CN102036301B - Method and device for transmitting downlink demodulation reference signals of relay link and relay system - Google Patents

Abstract

The invention discloses a transmission method, device and relay system for a downlink demodulation reference signal of a relay link. The method maps the demodulation reference signal on a time-frequency two-dimensional resource, wherein the demodulation reference signal is a non- The precoded reference signal is used for coherent demodulation of the downlink data transmission of the relay link. The present invention solves the transmission problem of the demodulation reference signal of the relay link, ensures the reliability of the data transmission of the relay link, and does not It affects terminals in the same cell while reducing the overhead and design complexity of demodulation reference signals.

Description

Relay link downlink demodulation reference signal transmission method, device and relay system

technical field

The present invention relates to the field of wireless communication, in particular, to a transmission method, device and relay system of a relay link downlink demodulation reference signal (Demodulation Reference Signal, DMRS for short).

Background technique

At present, the development requirement of mobile communication is to support higher transmission rate, better signal coverage and higher resource utilization. In order to meet the requirements of high transmission rate, the next generation mobile communication system will use higher frequency bandwidth to transmit signals, and higher frequency bandwidth will bring greater path loss at the same time, affecting network coverage. The relay (Relay) technology can not only increase the coverage and balance and increase the throughput of the cell, but also the relay node (Relay Node, RN for short) has a relatively small configuration cost compared with the base station, therefore, the relay technology is regarded as It is a key technology in the Long Term Evolution (LTE for short) evolution technology of 3GPP (the 3rd Generation Partnership Project, referred to as 3GPP)-LTE-Advanced (LTE-A for short) system.

The LTE/LTE-A system is based on Orthogonal Frequency Division Multiplexing (OFDM for short) technology. In OFDM systems, communication resources are in the form of time-frequency two dimensions. For example, in an LTE system, communication resources are divided in units of frames in the time direction, and each radio frame (radioframe) has a length of 10 ms and includes 10 sub-frames (sub-frames) with a length of 1 ms. As shown in Figure 1. According to the length of the cyclic prefix (Cyclic Prefix, CP for short), each subframe may contain 12 or 14 OFDM symbols. In the frequency direction, resources are divided in units of sub-carriers. Specifically, in communication, the smallest unit of resource allocation is a resource block (Resource Block, RB for short), which corresponds to a physical resource block (Physical RB) of physical resources. , referred to as PRB). One PRB includes 12 subcarriers in the frequency domain. A resource corresponding to one subcarrier on each OFDM symbol is called a resource element (Resource Element, RE for short).

After the introduction of the relay station, it is equivalent to one more hop for data transmission. Taking the two-hop system as an example, the original base station-terminal communication mode has changed to the base station-relay station-terminal communication mode, in which the base station-relay station link is called Relay link (backhaul link), relay station-terminal link is called access link (access link), base station-terminal link is called direct link (direct link). In the multi-hop system, some terminals are connected to the relay station, and the communication service is completed through the relay station. After introducing the relay station, it is necessary to ensure the backward compatibility of the terminal, that is, to ensure that the terminal of the previous version (such as LTE Release-8, referred to as Rel-8) can also be connected to the relay station. On the premise of communication, a part of resources is allocated to ensure the communication between the base station and the relay station.

Taking the LTE-A system as an example, the current LTE-A system determines that the base station-relay station communication and relay station-terminal communication are performed in a time-division manner. Specifically, a part of the downlink subframe is used for base station-relay station communication. These subframes It is called a relay (Relay) subframe. For the Rel-8 terminal under the relay station, the Relay subframe is indicated as an MBSFN (Multicast Broadcast Single Frequency Network, MBSFN for short) subframe, so that the Rel-8 terminal can skip these subframes , while completing the base station-relay station communication, the backward compatibility for the Rel-8 terminal is guaranteed. In the LTE-A system, the structure of the Relay subframe is shown in FIG. 2 .

In the Relay subframe, the RN sends control information to the subordinate terminal in the first 1 or 2 OFDM symbols, and then receives the downlink data information of the relay link from the base station after the switching time interval from the sending state to the receiving state, and then The transition interval for switching from the receive state to the transmit state elapses. In the present invention, only the effective resources transmitted from the base station to the relay station in the Relay subframe will be concerned. In the Relay subframe, it will include the traffic channel (Relay-Physical Downlink Shared Channel, R-PDSCH for short), the control channel (Relay-Physical Downlink Control Channel, R-PDCCH for short) from the base station to the relay station, and possible broadcast channels ( Relay-Physical BroadcastChannel, referred to as R-PBCH) and so on. The reliable transmission of the above channels must be based on the support of the corresponding demodulation reference signal.

In the LTE-A system, considering the characteristics of the channel and resource structure of the downlink transmission of the relay link, the corresponding DMRS transmission method will be different from that of the direct transmission link. The relay link downlink control data, such as the relay physical downlink control channel (R-PDCCH), and the data in the relay link physical broadcast channel (R-PBCH), may be cell-specific for the relay station ( cell-specific), cannot perform precoded transmission, then the precoded DMRS discussed in LTE-A will not be suitable for demodulation of these channels.

At the same time, since the overhead of the common reference signal (cell-specific reference signal, CRS for short) of the LTE system is relatively large and the efficiency is relatively low, the LTE-A system will support the use of MBSFN subframes to transmit unicast services. Since there is no CRS in the multicast domain of the MBSFN subframe, if the base station uses the MBSFN subframe to transmit data to the relay station, the relay station will have no available reference signal for data demodulation under the current technology.

On the other hand, in the LTE-A system, the number of antenna ports of the base station may be up to 8. When transmit diversity is used to transmit data, the diversity gain will not be improved significantly with the increase of the diversity order, but since the diversity order corresponds to the corresponding reference signal port, that is, the increase of the diversity order will lead to the corresponding DMRS The increase in the number of ports will also lead to an increase in the overhead of the reference signal and the complexity of the design. This is also a problem that needs to be solved in the relay link. At the same time, in the transmit diversity transmission mode, the receiving end needs to know the number of transmit ports of the demodulation reference signal, so as to determine the corresponding reference signal pattern for data demodulation.

Compared with diversity transmission to improve the reliability of data transmission, multiplexing transmission can improve system capacity. In the space division multiplexing transmission mode, it is equivalent to multiplexing and transmitting data of multiple layers on the same time-frequency resource, and the data of multiple layers is pre-coded before being mapped. The specific number of multiplexed layers is determined according to the rank of a multiple-input multiple-output (Multi-InputMulti-Output, MIMO for short) channel.

At present, in the discussion of 3GPP LTE-A related technologies, the discussion of relay link downlink DMRS and related issues has not yet started, and no effective solution has been proposed yet.

Contents of the invention

The present invention is proposed for the problem that there is no processing scheme for the relay link downlink demodulation reference signal in the related discussions of 3GPP LTE-A. Therefore, the main purpose of the present invention is to provide a relay link downlink demodulation reference signal transmission scheme to solve the above problems.

In order to achieve the above purpose, according to one aspect of the present invention, a method for transmitting a relay link downlink demodulation reference signal is provided.

The transmission method of the relay link downlink demodulation reference signal according to the present invention includes: mapping the demodulation reference signal on time-frequency two-dimensional resources, wherein the demodulation reference signal is a non-precoded reference signal for relay Coherent demodulation of link downlink data transmission.

Preferably, the relay link downlink data includes at least one of the following: relay link downlink control data, relay link physical broadcast channel data, and relay link physical downlink shared channel data, wherein the relay link The downlink control data includes at least one of the following: data of the physical downlink control channel of the relay link, downlink control format indication information of the relay link, and downlink hybrid automatic repeat transmission indication information of the relay link.

Preferably, the time-frequency two-dimensional resources include physical resource blocks allocated for transmitting downlink data in the frequency direction.

Preferably, the time-frequency two-dimensional resources include OFDM symbols carrying relay link downlink data in a downlink relay subframe in the time direction.

Wherein, the position of the subcarrier mapped in the physical resource block by the demodulation reference signal is adjusted according to the physical cell identification number.

Wherein, the position of the OFDM symbol to which the demodulation reference signal is mapped is fixed in the physical resource block.

Wherein, the position of the OFDM symbol mapped to the demodulation reference signal is adjusted according to the system bandwidth, or the position of the OFDM symbol mapped to the demodulation reference signal is adjusted according to the difference of OFDM symbols occupied by the relay link downlink data.

Preferably, the demodulation reference signal corresponds to a port for relay link downlink data transmission or a layer association for relay link downlink data transmission.

Preferably, in the transmit diversity transmission mode, the demodulation reference signal is associated with a port for relay link downlink data transmission, wherein when the relay link downlink data is transmitted on multiple ports for relay link downlink data transmission , the demodulation reference signals associated with different relay link downlink data transmission ports are orthogonal to each other.

