CN101667893B

CN101667893B - Virtual multi-input multi-output relay transmission method based on space-time block coding

Info

Publication number: CN101667893B
Application number: CN 200910070714
Authority: CN
Inventors: 刘海涛; 王勇; 李冬霞
Original assignee: Civil Aviation University of China
Current assignee: Civil Aviation University of China
Priority date: 2009-09-29
Filing date: 2009-09-29
Publication date: 2013-01-09
Anticipated expiration: 2029-09-29
Also published as: CN101667893A

Abstract

A virtual multiple-input multiple-output relay transmission method based on block space-time block coding. The link between each relay station and the base station adopts the virtual MIMO method of block space-time block coding for transmission. The link between the user equipment and the relay station The road adopts the maximum ratio combining method for transmission. In the uplink, each relay station transmitter adopts the transmission mode of space-time block coding of two transmitting antenna blocks, and uses the same time-frequency resource to communicate with the base station receiver under the scheduling of the base station. In the uplink relay station receiver, the estimation and detection of the modulation symbols transmitted by the user terminal are completed, and the detected modulation symbols transmitted by the user terminal are forwarded to the receiver of the base station in the subsequent time slot of the link between the relay station and the base station. The uplink base station receiver completes the separation of user signals by adopting multi-user space-time joint equalization algorithm. The invention increases network coverage, uplink transmission capacity and frequency band utilization; maintains the low peak-to-average ratio of uplink transmitters in relay stations.

Description

Virtual MIMO Relay Transmission Method Based on Block Space-Time Block Coding

技术领域 technical field

本发明涉及一种LTE通信系统上行链路中继传输方法。特别是涉及一种可充分利用中继站与基站间多天线提供的分集增益，显著提供蜂窝移动通信系统中边缘小区或网络盲区用户链路传输的可靠性的基于块空时分组编码的虚拟多输入多输出中继传输方法。The invention relates to an uplink relay transmission method of an LTE communication system. In particular, it relates to a block-space-time block coding-based virtual multiple-input multiple Output relay transfer method.

背景技术 Background technique

LTE系统上行链路采用单载波频分复用(SC-FDMA)多址接入方案，下行链路采用正交频分复用(OFDMA)传输方案，目前，3GPP已完成LTE Rel 8系统标准化。然而，LTE Rel8系统与ITU IMT-Advanced技术要求存在较大差距，这主要体现在小区边缘用户吞吐量及频谱效率较低。为达到并超过IMT-Advanced系统技术指标的要求，3GPP进一步启动LTE-Advanced研究计划，该计划目标是在LTE Rel 8确定的技术框架基础上，对LTE系统上/下行链路传输方案进行优化，以满足IMT-Advanced系统的要求。The uplink of the LTE system adopts the single-carrier frequency division multiplexing (SC-FDMA) multiple access scheme, and the downlink adopts the orthogonal frequency division multiplexing (OFDMA) transmission scheme. At present, 3GPP has completed the standardization of the LTE Rel 8 system. However, there is a large gap between the LTE Rel8 system and ITU IMT-Advanced technical requirements, which is mainly reflected in the low user throughput and spectrum efficiency at the cell edge. In order to meet and exceed the requirements of the technical indicators of the IMT-Advanced system, 3GPP further launched the LTE-Advanced research plan. The goal of this plan is to optimize the uplink/downlink transmission scheme of the LTE system on the basis of the technical framework determined in LTE Rel 8. To meet the requirements of the IMT-Advanced system.

LTE-Advanced系统下行链路需解决核心问题：提高小区中部/小区边缘干扰受限用户的吞吐量，拟采用主要技术手段：对小区中心非干扰受限用户，采用单小区MU-MIMO技术来提高下行链路频谱效率；对于小区边缘干扰受限用户，采用多小区协作式多点传输(CoMP)来提高小区边缘用户的吞吐量。上行链路传输需解决核心问题：克服由于用户终端发射功率受限及阴影衰落而产生网络覆盖盲区，提高小区边缘用户传输可靠性与频谱效率，拟采用主要技术手段：中继传输。相关研究表明：在蜂窝移动通信系统中，通过中继传输可增加网络覆盖、提高链路传输可靠性，但由于中继站需要使用额外时/频资源才能完成中继传输(时分中继通信系统中，中继站需要使用额外时隙资源；频分中继通信系统中，中继站需要使用额外频率资源)，从而导致系统信道利用率下降。因此在LTE-Advanced上行链路传输中，如何提高小区边缘用户及网络覆盖盲区的链路可靠性，同时保证系统的信道利用率不降低是亟待解决的问题。The downlink of the LTE-Advanced system needs to solve the core problem: to improve the throughput of the interference-limited users in the center of the cell/cell edge, and to adopt the main technical means: for the non-interference-limited users in the center of the cell, use single-cell MU-MIMO technology to improve Downlink spectrum efficiency; for cell-edge interference-limited users, multi-cell coordinated multipoint transmission (CoMP) is used to improve the throughput of cell-edge users. Uplink transmission needs to solve the core problems: overcome the network coverage blind area caused by the limited transmission power of user terminals and shadow fading, improve the transmission reliability and spectrum efficiency of cell edge users, and plan to adopt the main technical means: relay transmission. Relevant studies have shown that in cellular mobile communication systems, network coverage and link transmission reliability can be increased through relay transmission, but relay stations need to use additional time/frequency resources to complete relay transmission (in time-division relay communication systems, The relay station needs to use additional time slot resources; in the frequency division relay communication system, the relay station needs to use additional frequency resources), which leads to a decrease in system channel utilization. Therefore, in LTE-Advanced uplink transmission, how to improve the link reliability of cell edge users and network coverage blind areas, and at the same time ensure that the channel utilization rate of the system does not decrease is an urgent problem to be solved.

图1给出基于DFT-S-OFDM中继传输系统的示意图，系统由三种不同类型网络设备组成：基站(eNodeB)、中继站(Relay)及用户设备(UE)。系统下行链路采用MIMO结合OFDM方式工作，上行链路采用DFT-S-OFDM方式工作。在上行链路传输中，位于基站覆盖范围内用户终端直接以DFT-S-OFDM方式与基站直接进行通信；而位于网络盲区或小区边缘用户终端则通过中继站与基站保持通信。Figure 1 shows a schematic diagram of a relay transmission system based on DFT-S-OFDM. The system consists of three different types of network equipment: base station (eNodeB), relay station (Relay) and user equipment (UE). The downlink of the system adopts MIMO combined with OFDM, and the uplink adopts DFT-S-OFDM. In the uplink transmission, the user terminal located within the coverage of the base station directly communicates with the base station in DFT-S-OFDM mode; while the user terminal located in the network blind area or cell edge maintains communication with the base station through the relay station.

用户终端通过中继站与基站通信过程如下：假设中继通信开始前，用户终端已通过中继站向基站申请中继通信所使用时频资源(用户终端与中继站通信所使用的时频资源(简称为用户时频资源)，中继站向基站转发用户终端信息所使用的时频资源(简称为中继时频资源))，用户终端使用系统分配的用户时频资源以DFT-S-OFDM方式发射用户信息给中继站，中继站在系统指定的用户时频资源内接收用户终端发射信号，并经FFT、频域均衡、IDFT、解调后，得到用户发送的比特信息，然后重新进行调制、DFT、映射、IFFT及插入循环前缀得到中继转发信号，并使用系统分配中继时频资源转发给基站接收机，基站在系统分配的中继时频资源内接收中继站转发的信号，并恢复出用户终端发射信息。The communication process between the user terminal and the base station through the relay station is as follows: Assume that before the start of the relay communication, the user terminal has applied to the base station for the time-frequency resource used for the relay communication through the relay station (the time-frequency resource used for the communication between the user terminal and the relay station (referred to as the user time-frequency resource for short). Frequency resource), the time-frequency resource used by the relay station to forward the user terminal information to the base station (referred to as the relay time-frequency resource)), the user terminal uses the user time-frequency resource allocated by the system to transmit user information to the relay station in DFT-S-OFDM mode , the relay station receives the signal transmitted by the user terminal in the user time-frequency resource specified by the system, and after FFT, frequency domain equalization, IDFT, and demodulation, obtains the bit information sent by the user, and then performs modulation, DFT, mapping, IFFT, and insertion again The cyclic prefix obtains the relay forwarding signal, and forwards it to the base station receiver using the relay time-frequency resources allocated by the system. The base station receives the signal forwarded by the relay station in the relay time-frequency resources allocated by the system, and recovers the transmission information of the user terminal.

与非中继方式上行链路传输方案相比，基于DFT-S-OFDM的中继传输方案具有以下优点：可提高网络覆盖范围，克服网络通信盲区，但在中继通信系统中，该方案存在用户终端～中继站链路额外占用时频资源，从而带来系统吞吐量及频谱利用率降低的缺点。Compared with the non-relay uplink transmission scheme, the relay transmission scheme based on DFT-S-OFDM has the following advantages: it can improve the network coverage and overcome the blind spots of network communication, but in the relay communication system, this scheme has The link from the user terminal to the relay station occupies additional time-frequency resources, which brings about the disadvantages of reduced system throughput and spectrum utilization.

