operation described as performed by the base station in this document may be performed by an upper node of the base station in some cases.

That is, various operations performed for communication with a mobile station in a network consisting of a plurality of network nodes including a base station may be performed by the base station or network nodes other than the base station. In this case, the 'base station' may be replaced by terms such as a fixed station, a Node B, an eNode B (eNB), an advanced base station (ABS), or an access point.

In addition, a 'mobile station (MS)' may be a user equipment (UE), a subscriber station (SS), a mobile subscriber station (MSS), a mobile terminal, an advanced mobile station (AMS), a terminal. (Terminal) or a station (STAtion, STA) and the like can be replaced.

Also, the transmitting end refers to a fixed and / or mobile node that provides a data service or a voice service, and the receiving end refers to a fixed and / or mobile node that receives a data service or a voice service. Therefore, in uplink, a mobile station may be a transmitting end and a base station may be a receiving end. Similarly, in downlink, a mobile station may be a receiving end and a base station may be a transmitting end.

In addition, the description that the device communicates with the 'cell' may mean that the device transmits and receives a signal with the base station of the cell. That is, a substantial target for the device to transmit and receive a signal may be a specific base station, but for convenience of description, it may be described as transmitting and receiving a signal with a cell formed by a specific base station. Similarly, the description of 'macro cell' and / or 'small cell' may not only mean specific coverage, but also 'macro base station supporting macro cell' and / or 'small cell supporting small cell', respectively. It may mean 'base station'.

Embodiments of the present invention may be supported by standard documents disclosed in at least one of the wireless access systems IEEE 802.xx system, 3GPP system, 3GPP LTE system and 3GPP2 system. That is, obvious steps or parts which are not described among the embodiments of the present invention may be described with reference to the above documents.

In addition, all terms disclosed in the present document can be described by the above standard document. In particular, embodiments of the present invention may be supported by one or more of the standard documents P802.16e-2004, P802.16e-2005, P802.16.1, P802.16p, and P802.16.1b standard documents of the IEEE 802.16 system. have.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. The detailed description, which will be given below with reference to the accompanying drawings, is intended to explain exemplary embodiments of the present invention and is not intended to represent the only embodiments in which the present invention may be practiced.

In addition, specific terms used in the embodiments of the present invention are provided to help the understanding of the present invention, and the use of the specific terms may be changed to other forms without departing from the technical spirit of the present invention.

Phase Noise Analysis and Phase Tracking Reference Signal Design (PTRS) Design

1 is a diagram illustrating phase distortion caused by phase noise. Phase noise may be a fluctuation that occurs over a short period of time with respect to the phase of the signal. At this time, the phase noise may randomly change the phase in the time domain of the received signal, which may interfere with signal reception. For example, referring to FIG. 1A, phase noise may occur randomly. However, the phase noise may have a constant correlation with a common phase error (CPE) for an adjacent time sample and intercarrier interference (ICI) in the frequency domain.

At this time, Figure 1 (b) shows the effect on the CPE and ICI at the received constellation point. In this case, all constellation points in the rectangle “A” of FIG. 1B may be rotated by 3 degrees based on the CPE. In addition, constellation points may be randomly distributed on the circle “B” based on the ICI. That is, the compensation for the CPE may be required based on the phase noise. To this end, a PTRS (Phase Tracking Reference Signal) for CPE estimation may be used, and Table 1 below may be a simulation condition value for phase noise.

TABLE 1

Based on Table 1, we can determine the effect of PTRS on CPE estimation by varying the number of Traffic RBs.

2 illustrates a block error rate (BLER) performance based on the PTRS density of the frequency domain. More specifically, FIGS. 2 (a) and 2 (b) may be diagrams of BLER performance measured while changing the PTRS density to 0, 1, 4, 8, and 16 in the frequency domain of an OFDM symbol. In this case, “PTRS = 0” may be a state without CPE compensation, and “Ideal” may be a state where CEP compensation is performed. FIG. 2 (a) shows BLER performance while changing PTRS density in the frequency domain when 4TRB, and FIG. 2 (b) shows BLER performance while varying PTRS density in the frequency domain when 64TRB. to be.

Comparing Fig. 2 (a) and Fig. 2 (b) it can be seen that the BLER performance according to the PTRS density is much different as the TBR size increases. Specifically, in FIG. 2 (a) where the TRB size is small, it can be seen that the BLER performance without the CPE compensation differs only by 1 dB from the BLER performance on which the CPE compensation is performed based on PTRS = 8. On the other hand, in FIG. 2 (b) where the TRB size is large, it can be seen that the BLER performance without the CPE compensation is larger than that of the BLER performing the CPE compensation based on PTRS = 8 to 5.8 dB.

In addition, referring to FIG. 2 (b), it can be seen that as the PTRS density increases, the BLER performance ideally converges based on CPE compensation. More specifically, when the PTRS is 4 or more in FIG. 2 (b), the BLER performance may converge in a rational state, and sufficient CPE compensation may be performed when the PTRS density is 4 or 8. In this case, as an example, sufficient CPE compensation is performed when the PTRS density is 4 or 8 in both FIGS. 2 (a) and 2 (b). When the PTRS density is 4 or 8 regardless of the TRB size, sufficient CPE compensation is obtained. Can be performed.

As another example, FIG. 3 illustrates BLER performance based on the PTRS density in the time domain.

FIG. 3 may be a result of measuring BLER performance by changing PTRS intervals in the time domain. In FIG. 3, the number of PTRSs in one OFDM may be 4. Referring to FIG. 3, it can be seen that results similar to those of FIG. 2 appear. More specifically, it can be seen that as the TRB size increases, the difference due to PTRS density in the time domain increases. That is, when the TRB size is small (4TRBs in FIG. 3), the BRS performance may be similar without being significantly influenced by the PTRS density in the time domain. On the other hand, when the TRB size is large (64 TRBs in FIG. 3), it can be seen that the BLER performance greatly varies according to the PTRS density in the time domain. That is, the BLER performance difference due to the PTRS density may change sensitively as the TRB size increases.

4 is a diagram showing the spectral efficiency for the PTRS density based on the TRB size of each other.

4 (a) is a diagram illustrating spectral efficiency according to the number of PTRS when the TRB size is 4; In this case, referring to FIG. 4 (a), when the TRB size is 4, it can be seen that the case where the CPE compensation is not performed has more efficient spectral efficiency than the case where the CPE compensation is performed based on a certain number of PTRSs. . In this case, when the TRB size is 4, only one code block may be defined and used in the codeword, and the code block is spread in the subframe, thereby reducing the influence on the phase noise. This may be similar to that in FIG. 2 (a), which does not significantly affect CPE compensation when the TRB size is small. On the other hand, when the number of PTRSs increases, the size of information increases, so that a loss in throughput may occur based on the portion of the PTRS allocation. In this case, the throughput loss may be larger than the CPE compensation at a small TRB size, and thus PTRS may be unnecessary.

On the other hand, referring to Figure 4 (b), when the TRB size is 64 it can be seen that the ideal spectral efficiency as the number of PTRS increases. This is because, when the TRB size is large, a plurality of code blocks may be defined in one codeword, and each code block may be spread in one or two OFMB symbols, which may have a large effect on phase noise. That is, when high phase noise occurs in a specific OFDM symbol, the decoding failure rate for the code block located in the specific OFDM symbol can be increased. This may be similar to FIG. 2 (b). In other words, the larger the TRB size, the greater the influence of phase noise and the smaller the overhead for PTRS. As the number of PTRSs increases, throughput may improve.

FIG. 4 (c) is a diagram illustrating the influence of PTRS density change based on the time domain, and may be similar to FIG. 3. In other words, when the TRB size is small, the PTRS time density does not significantly affect the throughput. However, when the TRB size is large, the throughput may be greatly changed according to the PTRS time density, which may be similar to the above.

5 is a diagram illustrating BLER performance based on a carrier frequency offset (CFO).

