CN102098142A

CN102098142A - Data transmission method, device and system

Info

Publication number: CN102098142A
Application number: CN2009102592648A
Authority: CN
Inventors: 李颖; 李海强; 楼群芳
Original assignee: Huawei Technologies Co Ltd; Xidian University
Current assignee: Huawei Technologies Co Ltd; Xidian University
Priority date: 2009-12-15
Filing date: 2009-12-15
Publication date: 2011-06-15

Abstract

The embodiment of the invention provides a data transmission method, device and system. The method comprises the following steps of: receiving source signals transmitted by at least two source nodes to obtain received signals; decoding the received signals to obtain estimation signals of the source signals; performing network pre-coding on the estimation signals, and transmitting the pre-coded signals to destination nodes. In the embodiment of the invention, relay nodes perform network pre-coding on the signals transmitted by the source nodes, so that the data transmission of a multi-user multi-input multi-output (MIMO) relay channel in a wireless communication network has high throughput, and the transmission efficiency is effectively increased.

Description

Data transmission method, device and system

技术领域technical field

本发明涉及无线技术领域，尤其涉及无线中继网络中一种多用户的多输入多输出(Multiple-Input Multiple Output，MIMO)中继信道的数据传输方法、装置和系统。The present invention relates to the field of wireless technology, in particular to a data transmission method, device and system for a multiple-input multiple-output (Multiple-Input Multiple Output, MIMO) relay channel of multiple users in a wireless relay network.

背景技术Background technique

目前，移动通信领域广泛采用中继来帮助移动用户转发数据，这种通信方式利用了中继的协作功能，使得数据传输中可以获得额外的协作分集增益，从而改善接收端的误码率(Bit Error Rate，BER)性能。另外，随着MIMO技术的提出，可以更加有效地提高中继转发数据的质量。At present, in the field of mobile communication, relays are widely used to help mobile users forward data. This communication method utilizes the cooperation function of relays, so that additional cooperative diversity gains can be obtained in data transmission, thereby improving the bit error rate (Bit Error Rate) at the receiving end. Rate, BER) performance. In addition, with the introduction of the MIMO technology, the quality of relayed and forwarded data can be improved more effectively.

在大规模的无线中继通信网络中，通常是多个源节点和多个中继节点共存，传统的中继方案中，各个中继需要为每个源节点逐个转发数据，使得传输效率随着网络规模的增大而大幅下降。在中继处通过网络编码来对接收到的多个源节点的数据进行编码处理，再发送编码后的数据至目的节点，最后由目的节点解码出需要的数据。这种网络编码的传输方式可以提高网络吞吐量、减少数据包的传输次数、增强无线网络的容错性和鲁棒性。In a large-scale wireless relay communication network, usually multiple source nodes and multiple relay nodes coexist. In the traditional relay scheme, each relay needs to forward data for each source node one by one, so that the transmission efficiency increases with the The size of the network increases and decreases significantly. At the relay, network coding is used to encode the data received from multiple source nodes, and then the encoded data is sent to the destination node, and finally the destination node decodes the required data. This network coding transmission method can improve network throughput, reduce the number of data packet transmissions, and enhance the fault tolerance and robustness of the wireless network.

现有的基于网络编码的中继传输方案大致可以分为两种：有限域网络编码的中继传输方案和复数域网络编码的中继传输方案，其中有限域网络编码的中继传输方案的网络吞吐量为1/(N_S+1)符号/信源/时隙，N_S为网络中源节点的个数，可见，随着网络规模的增加，该方案的网络吞吐量下降过多；复数域网络编码的中继传输方案的网络吞吐量固定在1/2符号/信源/时隙，其不受信源数的限制，不过该吞吐量并不是十分理想。The existing relay transmission scheme based on network coding can be roughly divided into two types: the relay transmission scheme of finite field network coding and the relay transmission scheme of complex field network coding, among which the network of relay transmission scheme of finite field network coding The throughput is 1/( _NS +1) symbol/source/time slot, and _NS is the number of source nodes in the network. It can be seen that with the increase of the network scale, the network throughput of this scheme drops too much; the complex number The network throughput of the domain network coding relay transmission scheme is fixed at 1/2 symbol/source/time slot, which is not limited by the number of sources, but the throughput is not very ideal.

发明内容Contents of the invention

本发明提供了一种数据传输方法、装置和系统，为无线通信网络中多用户MIMO中继信道提供一种具有高吞吐量的传输方案。The invention provides a data transmission method, device and system, and provides a transmission scheme with high throughput for a multi-user MIMO relay channel in a wireless communication network.

本发明实施例提供了一种数据传输方法，该方法包括：接收至少两个源节点发送的源信号，得到接收信号；对所述接收信号进行解码，得到所述源信号的估计信号；对所述估计信号进行网络预编码，并将预编码信号发送至目的节点。An embodiment of the present invention provides a data transmission method. The method includes: receiving source signals sent by at least two source nodes to obtain a received signal; decoding the received signal to obtain an estimated signal of the source signal; Perform network precoding on the estimated signal, and send the precoded signal to the destination node.

本发明实施例还提供了一种数据传输方法，该方法包括：接收至少两个源节点发送的源信号，得到接收信号；接收中继节点发送的预编码信号，所述预编码信号由所述中继节点对根据所述至少两个源节点发送的源信号得到的接收信号进行解码，得到估计信号，并对估计信号进行网络预编码得到；根据所述接收信号和所述预编码信号进行解码。An embodiment of the present invention also provides a data transmission method, the method includes: receiving source signals sent by at least two source nodes to obtain a received signal; receiving a precoded signal sent by a relay node, the precoded signal is obtained by the The relay node decodes the received signal obtained according to the source signals sent by the at least two source nodes to obtain an estimated signal, and performs network precoding on the estimated signal to obtain it; and performs decoding according to the received signal and the precoded signal .

本发明实施例提供了一种中继，包括：源信号接收单元，用于接收至少两个源节点发送的源信号，得到接收信号；解码单元，用于对所述接收信号进行解码，得到所述源信号的估计信号；网络预编码单元，用于对所述估计信号进行网络预编码；发送单元，用于将经过所述网络预编码单元预编码后的信号发送至目的节点。An embodiment of the present invention provides a relay, including: a source signal receiving unit configured to receive source signals sent by at least two source nodes to obtain a received signal; a decoding unit configured to decode the received signal to obtain the received signal An estimated signal of the source signal; a network precoding unit, configured to perform network precoding on the estimated signal; a sending unit, configured to send the signal precoded by the network precoding unit to a destination node.

本发明实施例还提供了一种装置，包括：源信号接收单元，用于接收至少两个源节点发送的源信号，得到接收信号；编码信号接收单元，用于接收中继节点发送的预编码信号，所述预编码信号由所述中继节点对根据所述至少两个源节点发送的源信号得到的接收信号进行解码，得到估计信号，并对估计信号进行网络预编码得到；解码单元，用于根据所述接收信号和所述预编码信号进行解码。The embodiment of the present invention also provides a device, including: a source signal receiving unit, configured to receive source signals sent by at least two source nodes to obtain received signals; a coded signal receiving unit, configured to receive the precoded signal sent by the relay node signal, the precoded signal is obtained by the relay node decoding the received signal obtained according to the source signals sent by the at least two source nodes to obtain an estimated signal, and performing network precoding on the estimated signal; the decoding unit, It is used for decoding according to the received signal and the precoded signal.