基于DFT-S-OFDM单天线中继传输方案具有用户终端与中继站链路传输容量低，中继站与基站链路可靠性低的缺点，具有无法利用中继站～基站链路多天线系统提供的分集增益，使得边缘小区或网络盲区用户终端链路传输可靠性得不到充分保证等缺点。并且基于DFT-S-OFDM单天线中继传输方案当中继站数目较多时，具有增加基站接收机检测复杂度的缺点。The single-antenna relay transmission scheme based on DFT-S-OFDM has the disadvantages of low transmission capacity of the link between the user terminal and the relay station, and low reliability of the link between the relay station and the base station. The disadvantages are that the transmission reliability of user terminal links in edge cells or network blind areas cannot be fully guaranteed. Moreover, when the number of relay stations is large in the single-antenna relay transmission scheme based on DFT-S-OFDM, it has the disadvantage of increasing the detection complexity of the base station receiver.

发明内容 Contents of the invention

本发明所要解决的技术问题是：在LTE上行链路中，提供一种可充分利用中继站与基站间多天线提供的分集增益，显著提高蜂窝移动通信系统中边缘小区或网络盲区用户链路传输的可靠性的基于块空时分组编码的虚拟多输入多输出中继传输方法。The technical problem to be solved by the present invention is: in the LTE uplink, provide a kind of diversity gain that can make full use of the multi-antenna between relay station and base station to provide, significantly improve the edge cell or network blind zone user link transmission efficiency in the cellular mobile communication system Reliable Block Space-Time Block Coding Based Virtual MIMO Relay Transmission Method.

本发明所采用的技术方案是：一种基于块空时分组编码的虚拟多输入多输出中继传输方法，在由用户设备、中继站和基站构成的中继传输系统中，所述的每个中继站与基站之间的链路采用块空时分组编码的虚拟MIMO方式进行传输，所述的用户设备与中继站之间的链路采用最大比值合并方式进行传输。The technical solution adopted in the present invention is: a virtual multiple-input multiple-output relay transmission method based on block space-time block coding. In the relay transmission system composed of user equipment, relay stations and base stations, each of the relay stations The link between the base station and the base station adopts the virtual MIMO method of block space-time block coding for transmission, and the link between the user equipment and the relay station adopts the maximum ratio combining method for transmission.

在上行链路中所述的每个中继站发射机中均采用两发射天线块空时分组编码的传输方式，并在基站调度下使用相同的时频资源与基站接收机实现通信。In the uplink, each relay station transmitter adopts the transmission mode of space-time block coding of two transmitting antenna blocks, and uses the same time-frequency resource to communicate with the base station receiver under the scheduling of the base station.

在上行链路中所述的中继站接收机中，完成对用户终端发射调制符号的估计与检测，并在随后中继站与基站链路的时隙将检测到的用户终端所发射的调制符号转发给基站的接收机。In the relay station receiver described in the uplink, the estimation and detection of the modulation symbols transmitted by the user terminal are completed, and the detected modulation symbols transmitted by the user terminal are forwarded to the base station in the subsequent time slot of the link between the relay station and the base station receiver.

在上行链路中所述的基站接收机中，通过采用多用户空时联合均衡算法完成用户信号的分离。In the base station receiver described in the uplink, the separation of user signals is accomplished by using a multi-user space-time joint equalization algorithm.

所述的块空时分组编码的传输是由如下步骤实现：The transmission of the block space-time block coding is realized by the following steps:

第一步骤：对输入比特序列进行调制；The first step: modulating the input bit sequence;

第二步骤：对调制器输出进行N点快速傅里叶变换；The second step: performing N-point fast Fourier transform on the output of the modulator;

第三步骤：将快速傅里叶变换输出送入块空时分组编码器进行编码处理；The third step: send the fast Fourier transform output to the block space-time block encoder for encoding processing;

第四步骤：将编码处理后的两路信号分别进行相同的处理，各路处理后信号通过该路对应的天线进行发送。Step 4: Perform the same processing on the encoded signals of the two channels, and send the processed signals of each channel through the antenna corresponding to the channel.

第四步骤所述的相同处理包括如下过程：The same processing described in the fourth step includes the following procedures:

1)分别将两路数据信号映射到L个频率域子载波上，其中L＞N，N为大于等于1的整数；1) respectively mapping the two data signals to L subcarriers in the frequency domain, where L>N, where N is an integer greater than or equal to 1;

2)将映射器输出进行L点的反向快速傅里叶变换；2) carry out the inverse fast Fourier transform of point L with mapper output;

3)插入循环前缀，经D/A转换；3) Insert the cyclic prefix and convert through D/A;

4)送入中频及射频单元；4) Send to the intermediate frequency and radio frequency unit;

5)经天线发射。5) Transmitted through the antenna.

在上行链路中基站接收机的信号处理包括如下步骤：The signal processing of the base station receiver in the uplink includes the following steps:

1)与各接收天线对应的接收通路将接收到的信号进行相同的信号处理：1) The receiving channel corresponding to each receiving antenna performs the same signal processing on the received signal:

a.将来自天线的射频信号经射频与中频单元处理，经采样后形成数字基带信号；a. The radio frequency signal from the antenna is processed by the radio frequency and intermediate frequency unit, and the digital baseband signal is formed after sampling;

b.对数字基带信号进行移除循环前缀；b. remove the cyclic prefix from the digital baseband signal;

c.进行L点傅里叶变换；c. Carry out L-point Fourier transform;

d.进行解映射处理，即从L个子载波上取出数据信号；d. Perform demapping processing, that is, take out data signals from L subcarriers;

2)将各接收通路处理后的信号汇总进行空时联合均衡处理；2) Summarize the processed signals of each receiving channel and perform joint space-time equalization processing;

3)将空时联合均衡器分离出的各用户信号仍以各通路为单位进行相同的信号处理，包括有进行N点反向离散傅立叶变换、解调和译码得到各用户终端发射的信息。3) The user signals separated by the space-time joint equalizer are still subjected to the same signal processing in units of each channel, including performing N-point inverse discrete Fourier transform, demodulation and decoding to obtain information transmitted by each user terminal.

所述的多用户空时联合均衡处理是由如下公式完成：The multi-user space-time joint equalization process is completed by the following formula:

利用信道矩阵的类Alamouti特性，引入两用户线性迫零矩阵Using the Alamouti-like property of the channel matrix, a two-user linear zero-forcing matrix is introduced

$Φ Φ = = [\begin{matrix} {I I}_{22 N N} & - - {Λ Λ}_{1,2 1,2} {Λ Λ}_{2,2 2,2}^{- - 11} \\ - - {Λ Λ}_{2,1 2,1} {Λ Λ}_{1,1 1,1}^{- - 11} & {I I}_{22 N N} \end{matrix}]$

并构造修正接收信号矢量：And construct the corrected received signal vector:

$\overset{~ ~}{Y Y} = = Φ Φ [\begin{matrix} {Y Y}_{D D.}^{11} \\ {Y Y}_{D D.}^{22} \end{matrix}] = = [\begin{matrix} Σ Σ & 00 \\ 00 & Δ Δ \end{matrix}] [\begin{matrix} Z Z \\ C C \end{matrix}] + + [\begin{matrix} {\overset{~ ~}{N N}}_{D D.}^{11} \\ {\overset{~ ~}{N N}}_{D D.}^{22} \end{matrix}]$

其中， $Σ = Λ_{1,1} - Λ_{1,2} Λ_{2,2}^{- 1} Λ_{2,1},$ $Δ = Λ_{2,2} - Λ_{2,1} Λ_{1,1}^{- 1} Λ_{1,2},$ 再次利用矩阵∑及Δ的类Alamouti特性，若记 $\tilde{Y} = {[{\tilde{Y}}_{1} {\tilde{Y}}_{2}]}^{T},$ 则in, $Σ = Λ_{1,1} - Λ_{1,2} Λ_{2,2}^{- 1} Λ_{2,1},$ $Δ = Λ_{2,2} - Λ_{2,1} Λ_{1,1}^{- 1} Λ_{1,2},$ Using the Alamouti-like properties of matrices Σ and Δ again, if write $\tilde{Y} = {[{\tilde{Y}}_{1} {\tilde{Y}}_{2}]}^{T},$ but

按照以下方式处理：Proceed as follows:

${\overset{~ ~}{\overset{~ ~}{Y Y}}}_{11} = = {Σ Σ}^{H h} {\overset{~ ~}{Y Y}}_{11} = = {Σ Σ}^{H h} ΣZ ΣZ + + {\overset{~ ~}{\overset{~ ~}{N N}}}_{D D.}^{11}$