Preferably, in the space division multiplexing transmission mode, the demodulation reference signal pattern is associated with the number of layers of the relay link downlink data transmission, and when multi-layer transmission is performed, the demodulation reference signal corresponding to each layer is mutually positive pay.

Wherein, the orthogonal mode includes at least one of the following: time division multiplexing TDM, frequency division multiplexing FDM, code division multiplexing CDM.

In order to achieve the above purpose, according to another aspect of the present invention, a method for processing downlink data of a relay link is provided.

The processing method for relay link downlink data according to the present invention includes: setting the number of ports for relay link downlink data transmission in transmit diversity mode, and when the number of base station antenna ports is greater than N, the number of ports for relay link downlink data transmission The number of ports is set to N, and N is less than or equal to 4.

Wherein, the setting method is: the base station uses N of the antenna ports to perform data transmission in the diversity transmission mode; or the base station uses virtual antenna port technology to map the data transmission ports to N.

Wherein, the number of ports for relay link downlink data transmission includes one of the following: 2, 4, the number of ports for the common reference signal CRS in the current subframe.

In order to achieve the above object, according to another aspect of the present invention, a method for indicating the number of demodulation reference signal ports is provided.

The method for indicating the number of demodulation reference signal ports according to the present invention includes: the base station indicates to the relay station the number of ports of the relay link downlink demodulation reference signal, and the indication method is an indirect indication method and/or a direct indication method.

Wherein, the indirect indication method includes one of the following: the base station establishes a first mapping relationship between the number of ports of the demodulation reference signal and the number of antenna ports of the base station, and indicates the number of ports of the demodulation reference signal according to the first mapping relationship; The CRC mask of the physical broadcast channel of the relay link indicates the number of ports of the demodulation reference signal to the relay station; the base station establishes a second mapping relationship between the number of ports of the demodulation reference signal and the number of ports of the base station common reference signal, and according to the second The mapping relationship indicates the number of ports of the demodulation reference signal.

Further, the base station establishes a first mapping relationship between the number of ports of the demodulation reference signal and the number of antenna ports of the base station, and the first mapping relationship includes one of the following: when the number of antenna ports of the base station is 1, the number of ports of the demodulation reference signal is 1 , when the number of base station antenna ports is greater than or equal to 2, the number of demodulation reference signal ports is 2; or when the number of base station antenna ports is 1 or 2, the number of demodulation reference signal ports is 1 or 2, when the number of base station antenna ports When greater than or equal to 4, the number of ports for demodulating the reference signal is 4.

Preferably, after the base station establishes the second mapping relationship between the number of ports of the demodulation reference signal and the number of ports of the base station common reference signal, the method further includes: the relay station obtains the number of base station common reference signal ports through the CRC mask of the physical broadcast channel of the base station , the number of demodulation reference signal ports is obtained from the second mapping relationship; the mapping relationship is that the number of demodulation reference signal ports is equal to the number of base station common reference signal ports.

Wherein, the direct indication method includes: indicating the number of ports of the downlink demodulation reference signal through an indication bit in the relay link downlink control signaling.

In order to achieve the above object, according to another aspect of the present invention, a base station is provided.

The base station according to the present invention includes: a storage module for storing demodulation reference signal patterns to be transmitted from the base station; an association module for associating the demodulation reference signals stored in the corresponding storage module according to the number of ports or layers of data transmission pattern; the mapping module is used to map the demodulation reference signal on the corresponding time-frequency two-dimensional resource according to the demodulation reference signal pattern obtained by the association module; the sending module is used to transmit the corresponding demodulation reference signal, wherein, the demodulation reference signal The modulation reference signal is a non-precoding reference signal, and is used to coherently demodulate the downlink data of the relay link.

Preferably, the association module includes an adjustment sub-module for adjusting the demodulation reference signal pattern in the time direction and/or the frequency direction.

Further, the adjustment sub-module also includes a first adjustment sub-module, which is used to adjust the OFDM symbol position mapped by the demodulation reference signal according to the system bandwidth; or adjust the demodulation reference signal according to the OFDM symbol occupied by the downlink data of the relay link The mapped OFDM symbol position; the second adjustment sub-module, configured to adjust the sub-carrier position where the demodulation reference signal is mapped in the physical resource block according to the physical cell identification number.

Preferably, the base station also includes a processing module, configured to set the number of ports for relay link downlink data transmission in transmit diversity mode, and when the number of base station antenna ports is greater than N, set the number of ports for relay link downlink data transmission It is N, and N is less than or equal to 4.

Wherein, the processing module determines N ports among the antenna ports of the base station as ports for relay link downlink data transmission; or uses virtual ports to map the number of ports for relay link downlink data transmission to N.

Preferably, the base station further includes an indication information generation module, configured to generate relay link downlink indication information, and the relay link downlink indication information is used for the base station to indicate to the relay station that the downlink data transmission of the relay link corresponding to the demodulation reference signal is associated. number of ports or layers.

Wherein, the indication information generation module indicates in one of the following ways: the relay link downlink indication information is the CRC mask of the relay link physical broadcast channel, and the port number of the demodulation reference signal is passed through the CRC mask of the relay link physical broadcast channel. The CRC mask indicates; the relay link downlink indication information is the indication information of the number of antenna ports of the base station, and the base station establishes the first mapping relationship between the number of ports of the demodulation reference signal and the number of antenna ports of the base station, and according to the first mapping relationship Indicate the number of ports of the demodulation reference signal; the indication information is the indication information of the number of common reference signal ports of the base station, and the base station establishes a second mapping relationship between the number of ports of the demodulation reference signal and the number of common reference signal ports of the base station, and according to the second The mapping relationship indicates the number of ports of the demodulation reference signal.

In order to achieve the above purpose, according to another aspect of the present invention, a relay station is provided.

The relay station according to the present invention includes: a receiving module for receiving the downlink demodulation reference signal of the relay link, the downlink demodulation reference signal of the relay link is a non-precoding reference signal, and is used for the coherence of the downlink data transmission of the relay link demodulation.

Preferably, the relay station further includes an indication information receiving module, configured to receive the relay link downlink indication information generated by the indication information generating module, and the relay link downlink indication information is used for the relay station to determine to associate the relay link corresponding to the demodulation reference signal The number of ports or layers for downlink data transmission.

In order to achieve the above object, according to another aspect of the present invention, a relay system is provided.

The relay system according to the present invention includes: a base station and a relay station, wherein,

The base station includes: a storage module for storing demodulation reference signal patterns to be transmitted from the base station; an association module for associating the demodulation reference signal patterns stored in the corresponding storage module according to the number of ports or layers of data transmission; the mapping module , is used to map the demodulation reference signal on the corresponding time-frequency two-dimensional resource according to the demodulation reference signal pattern obtained by the association module; the sending module is used to transmit the corresponding demodulation reference signal, wherein the demodulation reference signal is The non-precoded reference signal is used to coherently demodulate the relay link downlink data;

The relay station includes: a receiving module, configured to receive a relay link downlink demodulation reference signal, the relay link downlink demodulation reference signal is a non-precoding reference signal, and is used for coherent demodulation of relay link downlink data transmission.

Through the present invention, the DMRS is mapped on the time-frequency two-dimensional resources to form a DMRS pattern, and at the same time, the indication operation of the DMRS port is included, which solves the problem of sending the downlink demodulation reference signal of the relay link and ensures the downlink of the relay link The reliability of data transmission will not affect the terminals in the same cell. At the same time, the data mapping method is adopted in diversity transmission, that is, the number of ports for diversity transmission is set, and the overhead of demodulating reference signals and the complexity of design are reduced under the premise of ensuring diversity transmission gain.

Description of drawings

The accompanying drawings described here are used to provide a further understanding of the present invention and constitute a part of the application. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations to the present invention. In the attached picture:

FIG. 1 is a schematic diagram of a frame structure in an LTE/LTE-A system according to related technologies;

FIG. 2 is a schematic diagram of a Relay subframe structure according to related technologies;

Fig. 3 is the optimization flowchart of the DMRS transmission method according to the embodiment of the present invention;

4 is a schematic diagram of a DMRS pattern of Example 1 of the present invention;

5 is a schematic diagram of a DMRS pattern of Example 1 of the present invention;

6 is a schematic diagram of a DMRS pattern of Example 1 of the present invention;

7 is a schematic diagram of a DMRS pattern of Example 2 of the present invention;

8 is a schematic diagram of a DMRS pattern of Example 2 of the present invention;

9 is a schematic diagram of a DMRS pattern of Example 2 of the present invention;

Fig. 10 is a schematic diagram of a DMRS pattern of Example 3 of the present invention;

11 is a schematic diagram of a DMRS pattern of Example 3 of the present invention;

Fig. 12 is a schematic diagram of a DMRS pattern of Example 4 of the present invention;

Fig. 13 is a schematic diagram of a DMRS pattern of Example 5 of the present invention;

Fig. 14 is a schematic diagram of a DMRS pattern of Example 6 of the present invention;

Fig. 15 is a schematic diagram of a DMRS pattern of Example 7 of the present invention;

Fig. 16 is a schematic diagram of a DMRS pattern of Example 7 of the present invention;

Fig. 17 is a structural block diagram of a base station according to an embodiment of the present invention;

Fig. 18 is a preferred structural block diagram of a base station according to an embodiment of the present invention;

Fig. 19 is a structural block diagram of a relay station according to an embodiment of the present invention;

Fig. 20 is a structural block diagram of a relay system according to an embodiment of the present invention.