本发明实施例还提供了一种数据传输系统，包括上述中继、上述装置以及至少两个源节点，所述源节点通过上述中继向上述装置传送数据。An embodiment of the present invention also provides a data transmission system, including the above-mentioned relay, the above-mentioned device, and at least two source nodes, where the source node transmits data to the above-mentioned device through the above-mentioned relay.

本发明实施例通过中继节点对源节点所发送的信号进行网络预编码，从而使得无线通信网络中多用户MIMO中继信道的数据传输具有较高的吞吐量，传输效率得到了有效提高，同时进一步提高了系统的误码率性能。In the embodiment of the present invention, the relay node performs network precoding on the signal sent by the source node, so that the data transmission of the multi-user MIMO relay channel in the wireless communication network has a higher throughput, and the transmission efficiency is effectively improved. At the same time The bit error rate performance of the system is further improved.

附图说明Description of drawings

为了更清楚地说明本发明实施例或现有技术中的技术方案，下面将对实施例或现有技术描述中所需要使用的附图作简单地介绍，显而易见地，下面描述中的附图仅仅是本发明的一些实施例，对于本领域普通技术人员来讲，在不付出创造性劳动的前提下，还可以根据这些附图获得其他的附图。In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only These are some embodiments of the present invention. Those skilled in the art can also obtain other drawings based on these drawings without creative work.

图1为本发明实施例应用的一种无线中继网络结构图；FIG. 1 is a structural diagram of a wireless relay network applied in an embodiment of the present invention;

图2为本发明实施例提供的一种数据传输方法流程图；FIG. 2 is a flowchart of a data transmission method provided by an embodiment of the present invention;

图3为本发明实施例提供的另一种数据传输方法流程图；FIG. 3 is a flowchart of another data transmission method provided by an embodiment of the present invention;

图4为本发明实施例提供的另一种数据传输方法流程图；FIG. 4 is a flowchart of another data transmission method provided by an embodiment of the present invention;

图5为本发明实施例提供的另一种数据传输方法流程图；FIG. 5 is a flow chart of another data transmission method provided by an embodiment of the present invention;

图6为本发明实施例提供的一种中继的结构示意图；FIG. 6 is a schematic structural diagram of a relay provided by an embodiment of the present invention;

图7为本发明实施例提供的一种网络编码单元的结构示意图；FIG. 7 is a schematic structural diagram of a network coding unit provided by an embodiment of the present invention;

图8为本发明实施例提供的一种装置的结构示意图；Fig. 8 is a schematic structural diagram of a device provided by an embodiment of the present invention;

图9为本发明实施例提供的另一种装置的结构示意图；Fig. 9 is a schematic structural diagram of another device provided by an embodiment of the present invention;

图10为本发明实施例提供的一种系统结构图；FIG. 10 is a system structure diagram provided by an embodiment of the present invention;

图11为本发明实施例的网络预编码方案与复数域网络编码的性能比较仿真数据图；Fig. 11 is a simulation data diagram of performance comparison between the network precoding scheme of the embodiment of the present invention and the complex domain network coding;

图12为本发明实施例的网络预编码方案在不同吞吐量情况下的性能比较仿真数据图。FIG. 12 is a simulation data diagram of performance comparison of the network precoding scheme according to the embodiment of the present invention under different throughput conditions.

具体实施方式Detailed ways

下面将结合本发明实施例中的附图，对本发明实施例中的技术方案进行清楚、完整地描述，显然，所描述的实施例仅仅是本发明一部分实施例，而不是全部的实施例。基于本发明中的实施例，本领域普通技术人员在没有作出创造性劳动前提下所获得的所有其他实施例，都属于本发明保护的范围。The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some, not all, embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without creative efforts fall within the protection scope of the present invention.

首先对本发明实施例所应用的环境进行说明，如图1所示为本发明实施例应用的一种无线中继网络结构图。由图中可知，该无线中继网络包括源节点S₁-S_Ns、中继节点R和目的节点D，其中中继节点R和目的节点D都为多天线结构。图中实线表示源节点向中继节点和目的节点进行广播，而虚线表示中继节点向目的节点发送数据。当然，在实际情况中，该无线中继网络中可以包括多个中继节点，但是对于每一个中继节点，它们所执行的操作都是相类似的，因此在此只图示了一个中继节点的情况。First, the environment in which the embodiment of the present invention is applied is described. FIG. 1 is a structural diagram of a wireless relay network applied in the embodiment of the present invention. It can be seen from the figure that the wireless relay network includes source nodes S ₁ -S _Ns , a relay node R and a destination node D, wherein both the relay node R and the destination node D have a multi-antenna structure. The solid line in the figure indicates that the source node broadcasts to the relay node and the destination node, while the dotted line indicates that the relay node sends data to the destination node. Of course, in actual situations, the wireless relay network may include multiple relay nodes, but for each relay node, the operations they perform are similar, so only one relay node is shown here The condition of the node.

如图2所示为本发明实施例提供的一种数据传输方法流程图，本实施例是从中继节点的角度进行说明，该方法包括如下步骤：As shown in FIG. 2, it is a flow chart of a data transmission method provided by an embodiment of the present invention. This embodiment is described from the perspective of a relay node. The method includes the following steps:

S201：接收至少两个源节点发送的源信号，得到接收信号。由于无线信号的广播特性，中继节点上的每根天线都会收到所有源节点所发送的信号，即收到N_S个信号，假设图1中的中继节点具有N根天线，则中继节点在时隙t会收到如下信号：S201: Receive source signals sent by at least two source nodes to obtain received signals. Due to the broadcast characteristics of wireless signals, each antenna on the relay node will receive the signals sent by all source nodes, that is, N _S signals are received. Assuming that the relay node in Figure 1 has N antennas, the relay node The node will receive the following signal at time slot t:

y_SR(t)＝H_SRx(t)+n_SR(t)；y _SR (t) = H _SR x (t) + n _SR (t);

其中， $x (t) = {(θ_{1} x_{1} (t), . . ., θ_{N_{S}} x_{Ns} (t))}^{T}$ 表示N_S个源节点在第t个时隙内发送的信号；n_SR(t)表示源节点与中继节点R之间的高斯白噪声；H_SR表示N_S个源节点与中继节点R之间的信道衰落矩阵，且in, $x (t) = {(θ_{1} x_{1} (t), . . ., θ_{N_{S}} x_{NS} (t))}^{T}$ Indicates the signals sent by N _S source nodes in the tth time slot; n _SR (t) represents the Gaussian white noise between the source node and the relay node R; H _SR represents the N _S source nodes and the relay node R The channel fading matrix between, and

${H h}_{SR SR} = = (\begin{matrix} {h h}_{{S S}_{11} R R}^{11} & . . . . . . & {h h}_{{S S}_{{N N}_{S S}} R R}^{11} \\ . . & . . & . . \\ . . & . . & . . \\ . . & . . & . . \\ {h h}_{{S S}_{11} R R}^{N N} & . . . . . . & {h h}_{{S S}_{{N N}_{S S}} R R}^{N N} \end{matrix})$

其中

表示源节点i到中继节点的第j根天线之间的信道衰落系数，j＝1，…，N。in

Indicates the channel fading coefficient between the source node i and the jth antenna of the relay node, j=1,...,N.

S202：对该接收信号进行解码，得到上述源信号的估计信号。S202: Decode the received signal to obtain an estimated signal of the above source signal.