${\overset{~ ~}{\overset{~ ~}{Y Y}}}_{22} = = {Δ Δ}^{H h} {\overset{~ ~}{Y Y}}_{22} = = {Δ Δ}^{H h} ΔC ΔC + + {\overset{~ ~}{\overset{~ ~}{N N}}}_{D D.}^{22}$

并利用 $Σ^{H} Σ = (\begin{matrix} A & 0 \\ 0 & A \end{matrix})$ 及 $Δ^{H} Δ = (\begin{matrix} B & 0 \\ 0 & B \end{matrix})$ 为对角阵，进一步化简为：and use $Σ^{h} Σ = (\begin{matrix} A & 0 \\ 0 & A \end{matrix})$ and $Δ^{h} Δ = (\begin{matrix} B & 0 \\ 0 & B \end{matrix})$ is a diagonal matrix, which can be further simplified as:

${\overset{~ ~}{\overset{~ ~}{Y Y}}}_{1,1 1,1} = = AZ AZ ((k k)) + + {\overset{~ ~}{\overset{~ ~}{N N}}}_{D D.}^{1,1 1,1};;$ ${\overset{~ ~}{\overset{~ ~}{Y Y}}}_{1,2 1,2} = = AZ AZ ((k k + + 11)) + + {\overset{~ ~}{\overset{~ ~}{N N}}}_{D D.}^{1,2 1,2}$

${\overset{~ ~}{\overset{~ ~}{Y Y}}}_{2,1 2,1} = = BC BC ((k k)) + + {\overset{~ ~}{\overset{~ ~}{N N}}}_{D D.}^{2,1 2,1};;$ ${\overset{~ ~}{\overset{~ ~}{Y Y}}}_{2,2 2,2} = = BC BC ((k k + + 11)) + + {\overset{~ ~}{\overset{~ ~}{N N}}}_{D D.}^{2,2 2,2}$

其中， ${\tilde{\tilde{Y}}}_{1} = {[{\tilde{\tilde{Y}}}_{1,1}^{T} {, \tilde{\tilde{Y}}}_{1,2}^{T}]}^{T},$ ${\tilde{\tilde{Y}}}_{2} = {[{\tilde{\tilde{Y}}}_{2,1}^{T}, {\tilde{\tilde{T}}}_{2,2}^{T}]}^{T},$ ${\tilde{\tilde{N}}}_{D}^{1} = {[{\tilde{\tilde{N}}}_{D}^{1,1 T}, {\tilde{\tilde{N}}}_{D}^{1,2 T}]}^{T},$ ${\tilde{\tilde{N}}}_{D}^{2} = {[{\tilde{\tilde{N}}}_{D}^{2,1 T}, {\tilde{\tilde{N}}}_{D}^{2,2 T}]}^{T}$ 再利用A及B的对角矩阵特性，可方便得到{Z(k)，Z(k+1)}及{C(k)，C(k+1)}的估计为：in, ${\tilde{\tilde{Y}}}_{1} = {[{\tilde{\tilde{Y}}}_{1,1}^{T} {, \tilde{\tilde{Y}}}_{1,2}^{T}]}^{T},$ ${\tilde{\tilde{Y}}}_{2} = {[{\tilde{\tilde{Y}}}_{2,1}^{T}, {\tilde{\tilde{T}}}_{2,2}^{T}]}^{T},$ ${\tilde{\tilde{N}}}_{D.}^{1} = {[{\tilde{\tilde{N}}}_{D.}^{1,1 T}, {\tilde{\tilde{N}}}_{D.}^{1,2 T}]}^{T},$ ${\tilde{\tilde{N}}}_{D.}^{2} = {[{\tilde{\tilde{N}}}_{D.}^{2,1 T}, {\tilde{\tilde{N}}}_{D.}^{2,2 T}]}^{T}$ Using the diagonal matrix characteristics of A and B, the estimates of {Z(k), Z(k+1)} and {C(k), C(k+1)} can be easily obtained as:

$\overset{~ ~}{Z Z} ((k k)) = = {A A}^{- - 11} {\overset{~ ~}{\overset{~ ~}{Y Y}}}_{1,1 1,1};;$ $\overset{~ ~}{Z Z} ((k k + + 11)) = = {A A}^{- - 11} {\overset{~ ~}{\overset{~ ~}{Y Y}}}_{1,2 1,2}$

$\overset{~ ~}{C C} ((k k)) = = {A A}^{- - 11} {\overset{~ ~}{\overset{~ ~}{Y Y}}}_{2,1 2,1};;$ $\overset{~ ~}{C C} ((k k + + 11)) = = {A A}^{- - 11} {\overset{~ ~}{\overset{~ ~}{Y Y}}}_{2,2 2,2}$

及

进行N点的IDFT运算得到

及

最后分别对

及每分量进行最大似然检测可得到中继转发符号矢量{z(k)，z(k+1)}及{c(k)，c(k+1)}的估计值

及

and

Perform IDFT operation of N points to get

and

Finally, respectively

and The maximum likelihood detection of each component can obtain the estimated value of the relay forwarding symbol vector {z(k), z(k+1)} and {c(k), c(k+1)}

and

本发明基于块空时分组编码的虚拟多输入多输出中继传输方法，可充分利用中继站与基站间多天线提供的分集增益，显著提供蜂窝移动通信系统中边缘小区或网络盲区用户链路传输的可靠性，进而增加网络覆盖范围；此外在中继站与基站链路间，利用虚拟MIMO技术显著提高上行链路传输容量及频带利用率，克服传统中继方案频谱效率降低的缺点；基于块空时分组编码传输方案亦保持了中继站上行链路发射机低峰均比的优良特性。本发明的方法可应用于LTE-Advanced及4G宽带移动通信系统。The virtual multiple-input multiple-output relay transmission method based on block space-time packet coding in the present invention can make full use of the diversity gain provided by multiple antennas between the relay station and the base station, and significantly provide the advantages of user link transmission in edge cells or network blind areas in cellular mobile communication systems Reliability, thereby increasing network coverage; In addition, between the relay station and the base station link, the use of virtual MIMO technology significantly improves the uplink transmission capacity and frequency band utilization, and overcomes the shortcomings of traditional relay schemes that reduce spectrum efficiency; based on block space-time grouping The coded transmission scheme also maintains the excellent characteristic of low peak-to-average ratio of the uplink transmitter of the relay station. The method of the invention can be applied to LTE-Advanced and 4G broadband mobile communication systems.

附图说明 Description of drawings

图1是基于DFT-S-OFDM单天线中继传输示意图；Figure 1 is a schematic diagram of single-antenna relay transmission based on DFT-S-OFDM;

图2是基于LTE TDD上行链路虚拟MIMO中继传输示意图；Fig. 2 is a schematic diagram of virtual MIMO relay transmission based on LTE TDD uplink;

图3是基于最大比值合并的用户终端与中继站链路传输示意图；FIG. 3 is a schematic diagram of link transmission between a user terminal and a relay station based on maximum ratio combining;

图4是基于B-STBC虚拟MIMO中继站与基站链路传输示意图；FIG. 4 is a schematic diagram of link transmission between a B-STBC virtual MIMO relay station and a base station;

图5是基于块空时分组编码的中继站发射机流程图；Fig. 5 is a relay station transmitter flow chart based on block space-time block coding;

图6是上行链路基站虚拟MIMO接收机流程图；Fig. 6 is a flow chart of uplink base station virtual MIMO receiver;

图7-1是基于LTE TDD上行链路虚拟MIMO中继传输第一实施例流程图；Figure 7-1 is a flow chart of the first embodiment of virtual MIMO relay transmission based on LTE TDD uplink;

图7-2是基于LTE TDD上行链路虚拟MIMO中继传输第二实施例流程图；Fig. 7-2 is the flowchart of the second embodiment based on LTE TDD uplink virtual MIMO relay transmission;

图7-3是基于LTE TDD上行链路虚拟MIMO中继传输第三实施例流程图；Fig. 7-3 is the flowchart of the third embodiment based on LTE TDD uplink virtual MIMO relay transmission;

图7-4是基于LTE TDD上行链路虚拟MIMO中继传输第四实施例流程图；Fig. 7-4 is the flowchart of the fourth embodiment based on LTE TDD uplink virtual MIMO relay transmission;

图7-5是基于LTE TDD上行链路虚拟MIMO中继传输第五实施例流程图；Fig. 7-5 is the flowchart of the fifth embodiment based on LTE TDD uplink virtual MIMO relay transmission;

图7-6是基于LTE TDD上行链路虚拟MIMO中继传输第五实施例流程图；Fig. 7-6 is the flowchart of the fifth embodiment based on LTE TDD uplink virtual MIMO relay transmission;

图8-1是虚拟MIMO中继传输方法BER性能比较(QPSK调制)；Figure 8-1 is the BER performance comparison of the virtual MIMO relay transmission method (QPSK modulation);

图8-2是虚拟MIMO中继传输方案BER性能比较(16QAM调制)。Figure 8-2 shows the BER performance comparison of the virtual MIMO relay transmission scheme (16QAM modulation).