Detailed ways

Functional Overview

The embodiment of the present invention provides a design scheme of the relay link downlink DMRS, maps the DMRS on the time-frequency two-dimensional resource, and indicates the DMRS port, solves the problem of sending the relay link downlink DMRS, and ensures Reliability of downlink data transmission on the relay link, and will not affect terminals in the same cell. At the same time, a method for transmitting downlink data of the relay link during diversity transmission is provided, the number of ports for diversity transmission is set, and the overhead of demodulation reference signals and the complexity of design are reduced on the premise of ensuring diversity transmission gain.

method embodiment

According to an embodiment of the present invention, a method for transmitting a relay link downlink demodulation reference signal is provided, the method includes mapping the DMRS on a time-frequency two-dimensional resource, wherein the demodulation reference signal is a non-precoded ( non-precoded) reference signal for coherent demodulation of relay link downlink data transmission.

The relay link downlink data includes at least one of the following: relay link downlink control data, relay link physical broadcast channel data, and relay link physical downlink shared channel data. And the relay link downlink control data includes at least one of the following: data of the relay link physical downlink control channel, relay link downlink control format indication information, or relay link downlink hybrid automatic retransmission indication information. The relay link downlink service data includes data transmitted in the relay link downlink physical shared channel, and its transmission mode may be transmit diversity or space division multiplexing.

The mapping position of DMRS includes physical resource blocks allocated for transmitting downlink data in the frequency direction; the mapping position of DMRS includes OFDM symbols carrying downlink data in a downlink relay subframe in the time direction. That is, the DMRS described in the present invention is only located in scheduled resources. For example, if the DMRS is used for data demodulation of the physical broadcast channel of the relay link, then the DMRS will only be mapped to resources occupied by R-PBCH transmission, such as some specific PRBs; Demodulation of relay link control data, such as R-PDCCH, R-PCFICH, R-PHICH, etc., then the DMRS will only be mapped to the relay link downlink control domain, such as some PRBs or some OFDM symbols in PRBs ; If the DMRS is used for coherent demodulation of downlink service data transmission on the relay link, then the DMRS will only be mapped to resources occupied by the corresponding data transmission.

Preferably, the OFDM symbols mapped by the DMRS do not include OFDM symbols mapped with common reference signals.

Fig. 3 is the optimization flowchart of the DMRS processing method according to the embodiment of the present invention; As shown in Fig. 3, this method comprises following step S302 to step S306:

In step S302, the DMRS corresponds to a port or a layer for downlink data transmission of the relay link.

In the transmission mode of transmit diversity, the DMRS described in the present invention corresponds to the antenna port for corresponding data transmission, and the DMRS of each port are orthogonal to each other. The antenna ports here refer to the number of antenna ports that the receiving end can see when receiving data, that is, when the virtual antenna technology is not used, the number of antenna ports is the actual number of antenna ports, and when the virtual antenna technology is used, The number of antenna ports is the number of antenna ports after virtualization. In the transmission mode of space division multiplexing, the DMRS described in the present invention corresponds to the corresponding data transmission layer, and the DMRSs of each layer are orthogonal to each other. And in this case, the base station needs to indicate the corresponding precoding codebook or the index of the precoding codebook while performing data transmission. The orthogonal mode of the multi-port/multi-layer DMRS described in the present invention may be one or a combination of FDM, TDM and CDM.

Step S304, adjusting the DMRS pattern in the time direction and/or the frequency direction.

The pattern of the demodulation reference signal DMRS described in the present invention can be fixed or flexibly adjusted. The adjustment includes adjustment in the time direction and adjustment in the frequency direction. The adjustment in the time direction refers to changing the OFDM symbol position mapped by the DMRS. For example, in an LTE system, when the downlink system bandwidth is greater than 10 RBs and less than or equal to 10 RBs, the number of symbols occupied by the PDCCH may be different, which will lead to the start of the OFDM symbol for the downlink transmission of the relay link in these two cases The location is different. At this time, a DMRS pattern can be designed for different situations to be compatible with different system bandwidths, or different DMRS patterns can be designed for different system bandwidths to ensure a better channel estimation performance in different situations . The adjustment in the time direction may also be adjusted for different OFDM symbols occupied by data transmission. For example, if the DMRS is used for data demodulation of the R-PDCCH, the number of OFDM symbols occupied by the R-PDCCH may also change due to changes in the content of the control channel. At this time, a DMRS pattern can be designed for all allowed situations, or the symbol positions mapped by the DMRS can be flexibly adjusted for different situations. The adjustment of the frequency direction refers to changing the subcarrier position mapped by the DMRS in one RB. For example, the mapped subcarrier position of DMRS in RB can be fixed, or the physical cell identification number (Physical Cell ID, PCID for short) can be used to determine the mapped subcarrier position of DMRS in RB like LTECRS, so that when adjacent cells are also When the DMRS is transmitted in the RB, mutual interference of the DMRS can be avoided.

It should be noted that step S304 is an optional step, and this step is not required when the DMRS pattern described in the present invention is not adjusted.

Step S306, mapping the DMRS on time/frequency two-dimensional resources.

Considering factors such as DMRS overhead and design complexity, the present invention provides a method for processing downlink data of a relay link. The method includes: setting the number of ports for downlink data transmission of the relay link in transmit diversity mode, and setting the number of ports for downlink data transmission of the relay link to N when the number of base station antenna ports is greater than N N is less than or equal to 4. That is, the base station uses N of the antenna ports to perform data transmission in the diversity transmission mode; or the base station uses a virtual antenna port technology to map the transmit ports to N.

Specifically, when the number of base station antenna ports exceeds a certain number, the number of ports for diversity transmission is limited to ensure that the overhead of the DMRS is within a reasonable range and the flexibility of DMRS design is ensured. The restriction here can be to determine a part of the antenna ports of the base station for data transmission, or to use virtual port technology to limit the number of diversity transmission ports by mapping the same data and DMRS on different antenna ports.

The invention also provides a method for indicating the number of demodulation reference signal ports, which is used for the base station to indicate the number of DMRS ports to the relay station, so as to ensure that the receiving end can accurately obtain the number of DMRS transmission ports, thereby implementing corresponding detection algorithms.

Specifically, the port number of the DMRS is indicated by the CRC mask of the relay physical broadcast channel, and the CRC mask is the same as the CRC mask of the LTE physical broadcast channel;

Specifically, a mapping relationship is established between the number of ports of the DMRS and the number of antenna ports of the base station, and the number of antenna ports of the base station implicitly indicates the number of ports of the demodulation reference signal. And the mapping relationship is: when the number of base station antenna ports is 1, the number of demodulation reference signal ports is 1, when the number of base station antenna ports is greater than or equal to 2, the number of ports of the demodulation reference signal is 2; or when the base station When the number of antenna ports is 1 or 2, the number of demodulation reference signal ports is 1 or 2, and when the number of base station antenna ports is greater than or equal to 4, the number of ports of the demodulation reference signal is 4;

Specifically, a mapping relationship is established between the number of ports of the DMRS and the number of ports of the base station common reference signal. Specifically, the relay station obtains the number of the base station common reference signal ports through the CRC mask of the base station physical broadcast channel, and the base station common reference signal port The number implicitly indicates the number of ports of the demodulation reference signal; preferably, the mapping relationship is that the number of ports of the demodulation reference signal is equal to the number of ports of the common reference signal of the base station.

Alternatively, the port number of the DMRS is indicated by an indication bit in the downlink control signaling of the relay link.

It should be noted that the steps shown in the flowcharts of the accompanying drawings may be performed in a computer system, such as a set of computer-executable instructions, and that although a logical order is shown in the flowcharts, in some cases, The steps shown or described may be performed in an order different than here.

The implementation process of the embodiment of the present invention will be described in detail below with reference to examples.