可以根据下式计算得到上述源信号的估计信号

The estimated signal of the above source signal can be calculated according to the following formula

$\overset{^^}{x x} ((t t)) = = \underset{x x ((t t))}{arg arg min min} {| | | | {y the y}_{SR SR} ((t t)) - - {H h}_{SR SR} x x ((t t)) | | | |}^{22};;$

得到具有N_S个元素的估计信号向量： $\hat{x} (t) = {(\begin{matrix} {\hat{x}}_{1} (t) & . . . & {\hat{x}}_{N_{S}} (t) \end{matrix})}^{T} .$ Get an estimated signal vector with N _S elements: $\hat{x} (t) = {(\begin{matrix} {\hat{x}}_{1} (t) & . . . & {\hat{x}}_{N_{S}} (t) \end{matrix})}^{T} .$

S203：对该估计信号进行网络预编码，并将预编码信号发送至目的节点。S203: Perform network precoding on the estimated signal, and send the precoded signal to the destination node.

所谓网络预编码是指中继节点网络编码和预编码技术的联合设计，通过网络编码向量和预编码向量的确定，首先将估计信号进行复数域网络编码，然后再将得到的合并信息进行预编码处理，与现有的中继网络编码技术相比极大的提高了系统性能。The so-called network precoding refers to the joint design of relay node network coding and precoding technology. Through the determination of the network coding vector and the precoding vector, the estimated signal is firstly subjected to complex domain network coding, and then the obtained combined information is precoded. Compared with the existing relay network coding technology, the system performance is greatly improved.

在本发明实施例中，中继节点R根据在T_S个时隙内的估计信号

构造网络预编码方案，这些估计信号可以构成估计信号向量

\hat{x} = {(\hat{x} (t), \hat{x} (t + 1), . . ., \hat{x} (t + T_{S} - 1))}^{T},

为了对该估计信号向量进行网络预编码，需要得到m个预编码向量P_m和网络编码向量θ_Rm，其中m为参与网络预编码的子信息流的个数。然后根据下式得到经过网络编码后的m个N维子信息流：In the embodiment of the present invention, the relay node R according to the estimated signal in T _S time slots

To construct a network precoding scheme, these estimated signals can form an estimated signal vector

\hat{x} = {(\hat{x} (t), \hat{x} (t + 1), . . ., \hat{x} (t + T_{S} - 1))}^{T},

In order to perform network precoding on the estimated signal vector, m precoding vectors P _m and network encoding vectors θ _Rm need to be obtained, where m is the number of sub-information streams participating in network precoding. Then, m N-dimensional sub-information streams after network coding are obtained according to the following formula:

${x x}_{R R} = = (({P P}_{11} {θ θ}_{R R 11} \overset{^^}{x x},, {P P}_{22} {θ θ}_{R R 22} \overset{^^}{x x} . . . . . .,, {P P}_{m m} {θ θ}_{Rm R m} \overset{^^}{x x}));;$

最后中继节点R将上述x_R通过N根天线发送给目的节点D，目的节点D对其进行解码以得到所需的信息。目的节点D可以通过下述方式对x_R进行解码：Finally, the relay node R sends the above x _R to the destination node D through the N antennas, and the destination node D decodes it to obtain the required information. Destination node D can decode x _R in the following way:

首先，由于无线信号的广播特性，目的节点D同中继节点R一样，也会收到源节点S₁-S_Ns所发出的信号，在此假设目的节点也具有N根天线，其收到的源节点信号记为y_SD(t)，则：First of all, due to the broadcast characteristics of wireless signals, the destination node D, like the relay node R, will also receive the signal sent by the source node S ₁ -S _Ns . Here, it is assumed that the destination node also has N antennas, and the received The source node signal is denoted as y _SD (t), then:

y_SD(t)＝H_SDx(t)+n_SD(t)；y _SD (t) = H _SD x (t) + n _SD (t);

其中， $x (t) = {(θ_{1} x_{1} (t), . . ., θ_{N_{S}} x_{Ns} (t))}^{T}$ 表示N_S个源节点在第t个时隙内发送的信号；n_SD(t)表示源节点与目的节点D之间的高斯白噪声；H_SD表示N_S个源节点与目的节点D之间的信道衰落矩阵：in, $x (t) = {(θ_{1} x_{1} (t), . . ., θ_{N_{S}} x_{NS} (t))}^{T}$ Indicates the signal sent by N _S source nodes in the tth time slot; n _SD (t) represents the Gaussian white noise between the source node and the destination node D; H _SD represents the signal between the N _S source nodes and the destination node D The channel fading matrix of :

${H h}_{SD SD} = = (\begin{matrix} {h h}_{{S S}_{11} D D.}^{11} & . . . . . . & {h h}_{{S S}_{{N N}_{S S}} D D.}^{11} \\ . . & . . \\ . . & . . . . . . & . . \\ . . & . . \\ {h h}_{{S S}_{11} D D.}^{N N} & . . . . . . & {h h}_{{S S}_{{N N}_{S S}} D D.}^{N N} \end{matrix})$

其中

表示源节点i到目的节点D的第j根天线之间的信道衰落系数，j＝1，…，N；in

Indicates the channel fading coefficient between the source node i and the jth antenna of the destination node D, j=1,...,N;

然后，目的节点D根据收到的源节点信号y_SD(t)和中继节点R所转发的经过网络编码后的信号x_R，利用最大似然解码得到所需要的信号。所谓最大似然解码即解调器送给译码器一个关于“不同调制器输入符号可能性”的似然信息序列、或未量化的输出，让译码器将这些信息与编码信息综合在一起做出判决，这样系统性能可以得到较大的提高，因此可以先计算出源节点和中继节点的似然信息并相加，然后再通过译码器译出码字。Then, according to the received signal y _SD (t) of the source node and the network-coded signal x _R forwarded by the relay node R, the destination node D uses maximum likelihood decoding to obtain the required signal. The so-called maximum likelihood decoding means that the demodulator sends a sequence of likelihood information about "possibility of input symbols of different modulators" to the decoder, or an unquantized output, so that the decoder can integrate these information with the encoding information In this way, the system performance can be greatly improved, so the likelihood information of the source node and the relay node can be calculated and added first, and then the codeword can be decoded by the decoder.

本实施例是对上述实施例的进一步描述，如图3所示为本发明实施例提供的另一种数据传输方法流程图，该方法包括如下步骤：This embodiment is a further description of the above embodiments. As shown in FIG. 3, it is a flow chart of another data transmission method provided by the embodiment of the present invention. The method includes the following steps:

S301：利用多根天线接收至少两个源节点发送的源信号，得到接收信号。S301: Use multiple antennas to receive source signals sent by at least two source nodes to obtain received signals.

S302：对该接收信号进行解码以得到上述源信号的估计信号。S302: Decode the received signal to obtain an estimated signal of the above source signal.

本发明实施例中的步骤S301和步骤S302和图2所述实施例提供的方法中步骤201和202类似，在此就不再进行赘述。Step S301 and step S302 in the embodiment of the present invention are similar to steps 201 and 202 in the method provided by the embodiment shown in FIG. 2 , and will not be repeated here.

S303：通过无限反馈信道和/或有限反馈信道接收目的节点反馈的预编码向量和网络编码向量。S303: Receive a precoding vector and a network coding vector fed back by the destination node through an infinite feedback channel and/or a limited feedback channel.