具体实施方式 Detailed ways

下面结合实施例附图对本发明基于块空时分组编码的虚拟多输入多输出中继传输方法做出详细说明。The virtual MIMO relay transmission method based on block space-time block coding of the present invention will be described in detail below in conjunction with the accompanying drawings of the embodiments.

如图2所示，基站(eNodeB)位于小区中央，小区内部署若干个固定中继站(Relay)，网络盲区与小区边缘用户终端与基站没有直接传输链路，而中继站以时分方式为小区边缘及网络盲区内用户终端(UE)提供中继传输服务。在时分中继通信系统中，基站时隙分为两个部分，一部分时隙分配给用户终端～中继站链路传输使用，另一部分时隙分配给中继站～基站链路或用户终端～基站链路间使用。As shown in Figure 2, the base station (eNodeB) is located in the center of the cell, and several fixed relay stations (Relay) are deployed in the cell. There is no direct transmission link between the user terminal and the base station in the network blind area and the cell edge, and the relay station is used as a link between the cell edge and the network in a time-division manner. The user terminal (UE) in the blind zone provides relay transmission service. In the time division relay communication system, the time slot of the base station is divided into two parts, one part of the time slot is allocated to the link transmission between the user terminal and the relay station, and the other part of the time slot is allocated to the link between the relay station and the base station or the link between the user terminal and the base station use.

在LTE TDD(基于时分双工的长期演进计划)系统上行链路，考虑到用户终端体积受限，假设用户终端仅安装单个天线，固定部署中继站安装多个接收/发射天线，基站也配备多个接收天线。另外进一步假设基站利用信道估计完全知晓各个中继站至基站的信道信息，中继站亦可通过信道估计获取其服务用户终端的信道信息。In the uplink of the LTE TDD (Long Term Evolution Plan based on Time Division Duplex) system, considering the limited size of the user terminal, it is assumed that the user terminal is only equipped with a single antenna, and the fixed deployment relay station is equipped with multiple receiving/transmitting antennas, and the base station is also equipped with multiple antennas. Receive antenna. In addition, it is further assumed that the base station fully knows the channel information from each relay station to the base station through channel estimation, and the relay station can also obtain the channel information of the user terminal it serves through channel estimation.

本发明提出的基于块空时分组编码的虚拟多输入多输出中继传输方法属于检测～转发方案(DF)。在第一阶段用户终端到中继站链路传输中，中继站接收机采用最大比值合算法接收用户终端传输的信息；在第二阶段中继站到基站链路传输中，各个中继站采用块空时分组编码(B-STBC)传输，且多个中继站在基站调度下以虚拟MIMO方式工作。The virtual MIMO relay transmission method based on block space-time packet coding proposed by the present invention belongs to the detection-forwarding scheme (DF). In the first stage of link transmission from the user terminal to the relay station, the relay station receiver adopts the maximum ratio combination algorithm to receive the information transmitted by the user terminal; in the second stage of the link transmission from the relay station to the base station, each relay station uses block space-time block coding (B -STBC) transmission, and multiple relay stations work in a virtual MIMO mode under the scheduling of the base station.

本发明的基于块空时分组编码的虚拟多输入多输出中继传输方法，具体是在由用户设备A、中继站B和基站C构成的中继传输系统中，所述的每个中继站B与基站C之间的链路采用块空时分组编码的虚拟MIMO方式进行传输，所述的用户设备A与中继站B之间的链路采用最大比值合并方式进行传输。The virtual multiple-input multiple-output relay transmission method based on block space-time block coding of the present invention, specifically, in the relay transmission system composed of user equipment A, relay station B and base station C, each relay station B and base station The link between C is transmitted in a block space-time block coding virtual MIMO manner, and the link between user equipment A and relay station B is transmitted in a maximum ratio combining manner.

图3给出了基于最大比值合并的用户终端与中继站链路传输方法。各用户终端使用标准DFT-S-OFDM发射机，其工作原理如下：用户终端信源输出比特序列经交织与信道编码后送入调制器，用户终端的第k个调制符号分组表示为x(k)＝[x(k，0)，x(k，1)，...，x(k，i)，...，x(k，N-1)]^T，其中x(k，i)代表用户终端第k个调制符号分组内第i个调制符号，调制符号分组长度N与基站分配给用户终端的子信道数相同，x(k)经N点DFT预处理后表示为X(k)＝[X(k，0)，X(k，1)，...，X(k，j)，...，X(k，N-1)]^T，X(k，j)与x(k，i)为离散傅里叶变换关系：FIG. 3 shows a link transmission method between a user terminal and a relay station based on maximum ratio combining. Each user terminal uses a standard DFT-S-OFDM transmitter, and its working principle is as follows: the source output bit sequence of the user terminal is sent to the modulator after interleaving and channel coding, and the kth modulation symbol group of the user terminal is expressed as x(k )=[x(k, 0), x(k, 1), ..., x(k, i), ..., x(k, N-1)] ^T , where x(k, i) Represents the i-th modulation symbol in the k-th modulation symbol group of the user terminal, the length of the modulation symbol group N is the same as the number of sub-channels allocated by the base station to the user terminal, x(k) is expressed as X(k) after N-point DFT preprocessing =[X(k, 0), X(k, 1), ..., X(k, j), ..., X(k, N-1)] ^T , X(k, j) and x (k, i) is the discrete Fourier transform relationship:

$X x ((k k,, j j)) = = {Σ Σ}_{i i = = 00}^{N N - - 11} x x ((k k,, i i)) \cdot &Center Dot; {e e}^{- - j j 22 πij πij / / N N},, j j = = 00,, . . . . . .,, N N - - 11 - - - - - - ((11))$

X(k)通过映射器映射到基站分配的N个连续子信道{l|l＝0，...，N-1}传输；映射器输出信号经L点IFFT变换，然后插入循环前缀，经D/A转换，送入中频及射频单元，最后射频信号送入单个发射天线。X(k) is mapped to the N continuous sub-channels {l|l=0,...,N-1} allocated by the base station through the mapper for transmission; the output signal of the mapper is transformed by L-point IFFT, and then inserted into the cyclic prefix, and passed through The D/A conversion is sent to the intermediate frequency and radio frequency unit, and finally the radio frequency signal is sent to a single transmitting antenna.

在中继站接收机中，来自天线的射频信号经射频与中频单元处理，通过A/D转换后送入基带数字信号处理单元。数字基地信号首先移除循环前缀，然后进行L点FFT变换，解映射器从{l|l＝0，...，N-1}个子信道提取接收信号，第k时刻中继站接收机的第s个接收天线第l个子信道接收信号Y_R ^s(k，l)表示为：In the relay station receiver, the radio frequency signal from the antenna is processed by the radio frequency and intermediate frequency unit, and then sent to the baseband digital signal processing unit after A/D conversion. The digital base signal first removes the cyclic prefix, and then performs L-point FFT transformation. The demapper extracts the received signal from {l|l=0,...,N-1} sub-channels, and the s-th The received signal Y _R ^s (k, l) of the lth sub-channel of a receiving antenna is expressed as:

${Y Y}_{R R}^{s the s} ((k k,, l l)) = = {H h}_{SR SR}^{s the s,, 11} ((k k,, l l)) X x ((k k,, l l)) + + {N N}_{R R}^{s the s} ((k k,, l l)),, l l = = 00,, . . . . . .,, N N - - 11,, s the s = = 00,, . . . . . .,, {N N}_{rr rr} - - - - - - ((22))$

其中，H_SR ^s，t(k，l)代表第k时刻用户终端第t个发射天线到中继站第s个接收天线第l个子信道的频率响应，X(k，l)代表用户终端第k时刻第l个子信道传输的复信号，N_R ^s(k，l)代表第k时刻中继站第s个接收天线第l个子信道接收到复高斯白噪声，N_rr代表中继站接收机的天线数目。将中继站N_rr个天线相同子信道接收信号进行最大比值合并，并通过迫零均衡得到X(k，l)的估计值：Among them, H _SR ^{s, t} (k, l) represents the frequency response of the t-th transmit antenna of the user terminal to the l-th sub-channel of the s-th receive antenna of the relay station at the k-th moment, and X(k, l) represents the frequency response of the user terminal at the k-th moment The complex signal transmitted by the l-th sub-channel, N _R ^s (k, l) represents the complex white Gaussian noise received by the s-th receiving antenna of the relay station on the l-th sub-channel at the k-th moment, and N _rr represents the number of antennas of the relay station receiver. Combine the received signals of the same sub-channel of the N _rr antennas of the relay station at the maximum ratio, and obtain the estimated value of X(k,l) through zero-forcing equalization:

$\overset{^^}{X x} ((k k,, l l)) = = \frac{{Σ Σ}_{s the s = = 00}^{{N N}_{rr rr} - - 11} (({(({H h}_{SR SR}^{s the s,, 11} ((k k,, l l))))}^{* *} \times \times {Y Y}_{R R}^{s the s} ((k k,, l l))))}{{Σ Σ}_{s the s = = 00}^{{N N}_{rr rr} - - 11} {| | {H h}_{SR SR}^{s the s,, 11} ((k k,, l l)) | |}^{22}},, l l = = 00,, . . . . . .,, N N - - 11 - - - - - - ((33))$

进一步对信号矢量 $\hat{X} (k) = [\hat{X} (k, 0), \hat{X} (k, 1), . . ., \hat{X} (k, N - 1)]$ 进行N点IDFT处理得到 $\hat{x} (k) = [\hat{x} (k, 0), \hat{x} (k, 1), . . ., \hat{x} (k, N - 1)],$ 最后对

每分量进行最大似然检测得到用户终端发射调制符号的估计值，中继站发射机在随后中继站～基站链路时隙将检测得到的信号发送给基站接收机。Further to the signal vector

\hat{x} (k) = [\hat{x} (k, 0), \hat{x} (k, 1), . . ., \hat{x} (k, N - 1)]

Perform N-point IDFT processing to get

\hat{x} (k) = [\hat{x} (k, 0), \hat{x} (k, 1), . . ., \hat{x} (k, N - 1)],

last to

The estimated value of the modulation symbol transmitted by the user terminal is obtained by performing maximum likelihood detection on each component, and the relay station transmitter sends the detected signal to the base station receiver in the subsequent relay station-base station link time slot.