As mentioned above, PTRS may be unnecessary if the TRB size is small. However, even if the TRB size is small, PTRS may be required based on the oscillator error and the CFO by the Doppler. In this case, referring to FIG. 5, even when the TRB size is small as 4, when the CFO = 1.4 kHz, the BLER performance may be reduced. At this time, the CFO between the base station and the terminal may be ± 0.1ppm, the maximum CFO may be 3kHz at 30GHz. In other words, in the case of using a high frequency, the CFO can greatly affect the BLER performance. Therefore, there is a need to determine the number of PTRS in consideration of the trade-off CPE compensation and PTRS overhead, which will be described later.

6 illustrates BLER performance based on the time domain and frequency domain mapping order of PTRS.

FIG. 6 is a diagram illustrating a case where PTRS is first mapped in the time domain and a case where the PTRS is mapped first in the frequency domain. In this case, referring to FIG. 6, it can be seen that the case where PTRS is first mapped in the time domain has better BLER performance than when the PTRS is first mapped in the frequency domain. This is based on the above-described ICI. When the code block is spread in the time domain, the influence on the phase noise is reduced. A graph as shown in FIG. 6 may be displayed. This indicates that code block spreading can be effective in reducing phase noise in the time domain, as will be described later.

2. PTRS design considering MCS level

As described above, it is necessary to use PTRS in consideration of the effect of phase noise. At this time, it is necessary to allocate the PTRS to consider the overhead of the reference signal as described above.

7 is a diagram illustrating a pattern to which PTRS is assigned. In this case, referring to FIG. 7, the pattern 1 may have a time period of 1, the pattern 2 may have a time period of 2, and the pattern 3 may have a time period of 3. That is, pattern 1 may be a pattern in which PTRS is allocated at the highest density in the time domain, and pattern 3 may be a pattern in which PTRS is allocated at the lowest density in the time domain. In this case, Table 2 below may be a simulation setup configuration for confirming the effect of each PTRS pattern on the performance degradation. For example, in Table 2, CFO 7 may be randomly selected from -3kHz to 3kHz. In addition, the modulation and code rate may be set to QPSK (1/2), 16QAM (3/4), and 64QAM (5/6).

TABLE 2

8 to 11 are diagrams of measuring the BLER performance based on the above-described Table 2, through which the influence on the PTRS can be seen.

In this case, as an example, FIG. 8 (a) shows the effect of frequency offset on the BLER performance in the absence of phase noise. Referring to FIG. 8 (a), in the absence of CFO compensation, the performance of the BLER is deteriorated despite the low MCS level QPSK (1/2). On the other hand, when there is CFO compensation, the performance of the BLER can be maintained. That is, even if the MCS level is low, CFO compensation can affect BLER performance.

Also, as an example, FIG. 8B is a diagram showing the effect of phase noise on the BLER performance in the absence of a frequency offset. At this time, it can be seen that BLER performance is improved through CPE compensation at 64QAM (5/6), which is a high MCS level. However, it can be seen that the same BLER performance appears in the 16QAM (3/4) with a low MCS level, with or without CPE compensation. In other words, the effect of phase noise on ER performance may be higher in MCS.

9 is a diagram showing the effect on BLER performance when both frequency offset and phase noise are present. At this time, it can be seen that BLER performance is greatly changed according to different PTRS patterns. That is, in the case where both the frequency offset and the phase noise exist, whether or not the BLER performance deteriorates depending on the pattern of the PTRS.

10 is a diagram illustrating spectral efficiency based on MCS. 10 (a) and 10 (b), in the QPSK (1/2) and 16QAM (3/4), all of the patterns 1, 2, and 3 in FIG. 7 described above have high spectral regardless of the PRB size. You can see that it has efficiency. That is, as described above, the effect on the phase noise can be neglected at a low MCS level, and thus may have a high spectral efficiency. At this time, as an example, in FIG. 10A, the PRB size is small, and considering the overhead of the reference signal, the PRB may have a higher spectral efficiency in the pattern 3, as described above.

11 is a diagram illustrating spectral efficiency based on MCS. In this case, referring to FIG. 11A, in the 4PRB, all of the patterns 1, 2, and 3 in FIG. 7 may have high spectral efficiency regardless of the PRB size. That is, as described above, the effect on the phase noise can be neglected at a low MCS level, and thus may have a high spectral efficiency. In this case, for example, in FIG. 11A, since the PRB size is small, considering the overhead of the reference signal, it may have a relatively high spectral efficiency in the pattern 3, as described above.

On the other hand, referring to Figure 11 (b), it can be seen that 64QAM (5/6) and 32 PRB has a high spectral efficiency in the patterns 1 and 2 of FIG. This is because 32PRB has a plurality of code blocks defined in one codeword, and each code block is spread in one or two OFDM symbols, and thus may have a large effect on phase noise. That is, when the transmission is performed based on the high level of the MCS and the large PRB size, it may be more affected by the phase noise, as described above.

In this case, as an example, PTRS may be used when each UE performs uplink transmission. However, when a plurality of terminals exist as UL MU-MIMO, an overhead of a reference signal may increase when the number of terminals increases. Therefore, it is necessary to determine whether to use PTRS in consideration of the overhead of the reference signal at a low MCS level and a small PRB size.

 As another example, in downlink transmission, signals (ex, PSS, SSS) or channels (ex, PBCH) that are repeatedly transmitted are designed, and thus the CFO may be estimated before data reception. Therefore, in consideration of the high MCS level and the large PRB size, the pattern for PTRS can be set and used before data reception, and is not limited to the above-described embodiment.

Proposition 1 (fixed number of PTRS frequency axes)

Referring to the drawings, it can be seen that the siege for BLER performance is close to an ideal case curve when the number of PTRS frequency axes is 4 or 8. That is, the number of frequency axes of the PTRS may be determined regardless of the number (or magnitude) of the TRBs. Therefore, the number of frequency axes of the PTRS can be fixed to a specific value regardless of the number of TRBs.

More specifically, when defining the number of frequency axes of the PTRS as N, N may be determined based on the following method.

1. Determined to be 4 or 8, regardless of the number of TRBs (N can be defined as a rule in the spec)

2. The number of N can be informed through RRC and / or DCI.

That is, the number of frequency axes of the PTRS is a predetermined specific value, which may be determined and used as 4 or 8. As another example, the number of PTRS frequency axes may be informed in advance through RRC or DCI. In this case, the above-described methods may be used in consideration of the overhead of PTRS as a reference signal.

12 is a diagram illustrating a method of arranging PTRS. For example, in FIG. 12, the number of frequency axes of the PTRS may be four. In this case, the PTRS may be arranged through distributed or localized. For example, the variance may uniformly design a frequency interval between PTRSs in a given TRB. In addition, localization may mean placing PTRS adjacent to a center or a specific position of a given TRB.

In this case, as an example, the base station may signal the RRC and / or RRC to the UE for the above-described arrangement. Also, as an example, one form may be defined as a predefined placement method (one form may be defined as a rule in spec). In addition, the uplink transmission may be signaled by being included in the control information, or a predefined arrangement method may be used, and the present invention is not limited to the above-described embodiment.

As another example, the number of frequency axes of the PTRS may be set differently in consideration of the number (or size) of TRBs. This allows the ICI generated by the CFO to reduce the CFO and CPE estimation performance. At this time, as shown in the above-described drawings, as the number of TRBs increases, the estimated performance decrease may significantly reduce the BLER performance. However, as the number of TRBs increases, overhead for the reference signal may decrease, and thus, the estimation performance may be improved by allocating more PTRSs on the frequency axis. That is, the number of frequency axes of the PTRS may be determined based on the number of TRBs in consideration of the decrease in BLER performance and the reference signal overhead of the PTRS. For example, the number of PTRS may be defined as shown in Table 3 below. At this time, according to Table 3, when the number (or size) of TRBs is less than or equal to N, the number of PTRSs on the frequency axis may be set to M1. On the other hand, when the number of TRBs is greater than N, the PTRS on the frequency side may be set to the M2 value. In this case, as an example, the reference TRB number may be eight. In addition, as an example, M1 may be 4 and M2 may be 8, but is not limited to the above-described embodiment, and may be determined as a specific value.