In the LTE/LTE-A system, according to the difference in CP length, it is divided into normal CP (Normal CP) and extended CP (Extend CP). Under normal CP length, one subframe has 14 OFDM symbols; under extended CP length, one subframe has 12 OFDM symbols. Due to the different CP lengths, the OFDM symbol positions mapped by the DMRS may vary. The following will be described through specific examples.

Example 1:

In Example 1, it is assumed that the DMRS described in the present invention is used for demodulation of the R-PDCCH, and it is assumed that the transmission of the R-PDCCH occupies a part of the OFDM symbols transmitted from the base station to the relay station in the relay subframe. Specifically, it is assumed that the number of OFDM symbols occupied by R-PDCCH transmission is _NR-PDCCH , where _NR-PDCCH can be dynamically or semi-statically set by the base station according to the capacity of the relay link control channel; it can also be set between the base station and the relay station The interval is agreed, that is, the static setting. When it is assumed that the value of NR _-PDCCH is set dynamically or semi-statically, it is agreed that $N_{R-\mathrm{PDCCH}}^{\min }\≤N_{R-\mathrm{PDCCH}}\≤N_{R-\mathrm{PDCCH}}^{\max },$ Where _NR-PDCCH ^min is the minimum number of OFDM symbols that the agreed R-PDCCH can occupy, and _NR-PDCCH ^max is the maximum number of OFDM symbols that the agreed R-PDCCH can occupy; when the value of _NR-PDCCH is set statically, it is assumed that The value of _NR-PDCCH is agreed to be $N_{R-\mathrm{PDCCH}}=N_{R-\mathrm{PDCCH}}^{\mathrm{static}}.$

In this example, the design principle of the DMRS of the R-PDCCH is that in one RB, the interval of the DMRS of the same port in the frequency domain is 6 subcarriers. In the time domain, if the value of _NR-PDCCH is set dynamically or semi-statically, the OFDM symbol mapped by DMRS is the R-PDCCH domain under the assumption that R-PDCCH occupies the minimum number of OFDM symbols (ie _NR-PDCCH ^min ). The first OFDM symbol that does not contain CRS and the last OFDM symbol that does not contain CRS; if the value of N _R-PDCCH is set statically, the OFDM symbol mapped by DMRS in the time domain is the first OFDM symbol occupied by R-PDCCH that does not contain CRS and the last OFDM symbol that does not contain a CRS. The premise here is assuming that the base station uses normal subframes (non-MBSFN subframes) to transmit data to the relay station. When the base station uses the MBSFN subframe (that is, the backhaul link has no CRS) to transmit data to the relay station, the DMRS of the R-PDCCH adopts the same pattern as that of the normal subframe transmission.

For example, it is assumed that the number of ports for downlink control data diversity transmission of the relay link is limited to 2. When the value of _NR-PDCCH is set dynamically or semi-statically, in $N_{R-\mathrm{PDCCH}}^{\min }=3,$ $N_{R-\mathrm{PDCCH}}^{\max }=4$ Under the assumption of , an example of a DMRS pattern when the system bandwidth is greater than 10 RBs under a common CP length is shown in FIG. 4 . It is assumed here that the start symbol of the R-PDCCH is the fourth OFDM symbol. Similarly, the pattern shown in Figure 4 is also applicable when the value of _NR-PDCCH is set statically, when $N_{R-\mathrm{PDCCH}}^{\mathrm{static}}=3$ The DMRS pattern at the time.

In this example, it is further assumed that the position of the subcarrier mapped by the DMRS in the RB is determined according to the physical cell identity, and the specific method is the same as that of the CRS mapping position in the LTE system. For the DMRS pattern shown in FIG. 4 , the specific position mapped in one RB is as follows.

k={(v+v _shift )mod6, 6+(v+v _shift )mod6}

${\mathrm{<span\; class="notranslate">\; v</span>}}_{\mathrm{<span\; class="notranslate">\; shift</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; ID</span>}}^{\mathrm{<span\; class="notranslate">\; cell</span>}}\mathrm{<span\; class="notranslate">\; mod</span>}\mathrm{<span\; class="notranslate">\; 6</span>}$

Where k represents the subcarrier position mapped by the DMRS in one RB, l represents the OFDM symbol position mapped by the DMRS, p ^DMRS represents the port number of the DMRS, and N _ID ^cell represents the physical cell identification number.

When the system bandwidth is less than or equal to 10 RBs, assuming that the start symbol of the R-PDCCH is the fifth OFDM symbol, the DMRS pattern is adjusted as shown in FIG. 5 . The specific mapping position of the DMRS is as follows.

k={(v+v _shift )mod6, 6+(v+v _shift )mod6}

${\mathrm{<span\; class="notranslate">\; v</span>}}_{\mathrm{<span\; class="notranslate">\; shift</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; ID</span>}}^{\mathrm{<span\; class="notranslate">\; cell</span>}}\mathrm{<span\; class="notranslate">\; mod</span>}\mathrm{<span\; class="notranslate">\; 6</span>}$

The meaning of each parameter is the same as above.

Under the extended CP length, when the system bandwidth is greater than 10 RBs, under the DMRS design principle of this example, an example of a DMRS pattern is shown in FIG. 6 . The specific mapping position of DMRS in one RB becomes

k={(v+v _shift )mod6, 6+(v+v _shift )mod6}

${\mathrm{<span\; class="notranslate">\; v</span>}}_{\mathrm{<span\; class="notranslate">\; shift</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; ID</span>}}^{\mathrm{<span\; class="notranslate">\; cell</span>}}\mathrm{<span\; class="notranslate">\; mod</span>}\mathrm{<span\; class="notranslate">\; 6</span>}$

The meaning of each parameter in the formula is the same as above.

Under the extended CP length, when the system bandwidth is less than or equal to 10 RBs, under the DMRS design principle of this example, the DMRS pattern is still as shown in Figure 6, but at this time it is assumed that the start symbol of the R-PDCCH becomes the fifth OFDM symbols. The specific position where the DMRS is mapped in one RB is the same as the DMRS pattern when the system bandwidth is greater than 10 RBs.

In this example, if the size of the REG (Resource Element Group, referred to as resource element group) of the R-PDCCH is the same as that of the LTE REG, then when the R-PDCCH is transmitted on a single port, the R-PDCCH data is still 2 according to the DMRS port to map.

It should be noted that the schematic diagram of this example only schematically describes the CRS pattern of the LTE system, but does not represent the corresponding relationship between the number of CRS ports and the number of DMRS ports. And when the base station uses the MBSFN subframe to transmit data to the relay station, there will be no CRS in the OFDM symbols after the third OFDM symbol.

It should be understood that the DMRS pattern in this example is only for the purpose of describing and explaining the present invention, and is not enough to limit the present invention.

Example 2:

Under the assumption of Example 1 and the DMRS design principle, when the number of OFDM symbols occupied by R-PDCCH is dynamically or semi-statically configured, or the number of OFDM symbols occupied by R-PDCCH is statically configured, another example of DMRS pattern is shown in Figure 7. 8, 9 shown. It is still assumed that when the number of OFDM symbols occupied by R-PDCCH is dynamically or semi-statically configured $N_{R-\mathrm{PDCCH}}^{\min }=3,$ $N_{R-\mathrm{PDCCH}}^{\max }=4;$ When the number of OFDM symbols occupied by R-PDCCH is statically set to the value of N _R-PDCCH $N_{R-\mathrm{PDCCH}}^{\mathrm{static}}=3.$

FIG. 7 is an example of a DMRS pattern when the system bandwidth is greater than 10 RBs. The specific mapping resource position in one RB is as follows.

k={(v+v _shift )mod6, 6+(v+v _shift )mod6}

${\mathrm{<span\; class="notranslate">\; v</span>}}_{\mathrm{<span\; class="notranslate">\; shift</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; ID</span>}}^{\mathrm{<span\; class="notranslate">\; cell</span>}}\mathrm{<span\; class="notranslate">\; mod</span>}\mathrm{<span\; class="notranslate">\; 6</span>}$

The meanings of the parameters are the same as in Example 1.

FIG. 8 shows an example of a DMRS pattern when the system bandwidth is less than or equal to 10 RBs. The specific mapping resource position in one RB is as follows.

k={(v+v _shift )mod6, 6+(v+v _shift )mod6}

${\mathrm{<span\; class="notranslate">\; v</span>}}_{\mathrm{<span\; class="notranslate">\; shift</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; ID</span>}}^{\mathrm{<span\; class="notranslate">\; cell</span>}}\mathrm{<span\; class="notranslate">\; mod</span>}\mathrm{<span\; class="notranslate">\; 6</span>}$

The meaning of each parameter is the same as above.