在上行链路中所述的每个中继站B发射机中均采用两发射天线块空时分组编码的传输方式，并在基站C调度下使用相同的时频资源与基站C接收机实现通信。In the uplink, each relay station B transmitter adopts the transmission mode of space-time block coding with two transmitting antenna blocks, and uses the same time-frequency resource to communicate with the base station C receiver under the scheduling of the base station C.

所述的基于块空时分组编码的发射机传输如图5所示，是由如下步骤实现：The described transmitter transmission based on block space-time block coding is as shown in Figure 5, and is realized by the following steps:

第二步骤：对调制器输出进行N点快速傅里叶变换FFT；The second step: performing N-point fast Fourier transform FFT on the output of the modulator;

第三步骤：将快速傅里叶变换输出送入块空时分组编码器B-STBC进行编码处理；The third step: send the fast Fourier transform output to the block space-time block encoder B-STBC for encoding processing;

1)分别将两路数据信号映射到L个频率域子载波上L＞N，N为大于等于1的整数；1) respectively mapping the two data signals to L subcarriers in the frequency domain L>N, where N is an integer greater than or equal to 1;

2)将映射器输出进行L点的反向快速傅里叶变换IFFT；2) carry out the inverse fast Fourier transform IFFT of L point with mapper output;

5)经天线发射。5) Transmitted through the antenna.

图4给出基于B-STBC虚拟MIMO中继站与基站链路传输方法。中继站1，2，…N_rt均采用两天线块空时分组编码(B-STBC)传输方案，并在基站调度下使用相同时/频资源构成2N_rt×N_d的虚拟MIMO系统。在实际通信系统中，考虑到基于虚拟MIMO的中继节点数目较多时，基站接收机检测复杂度极高，因此通常仅考虑由两个中继站构成的虚拟MIMO系统，由于各个中继站发射机工作原理相同，以下仅以中继站1为例来说明块空时分组编码过程。Figure 4 shows the link transmission method between the B-STBC virtual MIMO relay station and the base station. The relay stations 1, 2, ... N _rt all adopt the two-antenna block space-time block coding (B-STBC) transmission scheme, and use the same time/frequency resources under base station scheduling to form a 2N _rt × N _d virtual MIMO system. In the actual communication system, considering that when the number of relay nodes based on virtual MIMO is large, the detection complexity of the base station receiver is extremely high, so usually only the virtual MIMO system composed of two relay stations is considered, because the transmitters of each relay station have the same working principle , the relay station 1 is taken as an example below to illustrate the block space-time block coding process.

如图5所示，第k时刻第1个中继站待传输的调制符号分组表示为z(k)＝[z(k，0)，z(k，1)，...，z(k，N-1)]^T，z(k)经N点DFT处理后表示为Z(k)＝[Z(k，0)，Z(k，1)，...，Z(k，N-1)]^T，中继站1的两个连续分组{Z(k)，Z(k+1)}同时送入块空时分组编码器(B-STBC)进行编码处理，块空时分组编码器输出信号矢量{Z(k)，-Z^*(k+1)}送入第一个发射支路，{Z(k+1)，Z^*(k)}送入第二发射支路；两个支路信号通过映射器映射到基站分配的N个连续子信道{l|l＝0，...，N-1}传输；映射器输出信号经L点IFFT变换，然后插入循环前缀，经D/A转换，送入中频及射频单元，最后发射信号送入两个天线发射。As shown in Figure 5, the modulation symbol group to be transmitted by the first relay station at the kth moment is expressed as z(k)=[z(k, 0), z(k, 1), ..., z(k, N -1)] ^T , z(k) is expressed as Z(k)=[Z(k, 0), Z(k, 1), ..., Z(k, N-1) after N-point DFT processing ] ^T , two consecutive packets {Z(k), Z(k+1)} of relay station 1 are simultaneously sent to the block space-time block coder (B-STBC) for encoding processing, and the block space-time block coder outputs a signal vector {Z(k), -Z ^* (k+1)} is sent to the first emission branch, {Z(k+1), Z ^* (k)} is sent to the second emission branch; two branches The signal is mapped to N continuous sub-channels {l|l=0,...,N-1} allocated by the base station through the mapper for transmission; the output signal of the mapper is transformed by L-point IFFT, then inserted into a cyclic prefix, and passed through D/A Converted, sent to the intermediate frequency and radio frequency unit, and finally the transmitted signal is sent to the two antennas for transmission.

中继站2的传输过程与中继站1完全相同，其待传输调制符号矢量记为c(k)，DFT预处理后信号矢量为C(k)，中继站2两个连续分组{C(k)，C(k+1)}经块空时分组编码后送入第1发射支路信号矢量为{C(k)，-C^*(k+1)}，送入第2发射支路信号矢量为{C(k+1)，C^*(k)}。The transmission process of relay station 2 is exactly the same as that of relay station 1. The modulation symbol vector to be transmitted is denoted as c(k), and the signal vector after DFT preprocessing is C(k). Two consecutive groups of relay station 2 {C(k), C( k+1)} after block space-time block coding, the signal vector sent to the first transmission branch is {C(k), -C ^* (k+1)}, and the signal vector sent to the second transmission branch is {C (k+1), C ^* (k)}.

在上行链路中所述的中继站B的接收机中，完成对用户终端A发射调制符号的估计与检测，并在随后中继站B与基站C链路的时隙将检测到的用户终端A所发射的调制符号转发给基站C的接收机。In the receiver of the relay station B described in the uplink, the estimation and detection of the modulation symbols transmitted by the user terminal A are completed, and the detected user terminal A transmits The modulation symbols of are forwarded to the receiver of base station C.

在上行链路中基站C接收机的信号处理如图6所示，包括如下步骤：The signal processing of the base station C receiver in the uplink is shown in Figure 6, including the following steps:

c.进行L点傅里叶变换；c. Carry out L-point Fourier transform;

为方便叙述，基站接收机使用两副接收天线，本传输方案可方便推广到接收机天线数为1/4/6/8的情况。基站接收机中，来自天线射频信号经射频与中频单元处理，经采样后形成数字基带信号，数字基带信号在移除循环前缀后，进行L点FFT变换，基站接收机第k时刻第1个接收天线第l个子信道接收信号Y_D ¹(k，l)表示为：For the convenience of description, the base station receiver uses two receiving antennas, and this transmission scheme can be easily extended to the case where the number of receiver antennas is 1/4/6/8. In the base station receiver, the radio frequency signal from the antenna is processed by the radio frequency and intermediate frequency unit, and the digital baseband signal is formed after sampling. After the cyclic prefix is removed, the digital baseband signal is subjected to L-point FFT transformation, and the base station receiver is the first to receive at the kth moment The received signal Y _D ¹ (k, l) of the lth sub-channel of the antenna is expressed as:

${Y Y}_{D D.}^{11} ((k k,, l l)) = = {H h}_{}^{RD RD} ((k k,, l l)) Z Z ((k k,, l l)) + + {H h}_{}^{RD RD} ((k k,, l l)) Z Z ((k k + + 11,, l l)) + + {G G}_{}^{RD RD} ((k k,, l l)) C C ((k k,, l l)) + + {G G}_{}^{RD RD} ((k k,, l l)) C C ((k k + + 11,, l l)) + + {N N}_{D D.}^{11} ((k k,, l l)) - - - - - - ((44))$