In addition, as an example, the above-described N, M1, M2 may be set through the RRC and / or DCI. In addition, as an example, the above-described N, M1, M2 may be set and used as a predetermined value may be determined as a rule in spec).

TABLE 3

Proposal 2 (PTRS time axis spacing varies with TRB size)

The spectral efficiency may vary depending on the time axis interval of the PTRS, as described above.

More specifically, it can be seen that when the TRB size is 4 in FIG. 3, the spectral efficiency is better when the interval is 2 than when the interval is 1. On the other hand, when the TRB size is 64, the spectral efficiency of the interval 1 is better than that of the interval 2. That is, as described above, when the TRB size is small, the overhead of the reference signal may have a larger throughput loss than the CPE compensation gain, and thus the influence of the reference signal overhead may be large. On the other hand, when the TRB size is large, the overhead of the reference signal may be reduced, whereas the CPE compensation gain may be large, and thus the spectral efficiency may be good.

In this case, as an example, the time axis interval of the PTRS may be defined as shown in Table 4 below. More specifically, when the TRB size is less than or equal to N, the PTRS time interval may be defined as M1. On the other hand, when the TRB size is larger than N, the PTRS time interval may be defined as M2. At this time, M1 may be greater than M2. For example, M1 may be 2 and M2 may be 1. Also, as an example, N may be eight.

That is, when the TRB size is small, the PTRS time interval may be longer in consideration of the overhead of the PTRS. On the other hand, when the TRB size is large, the PTRS time interval can be shortened in consideration of CPE compensation.

In addition, as an example, the above-described N, M1, M2 may be set through the RRC and / or DCI. In addition, as an example, the above-described N, M1, M2 may be set and used as a predetermined value may be determined as a rule in spec).

TABLE 4

As another example, the time interval of PTRS may be determined by further considering a code rate (CR) and a modulation order (MO). That is, the time axis interval of PTRS may be determined by TRB size, CR (Code Rate) and MO (Modulation Order).

In this case, in FIG. 4 (c), MO = 64QAM and code rate = 5/6. As an example, when the MO and / or CR increases, the PTRS time interval may be reduced from 2 to 1. In consideration of MO and CR, Table 4 may be modified as shown in Table 5.

In addition, as an example, “If CR <= M (e.g. 5/6)” in Table 5 may be set based on the MO, and is not limited to the above-described embodiment. That is, the PTRS time interval may be set even if the TRB size is small when the MO and / or CR becomes large, and is not limited to the above-described embodiment.

TABLE 5

As another example, PTRS may be used for CFO estimation. In this case, the base station may determine the PTRS time interval and signal the terminal. In addition, as an example, when only CFP estimation is performed, PTRS time intervals are already promised (or preset) to the transmitter and the receiver, and only on / off may be signaled through DCI when necessary.

As a specific embodiment of the time interval arrangement of PTRS, FIG. 13 is a diagram showing different PTRS patterns according to MCS and PRB.

More specifically, FIG. 13 illustrates a case in which PTRS patterns are defined according to different MCSs and PRBs, and patterns 1-3 may correspond to the following 1-3 conditions. On the other hand, the following mapping scheme may be set to the terminal by the RRC, DCI and / or rule.

At this time, in relation to the following conditions, pattern 1 may have the shortest interval, and pattern 3 may have the longest interval. That is, when the MCS level is high and the PRB size is large, the time interval of the PTRS can be shortened. On the other hand, even if the MCS level is high, if the PRB size is small, the time interval of the PTRS can be made longer. In addition, if the MCS level is low and the PRB size is small, the time interval of the PTRS may be set to be the longest. That is, the time interval of PTRS can be reduced as the PRB size and MCS level information increases, as described above. Through this, the TRB pattern may be set differently according to the MCS level and the PRB size, and each pattern may be defined in consideration of the overhead of PTRS.

1.High MCS (e.g. # 26) + large PRB (e.g. 32PRBs): Pattern 1

2.High MCS (e.g. # 26) + middle PRB (e.g. 8PRBs): Pattern 2

3.Low MCS (e.g. # 16) or small PRB (e.g. 4PRBs): Pattern 3

Proposition 3 (PTRS by TRB Size Mapping  Way)

The PTRS mapping method may be determined according to the TRB size. That is, any one of a time priority mapping method and a frequency priority mapping method may be determined according to the TRB size. For example, referring to FIG. 5, when data is mapped according to a time first mapping method, the data is more robust to phase noise than frequency first mapping. That is, it can be less affected by phase noise.

For example, as described above, when the TRB is small, only one code block is defined in the codeword. As a result, even if frequency first mapping is performed, time first mapping is performed. It may be the same as the effect.

On the other hand, when the TRB size is large, a time first mapping or a code spreading method based on a time axis can obtain a large performance gain. Therefore, when the TRB size increases, it is necessary to consider the PTRS mapping method, which may be as shown in Table 6 below.

That is, when the TRB size is smaller than or equal to N, data may be mapped according to a frequency-priority mapping method. On the other hand, when the TRB size is larger than N, data may be mapped based on a time-priority mapping method, a time domain code spreading method, or the above-described Inter-CB interleaving, and is not limited to the above-described embodiment.

Also, for example, N may be 8. In this case, N may be another value and may be defined as a preset value (it may be defined as a rule in spec). Also, as an example, N may be determined by DCI and / or RRC, and is not limited to the above-described embodiment.

Meanwhile, a service in which decoding latency is very important, such as ultra-reliable and low latency communications (URLLC), may always be mapped through a frequency-priority mapping scheme irrespective of N described above.

In addition, when the CR or MO is lowered, performance degradation due to the frequency-priority mapping scheme may be reduced. Thus, as an example, the above-described N may be determined in consideration of the TRB size, CR and / or MO, and is not limited to the above-described embodiment.

TABLE 6

Proposal 4 (method for determining whether to send PTRS)

The presence or absence of the PTRS may be determined by the TRB size, base station capability and / or terminal capability.

In this case, as an example, in FIG. 4A, the spectral efficiency is higher than that in which the PTRS is not transmitted is transmitted.

On the other hand, as shown in FIG. 5, when CFO = 1.4 kHz, communication itself may fail when no PTRS is transmitted. In this case, the CFO is a capability of the terminal and the base station, and may occur differently according to an oscillator. That is, when the CFO is very small because the capabilities of the terminal and the base station are very good, when the TRB size is small, it is possible to obtain high spectral efficiency by not transmitting PTRS.

That is, not only the TRB size, but also the capability of the terminal and the capability of the base station may be a determining factor in the presence or absence of PTRS transmission. To this end, the terminal may transmit related information (e.g. oscillator, movement or speed) to the base station to its CFO. In this case, the base station may determine whether the PTRS transmission (or transmission) using the information received from the terminal and its capability information, and is not limited to the above-described embodiment.

In the above description, the density of the PTRS on the frequency and time axis has been described, and the method of arranging the PTRS will be described below.

Proposition 5 (PTRS resource allocation and Precoding  Way)

The PTRS resource may be defined based on an RB index and / or a symbol index. In this case, the defined one or more PTRS resources may be configured for the UE through RRC and / or DCI. The selected PTRS resource may be signaled to the terminal through the DCI.

In more detail, FIG. 14 is a diagram illustrating a method of allocating PTRS resources. In this case, referring to FIG. 14, there may be a plurality of PTRS resource sets. For example, FIG. 14 shows three PTRS resource sets. In this case, resource 1 may be a resource set in which PTRS is defined in both A and B areas. On the other hand, resource 2 may be a resource set in which PTRS is defined only in area A, and resource 3 is defined in PT area only in area B. In this case, each PTRS resource set may be indicated as a resource block index and / or a symbol index, and through this, it may indicate a resource set in which each PTRS is defined.