在本实施例中，预编码向量P_m和网络编码向量θ_Rm是由目的节点D获得的，然后再通过两种反馈信道反馈给中继节点R。所谓无限反馈信道是指目的节点与中继节点之间反馈信道的反馈比特数是无限长的，而所谓有限反馈信道是指目的节点与中继节点之间的反馈信道只能反馈有限比特的信息。需要指出的是，当反馈信道不同时，预编码向量P_m和网络编码向量θ_Rm的获取也有所不同，下面分别对其进行说明：In this embodiment, the precoding vector P _m and the network coding vector θ _Rm are obtained by the destination node D, and then fed back to the relay node R through two feedback channels. The so-called infinite feedback channel means that the number of feedback bits of the feedback channel between the destination node and the relay node is infinitely long, and the so-called limited feedback channel means that the feedback channel between the destination node and the relay node can only feed back limited bits of information . It should be pointed out that when the feedback channels are different, the acquisition of the precoding vector P _m and the network coding vector θ _Rm is also different, and they are explained below:

当中继节点R和目的节点D间的反馈信道为无限反馈信道时，预编码向量P_m和网络编码向量θ_Rm的获取可以包括如下步骤：When the feedback channel between the relay node R and the destination node D is an infinite feedback channel, the acquisition of the precoding vector P _m and the network coding vector θ _Rm may include the following steps:

步骤1、目的节点D对与中继节点R之间的信道衰落矩阵H_RD进行奇异值分解来计算每个并行子信道的信噪比λ_iE_S/N₀，其中H_RD可以通过下式表示：Step 1. The destination node D performs singular value decomposition on the channel fading matrix H _RD with the relay node R to calculate the signal-to-noise ratio λ _i E _S /N ₀ of each parallel sub-channel, where H _RD can be obtained by the following formula express:

${H h}_{RD RD} = = (\begin{matrix} {h h}_{RD RD}^{11} \\ . . \\ . . \\ . . \\ {h h}_{RD RD}^{N N} \end{matrix})$

步骤2、目的节点D将步骤1中计算得到的每个并行子信道的信噪比和预设门限信噪比相比较，选出大于门限信噪比的m个信噪比所对应的特征向量作为预编码向量P_m。Step 2. Destination node D compares the SNR of each parallel sub-channel calculated in step 1 with the preset threshold SNR, and selects the eigenvectors corresponding to m SNRs greater than the threshold SNR as the precoding vector P _m .

步骤3、目的节点D选取反向快速傅里叶变换IFFT矩阵，并根据上述预编码向量及按照信道容量最大的原则从该IFFT矩阵中得到网络编码向量θ_Rm。Step 3. Destination node D selects an inverse fast Fourier transform IFFT matrix, and obtains a network coding vector θ _Rm from the IFFT matrix according to the above precoding vector and the principle of maximizing channel capacity.

目的节点D从中继节点R收到的转发信号为：The forwarding signal received by the destination node D from the relay node R is:

${y the y}_{RD RD} = = {H h}_{RD RD} {x x}_{R R} + + {n no}_{RD RD} = = {H h}_{RD RD} (({P P}_{11} {θ θ}_{R R 11} \overset{^^}{x x},, {P P}_{22} {θ θ}_{R R 22} \overset{^^}{x x} . . . . . .,, {P P}_{m m} {θ θ}_{Rm R m} \overset{^^}{x x})) + + {n no}_{RD RD};;$

其中，x_R为中继节点经过网络预编码后的信号，而n_RD为中继节点到目的节点的高斯白噪声，因此，从IFFT矩阵中选取的m个网络编码向量θ_Rm需要满足下式：Among them, x _R is the signal of the relay node after network precoding, and n _RD is Gaussian white noise from the relay node to the destination node. Therefore, the m network coding vectors θ _Rm selected from the IFFT matrix need to satisfy the following formula :

$(({θ θ}_{R R 11},, {θ θ}_{R R 22},, . . . . . .,, {θ θ}_{Rm R m})) = = arg arg \underset{{θ θ}_{i i} &Element; &Element; {{{θ θ}_{i i},, i i = = 1,2 1,2,, . . . . . .,, M m}}}{max max} \frac{11}{m m} {Σ Σ}_{i i = = 11}^{m m} {log log}_{22} det det (({I I}_{M m} + + \frac{{E E.}_{s the s}}{{NN NN}_{00}} {θ θ}_{i i}^{* *} {P P}_{i i}^{* *} {H h}_{RD RD}^{* *} {H h}_{RD RD} {P P}_{i i} {θ θ}_{i i})) . .$

上述IFFT矩阵的选取根据L＝N_sT_s进行的，其中N_s为所述源节点的个数，T_s为时隙个数，其可以分为如下三种情况：The selection of the above-mentioned IFFT matrix is carried out according to L=N _s T _s , wherein N _s is the number of the source nodes, and T _s is the number of time slots, which can be divided into the following three situations:

(1)若L＝2^k，k为正整数，则该IFFT矩阵为：(1) If L=2 ^k , k is a positive integer, then the IFFT matrix is:

${F f}_{11} = = (\begin{matrix} 11 & 11 & 11 & . . . . . . & 11 \\ 11 & exp exp ((\frac{π π ((((44 - - 11)) \times \times 11))}{22 L L} i i)) & exp exp ((\frac{π π ((((44 - - 11)) \times \times 22))}{22 L L} i i)) & . . . . . . & exp exp ((\frac{π π ((((44 - - 11)) ((L L - - 11))))}{22 L L} i i)) \\ 11 & exp exp ((\frac{π π ((((44 \times \times 22 - - 11)) \times \times 11))}{22 L L} i i)) & exp exp ((\frac{π π ((((44 \times \times 22 - - 11)) \times \times 22))}{22 L L} i i)) & . . . . . . & exp exp ((\frac{π π ((((44 \times \times 22 - - 11)) \times \times ((L L - - 11))))}{22 L L} i i)) \\ . . & . . & . . & . . & . . \\ . . & . . & . . & . . & . . \\ . . & . . & . . & . . & . . \\ 11 & exp exp ((\frac{π π ((((44 \times \times ((L L - - 11)) - - 11)) \times \times 11))}{22 L L} i i)) & exp exp ((\frac{π π ((((44 \times \times ((L L - - 11)) - - 11)) \times \times 22))}{22 L L} i i)) & . . . . . . & exp exp ((\frac{π π ((((44 \times \times ((L L - - 11)) - - 11)) \times \times ((L L - - 11))))}{22 L L} i i)) \end{matrix})$

(2)若L＝3×2^k，k为正整数，则该IFFT矩阵为：(2) If L=3×2 ^k , k is a positive integer, then the IFFT matrix is:

${F f}_{22} = = (\begin{matrix} 11 & 11 & 11 & . . . . . . & 11 \\ 11 & exp exp ((\frac{π π ((((66 - - 11)) \times \times 11))}{33 L L} i i)) & exp exp ((\frac{π π ((((66 - - 11)) \times \times 22))}{33 L L} i i)) & . . . . . . & exp exp ((\frac{π π ((((66 - - 11)) ((L L - - 11))))}{33 L L} i i)) \\ 11 & exp exp ((\frac{π π ((66 \times \times 22 - - 11)) \times \times 11))}{22 L L} i i)) & exp exp ((\frac{π π ((((66 \times \times 22 - - 11)) \times \times 22))}{33 L L} i i)) & . . . . . . & exp exp ((\frac{π π ((((66 \times \times 22 - - 11)) \times \times ((L L - - 11))))}{33 L L} i i)) \\ . . & . . & . . & . . & . . \\ . . & . . & . . & . . & . . \\ . . & . . & . . & . . & . . \\ 11 & exp exp ((\frac{π π ((((66 \times \times ((L L - - 11)) - - 11)) \times \times 11))}{33 L L} i i)) & exp exp ((\frac{π π ((((66 \times \times ((L L - - 11)) - - 11)) \times \times 22))}{33 L L} i i)) & . . . . . . & exp exp ((\frac{π π ((((66 \times \times ((L L - - 11)) - - 11)) \times \times ((L L - - 11))))}{33 L L} i i)) \end{matrix})$