Under the extended CP length, an example of a DMRS pattern is shown in Figure 9 . The DMRS pattern is the same when the system bandwidth is greater than 10 RBs and less than 10 RBs, except that when the system bandwidth is greater than 10 RBs, the start symbol of R-PDCCH is the fourth OFDM symbol, and when the system bandwidth is less than or equal to 10 RBs, the R-PDCCH The starting symbol is the fifth OFDM symbol. The specific resource position mapped in one RB in the DMRS pattern example shown in FIG. 9 is as follows.

k = {(v+v _shift ) mod 6, 6+(v+v _shift ) mod 6}

${\mathrm{<span\; class="notranslate">\; v</span>}}_{\mathrm{<span\; class="notranslate">\; shift</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; ID</span>}}^{\mathrm{<span\; class="notranslate">\; cell</span>}}\mathrm{<span\; class="notranslate">\; mod</span>}\mathrm{<span\; class="notranslate">\; 6</span>}$

The meaning of each parameter is the same as above.

In this example, if the size of the REG of the R-PDCCH is the same as that of the LTE REG, then when the R-PDCCH is transmitted on a single port, the R-PDCCH data is still mapped according to 2 DMRS ports.

It should be noted that the schematic diagram of this example only schematically describes the CRS pattern of the LTE system, but does not represent the corresponding relationship between the number of CRS ports and the number of DMRS ports. And when the base station uses the MBSFN subframe to transmit data to the relay station, there will be no CRS in the OFDM symbols after the third OFDM symbol.

It should be understood that the DMRS pattern in this example is only for the purpose of describing and explaining the present invention, and is not enough to limit the present invention.

Example 3:

Under the assumption of Example 1 and the DMRS design principle, when the number of OFDM symbols occupied by the R-PDCCH is dynamically or semi-statically configured, or the number of OFDM symbols occupied by the R-PDCCH is statically configured, the present invention provides another DMRS design method and Pattern example.

The design principle of the DMRS in this example is to design the pattern of the DMRS for the case where the system bandwidth is greater than 10 RBs. When the system bandwidth is less than or equal to 10 RBs, if the relay station cannot receive some OFDM symbols mapped with DMRS, the DMRS pattern when the system bandwidth is less than or equal to 10 RBs is to remove the unreceived symbols on the basis of the original DMRS pattern DMRS.

For example, suppose the number of OFDM symbols occupied by R-PDCCH is set statically, that is, the number of OFDM symbols occupied by R-PDCCH is agreed between the base station and the relay station: $N_{R-\mathrm{PDCCH}}=N_{R-\mathrm{PDCCH}}^{\mathrm{static}},$ And assume that under the normal CP length, when the system bandwidth is greater than 10 RB, $N_{R-\mathrm{PDCCH}}^{\mathrm{static}}=4,$ When the system bandwidth is less than or equal to 10 RB, $N_{R-\mathrm{PDCCH}}^{\mathrm{static}}=3.$ Assume that when the system bandwidth is greater than 10 RBs, the starting position of the R-PDCCH is the fourth OFDM symbol, and when the system bandwidth is less than or equal to 10 RBs, the starting position of the R-PDCCH is the fifth OFDM symbol. It is also assumed that the number of diversity ports of the R-PDCCH is limited to 2. Under the above assumptions, the DMRS pattern of the R-PDCCH is shown in Figure 10 when the system bandwidth is greater than 10 RBs under the normal CP length.

The specific position where the DMRS pattern shown in FIG. 10 is mapped in one RB is as follows.

k={(v+v _shift )mod6, 6+(v+v _shift )mod6}

${\mathrm{<span\; class="notranslate">\; v</span>}}_{\mathrm{<span\; class="notranslate">\; shift</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; ID</span>}}^{\mathrm{<span\; class="notranslate">\; cell</span>}}\mathrm{<span\; class="notranslate">\; mod</span>}\mathrm{<span\; class="notranslate">\; 6</span>}$

Where k represents the subcarrier position mapped by the DMRS in one RB, l represents the OFDM symbol position mapped by the DMRS, and p ^DMRS represents the port number of the DMRS. N _ID ^cell represents a physical cell identifier.

When the system bandwidth is less than or equal to 10 RBs, it is assumed that the start symbol of the R-PDCCH is the fifth OFDM symbol. At this time, under the design principle of this embodiment, the pattern of the DMRS is changed to the form of FIG. 11 on the basis of FIG. 10 , that is, the DMRS is no longer mapped in the fourth OFDM symbol.

The specific position where the DMRS pattern shown in FIG. 11 is mapped in one RB is as follows.

k={(v+v _shift )mod6, 6+(v+v _shift )mod6}

${\mathrm{<span\; class="notranslate">\; v</span>}}_{\mathrm{<span\; class="notranslate">\; shift</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; ID</span>}}^{\mathrm{<span\; class="notranslate">\; cell</span>}}\mathrm{<span\; class="notranslate">\; mod</span>}\mathrm{<span\; class="notranslate">\; 6</span>}$

The meaning of each parameter is the same as above.

It should be noted that the schematic diagram of this example only schematically describes the CRS pattern of the LTE system, but does not represent the corresponding relationship between the number of CRS ports and the number of DMRS ports. And when the base station uses the MBSFN subframe to transmit data to the relay station, there will be no CRS in the OFDM symbols after the third OFDM symbol.

It should be understood that the DMRS pattern in this example is only for the purpose of describing and explaining the present invention, and is not enough to limit the present invention.

Example 4:

In this example, it is assumed that the DMRS described in the present invention is used for demodulation of the R-PDCCH, and it is assumed that the transmission of the R-PDCCH occupies a part of the OFDM symbols transmitted from the base station to the relay station in the relay subframe. Specifically, it is assumed that the number of OFDM symbols occupied by R-PDCCH transmission is _NR-PDCCH , where _NR-PDCCH can be dynamically or semi-statically set by the base station according to the capacity of the relay link control channel; it can also be set between the base station and the relay station The interval is agreed, that is, the static setting. When it is assumed that the value of NR _-PDCCH is set dynamically or semi-statically, it is agreed that $N_{R-\mathrm{PDCCH}}^{\min }\&le;N_{R-\mathrm{PDCCH}}\&le;N_{R-\mathrm{PDCCH}}^{\max },$ Where _NR-PDCCH ^min is the minimum number of OFDM symbols that the agreed R-PDCCH can occupy, and _NR-PDCCH ^max is the maximum number of OFDM symbols that the agreed R-PDCCH can occupy; when the value of _NR-PDCCH is set statically, it is assumed that The value of _NR-PDCCH is agreed to be $N_{R-\mathrm{PDCCH}}=N_{R-\mathrm{PDCCH}}^{\mathrm{static}}.$

In this example, the design principle of the DMRS of the R-PDCCH is that in one RB, the interval of the DMRS of the same port in the frequency domain is 6 subcarriers. In the time domain, all DMRS will only be mapped to one OFDM symbol, and the symbol mapped to the DMRS is an OFDM symbol in the R-PDCCH domain that does not include a CRS, and when the CP length is determined, the OFDM symbol is fixed. The premise here is assuming that the base station uses normal subframes (non-MBSFN subframes) to transmit data to the relay station. When the base station uses the MBSFN subframe (that is, the backhaul link has no CRS) to transmit data to the relay station, the DMRS of the R-PDCCH adopts the same pattern as that of the normal subframe transmission.

For example, it is assumed that the number of ports for downlink control data diversity transmission of the relay link is limited to 2. An example of a DMRS pattern at a common CP length is shown in FIG. 12 . Figure 12 is also applicable to the case where the downlink system bandwidth is greater than or equal to 10 RBs, except that the start symbols mapped to the R-PDCCH are different in the two cases.

In this example, it is further assumed that the position of the subcarrier mapped by the DMRS in the RB is determined according to the physical cell identity, and the specific method is the same as that of the CRS mapping position in the LTE system. For the DMRS pattern shown in FIG. 12 , the specific position mapped in one RB is as follows.

k={(v+v _shift )mod6, 6+(v+v _shift )mod6}

${\mathrm{<span\; class="notranslate">\; v</span>}}_{\mathrm{<span\; class="notranslate">\; shift</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; ID</span>}}^{\mathrm{<span\; class="notranslate">\; cell</span>}}\mathrm{<span\; class="notranslate">\; mod</span>}\mathrm{<span\; class="notranslate">\; 6</span>}$

Where k represents the subcarrier position mapped by the DMRS in one RB, l represents the OFDM symbol position mapped by the DMRS, p ^DMRS represents the port number of the DMRS, and N _ID ^cell represents the physical cell identification number.

Under the extended CP length, the OFDM symbol mapped to the DMRS in this example is the fifth OFDM symbol, which will not be repeated here.

In this example, if the size of the REG (Resource Element Group, referred to as resource element group) of the R-PDCCH is the same as that of the LTE REG, then when the R-PDCCH is transmitted on a single port, the R-PDCCH data is still 2 according to the DMRS port to map.