In this case, as an example, the above-described PTRS resource set may be set to the terminal as RRC. That is, information on a resource set selectable by the terminal may be set through RRC. Thereafter, the base station may signal a PTRS resource currently operating to the terminal through the DCI. That is, information on the selectable resource set may be set through the RRC, and resources used among the selectable resource sets may be indicated through the DCI.

For example, when the resource block of the A region is allocated to the UE and PTRS resource 3 is configured, the UE may perform CPE estimation using the PTRS resource in the A region of the UE.

As another example, when PTRS resource 2 is configured for the UE, the CPE may be estimated using the PTRS resource in the B region.

As another example, when PTRS resource 1 is configured, the UE may perform more accurate CPE estimation using all PTRS resources in both A and B regions.

Meanwhile, the base station may define a subframe as PTRS resource 2 and may be allocated a resource block of the B region in a state where the UE does not need CPE compensation. At this time, the base station informs the corresponding terminal of the PTRS resource to the DCI, the terminal may determine the location of the PTRS through this and may not process it as a data resource element. At this time, if the terminal is allocated a resource block of the A region, the base station does not need to inform the DCI of the currently defined PTRS resources. That is, the base station may signal information on the PTRS resource to the terminal through the DCI in consideration of the selected PTRS resource set and the resource block region allocated to the terminal, but is not limited to the above-described embodiment.

Proposition 5-1

In relation to the proposal 5 described above, when the PTRS resource is arranged, the PTRS precoding may follow the precoding of the DMRS of the corresponding resource block.

More specifically, referring to FIG. 15, in the above-described PTRS resource 1, the PTRS resource located in the A region may follow DMRS precoding in the A region, and the PTRS resource located in the B region may perform the precoding of the DMRS in the B region. Can follow. That is, as described above, the PTRS resource set may be set based on the resource block index, so that the unnecessary delay may be prevented by following the precoding applied to the DMRS in each resource block.

In this case, as an example, the terminal 1 may be allocated an area A and the terminal 2 may be allocated an area B. In this case, the precoding of the PTRS defined in the A region and the B region may be the same as the precoding of the DMRS in each region. For example, when the terminal 1 receives the PTRS support 1, it may be recognized that there is a PTRS in the B region, and more accurate CPE estimation may be performed using this. That is, even if the terminal 1 is allocated the A region, it can be seen that the PTRS is located in the B region by the PTRS resource 1 and can perform the CPE estimation using the same.

On the other hand, when setting the PTRS resource 2 to the terminal 2, the terminal 2 can not know that there is a PTRS in the A region. That is, the terminal 2 is defined only in the B region, the PTRS resource 2 is a resource set in which the PTRS exists only in the B region, and the terminal 2 may perform CPE estimation using only the PTRS defined in the B region.

Proposition 5-2

The proposal 5-1 described above may be the same as or different from the precoding of the A region and the B region according to the DMRS precoding (ie, if the DMRS precoding of the A region and the B region is the same. The same precoding can be applied to each other)

In contrast, in FIG. 16A, precoding of the A region and the B region may be defined differently regardless of DMRS precoding. This allows different precodings to be defined in the PTRS by differently precoding the A region and the B region, thereby obtaining a spatial diversity gain in the CPE estimation. That is, different precodings may be applied to each PTRS of each region regardless of DMRS precoding.

As another example, in FIG. 16B, the PTRS may replace some resource elements of the DMRS. In this case, the CPE estimation performance is excellent between the second symbol and the third symbol, but the DMRS channel estimation performance may be partially reduced. That is, the reference signal may be determined in consideration of gains that are preferred as trade-off relations with respect to PTRS and DMRS resource allocation. At this time, if the phase noise has a large influence on the throughput, and if the CPE estimation is important, the DMRS may be allocated instead of the PTRS as described above.

Proposal 5-3

Unlike the above, all PTRS can be defined as non-precoding. In this case, as an example, the PTRS of the A region and the B region may be received with the same beam gain. That is, in the case where CPE estimation is performed through PTRS with all beam gains equal in an environment affected by phase noise, PTRS may be defined as non-precoding and may be allocated as shown in FIG. 22. . In addition, as an example, in FIG. 17, non-precoded PTRS may also replace some of the DRMS resource elements as described above, and is not limited to the above-described embodiment.

In this case, the precoding scheme may be set to RRC for the above-mentioned proposals. In addition, as an example, as described above, when the PTRS resource is configured through the RRC, information on a specific method among the precoding schemes for the above-described proposals 5-1 to 5-3 may be set through the RRC. And it is not limited to the above-described embodiment.

That is, the terminal may obtain information on the PTRS resource configuration and the precoding method of the PTRS from the base station, and is not limited to the above-described embodiment.

Proposal 6 Shared PTRS  And UE dedicated PTRS (UE dedicated PTRS)

For the above-described PTRS, the PTRS may be classified into a shared PTRS (UE) and a UE-specific PTRS (UE-dedicated PTRS).

In more detail, the base station may set one or more shared PTRS patterns to the terminal as RRC and / or DCI. In addition, one of the set PTRS patterns may be selected, and the RRC and / or DCI may be informed to the UE. In addition, the base station may inform the terminal of the terminal specific PTRS to the terminal through the RRC and / or DCI. That is, the shared PTRS and the terminal specific PTRS may be distinguished and used.

18 is a diagram illustrating performance according to PTRS compensation based on CFO based on MCS. Referring to Figure 18, when the CFO is 3kHz, the performance of the compensation with and without PTRS is shown based on the MCS # 9, 15 and 24. In this case, when CFO compensation is not performed with PTRS in FIG. 18, the BLER becomes 1 regardless of the MCS level. For example, in FIG. 18, when the MCS level is 9, the BLER according to the presence or absence of compensation is described. However, even when the MCS level is high, the BLER may be 1 if there is no compensation.

At this time, with respect to the phase noise, jitter occurring on the time axis may appear as phase noise on the frequency axis. This phase noise randomly changes the phase of the received signal on the time axis as shown in Equation 1 below.

[Equation 1]

파라미터들은 각각 수신 신호, 시간 축 신호, 주파수 축 신호, 위상 잡음으로 인한 위상 회전(phase rotation) 값을 나타낼 수 있다. 수학식 1에서의 수신 신호가 DFT(Discrete Fourier Transform) 과정을 거치는 경우, 아래의 수학식 2가 도출될 수 있다.At this time, in Equation 1

The parameters may indicate a phase rotation value due to the received signal, the time axis signal, the frequency axis signal, and the phase noise, respectively. When the received signal in Equation 1 undergoes a Discrete Fourier Transform (DFT) process, Equation 2 below may be derived.

[Equation 2]

파라미터들은 각각 CPE 및 ICI를 나타낼 수 있다. 이때, 위상 잡음 간의 상관관계가 클수록 수학식 2의 CPE 가 큰 값을 갖게 된다. 이러한 CPE는 무선랜 시스템에서의 CFO의 일종이지만, 단말 입장에서는 위상 잡음이라는 관점에서 CPE와 CFO를 유사하게 해석할 수 있다.In equation (2)

The parameters may indicate CPE and ICI, respectively. At this time, the larger the correlation between phase noise, the larger the CPE of Equation (2). The CPE is a kind of CFO in the WLAN system, but from the viewpoint of the terminal, the CPE and the CFO can be similarly interpreted.

At this time, referring to FIG. 18, when the CFO is 3 kHz, PTRS needs to be defined for CFO estimation even at a low MCS level. Also, as an example, the CFO may have the same value in one subframe (for a short time). That is, even when considering PTRS overhead, estimating the CFO using PTRS can increase the throughput when the CFO needs to be estimated.