其中，H_RD ^m，n(k，l)与G_RD ^m，n(k，l)分别代表第k时刻中继站1与中继站2第n个发射天线到基站第m个接收天线第l个子信道的频率响应，N_D ^m(k，l)代表k时刻基站第m接收天线第l个子信道输入复高斯白噪声。进一步假设第k及第k+1时刻中继站到基站各个子信道频率响应保持恒定不变，可得到基站k+1时刻第1个接收天线第l个子信道接收信号Y_D ¹(k+1，l)、k时刻与k+1时刻第2个接收天线第l个子信道接收信号Y_D ²(k，l)和Y_D ²(k+1，l)：Wherein, H _RD ^m,n (k,l) and G _RD ^m,n (k,l) respectively represent the k-th moment relay station 1 and relay station 2 transmit antenna n to the base station m receive antenna l sub-channel Frequency response, N _D ^m (k, l) represents complex white Gaussian noise input to the lth subchannel of the mth receiving antenna of the base station at time k. Further assuming that the frequency response of each subchannel from the relay station to the base station remains constant at the kth and k+1th moments, the received signal Y _D ¹ (k+1,l ), the received signals Y _D ² (k, l) and Y _D ² (k+1, l) of the first sub-channel of the second receiving antenna at time k and k+1:

${Y Y}_{D D.}^{11} ((k k + + 11,, l l)) = = - - {H h}_{}^{RD RD} ((k k,, l l)) {Z Z}^{* *} ((k k + + 11,, l l)) + + {H h}_{}^{RD RD} ((k k,, l l)) {Z Z}^{* *} ((k k,, l l)) - - {G G}_{}^{RD RD} ((k k,, l l)) {C C}^{* *} ((k k + + 11,, l l)) + + {G G}_{}^{RD RD} ((k k,, l l)) {C C}^{* *} ((k k,, l l)) + + {N N}_{D D.}^{11} ((k k + + 11,, l l)) - - - - - - ((55))$

${Y Y}_{D D.}^{22} ((k k,, l l)) = = {H h}_{}^{RD RD} ((k k,, l l)) Z Z ((k k,, l l)) + + {H h}_{}^{RD RD} ((k k,, l l)) Z Z ((k k + + 11,, l l)) + + {G G}_{}^{RD RD} ((k k,, l l)) C C ((k k,, l l)) + + {G G}_{}^{RD RD} ((k k,, l l)) C C ((k k + + 11,, l l)) + + {N N}_{D D.}^{22} ((k k,, l l)) - - - - - - ((66))$

${Y Y}_{D D.}^{22} ((k k + + 11,, l l)) = = - - {H h}_{}^{RD RD} ((k k,, l l)) {Z Z}^{* *} ((k k + + 11,, l l)) + + {H h}_{}^{RD RD} ((k k,, l l)) {Z Z}^{* *} ((k k,, l l)) - - {G G}_{}^{RD RD} ((k k,, l l)) {C C}^{* *} ((k k + + 11,, l l)) + + {G G}_{}^{RD RD} ((k k,, l l)) {C C}^{* *} ((k k,, l l)) + + {N N}_{D D.}^{22} ((k k + + 11,, l l)) - - - - - - ((77))$

式(4)、(5)、(6)与(7)进一步表示为矩阵形式为：Formulas (4), (5), (6) and (7) are further expressed in matrix form as:

$[\begin{matrix} {Y Y}_{D D.}^{11} ((k k)) \\ {Y Y}_{D D.}^{11} {((k k + + 11))}^{* *} \\ {Y Y}_{D D.}^{22} ((k k)) \\ {Y Y}_{D D.}^{22} {((k k + + 11))}^{* *} \end{matrix}] = = [\begin{matrix} {H h}_{}^{RD RD} & {H h}_{}^{RD RD} & {G G}_{}^{RD RD} & {G G}_{}^{RD RD} \\ {H h}_{}^{RD RD} & - - {H h}_{}^{RD RD} & {G G}_{}^{RD RD} & - - {G G}_{}^{RD RD} \\ {H h}_{}^{RD RD} & {H h}_{}^{RD RD} & {G G}_{}^{RD RD} & {G G}_{}^{RD RD} \\ {H h}_{}^{RD RD} & - - {H h}_{}^{RD RD} & {G G}_{}^{RD RD} & - - {G G}_{}^{RD RD} \end{matrix}] [\begin{matrix} Z Z ((k k)) \\ Z Z ((k k + + 11)) \\ C C ((k k)) \\ C C ((k k + + 11)) \end{matrix}] + + [\begin{matrix} {N N}_{D D.}^{11} ((k k)) \\ {N N}_{D D.}^{11} {((k k + + 11))}^{* *} \\ {N N}_{D D.}^{22} ((k k)) \\ {N N}_{D D.}^{22} {((k k + + 11))}^{* *} \end{matrix}] - - - - - - ((88))$

其中，T_D ^m(k)代表基站接收机k时刻第m个接收天线N个子信道接收信号矢量， $H_{RD}^{m, n} = diag (H_{RD}^{m, n} (k, 1), H_{RD}^{m, n} (k, 2), . . ., H_{RD}^{m, n} (k, l), . . . H_{RD}^{m, n} (k, N))$ 代表k时刻中继站1第n个发射天线到基站第m个接收天线频率响应矩阵， $G_{RD}^{m, n} = diag (G_{RD}^{m, n} (k, 1), G_{RD}^{m, n} (k, 2), . . ., G_{RD}^{m, n} (k, l), . . . G_{RD}^{m, n} (k, N))$ 代表k时刻中继站2第n个发射天线到基站第m个接收天线的频率响应矩阵，N_D ^m(k)代表k时刻基站第m个接收天线N个子信道输入的复高斯白噪声矢量。Among them, T _D ^m (k) represents the received signal vector of the N subchannels of the mth receiving antenna of the base station receiver at time k, $h_{RD}^{m, no} = diag (h_{RD}^{m, no} (k, 1), h_{RD}^{m, no} (k, 2), . . ., h_{RD}^{m, no} (k, l), . . . h_{RD}^{m, no} (k, N))$ Represents the frequency response matrix from the nth transmit antenna of relay station 1 to the mth receive antenna of the base station at time k, $G_{RD}^{m, no} = diag (G_{RD}^{m, no} (k, 1), G_{RD}^{m, no} (k, 2), . . ., G_{RD}^{m, no} (k, l), . . . G_{RD}^{m, no} (k, N))$ Represents the frequency response matrix from the nth transmit antenna of relay station 2 to the mth receive antenna of the base station at time k, N _D ^m (k) represents the complex white Gaussian noise vector input by the N subchannels of the mth receive antenna of the base station at time k.

对于(8)给出的接收信号模型，基站接收机可直接使用线性迫零或最小均方误差检测算法来得到两个用户终端发射信号矢量的估计值，但考虑到基站分配的子信道数较多时，(8)中信道传输矩阵的维数很大(4N×4N)，直接使用矩阵求逆方法进行信号检测运算复杂度极高，以下给出一种低复杂度虚拟MIMO检测算法。(8)进一步表示为分块矩阵形式：For the received signal model given in (8), the base station receiver can directly use the linear zero-forcing or minimum mean square error detection algorithm to obtain the estimated value of the transmitted signal vector of the two user terminals, but considering that the number of sub-channels allocated by the base station is relatively small For a long time, the dimension of the channel transmission matrix in (8) is very large (4N×4N), and the signal detection operation complexity is extremely high by directly using the matrix inversion method. A low-complexity virtual MIMO detection algorithm is given below. (8) is further expressed as a block matrix form:

$[\begin{matrix} {Y Y}_{D D.}^{11} \\ {Y Y}_{D D.}^{22} \end{matrix}] = = [\begin{matrix} {Λ Λ}_{1,1 1,1} & {Λ Λ}_{1,2 1,2} \\ {Λ Λ}_{2,1 2,1} & {Λ Λ}_{2,2 2,2} \end{matrix}] [\begin{matrix} Z Z \\ C C \end{matrix}] + + [\begin{matrix} {N N}_{D D.}^{11} \\ {N N}_{D D.}^{22} \end{matrix}] - - - - - - ((99))$

其中， $Y_{D}^{1} = {[\begin{matrix} Y_{D}^{1} (k) & Y_{D}^{1} {(k + 1)}^{*} \end{matrix}]}^{T},$ $Y_{D}^{2} = {[\begin{matrix} Y_{D}^{2} (k) & Y_{D}^{2} {(k + 1)}^{*} \end{matrix}]}^{T},$ Z＝[Z(k)Z(k+1)]^T，C＝[C(k)C(k+1)]^T。in, $Y_{D.}^{1} = {[\begin{matrix} Y_{D.}^{1} (k) & Y_{D.}^{1} {(k + 1)}^{*} \end{matrix}]}^{T},$ $Y_{D.}^{2} = {[\begin{matrix} Y_{D.}^{2} (k) & Y_{D.}^{2} {(k + 1)}^{*} \end{matrix}]}^{T},$ Z=[Z(k)Z(k+1)] ^T , C=[C(k)C(k+1)] ^T .

在上行链路中所述的基站C接收机中，通过采用多用户空时联合均衡算法完成用户信号的分离。In the base station C receiver described in the uplink, the separation of user signals is accomplished by using a multi-user space-time joint equalization algorithm.