It should be noted that the schematic diagram of this example only schematically describes the CRS pattern of the LTE system, but does not represent the corresponding relationship between the number of CRS ports and the number of DMRS ports. And when the base station uses the MBSFN subframe to transmit data to the relay station, there will be no CRS in the OFDM symbols after the third OFDM symbol.

It should be understood that the DMRS pattern in this example is only for the purpose of describing and explaining the present invention, and is not enough to limit the present invention.

Example 5:

Under the assumption of Example 2, this example provides a DMRS design method when the maximum number of DMRS ports is limited to 4. In this example, the design principles of DMRS ports 0 and 1 are the same as those in Example 2; the 4 DMRS ports are transmitted using CDM+FDM in an orthogonal manner. Specifically, on the basis of the DMRS patterns of the 2 ports, CDM spread spectrum multiplexes 4 layer, where CDM spread spectrum is time domain spread spectrum. In this example, no matter whether the base station transmits data to the relay station using the MBSFN subframe (that is, the backhaul link has no CRS) or the normal subframe, the pattern of the DMRS remains unchanged.

Under the above assumptions, the DMRS pattern when the system bandwidth is greater than 10 RBs under the normal CP length is shown in Figure 13 . The ellipse in the figure represents a spreading unit during CDM multiplexing. When spreading, Walsh codes can be used as spreading codes, for example, Walsh codes [1, 1] and [1, -1] with a length of 2. In FIG. 13 , DMRS ports 0 and 2 are multiplexed on the same resource through CDM, and ports 1 and 3 are multiplexed on the same resource through CDM. The resource mapping of DMRS in one RB is as follows.

k={(v+v _shift )mod6, 6+(v+v _shift )mod6}

l = {4, 6}

${\mathrm{<span\; class="notranslate">\; v</span>}}_{\mathrm{<span\; class="notranslate">\; shift</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; N</span>}}_{\mathrm{<span\; class="notranslate">\; ID</span>}}^{\mathrm{<span\; class="notranslate">\; cell</span>}}\mathrm{<span\; class="notranslate">\; mod</span>}\mathrm{<span\; class="notranslate">\; 6</span>}$

Where k represents the subcarrier position mapped by the DMRS in one RB, l represents the OFDM symbol position mapped by the DMRS, p ^DMRS represents the port number of the DMRS, and N _ID ^cell represents the physical cell identification number. Under the extended CP length, the DMRS mapping OFDM symbols is adjusted to l={6, 7}, which will not be repeated here.

In this example, if the REG size of the R-PDCCH is the same as the LTE REG size, then when the R-PDCCH transmission port is less than 2, the R-PDCCH data is still mapped according to the DMRS port being 2.

It should be noted that the schematic diagram of this example only schematically describes the CRS pattern of the LTE system, but does not represent the corresponding relationship between the number of CRS ports and the number of DMRS ports. And when the base station uses the MBSFN subframe to transmit data to the relay station, there will be no CRS in the OFDM symbols after the third OFDM symbol.

It should be understood that the DMRS pattern in this example is only for the purpose of describing and explaining the present invention, and is not enough to limit the present invention.

Example 6:

In this example, it is assumed that the DMRS described in the present invention is used for coherent demodulation of relay link downlink data transmission, the data may be relay link downlink control data, or relay link downlink physical broadcast channel data, Or it is the data transmitted in diversity in the downlink shared channel of the relay link, etc.

The DMRS design principle of this example is: the resource overhead and occupied resource location are the same when DMRS transmits on one port, two ports and four ports, but the CDM method is used to ensure that the DMRSs of each port are orthogonal during DMRS multi-port transmission; The OFDM symbols mapped by the DMRS are OFDM symbols without CRS transmission in a normal subframe (non-MBSFN subframe), and if the base station uses the MBSFN subframe to transmit data to the relay station, the DMRS pattern is the same as the DMRS pattern transmitted in the normal subframe.

Under the above assumptions, a pattern example of DMRS design is shown in Figure 14. The frequency domain position of the DMRS is subcarrier k={3, 9}, and the time domain position is OFDM symbol l={6, 7, 11, 13} . The DMRS of each port is separated by 6 subcarriers in the frequency domain; the DMRS occupies the same resources when transmitting on ports 1, 2, and 4, but when there are multiple ports, CDM spread spectrum is used on the same resource to ensure the transmission of different ports. DMRS Orthogonal. The ellipse in the figure represents a spreading unit in CDM. In CDM, Walsh codes can be selected as orthogonal codes, such as [1, 1] and [1, -1]. When transmitting on four DMRS ports, four DMRS REs on the same subcarrier are used as a spreading unit. For example, when the Walsh code is used as the spreading code, the Walsh code can be taken as:

$\left\{\begin{array}{c}<span\; class="notranslate">\; [</span>\mathrm{<span\; class="notranslate">\; 1,1,1,1</span>}<span\; class="notranslate">\; ]</span>\\ <span\; class="notranslate">\; [</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; ,</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1,1</span>}<span\; class="notranslate">\; ,</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; ]</span>\\ <span\; class="notranslate">\; [</span>\mathrm{<span\; class="notranslate">\; 1,1</span>}<span\; class="notranslate">\; ,</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; ,</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; ]</span>\\ <span\; class="notranslate">\; [</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; ,</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; ,</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1,1</span>}<span\; class="notranslate">\; ]</span>\end{array}\right.$

I won't go into details here.

In order to ensure the channel estimation performance of a single RB, the mapping position of the DMRS in the frequency domain may also be an edge subcarrier in the frequency domain of an RB, for example, the mapping subcarrier of the DMRS is k={1, 12}.

If the end position of the OFDM symbol that can be received by the relay station in one subframe is the 14th OFDM symbol, the position of the OFDM symbol mapped by the DMRS may be l={6, 7, 13, 14}.

It should be noted that the schematic diagram of this example only schematically describes the CRS pattern of the LTE system, but does not represent the corresponding relationship between the number of CRS ports and the number of DMRS ports. And when the base station uses the MBSFN subframe to transmit data to the relay station, there will be no CRS in the OFDM symbols after the third OFDM symbol.

It should be understood that the DMRS pattern in this example is only for the purpose of describing and explaining the present invention, and is not enough to limit the present invention.

Example 7:

In this example, it is assumed that the DMRS described in the present invention is used for coherent demodulation of relay link downlink data transmission, the data may be relay link downlink control data, or relay link downlink physical broadcast channel data, Or it is the data transmitted in diversity in the downlink shared channel of the relay link, etc.

The DMRS design principle of this example is: the resource overhead and occupied resource location are the same when the DMRS is transmitted on one port and two ports; the CDM method is used to ensure that the DMRSs of each port are The overhead of DMRS adopts CDM+FDM (Frequency Division Multiplexing, referred to as FDM) to ensure that each port is orthogonal; the OFDM symbols mapped by DMRS are OFDM symbols without CRS transmission in ordinary subframes (non-MBSFN subframes), and if the base station The MBSFN subframe is used to transmit data to the relay station, and the DMRS pattern is the same as the DMRS pattern transmitted in a normal subframe.

Under the above assumptions, a pattern example of DMRS design is shown in Figure 15. The resources occupied by DMRS are the same when one port and two ports are transmitting, but two layers are multiplexed by CDM on the same resource when two ports are used. The ellipse in the figure represents a spreading unit in CDM. In CDM, Walsh codes can be selected as orthogonal codes, such as [1, 1] and [1, -1]. When the four ports of DMRS are transmitted, the number of ports is divided into two groups, such as {0, 1} and {2, 3}. The DMRS of these two groups of ports is kept orthogonal by using FDM. In each group, use The CDM method ensures that the DMRSs of the two ports are orthogonal.

The OFDM symbol position occupied by the DMRS pattern shown in FIG. 15 in the time domain is l={6, 7, 11, 13}. If the end position of the OFDM symbol that can be received by the relay station in a subframe is the 14th OFDM symbol, the DMRS mapping symbols may also be adjusted to l={6, 7, 13, 14}.

Under the extended CP length, the two OFDM symbols mapped by the DMRS become l={5, 6, 9, 11}. Similarly, if the end position of the OFDM symbol that can be received by the relay station in a subframe is the 12th OFDM symbol, the DMRS mapping symbols may also be adjusted to l={5, 6, 11, 12}.

Under the assumption of this example, the mapping position of the DMRS in the frequency domain can also be determined as both ends of the frequency domain of an RB, so that the performance of channel estimation of a single RB can be guaranteed. An example of a DMRS pattern is shown in Figure 16. I won't go into details here.

It should be noted that the DMRS pattern described in this example can also be applied to data demodulation in the relay link data space division multiplexing transmission mode. At this time, the number of ports of the DMRS corresponds to the number of multiplexed transmission layers. I won't go into details here.