In this case, referring to FIG. 19, the shared PTRS may be set to different types. For example, FIG. 19 illustrates a shared PTRS type 1 and a shared PTRS type 1. In this case, three PTRSs may be allocated to the PTRS type 1 on the time axis, and six PTRSs may be allocated to the PTRS type 2 on the time axis.

In this case, the shared PTRS may be a reference signal that can be used by all terminals that receive the shared PTRS. For example, when resource A is configured for terminal A1, terminal A1 may also use PTRS defined in resource B. In this case, the PTRS is mainly used for CFO estimation, so that the interval can be widened on the time axis.

In addition, the base station may set both a shared PTRS type 1 and a shared PTRS type 2 pattern to the terminal through the RRC, and may signal that one of them is available to the terminal through the RRC and / or DCI.

As another example, only one shared PTRS type may be set. At this time, the base station may be on / off through the RRC and / or DCI transmission for one PTRS type, it is not limited to the above-described embodiment.

Also, as an example, FIG. 20 illustrates a method for allocating a terminal specific PTRS.

Referring to FIG. 20, the shared PTRS type 1 may be used in FIG. 19. At this time, for example, MCS # 26 is set to A1 terminal allocated to resource A, while MCS # 16 is set to terminal B1 allocated to resource B and MCS # 9 may be set to terminal C1 allocated to resource C.

In the above situation, since the C1 terminal has a low MCS level and is hardly influenced by phase noise, the C1 terminal may compensate by performing CFO estimation using only shared PTRS. On the other hand, the A1 / B1 terminal is greatly affected by the phase noise, so that the base station can estimate the UE-specific PTRS pattern 1 and the UE-specific PTRS pattern 2 to the A1 / B1 UE, respectively. dedicated PTRS with pattern 2) can be transmitted. In this case, the base station may signal the pattern to the terminal using RRC and / or DCI.

That is, in FIG. 20, the shared PTRS type may be configured for each UE through RRC, and the UE-specific PTRS may be signaled through RRC and / or DCI in consideration of each UE.

As another example, UE-specific PTRS may be allocated implicitly according to MCS level and / or TRB size. In this case, although the terminal does not have separate signaling, each terminal may determine that the terminal specific PTRS pattern 1 and the terminal specific PTRS pattern 2 are transmitted.

For example, it may be set that pattern 2 and pattern 1 are transmitted in MCS # 16 and # 26 in each terminal, respectively. In addition, as an example, the UE may be set to transmit the pattern 2 and the pattern 1 when the TRB sizes are # 4 and # 32. However, the above-described MCS level and TRB size may be one example, and the above-described value may be set differently. (The mapping relationship described above can be determined by a rule in the spec or can be configured in RRC.)

If the TRB size is small or the MCS level is small, the PTRS density can be made small because of the small effect on the phase noise. That is, UE-specific PTRSs having different time densities may be used according to MCS level or TRB size. This may also be configured to the terminal in RRC and / or DCI. It may also be implicitly determined according to MCS level or TRB size.

As another example, only one type of UE-specific PTRS may be defined, and only on / off may be determined depending on the TRB size or the MCS level. This may also be indicated by the aforementioned RRC and / or DCI or implicitly, and is not limited to the above-described embodiment.

As another example, FIG. 21 illustrates a method of defining and indicating whether a shared PTRS is transmitted as one type. That is, it can be defined as one type each that the shared PTRS is sent or that the shared PTRS is not sent in all OFDM symbols, each of which can be set to one type based on FIG. 19 described above. In this case, as an example, a type in which the shared PTRS is not transmitted may be set as a type set through RRC in FIG. 19. In this case, information on one type may be signaled to the terminal through RRC and / or DCI.

As another example, the case where only one shared PTRS type is used as described above may be similarly applied. That is, one shared PTRS type and one that does not have a shared PTRS type may be one type, which may be set through RRC. In addition, it may indicate whether transmission on or off through the RRC and / or DCI, as described above.

At this time, based on the above-described 19 to 21, each terminal may be assigned an appropriate PTRS in consideration of the situation. For example, in the case of the C1 terminal described above, since the CFO can be sufficiently estimated and compensated using sparse PTRS, the reference signal overhead of the C1 terminal can be minimized.

On the other hand, the A1 terminal may have a large overhead of the reference signal, but may overcome the CPE using PTRS. At this time, the CFO can be estimated using the shared PTRS, and the CPE and the CFO can be estimated using the UE-specific PTRS. That is, PTRS may be allocated differently in consideration of the situation of each terminal.

In addition, as an example, shared PTRS signaling may be intermittently signaled to the terminal through RRC. Through this, unnecessary signaling can be minimized. For example, when using a low MCS, such as the C1 terminal described above, it is not necessary to set a separate terminal specific PTRS to the DCI, it is possible to reduce unnecessary signaling by intermittent signaling.

In addition, referring to FIG. 22, the shared PTRS and the terminal specific PTRS may be arranged in a different form from the above-described method. In this case, referring to FIG. 22, the PTRS-S1 and the PTRS-U may be a shared PTRS and a terminal specific PTRS, respectively. As an example, when DMRS-1 and DMRS-2 assume the same phase source, the UE may perform CPE estimation for every OFDM symbol using PTRS-S1.

In this case, as an example, when the terminal is allocated only the C region and different precodings are applied to the C region and the D region, the corresponding terminal may not obtain sufficient estimation performance from PTRS-S2 in the D region. Accordingly, the terminal may additionally configure PTRS-U to increase PTRS estimation performance.

As another example, when the DM-RS2 comes from another transmission reception point (TRP), the phase source may be different. Therefore, a separate PTRS needs to be defined for this. At this time, the above-described PTRS-U may perform a separate PTRS role considering the DM-RS2.

That is, when sufficient estimation performance is not obtained through PTRS-S1 or a separate PTRS is required, PTRS-U may be allocated and used.

Proposition 6-1 (How Shared PTRS Works)

Shared PTRS can be operated on a periodic, semi-persistent and aperiodic basis. In this case, the operating method of the shared PTRS may be set through RRC and / or DCI.

More specifically, when periodically operating the shared PTRS, the base station may inform the terminal of the shared PTRS type (eg PTRS time axis / frequency axis pattern, period) through the cell specific RRC (eg SIB). . As an example, the shared PTRS may be defined cell specific. The UE checks the location and period of the shared PTRS based on the information obtained through the cell-specific RRC, and performs CFO and CPE estimation through this. That is, the shared PTRS may be always transmitted based on a predetermined position and period as cell specific information.

In addition, as an example, the base station may change the location and period of the shared PTRS through the SIB. In this case, the base station may signal information implicitly or explicitly changed to the terminal. For example, the explicit signaling may mean informing the UE whether the SIB is changed through separate signaling. On the other hand, implicit signaling may mean that the UE checks the SIB periodically to determine whether the change is made. That is, the information on the shared PTRS may be indicated to the terminal based on the change.

As another example, shared PTRS can be used semi-permanently. In this case, the base station may inform the terminal of at least one shared PTRS type through UE specific or cell specific RRC. Thereafter, the base station informs the terminal of one shared PTRS type and transmission through the terminal specific RRC and / or DCI.

In this case, as an example, in case of transmission (enable, by activation signaling), the shared PTRS may continue to be periodically transmitted until there is no separate signaling (by deactivation signaling).

In this case, the difference from the above-described periodic shared PTRS transmission may be a configuration in which the shared PTRS transmission is determined through RRC and / or DCI. This allows the base station to operate the shared PTRS flexibly with minimal overhead.

That is, in periodic shared PTRS transmission, RRC configure shared PTRS may be periodically transmitted regardless of activation / deactivation, and the UE may determine that the shared PTRS is periodically transmitted. On the other hand, the shared PTRS transmitted semi-permanently is determined whether it is active or inactive. Based on this, any one of the shared PTRS types indicated through the RRC may be determined to perform shared PTRS transmission.