(3)若L不满足对于L＝2^k和L＝3×2^k都不满足时，则该IFFT矩阵为：(3) If L is not satisfied, neither L=2 ^k nor L=3×2 ^k is satisfied, then the IFFT matrix is:

${F f}_{33} = = (\begin{matrix} 11 & 11 & 11 & . . . . . . & 11 \\ 11 & exp exp ((\frac{22 π π ((11 \times \times 11))}{22 L L} i i)) & exp exp ((\frac{22 π π ((11 \times \times 22))}{22 L L} i i)) & . . . . . . & exp exp ((\frac{22 π π ((11 \times \times ((L L - - 11))))}{22 L L} i i)) \\ 11 & exp exp ((\frac{22 π π ((22 \times \times 11))}{22 L L} i i)) & exp exp ((\frac{22 π π ((22 \times \times 22))}{22 L L} i i)) & . . . . . . & exp exp ((\frac{22 π π ((22 \times \times ((L L - - 11))))}{22 L L} i i)) \\ . . & . . & . . & . . & . . \\ . . & . . & . . & . . & . . \\ . . & . . & . . & . . & . . \\ 11 & exp exp ((\frac{22 π π ((((L L - - 11)) \times \times 11))}{22 L L} i i)) & exp exp ((\frac{22 π π ((L L - - 11)) \times \times 22))}{22 L L} i i)) & . . . . . . & exp exp ((\frac{22 π π ((L L - - 11)) \times \times ((L L - - 11))))}{22 L L} i i)) \end{matrix})$

上述IFFT矩阵中i²＝-1。In the above IFFT matrix, i ² =-1.

步骤4、目的节点D将上述网络编码向量θ_Rm的序号和预编码向量P_m通过无限反馈信道反馈给中继节点R；Step 4. The destination node D feeds back the serial number of the network coding vector θ _Rm and the precoding vector P _m to the relay node R through an infinite feedback channel;

步骤5、中继节点R根据上述网络编码向量θ_Rm的序号从预设的网络编码向量θ_Rm集合中获取网络编码向量θ_Rm。Step 5. The relay node R obtains the network coding vector θ _Rm from the preset network coding vector θ _Rm set according to the serial number of the above network coding vector θ _Rm .

当中继节点R和目的节点D间的反馈信道为有限反馈信道时，网络编码向量θ_Rm的获取和上述相同，只是预编码向量P_m的获取有所不同：When the feedback channel between the relay node R and the destination node D is a limited feedback channel, the acquisition of the network coding vector θ _Rm is the same as above, except that the acquisition of the precoding vector P _m is different:

在本实施例中，目的节点D内具有预设的预编码向量集合，因此目的节点D可以按照最小错误比特概率的原则从该预编码向量集合中选取预编码向量。所谓最小错误比特概率的原则即通过计算BER选择使其达到最小的预编码向量，表示为 $T_{opt} = \arg \min_{T &Element; τ} \overset{&OverBar;}{BER} (H, T),$ 其中BER(H，T)定义为当信道相应为H，预编码向量为T时k个数据流上的平均BER；In this embodiment, the destination node D has a preset precoding vector set, so the destination node D can select a precoding vector from the precoding vector set according to the principle of minimum error bit probability. The principle of the so-called minimum error bit probability is to select the minimum precoding vector by calculating BER, expressed as $T_{opt} = \arg \min_{T &Element; τ} \overset{&OverBar;}{BER} (h, T),$ Where BER(H, T) is defined as the average BER on k data streams when the channel response is H and the precoding vector is T;

由于当反馈信道为有限反馈信道时，中继节点R中除了预设有网络编码向量θ_Rm集合外，还预设有预编码向量P_m集合，因此目的节点D可以将预编码向量P_m的序号通过有限反馈信道反馈给中继节点R，而由中继节点R根据该预编码向量P_m的序号从预设的预编码向量P_m集合中获取预编码向量P_m。When the feedback channel is a limited feedback channel, in addition to the preset network coding vector θ _Rm set, the relay node R also presets the precoding vector P _m set, so the destination node D can use the precoding vector P _m The sequence number is fed back to the relay _node R through the limited feedback channel, and the relay node R obtains the precoding vector P _{m from the preset precoding vector P m} set according to the sequence number of the precoding vector P _m .

需要指出的是，本发明实施例中预编码向量P_m和网络编码向量θ_Rm的获取都是由目的节点D获取的，但是本发明实施例也不排除中继节点R完成上述预编码向量P_m和网络编码向量θ_Rm的获取。It should be pointed out that in the embodiment of the present invention, the acquisition of the precoding vector P _m and the network coding vector θ _Rm is obtained by the destination node D, but the embodiment of the present invention does not rule out that the relay node R completes the above precoding vector P Acquisition of _m and network encoding vector θ _Rm .

S304：根据所述预编码向量和网络编码向量对估计信号进行网络预编码，即得到经过网络预编码后的m个N维子信息流： $x_{R} = (P_{1} θ_{R 1} \hat{x}, P_{2} θ_{R 2} \hat{x} . . ., P_{m} θ_{Rm} \hat{x}) .$ S304: Perform network precoding on the estimated signal according to the precoding vector and the network coding vector, that is, obtain m N-dimensional sub-information streams after network precoding: $x_{R} = (P_{1} θ_{R 1} \hat{x}, P_{2} θ_{R 2} \hat{x} . . ., P_{m} θ_{R m} \hat{x}) .$

S305：将预编码信号通过多根天线发送至目的节点以使该目的节点对上述编码后的信号进行解码，该解码过程同图2所述实施例提供的方法，在此也不再进行赘述。S305: Send the precoded signal to the destination node through multiple antennas so that the destination node decodes the coded signal. The decoding process is the same as the method provided in the embodiment shown in FIG. 2 , and will not be repeated here.

本发明实施例通过中继节点对源节点所发送的信号进行网络预编码，从而使得无线通信网络中多用户MIMO中继信道的数据传输具有较高的吞吐量，传输效率得到了有效提高。另外本发明实施例针对不同的反馈信道，采用不同的反馈方案，使得编码效率有了进一步的提高。In the embodiment of the present invention, the relay node performs network precoding on the signal sent by the source node, so that the data transmission of the multi-user MIMO relay channel in the wireless communication network has higher throughput, and the transmission efficiency is effectively improved. In addition, the embodiments of the present invention adopt different feedback schemes for different feedback channels, so that the coding efficiency is further improved.

如图4所示为本发明实施例提供的另一种数据传输方法流程图，本实施例是从目的节点的角度对本发明进行说明，该方法包括如下步骤：As shown in FIG. 4, it is a flowchart of another data transmission method provided by the embodiment of the present invention. This embodiment describes the present invention from the perspective of the destination node. The method includes the following steps:

S401：接收至少两个源节点发送的源信号，得到接收信号。S401: Receive source signals sent by at least two source nodes to obtain received signals.