$Φ Φ = = [\begin{matrix} {I I}_{22 N N} & - - {Λ Λ}_{1,2 1,2} {Λ Λ}_{2,2 2,2}^{- - 11} \\ - - {Λ Λ}_{2,1 2,1} {Λ Λ}_{1,1 1,1}^{- - 11} & {I I}_{22 N N} \end{matrix}] - - - - - - ((1010))$

$\overset{~ ~}{Y Y} = = Φ Φ [\begin{matrix} {Y Y}_{D D.}^{11} \\ {Y Y}_{D D.}^{22} \end{matrix}] = = [\begin{matrix} Σ Σ & 00 \\ 00 & Δ Δ \end{matrix}] [\begin{matrix} Z Z \\ C C \end{matrix}] + + [\begin{matrix} {\overset{~ ~}{N N}}_{D D.}^{11} \\ {\overset{~ ~}{N N}}_{D D.}^{22} \end{matrix}] - - - - - - ((1111))$

其中， $Σ = Λ_{1,1} - Λ_{1,2} Λ_{2,2}^{- 1} Λ_{2,1},$ $Δ = Λ_{2,2} - Λ_{2,1} Λ_{1,1}^{- 1} Λ_{1,2},$ 再次利用矩阵∑及Δ的类Alamouti特性，若记 $\tilde{Y} = {[{\tilde{Y}}_{1} {\tilde{Y}}_{2}]}^{T},$ 则式(11)按照以下方式处理：in, $Σ = Λ_{1,1} - Λ_{1,2} Λ_{2,2}^{- 1} Λ_{2,1},$ $Δ = Λ_{2,2} - Λ_{2,1} Λ_{1,1}^{- 1} Λ_{1,2},$ Using the Alamouti-like properties of matrices Σ and Δ again, if write $\tilde{Y} = {[{\tilde{Y}}_{1} {\tilde{Y}}_{2}]}^{T},$ Then formula (11) is processed in the following way:

(12)(12)

并利用 $Σ^{H} Σ = (\begin{matrix} A & 0 \\ 0 & A \end{matrix})$ 及 $Δ^{H} Δ = (\begin{matrix} B & 0 \\ 0 & B \end{matrix})$ 为对角阵。(12)进一步化简为：and use $Σ^{h} Σ = (\begin{matrix} A & 0 \\ 0 & A \end{matrix})$ and $Δ^{h} Δ = (\begin{matrix} B & 0 \\ 0 & B \end{matrix})$ is a diagonal matrix. (12) is further simplified to:

(13)(13)

其中， ${\tilde{\tilde{Y}}}_{1} = {[{\tilde{\tilde{Y}}}_{1,1}^{T}, {\tilde{\tilde{Y}}}_{1,2}^{T}]}^{T},$ ${\tilde{\tilde{Y}}}_{2} = {[{\tilde{\tilde{Y}}}_{2,1}^{T}, {\tilde{\tilde{Y}}}_{2,2}^{T}]}^{T},$ ${\tilde{\tilde{N}}}_{D}^{1} = {[{\tilde{\tilde{N}}}_{D}^{1,1 T}, {\tilde{\tilde{N}}}_{D}^{1,2 T}]}^{T},$ ${\tilde{\tilde{N}}}_{D}^{2} = {[{\tilde{\tilde{N}}}_{D}^{2,1 T}, {\tilde{\tilde{N}}}_{D}^{2,2 T}]}^{T}$ 再利用A及B的对角矩阵特性，可方便得到{Z(k)，Z(k+1)}及{C(k)，C(k+1)}的估计为：in, ${\tilde{\tilde{Y}}}_{1} = {[{\tilde{\tilde{Y}}}_{1,1}^{T}, {\tilde{\tilde{Y}}}_{1,2}^{T}]}^{T},$ ${\tilde{\tilde{Y}}}_{2} = {[{\tilde{\tilde{Y}}}_{2,1}^{T}, {\tilde{\tilde{Y}}}_{2,2}^{T}]}^{T},$ ${\tilde{\tilde{N}}}_{D.}^{1} = {[{\tilde{\tilde{N}}}_{D.}^{1,1 T}, {\tilde{\tilde{N}}}_{D.}^{1,2 T}]}^{T},$ ${\tilde{\tilde{N}}}_{D.}^{2} = {[{\tilde{\tilde{N}}}_{D.}^{2,1 T}, {\tilde{\tilde{N}}}_{D.}^{2,2 T}]}^{T}$ Using the diagonal matrix characteristics of A and B, the estimates of {Z(k), Z(k+1)} and {C(k), C(k+1)} can be easily obtained as:

(14)(14)

及

进行N点的IDFT运算得到

及

最后分别对

及

每分量进行最大似然检测可得到中继转发符号矢量{z(k)，z(k+1)}及{c(k)，c(k+1)}的估计值

及 and

Perform IDFT operation of N points to get

and

Finally, respectively

and

The maximum likelihood detection of each component can obtain the estimated value of the relay forwarding symbol vector {z(k), z(k+1)} and {c(k), c(k+1)}

and

图7-1是本发明的第一实施方式；中继站2发1收，基站2接收天线，用户终端与中继站链路：1x1最大比值合并；中继站与基站链路：4x2虚拟MIMO传输。Figure 7-1 is the first embodiment of the present invention; relay station 2 transmits and receives one, base station 2 receives antenna, user terminal and relay station link: 1x1 maximum ratio combination; relay station and base station link: 4x2 virtual MIMO transmission.

图7-2是本发明的第二实施方式；中继站2发2收，基站2接收天线，用户终端与中继站链路：1x2最大比值合并；中继站与基站链路：4x2虚拟MIMO传输。Figure 7-2 is the second embodiment of the present invention; the relay station 2 transmits and receives 2 signals, the base station 2 receives antennas, the link between the user terminal and the relay station: 1x2 maximum ratio combination; the link between the relay station and the base station: 4x2 virtual MIMO transmission.

图7-3是本发明的第三实施方式；中继站2发4收，基站2接收天线，用户终端与中继站链路：1x4最大比值合并；中继站与基站链路：4x2虚拟MIMO传输。Figure 7-3 is the third embodiment of the present invention; the relay station 2 transmits and receives 4 receivers, the base station 2 receives antennas, the link between the user terminal and the relay station: 1x4 maximum ratio combination; the link between the relay station and the base station: 4x2 virtual MIMO transmission.

图7-4是本发明的第四实施方式；中继站2发1收，基站4接收天线，用户终端与中继站链路：1x1最大比值合并；中继站与基站链路：4x4虚拟MIMO传输。Figure 7-4 shows the fourth embodiment of the present invention; relay station 2 transmits and receives one, base station 4 receives antennas, user terminal and relay station link: 1x1 maximum ratio combination; relay station and base station link: 4x4 virtual MIMO transmission.

图7-5是本发明的第五实施方式；中继站2发2收，基站4接收天线，用户终端与中继站链路：1x2最大比值合并；中继站与基站链路：4x4虚拟MIMO传输。Figure 7-5 shows the fifth embodiment of the present invention; the relay station 2 transmits and receives 2, the base station 4 receives antennas, the link between the user terminal and the relay station: 1x2 maximum ratio combination; the link between the relay station and the base station: 4x4 virtual MIMO transmission.

图7-6是本发明的第六实施方式；中继站2发4收，基站4接收天线，用户终端与中继站链路：1x4最大比值合并；中继站与基站链路：4x4虚拟MIMO传输。Figure 7-6 shows the sixth embodiment of the present invention; the relay station 2 transmits and receives 4 receivers, the base station 4 receives antennas, the link between the user terminal and the relay station: 1x4 maximum ratio combination; the link between the relay station and the base station: 4x4 virtual MIMO transmission.

以上仅列出了采用本发明的基于块空时分组编码的虚拟多输入多输出中继传输方法的部分实施例。本发明提出的方法亦可方便推广到中继站接收机天线数为1/2/4/8；基站接收机天线数为2/4/6/8等情况。The above only lists some embodiments of the block-space-time block coding-based virtual MIMO relay transmission method of the present invention. The method proposed by the invention can also be conveniently extended to situations where the number of antennas of the relay station receiver is 1/2/4/8; the number of antennas of the base station receiver is 2/4/6/8.

下面给出采用本发明的基于块空时分组编码的虚拟多输入多输出中继传输方法，所达到的效果。The effect achieved by adopting the virtual MIMO relay transmission method based on block space-time block coding of the present invention is given below.