As another example, the shared PTRS may be transmitted aperiodically. More specifically, the periodic, semi-permanent shared PTRS transmission described above can reduce throughput. Accordingly, in order to minimize throughput reduction, the base station may inform aperiodic information about the shared PTRS type and / or whether the PTRS is transmitted through the DCI.

At this time, as an example, information on the PTRS type may be previously set to RRC in order to minimize CI overhead. That is, only when PTRS transmission is necessary, the base station may signal the base station whether the PTRS transmission is performed and information on the determined PTRS type through the DCI aperiodically. As a result, throughput reduction can be minimized as described above.

However, in the case of aperiodic transmission, the DCI overhead may increase, and may be selectively used during the periodic, semi-permanent, and aperiodic transmission described above in consideration of the system, and is not limited to the above-described embodiment.

Proposal 6-2 (PTRS allocation information indication method when a plurality of terminals are allocated to the same resource)

In connection with the above-described PTRS allocation, a plurality of terminals may be allocated in the same resource. That is, two or more terminals may be allocated in the same resource. In this case, as an example, when it is necessary to allocate the terminal specific PTRS to at least one or more terminals of the plurality of terminals, the base station may signal that the terminal specific PTRS has been allocated to all the terminals configured in the same resource.

In more detail, as an example, terminals A1 and B1 may be allocated to resource A in FIG. 19. In this case, the case where the MCS level for the A1 terminal is MCS # 26 and the MCS # 9 for the B1 terminal may be considered. That is, the MCS level of one terminal may be high and the MCS level of another terminal may be low, and the present invention is not limited to the above-described specific value.

At this time, the PTRS-U may be allocated to the A1 terminal in consideration of the high MCS level. The B1 terminal may not use the resource element allocated with the PTRS-U for the A1 terminal for data transmission and reception. Therefore, the base station needs to signal that the PTRS-U is allocated not only to the A1 terminal but also to the B1 terminal. In this case, as an example, the base station may signal that the PTRS-U has been transmitted to the above-described A1 and B1 terminals through RRC and / or DCI. Through this, the B1 terminal can be prevented from transmitting and receiving data through the resource element to which the PTRS-U is allocated.

Proposition 6-3 (Share of PTRS Precoding  Way)

As described above, the precoding of the PTRS is described in the case of following the DMRS, the case of applying independent precoding, and the case in which non-precoding is applied. In this case, the same may be applied to the shared PTRS as described above. That is, the precoding of shared PTRS may be defined as following the DMRS. As another example, the shared PTRS may use separate precoding. As another example, the shared PTRS may apply non-precoding, and the method of FIGS. 15 to 17 described above may be equally applied to the shared PTRS.

As another example, the above-described shared PTRS may be set for each cell. At this time, the shared PTRS for each cell may be set differently from each other in the frequency axis and time axis resources. In this case, as an example, the frequency axis and time axis resource positions of the shared PTRS may be determined using at least one of an RRC and a cell ID, which will be described later.

Also, as an example, the shared PTRS may have the same precoding as the DMRS located on the same frequency axis. In this case, the shared PTRS may be defined in one OFDM symbol.

As another example, the shared PTRS may have different precoding from the DMRS located on the same frequency axis. In this case, as an example, the shared PTRS may be defined in two OFDM symbols on a time axis, which will be described later.

As another example, when a plurality of shared PTRS patterns are configured in the terminal, the shared PTRS patterns may be set based on at least one of RRC and DCI. In this case, information for selecting any one of the plurality of shared PTRS patterns set in the terminal may be additionally set through at least one of RRC and DCI.

Proposition 7 (How to define shared PTRS in different cells)

In connection with the allocation of the shared PTRS, there is a need to design the shared PTRS of adjacent cells so that they do not overlap each other. More specifically, FIG. 23 is a diagram illustrating a shared PTRS allocation method for different cells. In this case, in FIG. 23, cell A and cell B may each be assigned with a cell (or terminal) specific shared PTRS. In this case, the PTRS may be power boosted, and the shared PTRSs of adjacent cells may be designed not to overlap each other. Through this, the influence on the PTRS of the adjacent cell can be reduced.

In this case, as an example, the base station may define a shared PTRS at a location different from the neighboring base station, and set the RRC. At this time, overhead due to signaling may additionally occur, but there is a need to set the location of the shared PTRS for each cell in consideration of the influence of neighboring cells.

As another example, similarly to the CRS, the location of the shared PTRS may be determined based on a cell ID. As an example, the frequency axis offset position may be determined as the cell ID% 12.

As a specific example, when the cell IDs of the cell A / B are 126/127, respectively, the position of the frequency axis offset of the cell A / B may be 6/7. In this case, FIG. 23 may be a diagram in which each shared PTRS is allocated in consideration of the aforementioned frequency axis offset position. At this time, the base station cannot set the shared PTRS location, but no separate signaling is required for this, and the overhead due to signaling may be reduced.

As another example, the aforementioned cell may be replaced with a TRP. For example, when different TRPs belong to one cell (ie, when a plurality of TRPs share one cell ID), each shared PTRS location of the above-described TRPs is configured to the UE through RRC and / or DCI. It may be, but is not limited to the above-described embodiment.

As another example, FIG. 24 may illustrate a PTRS allocation method based on multi-cell transmission. For example, referring to FIG. 24, UE A1 may receive resource C. In this case, cell A may be a serving cell, and cell B may be a non-serving cell. At this time, the A1 terminal may use all PTRS-S2-Cell A defined in the cell A. On the other hand, PTRS-S2-Cell B of cell B may use only shared PTRS defined in resource C. That is, the A1 terminal may not use PTRS-S2-Cell B defined in resource D. That is, all of the shared PTRS for the serving cell may be used, but the shared PTRS for the non-serving cell may be limitedly used only for the allocated resource region.

In this case, as an example, the PTRS-U-Cell B may be additionally allocated to the UE in consideration of performance degradation due to the above-described constraints of the shared PTRS. That is, by additionally allocating terminal specific PTRS for cell B, performance degradation can be overcome. In this case, as an example, PTRS-U Cell B may be allocated to the UE through RRC and / or DCI.

As another example, FIG. 25 illustrates that the shared PTRSs are all defined on the time axis. That is, in FIG. 24 described above, the configuration of the shared PTRS and the additional UE-specific PTRS allocated to the multi-cell may be the same, but PTRS may be defined on all time axes in order to efficiently perform CPE estimation. . In this case, when allocating PTRS in all time axes, a phase change may be estimated for every OFDM symbol, and may be advantageous for CPE estimation and compensation.

That is, the PTRS is utilized in consideration of the multi-cells and the time axis PTRS density may be set differently in consideration of the CPE estimation performance, and is not limited to the above-described embodiment.

Proposition 8 (Method of positioning time axis of shared PTRS in different cells)

Different cells may have a shared PTRS time axis position immediately after the DMRS. In this case, as an example, when the same precoding as the DMRS is used, only one line may be defined as the shared PTRS.

More specifically, in FIG. 23 and FIG. 24 described above, the shared PTRS may be disposed in OFDM symbols at regular intervals. In this case, if the shared PTRS is used only for CFO estimation, it may be defined only in the third OFDM symbol, which is the next symbol after DMRS.

In this case, FIG. 26 illustrates a method in which a shared PTRS is allocated only in an OFDM symbol immediately after a DMRS. Referring to FIG. 26, it may be sufficient that the shared PTRS is defined only in the third OFDM symbol if it is used only for CFO estimation. In this case, the precoding of the shared PTRS may follow the precoding of the adjacent DMRS.

That is, when PTRS is used only for CFO estimation, the shared PTRS may be allocated only in the OFDM symbol immediately after the DMRS in consideration of the overhead of the reference signal. In addition, as an example, the same precoding as the precoding of the DMRS may be applied to the PTRS in consideration of the decoding delay.