由于无线信号的广播特性，目的节点上的每根天线都会收到所有源节点所发送的信号，即收到N_S个信号，假设图1中的目的节点D具有N根天线，则目的节点D在时隙t会收到如下信号：Due to the broadcast characteristics of wireless signals, each antenna on the destination node will receive the signals sent by all source nodes, that is, receive N _S signals. Assuming that the destination node D in Figure 1 has N antennas, then the destination node D The following signal will be received at time slot t:

y_SD(t)＝H_SDx(t)+n_SD(t)；y _SD (t) = H _SD x (t) + n _SD (t);

其中， $x (t) = {(θ_{1} x_{1} (t), . . ., θ_{N_{S}} x_{Ns} (t))}^{T}$ 表示N_S个源节点在第t个时隙内发送的信号；n_SD(t)表示N_S个源节点与目的节点D之间的高斯白噪声；H_SD表示N_S个源节点与目的节点D之间的信道衰落矩阵，且in, $x (t) = {(θ_{1} x_{1} (t), . . ., θ_{N_{S}} x_{NS} (t))}^{T}$ Represents the signals sent by N _S source nodes in the tth time slot; n _SD (t) represents the Gaussian white noise between the N _S source nodes and the destination node D; H _SD represents the N _S source nodes and the destination node The channel fading matrix between D, and

${H h}_{SD SD} = = (\begin{matrix} {h h}_{{S S}_{11} D D.}^{11} & . . . . . . & {h h}_{{S S}_{{N N}_{S S}} D D.}^{11} \\ . . & . . \\ . . & . . . . . . & . . \\ . . & . . \\ {h h}_{{S S}_{11} D D.}^{N N} & . . . . . . & {h h}_{{S S}_{{N N}_{S S}} D D.}^{N N} \end{matrix});;$

其中

表示源节点i到目的节点第j根天线之间的信道衰落系数，j＝1，…，N。in

Indicates the channel fading coefficient between the source node i and the jth antenna of the destination node, j=1,...,N.

S402：接收中继节点发送的经过网络预编码后的预编码信号。S402: Receive a network precoded precoded signal sent by the relay node.

中继节点R对其接收到的源节点发出的信号进行网络预编码，将经过网络预编码后的编码信号发送给目的节点，网络预编码的过程如下：The relay node R performs network precoding on the signal received from the source node, and sends the encoded signal after network precoding to the destination node. The network precoding process is as follows:

中继节点R接收到的源节点信号为：y_SR(t)＝H_SRx(t)+n_SR(t)，其中各部分的释义已在实施例一步骤S201中进行了介绍，然后中继节点R对该接收信号进行解调以得到上述源信号的估计信号

\hat{x} (t) = \underset{x (t)}{\arg \min} {| | y_{SR} (t) - H_{SR} x (t) | |}^{2},

进而可以得到一具有N_S个元素的估计信号向量：

\hat{x} (t) = {(\begin{matrix} {\hat{x}}_{1} (t) & . . . & {\hat{x}}_{N_{S}} (t) \end{matrix})}^{T};

最后，中继节点R将T_S个时隙内的估计信号构成估计信号向量

\hat{x} = {(\hat{x} (t), \hat{x} (t + 1), . . ., \hat{x} (t + T_{S} - 1))}^{T},

并根据m个预编码向量P_m和网络编码向量θ_Rm对上述估计向量进行网络预编码，得到m个N维子信息流：

x_{R} = (P_{1} θ_{R 1} \hat{x}, P_{2} θ_{R 2} \hat{x} . . ., P_{m} θ_{Rm} \hat{x}),

该x_R即为网络预编码后的预编码信号。The source node signal received by the relay node R is: y _SR (t)=H _SR x(t)+n _SR (t), where the interpretation of each part has been introduced in step S201 of the first embodiment, and then The subsequent node R demodulates the received signal to obtain the estimated signal of the above source signal

\hat{x} (t) = \underset{x (t)}{\arg \min} {| | {the y}_{SR} (t) - h_{SR} x (t) | |}^{2},

In turn, an estimated signal vector with N _S elements can be obtained:

\hat{x} (t) = {(\begin{matrix} {\hat{x}}_{1} (t) & . . . & {\hat{x}}_{N_{S}} (t) \end{matrix})}^{T};

Finally, the relay node R constructs an estimated signal vector from the estimated signals in T _S time slots

\hat{x} = {(\hat{x} (t), \hat{x} (t + 1), . . ., \hat{x} (t + T_{S} - 1))}^{T},

And according to m precoding vectors P _m and network coding vector θ _Rm , network precoding is performed on the above estimated vectors to obtain m N-dimensional sub-information flows:

x_{R} = (P_{1} θ_{R 1} \hat{x}, P_{2} θ_{R 2} \hat{x} . . ., P_{m} θ_{R m} \hat{x}),

The x _R is the precoded signal after network precoding.

S403：根据接收到的上述接收信号和上述预编码信号进行解码。在本实施例中，可以目的节点可以根据最大似然解码对上述编码信号进行解码。S403: Perform decoding according to the received signal and the precoded signal. In this embodiment, the destination node may decode the above coded signal according to maximum likelihood decoding.

本发明实施例通过中继节点对源节点所发送的信号进行网络预编码，从而使得无线通信网络中多用户MIMO中继信道的数据传输具有较高的吞吐量，传输效率得到了有效提高。In the embodiment of the present invention, the relay node performs network precoding on the signal sent by the source node, so that the data transmission of the multi-user MIMO relay channel in the wireless communication network has higher throughput, and the transmission efficiency is effectively improved.

本实施例是对图4对应实施例的进一步描述，如图5所示为本发明实施例提供的另一种数据传输方法流程图，该方法包括如下步骤：This embodiment is a further description of the embodiment corresponding to FIG. 4. FIG. 5 is a flowchart of another data transmission method provided by the embodiment of the present invention. The method includes the following steps:

S501：利用多根天线接收至少两个源节点发送的源信号，得到接收信号。S501: Using multiple antennas to receive source signals sent by at least two source nodes, to obtain received signals.

S502：对与所述中继节点之间的信道衰落矩阵进行奇异值分解来计算每个并行子信道的信噪比。S502: Perform singular value decomposition on the channel fading matrix with the relay node to calculate the signal-to-noise ratio of each parallel sub-channel.

S503：将大于预设门限的信噪比所对应的特征向量作为预编码向量。S503: Use a feature vector corresponding to a signal-to-noise ratio greater than a preset threshold as a precoding vector.

S504：选取反向快速傅里叶变换IFFT矩阵，并根据所述预编码向量及按照信道容量最大的原则从所述IFFT矩阵中得到网络编码向量。S504: Select an inverse fast Fourier transform IFFT matrix, and obtain a network coding vector from the IFFT matrix according to the precoding vector and the principle of maximizing channel capacity.