1、不同传输方案下系统频谱利用率的比较1. Comparison of system spectrum utilization under different transmission schemes

表1给出了非中继传输，传统中继传输、基于单天线虚拟MIMO中继及基于块空时分组编码的虚拟MIMO中继传输方案时的频谱效率。在计算传输方案频谱效率时，假设DFT-S-OFDM系统子信道间隔为Δf，DFT-S-OFDM符号的传输周期为T，用户终端调制星座数目Q，用户终端分配子信道数为N；同时在基站的调度下，假设位于小区边缘用户UE1与中继站1进行通信的同时，位于网络盲区用户UE2与中继站2亦进行通信。Table 1 shows the spectral efficiency of non-relay transmission, traditional relay transmission, virtual MIMO relay based on single antenna and virtual MIMO relay transmission scheme based on block space-time block coding. When calculating the spectral efficiency of the transmission scheme, it is assumed that the subchannel spacing of the DFT-S-OFDM system is Δf, the transmission period of the DFT-S-OFDM symbol is T, the number of user terminal modulation constellations is Q, and the number of user terminal allocation subchannels is N; at the same time Under the scheduling of the base station, it is assumed that UE1 located at the edge of the cell communicates with relay station 1, and user UE2 located in a blind area of the network also communicates with relay station 2.

表1：不同传输方案频谱利用率比较Table 1: Comparison of Spectrum Utilization Efficiency of Different Transmission Schemes

表1比较表明：传统时分中继传输由于中继站需要占用额外时间资源，使得系统频谱效率较直接传输降低一倍，而基于虚拟MIMO中继传输由于采用了空间复用技术使得频谱效率提高一倍，从而弥补传统中继传输造成频谱效率的下降，最后使得整体的系统频谱利用率保持与直接传输相同。The comparison in Table 1 shows that the traditional time-division relay transmission requires additional time resources for the relay station, which makes the system spectral efficiency double that of direct transmission, while the virtual MIMO-based relay transmission doubles the spectral efficiency due to the use of spatial multiplexing technology. In this way, the decline in spectrum efficiency caused by traditional relay transmission is compensated, and finally the overall system spectrum utilization rate remains the same as that of direct transmission.

2、检测算法复杂度分析2. Analysis of detection algorithm complexity

表2：不同检测算法下复杂度比较Table 2: Comparison of complexity under different detection algorithms

表2给出了直接利用(8)式线性迫零检测算法与本发明提出算法的运算复杂度。比较表明本发明提出检测算法的运算复杂度仅是直接迫零算法复杂度的一半。Table 2 shows the computational complexity of the linear zero-forcing detection algorithm directly using (8) and the algorithm proposed by the present invention. The comparison shows that the computational complexity of the detection algorithm proposed by the present invention is only half of that of the direct zero-forcing algorithm.

3、块空时分组编码虚拟MIMO中继方案链路传输性能3. Link transmission performance of block space-time packet coding virtual MIMO relay scheme

不失去一般性，本发明给出中继站2发2收，基站2接收天线架构下(图7-2)基于块空时分组编码的虚拟MIMO中继传输系统比特差错性能。同时为方便比较，本发明亦给出中继站1发2收，基站2接收天线架构下基于VBLAST(垂直分层空时码)的虚拟MIMO中继传输系统比特差错性能。Without loss of generality, the present invention provides the bit error performance of the virtual MIMO relay transmission system based on block space-time block coding under the architecture of 2 relay stations transmitting 2 receiving and base station 2 receiving antennas (Fig. 7-2). At the same time, for the convenience of comparison, the present invention also provides the bit error performance of the virtual MIMO relay transmission system based on VBLAST (Vertical Layered Space-Time Code) under the structure of the relay station 1 transmitting and 2 receiving, and the base station 2 receiving antenna architecture.

图8-1给出QPSK调制下基于中继站一发两收，中继站两发两收基于块空时分组编码结构下虚拟MIMO中继传输方案下系统的比特差错性能，其中：QPSK调制，N＝120，L＝2048。曲线比较表明：在BER＝10^-4时，基于B-STBC DFT-S-OFDM虚拟MIMO中继传输系统较前者有3dB的性能改善。文中提出的基于B-STBC虚拟MIMO中继传输方案切实可行。Figure 8-1 shows the bit error performance of the system in the virtual MIMO relay transmission scheme based on the relay station’s one transmission and two receptions based on the relay station, and the relay station’s two transmissions and two receptions based on the block space-time block coding structure, where: QPSK modulation, N=120 , L=2048. The curve comparison shows that: when BER=10 ^-4 , the performance of the B-STBC DFT-S-OFDM virtual MIMO relay transmission system is improved by 3dB compared with the former. The proposed B-STBC-based virtual MIMO relay transmission scheme is feasible.

图8-2给出了基于16QAM调制下基于中继站一发两收，中继站两发两收基于块空时分组编码结构下虚拟MIMO中继传输方案下系统的比特差错性能，其中，16QAM调制，N＝120，L＝2048。所得结论与图8-1基本一致。Figure 8-2 shows the bit error performance of the system under the virtual MIMO relay transmission scheme based on the 16QAM modulation based on the relay station’s one transmission and two reception, and the relay station’s two transmission and two reception based on the block space-time block coding structure. Among them, 16QAM modulation, N =120, L=2048. The conclusions obtained are basically consistent with those in Figure 8-1.

Claims

1. A virtual multiple-input multiple-output relay transmission method based on block space-time block coding, in a relay transmission system composed of user equipment (A), relay station (B) and base station (C), it is characterized in that, The link between each said relay station (B) and the base station (C) adopts the virtual MIMO mode of block space-time block coding for transmission, and the virtual MIMO mode of block space-time block coding is: in the uplink Each of the relay station transmitters described in the above adopts the transmission mode of space-time block coding of two transmitting antenna blocks, and uses the same time-frequency resource to communicate with the base station (C) receiver under the scheduling of the base station (C). The link between the user equipment (A) and the relay station (B) adopts the maximum ratio combining method for transmission.

2. the virtual MIMO relay transmission method based on block space-time packet coding according to claim 1, characterized in that, in the relay station receiver (B2) described in the uplink, complete the user equipment (A) Estimate and detect the transmission modulation symbols, and forward the detected modulation symbols transmitted by the user equipment (A) to the reception of the base station (C) in the subsequent time slot of the link between the relay station (B) and the base station (C) machine.

3. the virtual MIMO relay transmission method based on block space-time block coding according to claim 1, characterized in that, in the base station (C) receiver described in the uplink, by adopting multi-user The space-time joint equalization algorithm completes the separation of user signals.

4. the virtual MIMO relay transmission method based on block space-time block coding according to claim 1, characterized in that, the transmission of the block space-time block coding is realized by the following steps:

The first step: modulating the input bit sequence;

The second step: performing N-point fast Fourier transform on the modulator output, wherein N is an integer power of 2;

The third step: send the fast Fourier transform output to the block space-time block encoder for encoding processing;

Step 4: Perform the same processing on the encoded signals of the two channels, and send the processed signals of each channel through the antenna corresponding to the channel.

5. The virtual MIMO relay transmission method based on block space-time packet coding according to claim 4, wherein the same processing described in the fourth step comprises the following process:

1) respectively mapping the two data signals to L subcarriers in the frequency domain, where L>N, where N is an integer power of 2;

2) carry out the inverse fast Fourier transform of point L with mapper output;

3) Insert the cyclic prefix and convert through D/A;

4) Send to the intermediate frequency and radio frequency unit;

5) Transmitted through the antenna.

6. The virtual MIMO relay transmission method based on block space-time block coding according to claim 3, characterized in that, the multi-user space-time joint equalization algorithm of the base station (C) in the uplink comprises the following steps :

1) The receiving channel corresponding to each receiving antenna performs the same signal processing on the received signal:

a. The radio frequency signal from the antenna is processed by the radio frequency and intermediate frequency unit, and the digital baseband signal is formed after sampling;

b. remove the cyclic prefix from the digital baseband signal;

c. Carry out L-point Fourier transform, wherein L is an integer power of 2;

d. Perform demapping processing, that is, take out data signals from L subcarriers;

2) Summarize the processed signals of each receiving channel for joint space-time equalization processing;

3) The user signals separated by the space-time joint equalizer are still subjected to the same signal processing in units of each channel, including performing N-point inverse discrete Fourier transform, demodulation and decoding to obtain information transmitted by each user terminal, N takes an integer power of 2.

7. the virtual MIMO relay transmission method based on block space-time packet coding according to claim 3, characterized in that, the multi-user space-time joint equalization algorithm is completed by the following formula:

Using the Alamouti-like property of the channel matrix, denote Φ as the two-user linear zero-forcing matrix

Wherein I _2N is the identity matrix of 2N*2N, Λ is the intermediate variable introduced, constructs and corrects the receiving signal vector:

in,

Using the Alamouti-like properties of matrices Σ and Δ again, if write

but

Among them, Z and C are the set of symbol sequences to be transmitted by each relay station after DFT processing,

For the set of noise sequences on the transmission link where each relay station is located, the

Proceed as follows:

and use

and

is a diagonal matrix, which can be further simplified as:

in,

T represents the conjugate transposition operation of the matrix, and then using the diagonal matrix characteristics of A and B, it is convenient to get {Z(k), Z(k+1)} and {C(k), C(k+1) )} is estimated as:

and

Perform IDFT operation of N points to get

and

Finally, respectively

and

and