That is, when the same precoding as the DMRS is applied to the shared PTRS, the shared PTRS may be allocated and used only in the OFDM symbol immediately after the DMRS, and is not limited to the above-described embodiment. In this case, as an example, in the case where the regions of C and D use different precodings in FIG. 26, the terminal allocated the region C may not obtain sufficient energy for phase tracking from the PTRS of the region D. It can be applied differently according to each situation.

Proposition 9 (Method for determining time axis position of shared PTRS in different cells)

As in FIG. 26, the shared PTRS time axis positions of different cells may be located immediately after the DMRS. In this case, as an example, when the shared PTRS uses different precoding from the DMRS or is non-precoding, the shared PTRS may be defined in two lines on the time axis.

More specifically, referring to FIG. 27, when the shared PTRS uses different precoding from the DMRS of the same subcarrier or when non-precoding is applied, the shared PTRS may be additionally allocated for phase tracking. That is, if the shared PTRS and the DMRS use different precodings or non-precodings are applied, additional PTRSs for phase estimation may be needed even if the PTRS overhead is considered. In this case, for example, in the above-described situation, a shared PTRS may be defined in two adjacent OFDM symbols. That is, the shared PTRS may be allocated in the two OFDM symbols following the DMRS.

As another example, in the case of non-precoding, a terminal allocated to the C region may not have a penalty for energy even when using the shared PTRS of the D region. Therefore, it may be applied differently in consideration of each case.

As another example, referring to FIG. 28, a shared PTRS may be defined at a DMRS location. That is, as described above, even if the channel estimation performance of the DMRS is reduced in consideration of the overhead of the reference signal, the shared PTRS for phase estimation may be allocated. Through this, channel estimation performance for DMRS may be reduced, but overhead for shared PTRS may be reduced, and the present invention is not limited to the above-described embodiment.

Meanwhile, as an example, the UE-specific PTRS may be allocated to the OFDM symbol following the DRMS. That is, the PTRS allocated to the DMRS location may be a shared PTRS.

Proposition 10 (PTRS Determination Method Considering Terminal Performance)

The terminal may transmit a parameter related to its phase noise generation level to the base station to the RRC. The base station may determine the PTRS pattern or transmission with reference to the parameter sent by the terminal.

More specifically, the phase noise generation level may mean “value of quantized signal to interference ratio (SIR) for phase noise” of a corresponding UE, or simply indicate whether there is a presence such as “no phase noise / with”. .

For example, when the oscillator of the terminal is not good, the phase noise is greatly generated, and there is a need to correct it for performance. In this case, the base station may allocate the PTRS to the corresponding terminal for the above-described correction (in the downlink, the base station may transmit the PTRS to the terminal, and in the uplink, the terminal may transmit the PTRS to the base station).

On the other hand, if the oscillator (oscillator) of the terminal is good, since there is no performance degradation due to phase noise, the PTRS defined by the base station to the terminal may rather serve to reduce the throughput. Therefore, in this case, the base station may not define PTRS to the corresponding terminal in consideration of the throughput gain.

That is, the terminal feeds back its own information related to the phase to the base station, and the base station may determine whether to transmit the PTRS. As another example, the base station may determine the PTRS resource set type based on the information transmitted by the terminal, which is not limited to the above-described embodiment.

As another example, even when the terminal feedbacks that there is no phase noise, if the base station defines the PTRS in the DCI, the terminal may estimate the CPE using the PTRS in the downlink. In the uplink, the terminal may transmit the PTRS to the base station.

Proposition 11 (Method of Determining PTRS Pattern)

As mentioned above, the PTRS pattern may be determined based on TRB size, CR and / or MO, as described above. In this case, as an example, the pattern of PTRS may be a time axis period.

At this time, FIG. 29 is a diagram illustrating a PTRS pattern. When the TRB size is small, even if the CR and MO are high, the pattern 2 or 3 can be selected in FIG. 29. As an example, the phase difference between OFDM symbols for which no PTRS is transmitted may be calculated using a value obtained between OFDM symbols for transmitting PTRS.

In detail, the phase of the fourth OFDM symbol of the pattern 3 may be obtained by using the phase difference between the third OFDM symbol and the seventh OFDM symbol. In this case, the seventh OFDM symbol needs to be received in order to calculate the channel value of the fourth OFDM symbol. However, this may be a problem in an application or a service in which delay is an important problem, and the PTRS pattern may be determined in consideration of this. In addition, as an example, in the case of pattern 1, since the PTRS is allocated on all time axes, there may be no delay problem described above.

In the case of services or applications where delay is important, PTRS can be assigned to all time axes as pattern 1 even if the TRB size is small.

That is, the PTRS pattern may be determined in consideration of the TRB size, CR, and MO as well as the service type (problem of delay), and is not limited to the above-described embodiment.

30 is a flowchart illustrating a method for transmitting a signal for removing phase noise by a base station in a communication system.

The base station may generate a shared PTRS. (S3010) In this case, as described above with reference to FIGS. 1 to 29, the base station may generate a shared PTRS that can be shared by all terminals. In addition, as an example, the UE-specific PTRS may be generated in consideration of the TRB size, the CR and the MO, and the like, and are not limited to the above-described embodiment. In addition, as an example, although described with reference to the base station in FIGS. 1 to 29, the same may be applied to the terminal. That is, subjects that operate according to whether the link is uplink or downlink may be different and are not limited to the above-described embodiment.

Next, the base station may transmit shared PTRS pattern information for the shared PTRS to the terminal through downlink signaling (S3020). As described above with reference to FIGS. 1 to 29, for example, the terminal may include a plurality of shared PRTSs. The pattern can be set. In this case, the base station may transmit shared PTRS pattern information indicating that one shared PTRS pattern of the plurality of shared PTRS patterns set in the terminal can be applied to the terminal. As another example, only one piece of shared PTRS pattern information may be configured in the terminal. In this case, the shared PTRS pattern information may be information indicating whether the shared PTRS is transmitted. That is, the shared PTRS pattern information may be information about on / off.

Next, the base station may transmit the shared PTRS to the terminal based on the shared PTRS pattern information transmitted to the terminal (S3030). As described above with reference to FIGS. 1 to 29, the shared PTRS transmitted by the base station to the terminal is It may be a PTRS shared to all terminals. In this case, the terminal specific PTRS may be further allocated in consideration of the MCS level or the TRB size applied to the terminal, as described above.

31 is a diagram illustrating a method of transmitting a shared PTRS and a terminal specific PTRS.

The base station may generate a PTRS. (S3110) In this case, the configuration of the base station to generate the PTRS may be the same as in FIG.

Next, it may be determined whether an additional PTRS is required based on phase noise in a specific terminal (S3120). As described above with reference to FIGS. 1 to 30, whether additional PTRS is required may be differently applied to each terminal. . For example, it may be determined that an additional PTRS is required for a terminal that is greatly affected by phase noise. In this case, as an example, the base station may signal that the terminal needs additional PTRS using DCI and / or RRC. In this case, as an example, the above-described shared PTRS type may be configured through the RRC, and the pattern of the UE-specific PTRS may be signaled through the DCI and / or the RRC, and is not limited to the above-described embodiment.

Another example. Whether additional PTRS is needed may be implicitly indicated based on MCS level, TRB size. That is, it may be indicated that additional PTRS is required without additional signaling based on the MCS level or TRB size applied to the terminal.

Next, when additional PTRS is required, shared PTRS pattern information for the shared PTRS and terminal specific PTRS pattern information for a specific terminal may be transmitted through downlink signaling. (S3130) In this case, the method described above with reference to FIGS. As one may, a terminal specific PTRS may be added based on the phase noise. In this case, the terminal specific PTRS is a configuration applied to the terminal unit, and may be a PTRS transmitted to a specific terminal, as described above.

Next, the shared PTRS and the terminal specific PTRS may be transmitted to the specific terminal based on the shared PTRS pattern information and the terminal specific PTRS pattern information, as described above with reference to FIGS. 1 to 30.