It should be noted that the schematic diagram in this example only schematically describes the CRS pattern of the LTE system, but does not represent the corresponding relationship between the number of CRS ports and the number of DMRS ports or the number of layers. And when the base station uses the MBSFN subframe to transmit data to the relay station, there will be no CRS in the OFDM symbols after the third OFDM symbol.

It should be understood that the DMRS pattern in this example is only for the purpose of describing and explaining the present invention, and is not enough to limit the present invention.

Example 8

In this example, an example of a relay link data mapping method is provided. Specifically, when the relay link data is transmitted in the transmit diversity mode, in order to ensure the flexibility and reasonable overhead of the corresponding DMRS design, the number of diversity ports for the relay link diversity transmission is limited.

In the LTE-A system, the number of antenna ports of the base station will be extended to 8, and the diversity transmission of 8 ports will not bring more obvious gains than the diversity of 4 ports, but it will make the corresponding DMRS design more complicated. DMRS increased overhead. Therefore, the number of diversity ports for trunk link data transmission can be limited. For example, when the base station is configured with 8 antenna ports, only 4-port diversity transmission, or even 2-port diversity transmission is used. At this time, only DMRS with 4 or 2 ports is required.

For example, the number of ports for downlink data diversity transmission on the relay link is uniformly limited to the number of CRS ports in the current subframe.

For example, when the number of base station antenna ports is greater than 2, the number of ports for downlink control data transmission on the relay link is limited to 2.

For example, when the number of base station antenna ports is greater than 4, the number of ports for relay link downlink data diversity transmission is limited to 4.

When the number of ports for diversity transmission is limited, a part of antenna ports of the base station may be selected as antenna ports for transmission in diversity mode, and the number of selected antenna ports is the number of ports for diversity transmission.

When the number of ports for diversity transmission is limited, the virtual antenna method can also be used for data mapping. For example, if the antenna ports of the base station are {0, 1, 2, 3, 4, 5, 6, 7}, and the number of diversity transmission ports is 2, then the antenna ports can be grouped into {0, 2, 4, 6} and {1, 3, 5, 7} as two virtual ports. On both virtual ports, map the same data and DMRS. From the perspective of the receiving end, DMRS and data only use 2 ports for transmission.

Example 9

After receiving the data, the receiver needs to know the number of ports or layers for data transmission, that is, the number of ports or layers of the corresponding DMRS, to match the corresponding DMRS pattern for channel estimation before performing channel estimation. This example will provide several indication methods of DMRS port numbers (or layer numbers).

In the diversity transmission mode, a mapping relationship may be established between the number of DMRS ports for diversity transmission and the number of CRS ports, for example, it is limited that the number of DMRS ports for diversity transmission is the same as the number of CRS ports. When the number of DMRS ports is the same as the number of CRS ports, the relay station receives the data of the physical broadcast channel, and obtains the number of ports for CRS transmission through the CRC mask of the physical broadcast channel, thereby obtaining the number of DMRS ports for diversity transmission. The specific method for obtaining the number of CRS ports is the same as the method for obtaining the terminal in LTE, which will not be repeated here.

In the diversity transmission mode, the number of ports for diversity transmission can be indicated through the CRC mask of the physical broadcast channel of the trunk link. Here, the CRC mask can be designed in the same way as the CRC mask of the physical broadcast channel in the LTE system, which will not be repeated here.

In the diversity transmission mode, a mapping relationship may also be established between the number of base station antenna ports and the number of diversity transmission ports. For example, when the number of base station antenna ports is greater than 2, the number of diversity transmission ports is limited to 2; or when the number of base station antenna ports is greater than 4, the number of diversity transmission ports is limited to 4. This mapping relationship is defined between the base station and the relay station. After the relay station obtains the information about the number of antenna ports of the base station, it can implicitly obtain the number of ports for diversity transmission.

It is also possible to add an indicator bit in DCI (Downlink Control Information, DCI for short) of the relay link, and indicate to the relay station the number of ports for diversity transmission or the number of layers for multiplexing transmission through the indicator bit.

Device embodiment

According to an embodiment of the present invention, a base station is provided, and the base station can be used for transmitting a downlink demodulation reference signal of a relay link.

FIG. 17 is a structural block diagram of a base station according to an embodiment of the present invention. As shown in FIG. 17 , the base station includes a storage module 1700 , an association module 1710 , a mapping module 1720 , and a sending module 1730 . The above structure will be specifically described below.

A storage module 1700, configured to store patterns of demodulation reference signals to be transmitted from the base station;

The association module 1710, connected to the storage module 1700, is used to associate the demodulation reference signal pattern stored in the corresponding storage module according to the number of ports or layers of data transmission;

The mapping module 1720 is connected to the association module 1710, and is used to map the demodulation reference signal on the corresponding time-frequency two-dimensional physical resource according to the associated demodulation reference signal pattern obtained by the association module;

A sending module 1730, configured to transmit a corresponding demodulation reference signal.

Fig. 18 is a block diagram of an optimized structure of a base station according to an embodiment of the present invention. As shown in FIG. 18 , the base station includes a processing module 1810 , an adjustment submodule 1820 , and an indication information generating module 1830 , and the above structures will be described in detail below.

The processing module 1810 is configured to set the number of ports for relay link data transmission in the transmit diversity mode. When the number of base station ports is greater than N (N>1), the number of ports is limited to N, and N≤4. The limited method may be to select N ports for transmission among the antenna ports of the base station, or to map the number of antenna ports of the base station to N in a virtual antenna manner.

The association module 1710 also includes an adjustment sub-module 1820, configured to adjust the pattern of the DMRS, including adjustment in the time direction and/or adjustment in the frequency direction. The adjustment module 1820 further includes a first adjustment sub-module 1821 and a second adjustment sub-module 1822 . The first adjustment sub-module 1821 adjusts the OFDM symbol position of the demodulation reference signal mapping according to the system bandwidth or the OFDM symbols occupied by the data that the DMRS is responsible for demodulating in the time direction; the second adjustment sub-module 1822 is a sub-module of the DMRS pattern mapping The adjustment of the position of the carrier, for example, determines the position of the sub-carrier to which the demodulation reference signal is mapped in the physical resource block according to the physical cell identification number.

The indication information generating module 1830 is configured to generate indication information, the indication information is used for the base station to indicate to the relay station the number of ports or the number of layers for demodulation reference signal transmission.

It should be noted that the adjustment sub-module described here is an optional module, which will be included only when the DMRS pattern needs to be adjusted.

According to an embodiment of the present invention, a relay station is provided, and the relay station is used for processing a downlink demodulation reference signal of a relay link.

Fig. 19 is a structural block diagram of a relay station according to an embodiment of the present invention. As shown in FIG. 19, the relay station includes a receiving module 1910, and the above structure will be described in detail below.

The receiving module 1910 is configured to receive the DMRS sent by the sending module 1730, the DMRS is a non-precoded reference signal, and is used for coherent demodulation of relay link downlink data transmission.

Further, the relay station includes an indication information receiving module 1920, configured to receive the indication information generated by the indication information generation module 1830, and the indication information is used for the relay station to determine the number of ports of the relay link DMRS.

System embodiment

According to an embodiment of the present invention, a relay system is provided, which can be used for transmission of a downlink demodulation reference signal of a relay link.

Fig. 20 is a structural block diagram of a relay system according to an embodiment of the present invention. As shown in Fig. 20, the relay system includes a base station 18 and a relay station 19, wherein the structures of the base station 18 and the relay station 19 are the same as those described in the above-mentioned device embodiments The structure is the same, and the implementation process of its specific functions has been described in detail in the device embodiment, and will not be repeated here.

To sum up, through the method, base station and relay station of the present invention, the transmission problem of the demodulation reference signal of the relay link is solved, the reliability of the data transmission of the relay link is ensured, and the terminals in the same cell will not be affected. make an impact. At the same time, by setting the number of ports in diversity transmission, the overhead of demodulating reference signals and the complexity of design are reduced under the premise of ensuring diversity transmission gain.