这里IFFT矩阵的选择和实施例二中相同，在此就不再赘述了。在本步骤中得到的网络编码向量θ_Rm需要满足下式：The selection of the IFFT matrix here is the same as that in the second embodiment, so it will not be repeated here. The network coding vector θ _Rm obtained in this step needs to satisfy the following formula:

S505：将所述网络编码向量的序号和所述预编码向量通过无限反馈信道反馈给所述中继节点，中继节点会根据该网络编码向量的序号从预设的网络编码向量集合中获得网络编码向量。S505: Feed back the sequence number of the network coding vector and the precoding vector to the relay node through an infinite feedback channel, and the relay node will obtain the network coding vector from the preset network coding vector set according to the sequence number of the network coding vector Encoding vector.

S506：接收中继节点发送的经过网络预编码后的预编码信号。S506: Receive the precoded signal sent by the relay node after being precoded by the network.

中继节点根据得到的预编码向量P_m和网络编码向量θ_Rm进行网络预编码，得到m个N维子信息流： $x_{R} = (P_{1} θ_{R 1} \hat{x}, P_{2} θ_{R 2} \hat{x} . . ., P_{m} θ_{Rm} \hat{x}) .$ The relay node performs network precoding according to the obtained precoding vector P _m and network coding vector θ _Rm , and obtains m N-dimensional sub-information flows: $x_{R} = (P_{1} θ_{R 1} \hat{x}, P_{2} θ_{R 2} \hat{x} . . ., P_{m} θ_{R m} \hat{x}) .$

S507：根据步骤S501接收到的接收信号和步骤S506接收到的预编码信号进行最大似然解码以得到所需信号。S507: Perform maximum likelihood decoding according to the received signal received in step S501 and the precoded signal received in step S506 to obtain a desired signal.

需要指出的是，上述方案目的节点是通过无限反馈信道向中继节点进行向量反馈的，但是，如果目的节点是通过有限反馈信道向中继节点进行向量反馈的时候，上述步骤S502-S505可以通过下述步骤予以替换：It should be pointed out that the destination node in the above scheme performs vector feedback to the relay node through the infinite feedback channel, but if the destination node performs vector feedback to the relay node through the limited feedback channel, the above steps S502-S505 can be passed The following steps are replaced:

按照最小错误比特概率的原则从预编码向量集合中选取预编码向量；Select the precoding vector from the precoding vector set according to the principle of minimum error bit probability;

选取适当的IFFT矩阵，并根据所述预编码向量并按照信道容量最大的原则从所述IFFT矩阵中得到网络编码向量；Selecting an appropriate IFFT matrix, and obtaining a network coding vector from the IFFT matrix according to the precoding vector and according to the principle of maximum channel capacity;

将所述预编码向量的序号和所述网络编码向量的序号通过有限反馈信道反馈给所述中继节点，中继节点根据该网络编码向量的序号从预设的网络编码向量集合中获取网络编码向量，并根据预编码向量的序号从预设的预编码向量集合中获取预编码向量。The sequence number of the precoding vector and the sequence number of the network coding vector are fed back to the relay node through a limited feedback channel, and the relay node obtains the network coding from a preset network coding vector set according to the sequence number of the network coding vector vector, and obtain the precoding vector from the preset precoding vector set according to the sequence number of the precoding vector.

如图6所示为本发明实施例提供的一种中继的结构示意图，该中继包括：源信号接收单元610、解调单元620、网络预编码单元630和发送单元640，其中，解调单元620分别和源信号接收单元610及网络预编码单元630相连，而发送单元640则和网络预编码单元630相连。FIG. 6 is a schematic structural diagram of a relay provided by an embodiment of the present invention. The relay includes: a source signal receiving unit 610, a demodulation unit 620, a network precoding unit 630, and a sending unit 640, wherein the demodulation The unit 620 is connected to the source signal receiving unit 610 and the network precoding unit 630 respectively, and the sending unit 640 is connected to the network precoding unit 630 .

源信号接收单元610用于接收至少两个源节点发送的源信号，得到接收信号。The source signal receiving unit 610 is configured to receive source signals sent by at least two source nodes to obtain received signals.

由于无线信号的广播特性，中继节点上的每根天线都会收到所有源节点所发送的信号，即收到N_S个信号，假设图1中的中继节点具有N根天线，则中继节点在时隙t会收到如下信号：Due to the broadcast characteristics of wireless signals, each antenna on the relay node will receive the signals sent by all source nodes, that is, N _S signals are received. Assuming that the relay node in Figure 1 has N antennas, the relay node The node will receive the following signal at time slot t:

y_SR(t)＝H_SRx(t)+n_SR(t)；y _SR (t) = H _SR x (t) + n _SR (t);

其中， $x (t) = {(θ_{1} x_{1} (t), . . ., θ_{N_{s}} x_{Ns} (t))}^{T}$ 表示N_S个源节点在第t个时隙内发送的信号；n_SR(t)表示源节点与中继节点R之间高斯白噪声；H_SR表示N_S个源节点与中继节点R之间的信道衰落矩阵，且in, $x (t) = {(θ_{1} x_{1} (t), . . ., θ_{N_{the s}} x_{NS} (t))}^{T}$ Represents the signals sent by N _S source nodes in the tth time slot; n _SR (t) represents the Gaussian white noise between the source node and the relay node R; H _SR represents the signal between the N _S source nodes and the relay node R The channel fading matrix between, and

${H h}_{SR SR} = = (\begin{matrix} {h h}_{{S S}_{11} R R}^{11} & . . . . . . & {h h}_{{S S}_{{N N}_{S S}} R R}^{11} \\ . . & . . \\ . . & . . . . . . & . . \\ . . & . . \\ {h h}_{{S S}_{11} R R}^{N N} & . . . . . . & {h h}_{{S S}_{{N N}_{S S}} R R}^{N N} \end{matrix})$

其中

解调单元620用于对所述接收信号进行解调，得到所述源信号的估计信号。具体来说，解调单元620是根据下式计算得到上述源信号的估计信号

The demodulation unit 620 is configured to demodulate the received signal to obtain an estimated signal of the source signal. Specifically, the demodulation unit 620 calculates the estimated signal of the above source signal according to the following formula

最后得到具有N_S个元素的估计信号向量： $\hat{x} (t) = {(\begin{matrix} {\hat{x}}_{1} (t) & . . . & {\hat{x}}_{N_{S}} (t) \end{matrix})}^{T} .$ Finally an estimated signal vector with N _S elements is obtained: $\hat{x} (t) = {(\begin{matrix} {\hat{x}}_{1} (t) & . . . & {\hat{x}}_{N_{S}} (t) \end{matrix})}^{T} .$

网络预编码单元630用于对所述估计信号进行网络预编码。The network precoding unit 630 is configured to perform network precoding on the estimated signal.