In addition, when additional PTRS is not required, shared PTRS pattern information on the shared PTRS may be transmitted to the terminal through downlink signaling. (S3150) In addition, the shared PTRS is transmitted based on the shared PTRS pattern information transmitted to the terminal. In other words, as described above with reference to FIGS. 1 to 30, when the additional PTRS is not required in consideration of phase noise, the UE-specific PTRS may not be allocated. May be the same.

Device configuration

32 is a diagram illustrating a configuration of a terminal and a base station according to an embodiment of the present invention. In FIG. 31, the terminal 100 and the base station 200 may include radio frequency (RF) units 110 and 210, processors 120 and 220, and memories 130 and 230, respectively. Although FIG. 32 illustrates only a 1: 1 communication environment between the terminal 100 and the base station 200, a communication environment may also be established between a plurality of terminals and a plurality of base stations. In addition, the base station 200 illustrated in FIG. 32 may be applied to both the macro cell base station and the small cell base station.

Each RF unit 110, 210 may include a transmitter 112, 212 and a receiver 114, 214, respectively. The transmitting unit 112 and the receiving unit 114 of the terminal 100 are configured to transmit and receive signals with the base station 200 and other terminals, and the processor 120 is functionally connected with the transmitting unit 112 and the receiving unit 114. In connection, the transmitter 112 and the receiver 114 may be configured to control a process of transmitting and receiving signals with other devices. In addition, the processor 120 performs various processes on the signal to be transmitted and transmits the signal to the transmitter 112, and performs the process on the signal received by the receiver 114.

If necessary, the processor 120 may store information included in the exchanged message in the memory 130. With such a structure, the terminal 100 can perform the method of various embodiments of the present invention described above.

The transmitter 212 and the receiver 214 of the base station 200 are configured to transmit and receive signals with other base stations and terminals, and the processor 220 is functionally connected to the transmitter 212 and the receiver 214 to transmit the signal. 212 and the receiver 214 may be configured to control the process of transmitting and receiving signals with other devices. In addition, the processor 220 may perform various processing on the signal to be transmitted, transmit the signal to the transmitter 212, and may perform processing on the signal received by the receiver 214. If necessary, the processor 220 may store information included in the exchanged message in the memory 230. With such a structure, the base station 200 may perform the method of the various embodiments described above.

Processors 120 and 220 of the terminal 100 and the base station 200 respectively instruct (eg, control, coordinate, manage, etc.) the operation in the terminal 100 and the base station 200. Respective processors 120 and 220 may be connected to memories 130 and 230 that store program codes and data. The memories 130 and 230 are coupled to the processors 120 and 220 to store operating systems, applications, and general files.

The processor 120 or 220 of the present invention may also be referred to as a controller, a microcontroller, a microprocessor, a microcomputer, or the like. The processors 120 and 220 may be implemented by hardware or firmware, software, or a combination thereof.

When implementing an embodiment of the present invention using hardware, application specific integrated circuits (ASICs) or digital signal processors (DSPs), digital signal processing devices (DSPDs), and programmable logic devices (PLDs) configured to perform the present invention. Field programmable gate arrays (FPGAs) may be provided in the processors 120 and 220.

In the case of an implementation by firmware or software, the method according to the embodiments of the present invention may be implemented in the form of a module, a procedure, or a function that performs the functions or operations described above. The software code may be stored in a memory unit and driven by a processor. The memory unit may be located inside or outside the processor, and may exchange data with the processor by various known means.

The detailed description of the preferred embodiments of the invention disclosed as described above is provided to enable any person skilled in the art to make and practice the invention. Although the above has been described with reference to the preferred embodiments of the present invention, those skilled in the art will variously modify and change the present invention without departing from the spirit and scope of the invention as set forth in the claims below. I can understand that you can. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein. In addition, while the above has been shown and described with respect to preferred embodiments of the present specification, the present specification is not limited to the specific embodiments described above, the technical field to which the invention belongs without departing from the spirit of the present specification claimed in the claims. Of course, various modifications can be made by those skilled in the art, and these modifications should not be individually understood from the technical spirit or prospect of the present specification.

In the present specification, both the object invention and the method invention are described, and the description of both inventions may be supplementarily applied as necessary.

The above description can be applied to various wireless communication systems including not only 3GPP LTE and LTE-A systems, but also IEEE 802.16x and 802.11x systems. Furthermore, the proposed method can be applied to mmWave communication system using ultra high frequency band.

Claims (20)

In the mmWave communication system, a base station transmits a signal for removing phase noise, Generating a shared phase tracking reference signal (PTRS) for phase noise of the downlink signal; Transmitting shared PTRS pattern information for the shared PTRS to a terminal through downlink signaling; And And transmitting the shared PTRS to the terminal based on the shared PTRS pattern information transmitted to the terminal. The method of claim 1, Generating a UE specific PTRS (UE dedicated PTRS) for phase noise of the downlink signal; And Transmitting terminal specific PTRS pattern information for the terminal specific PTRS to the terminal through the downlink signaling; And And transmitting the terminal specific PTRS to the terminal based on the terminal specific PTRS pattern information transmitted to the terminal. The method of claim 2, The shared PTRS is a PTRS shared with another terminal, The terminal specific PTRS is a PTRS used only by the terminal. The method of claim 1, The shared PTRS has a frequency axis and time axis resource position set differently for each cell. The method of claim 4, wherein The frequency axis and time axis resource position is determined by at least one of Radio Resource Control (RCC) and Cell ID (Cell ID). The method of claim 4, wherein The shared PTRS has the same precoding as a DeModulation Reference Signal (DMRS) located on the same frequency axis. The method of claim 6, The shared PTRS is set to one OFDM symbol on the time axis. The method of claim 4, wherein The shared PTRS has a different precoding than DMRS located on the same frequency axis. The method of claim 8, The shared PTRS is set to two OFDM symbols on the time axis. The method of claim 1, A plurality of shared PTRS patterns are set in the terminal based on at least one of Radio Resource Control (RRC) and Downlink Control Information (DCI), Information for selecting any one of the plurality of shared PTRS patterns set in the terminal is additionally set via at least one of RRC and DCI. A base station transmitting a signal for removing phase noise in an mmWave communication system, A receiver which receives a signal from an external device; A transmitter for transmitting a signal to an external device; And A processor for controlling the receiver and the transmitter; The processor, Generate a shared phase tracking reference signal (PTRS) for the phase noise of the downlink signal, Transmitting shared PTRS pattern information for the shared PTRS to a terminal through downlink signaling, and And transmitting the shared PTRS to the terminal based on the shared PTRS pattern information transmitted to the terminal. The method of claim 11, The processor, Generating a UE specific PTRS (UE dedicated PTRS) for phase noise of the downlink signal; Further transmitting terminal specific PTRS pattern information for the terminal specific PTRS to the terminal through the downlink signaling, and The base station further transmits the terminal specific PTRS to the terminal based on the terminal specific PTRS pattern information transmitted to the terminal. The method of claim 12, The shared PTRS is a PTRS shared with another terminal, And the terminal specific PTRS is a PTRS used only by the terminal. The method of claim 11, The shared PTRS is a base station, the frequency axis and time axis resource positions are set differently for each cell. The method of claim 14, The frequency axis and time axis resource position is determined by at least one of Radio Resource Control (RCC) and Cell ID (Cell ID). The method of claim 14, The shared PTRS has the same precoding as the DeModulation Reference Signal (DMRS) located on the same frequency axis. The method of claim 16, The shared PTRS is set to one OFDM symbol on the time axis. The method of claim 14, The shared PTRS has a different precoding than DMRS located on the same frequency axis. The method of claim 18, The shared PTRS is set to two OFDM symbols on the time axis. The method of claim 1, A plurality of shared PTRS patterns are set in the terminal based on at least one of Radio Resource Control (RRC) and Downlink Control Information (DCI), Information for selecting any one of the plurality of shared PTRS patterns set in the terminal is additionally set via at least one of RRC and DCI.

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