Obviously, those skilled in the art should understand that each module or each step of the above-mentioned present invention can be realized by a general-purpose computing device, and they can be concentrated on a single computing device, or distributed in a network formed by multiple computing devices Optionally, they can be implemented with program codes executable by a computing device, so that they can be stored in a storage device and executed by a computing device, or they can be made into individual integrated circuit modules, or they can be integrated into Multiple modules or steps are fabricated into a single integrated circuit module to realize. As such, the present invention is not limited to any specific combination of hardware and software.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and changes. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims (27)

1. A method for transmitting a relay link downlink demodulation reference signal, characterized in that the method comprises: Mapping demodulation reference signals on time-frequency two-dimensional resources, wherein the demodulation reference signals are non-precoded reference signals, used for coherent demodulation of relay link downlink data transmission; The method further includes: the demodulation reference signal corresponds to a port of the relay link downlink data transmission or a layer association of the relay link downlink data transmission. 2. The method according to claim 1, wherein the relay link downlink data includes at least one of the following: relay link downlink control data, relay link physical broadcast channel data, and relay link The data of the physical downlink shared channel, wherein the relay link downlink control data includes at least one of the following: data of the relay link physical downlink control channel, relay link downlink control format indication information, relay link Downlink hybrid automatic retransmission indication information. 3. The method according to claim 1, wherein the time-frequency two-dimensional resources include physical resource blocks allocated for transmitting the downlink data in the frequency direction. 4. The method according to claim 1, wherein the time-frequency two-dimensional resource comprises an Orthogonal Frequency Division Multiplexing (OFDM) that carries the downlink data of the relay link in a downlink relay subframe in the time direction. symbol. 5 . The method according to claim 3 , wherein the position of the subcarrier mapped in the physical resource block of the demodulation reference signal is adjusted according to the physical cell identification number. 5 . 6. The method according to claim 4, characterized in that, the OFDM symbol position to which the demodulation reference signal is mapped is fixed in a physical resource block. 7. The method according to claim 4, wherein the OFDM symbol position of the demodulation reference signal mapping is adjusted according to the system bandwidth; or Adjust the position of the OFDM symbol mapped to the demodulation reference signal according to the difference of the OFDM symbol occupied by the downlink data of the relay link. 8. The method according to claim 1, wherein, in transmit diversity transmission mode, the demodulation reference signal corresponds to the port associated with the relay link downlink data transmission, wherein, when the relay When the link downlink data is transmitted on multiple ports for the relay link downlink data transmission, the demodulation reference signals associated with different relay link downlink data transmission ports are orthogonal to each other. 9. The method according to claim 1, wherein, in the space division multiplexing transmission mode, the demodulation reference signal pattern is associated with the number of layers of the relay link downlink data transmission, and when multiple During layer transmission, the demodulation reference signals associated with each layer are orthogonal to each other. 10. The method according to claim 8 or 9, wherein the orthogonal manner comprises at least one of the following: time division multiplexing TDM, frequency division multiplexing FDM, code division multiplexing CDM . 11. The method of claim 1, further comprising: Set the number of ports for downlink data transmission of the relay link in transmit diversity mode. When the number of base station antenna ports is greater than N, set the number of ports for downlink data transmission of the relay link to N, and N is less than or equal to 4. 12. The method according to claim 11, characterized in that the setting method is: The base station uses N of the antenna ports to perform data transmission in a diversity transmission mode; or The base station uses virtual antenna port technology to map data transmission ports to N. 13. The method according to claim 11, wherein the number of ports for downlink data transmission of the relay link comprises one of the following: 2, 4. The number of ports of the common reference signal CRS in the current subframe. 14. The method of claim 1, further comprising: The base station indicates the number of ports of the downlink demodulation reference signal of the relay link to the relay station, and the indication method is an indirect indication method and/or a direct indication method. 15. The method according to claim 14, wherein the indirect indication method comprises one of the following: The base station establishes a first mapping relationship between the number of ports of the demodulation reference signal and the number of base station antenna ports, and indicates the number of ports of the demodulation reference signal according to the first mapping relationship; The base station indicates to the relay station the number of ports of the demodulation reference signal through the CRC mask of the physical broadcast channel of the relay link; The base station establishes a second mapping relationship between the number of ports of the demodulation reference signal and the number of ports of the base station common reference signal, and indicates the number of ports of the demodulation reference signal according to the second mapping relationship. 16. The method according to claim 15, wherein the base station establishes a first mapping relationship between the number of ports of the demodulation reference signal and the number of antenna ports of the base station, and the first mapping relationship includes one of the following: When the number of base station antenna ports is 1, the number of ports of the demodulation reference signal is 1, and when the number of base station antenna ports is greater than or equal to 2, the number of ports of the demodulation reference signal is 2; or When the number of base station antenna ports is 1 or 2, the number of demodulation reference signal ports is 1 or 2, and when the number of base station antenna ports is greater than or equal to 4, the number of demodulation reference signal ports is 4. 17. The method according to claim 15, after the base station establishes the second mapping relationship between the port number of the demodulation reference signal and the port number of the base station common reference signal, the method further comprises: The relay station obtains the number of ports of the common reference signal of the base station through the CRC mask of the physical broadcast channel of the base station, and obtains the number of ports of the demodulation reference signal from the second mapping relationship; The mapping relationship is that the number of ports of the demodulation reference signal is equal to the number of ports of the common reference signal of the base station. 18. The method according to claim 14, wherein the direct indication method comprises: The port number of the downlink demodulation reference signal is indicated by an indication bit in the relay link downlink control signaling. 19. A base station, characterized in that the base station comprises: a storage module for storing demodulation reference signal patterns to be transmitted from the base station; An associating module, configured to associate the demodulation reference signal patterns stored in the corresponding storage module according to the number of ports or layers of data transmission; A mapping module, configured to map the demodulation reference signal on the corresponding time-frequency two-dimensional resource according to the demodulation reference signal pattern obtained by the association module; The sending module is configured to transmit a corresponding demodulation reference signal, wherein the demodulation reference signal is a non-precoded reference signal and is used for coherent demodulation of relay link downlink data. 20. The base station according to claim 19, the association module comprises an adjustment sub-module for adjusting the demodulation reference signal pattern in time direction and/or frequency direction. 21. The base station according to claim 20, the adjusting submodule further comprises: The first adjustment submodule is configured to adjust the OFDM symbol position mapped by the demodulation reference signal according to the system bandwidth; or adjust the solution according to the OFDM symbol occupied by the relay link downlink data. Adjust the OFDM symbol position of the reference signal mapping; The second adjustment submodule is configured to adjust the position of the subcarrier mapped in the physical resource block of the demodulation reference signal according to the physical cell identification number. 22. The base station according to claim 19, further comprising a processing module configured to set the number of ports for downlink data transmission of the relay link in transmit diversity mode, and when the number of base station antenna ports is greater than N, set The number of ports for downlink data transmission on the relay link is set to N, and N is less than or equal to four. 23. The base station according to claim 22, wherein the processing module determines N ports for downlink data transmission of the relay link among the antenna ports of the base station; or The number of ports for downlink data transmission on the relay link is mapped to N in a virtual port manner. 24. The base station according to claim 19, further comprising an indication information generation module, configured to generate relay link downlink indication information, the relay link downlink indication information is used by the base station to indicate to the relay station that the association corresponds to The number of ports or the number of layers for the relay link downlink data transmission of the demodulation reference signal. 25. The base station according to claim 24, the indication information generation module indicates in one of the following ways: The relay link downlink indication information is a CRC mask of the relay link physical broadcast channel, and the number of ports of the demodulation reference signal is indicated by the CRC mask of the relay link physical broadcast channel; The relay link downlink indication information is indication information of the number of base station antenna ports, and the base station establishes a first mapping relationship between the number of demodulation reference signal ports and the number of base station antenna ports, and according to the first The mapping relationship indicates the number of ports of the demodulation reference signal; The indication information is indication information of the number of base station common reference signal ports, the base station establishes a second mapping relationship between the number of demodulation reference signal ports and the number of base station common reference signal ports, and according to the second mapping The relationship indicates the port number of the demodulation reference signal. 26. A relay station, characterized in that it comprises: A receiving module, configured to receive a relay link downlink demodulation reference signal, the relay link downlink demodulation reference signal is a non-precoding reference signal, and is used for coherent demodulation of relay link downlink data transmission; The relay station further includes: an indication information receiving module, configured to receive the relay link downlink indication information generated by the indication information generating module, and the relay link downlink indication information is used for the relay station to determine that the association corresponds to the The number of ports or the number of layers for the relay link downlink data transmission of the demodulation reference signal. 27. A relay system, characterized by comprising: a base station and a relay station, wherein, The base station includes: a storage module for storing demodulation reference signal patterns to be transmitted from the base station; An association module, configured to associate the corresponding demodulation reference signal patterns stored in the storage module according to the number of ports or layers of data transmission; A mapping module, configured to map the demodulation reference signal on a corresponding time-frequency two-dimensional resource according to the demodulation reference signal pattern obtained by the association module; A sending module, configured to transmit a corresponding demodulation reference signal, wherein the demodulation reference signal is a non-precoded reference signal, and is used to coherently demodulate the relay link downlink data; The relay station includes: The receiving module is configured to receive a relay link downlink demodulation reference signal, the relay link downlink demodulation reference signal is a non-precoding reference signal, and is used for coherent demodulation of relay link downlink data transmission.