首先，网络预编码单元630先将T_S个时隙内的估计信号构成估计信号向量 $\hat{x} = {(\hat{x} (t), \hat{x} (t + 1), . . ., \hat{x} (t + T_{S} - 1))}^{T},$ 然后再根据m个预编码向量P_m和网络编码向量θ_Rm对上述估计信号向量进行网络预编码，得到m个N维子信息流： $x_{R} = (P_{1} θ_{R 1} \hat{x}, P_{2} θ_{R 2} \hat{x} . . ., P_{m} θ_{Rm} \hat{x}) .$ First, the network precoding unit 630 constructs estimated signal vectors from the estimated signals in T _S time slots $\hat{x} = {(\hat{x} (t), \hat{x} (t + 1), . . ., \hat{x} (t + T_{S} - 1))}^{T},$ Then perform network precoding on the above estimated signal vector according to m precoding vectors P _m and network coding vector θ _Rm to obtain m N-dimensional sub-information flows: $x_{R} = (P_{1} θ_{R 1} \hat{x}, P_{2} θ_{R 2} \hat{x} . . ., P_{m} θ_{R m} \hat{x}) .$

如图7所示，作为本发明的一个实施例，网络编码单元630可以包括向量接收模块631、向量获取模块632和预编码模块633，其中：As shown in FIG. 7, as an embodiment of the present invention, the network coding unit 630 may include a vector receiving module 631, a vector obtaining module 632, and a precoding module 633, wherein:

向量接收模块631用于通过无限反馈信道接收目的节点反馈的网络编码向量的序号和预编码向量；向量获取模块632用于根据所述网络编码向量的序号从预设网络编码向量集合中获取网络编码向量；预编码模块633用于根据所述预编码向量和网络编码向量对所述估计信号进行网络预编码。这里，反馈信道为无限反馈信道，因此目的节点向网络编码单元630反馈的是网络编码向量的序号和预编码向量，关于该两种向量的获取与图3对应实施例的描述相类似，不再进行赘述。The vector receiving module 631 is used to receive the sequence number and precoding vector of the network coding vector fed back by the destination node through the infinite feedback channel; the vector obtaining module 632 is used to obtain the network coding vector from the preset network coding vector set according to the sequence number of the network coding vector vector; the precoding module 633 is configured to perform network precoding on the estimated signal according to the precoding vector and the network coding vector. Here, the feedback channel is an infinite feedback channel, so what the destination node feeds back to the network coding unit 630 is the sequence number of the network coding vector and the precoding vector. The acquisition of these two vectors is similar to the description of the corresponding embodiment in FIG. to repeat.

作为本发明的另一个实施例，向量接受模块631还用于通过有限反馈信道接收目的节点反馈的网络编码向量的序号和预编码向量的序号；向量获取模块632还用于根据所述预编码向量的序号从预设的预编码向量集合中获取预编码向量。即在反馈信道为有限反馈信道的时候，目的节点向网络编码单元630反馈的是网络编码向量的序号和预编码向量的序号，而由网络编码单元630根据该序号得到所需的网络编码向量和预编码向量。As another embodiment of the present invention, the vector accepting module 631 is also used to receive the sequence number of the network coding vector and the sequence number of the precoding vector fed back by the destination node through a limited feedback channel; the vector obtaining module 632 is also used to The sequence number of is to obtain the precoding vector from the preset precoding vector set. That is, when the feedback channel is a limited feedback channel, what the destination node feeds back to the network coding unit 630 is the sequence number of the network coding vector and the sequence number of the precoding vector, and the network coding unit 630 obtains the required network coding vector and precoded vector.

发送单元640用于将经过所述网络预编码单元编码后的信号发送至目的节点。目的节点可以通过下述方式对x_R进行解码：The sending unit 640 is configured to send the signal encoded by the network precoding unit to the destination node. The destination node can decode x _R in the following ways:

首先，由于无线信号的广播特性，目的节点同中继节点一样，也会收到源节点S₁-S_Ns所发出的信号，在此假设目的节点也具有N根天线，其收到的源节点信号记为y_SD(t)，则：First of all, due to the broadcast characteristics of wireless signals, the destination node, like the relay node, will also receive the signal sent by the source node S ₁ -S _Ns . Here, it is assumed that the destination node also has N antennas, and the received signal from the source node The signal is denoted as y _SD (t), then:

y_SD(t)＝H_SDx(t)+n_SD(t)；y _SD (t) = H _SD x (t) + n _SD (t);

其中， $x (t) = {(θ_{1} x_{1} (t), . . ., θ_{N_{S}} x_{Ns} (t))}^{T}$ 表示N_S个源节点在第t个时隙内发送的信号；n_SD(t)源节点与目的节点之间高斯白噪声；H_SD表示N_S个源节点与目的节点D之间的信道衰落矩阵：in, $x (t) = {(θ_{1} x_{1} (t), . . ., θ_{N_{S}} x_{NS} (t))}^{T}$ Indicates the signal sent by N _S source nodes in the tth time slot; n _SD (t) Gaussian white noise between the source node and the destination node; H _SD represents the channel fading between N _S source nodes and the destination node D matrix:

其中

表示源节点i到目的节点的第j根天线之间的信道衰落系数，j＝1，…，N；in

Indicates the channel fading coefficient between the source node i and the jth antenna of the destination node, j=1,...,N;

然后，目的节点根据其收到的源节点信号y_SD(t)和中继节点所转发的经过网络编码后的信号x_R，解码得到所需要的信号。Then, the destination node decodes and obtains the required signal according to the received signal y _SD (t) of the source node and the network-encoded signal x _R forwarded by the relay node.

如图8所示为本发明实施例提供的一种装置的结构示意图，该装置包括：源信号接收单元810、解码单元820和编码信号接收单元830，其中解码单元820分别和源信号接收单元810及编码信号接收单元830相连。As shown in FIG. 8, it is a schematic structural diagram of a device provided by an embodiment of the present invention. The device includes: a source signal receiving unit 810, a decoding unit 820, and an encoded signal receiving unit 830, wherein the decoding unit 820 and the source signal receiving unit 810 are respectively It is connected with the encoded signal receiving unit 830.

源信号接收单元810用于接收至少两个源节点发送的源信号，得到接收信号。假设图1中的目的节点D具有N根天线，则目的节点D在时隙t会收到如下信号：The source signal receiving unit 810 is configured to receive source signals sent by at least two source nodes to obtain received signals. Assuming that the destination node D in Figure 1 has N antennas, the destination node D will receive the following signal at time slot t:

y_SD(t)＝H_SDx(t)+n_SD(t)；y _SD (t) = H _SD x (t) + n _SD (t);

其中表示源节点i到目的节点第j根天线之间的信道衰落系数，j＝1，…，N。in Indicates the channel fading coefficient between the source node i and the jth antenna of the destination node, j=1,...,N.

编码信号接收单元830用于接收中继节点发送的经过网络预编码后的预编码信号。具体来说，是中继节点对其接收到的源节点发出的信号进行网络预编码，然后再将预编码后的数据发送给编码信号接收单元830，该网络预编码过程可以参见图6实施例中相应的描述。The coded signal receiving unit 830 is configured to receive the precoded signal sent by the relay node after being precoded by the network. Specifically, the relay node performs network precoding on the signal it receives from the source node, and then sends the precoded data to the coded signal receiving unit 830. For the network precoding process, refer to the embodiment in Figure 6 in the corresponding description.

解码单元820用于根据上述接收信号和预编码信号进行解码以得到所需信号，比如可以根据上述接收信号和预编码信号进行最大似然解码。The decoding unit 820 is configured to perform decoding according to the above-mentioned received signal and precoded signal to obtain a desired signal, for example, maximum likelihood decoding may be performed according to the above-mentioned received signal and precoded signal.

请参见图9，作为本发明的一个实施例，本装置还可以包括预编码向量生成单元840、网络编码向量生成单元850和反馈单元860。Referring to FIG. 9 , as an embodiment of the present invention, the device may further include a precoding vector generation unit 840 , a network coding vector generation unit 850 and a feedback unit 860 .

其中，网络编码向量生成单元850用于选取反向快速傅里叶变换IFFT矩阵，并根据所述预编码向量并按照信道容量最大的原则从IFFT矩阵中得到网络编码向量。Wherein, the network coding vector generating unit 850 is configured to select an inverse fast Fourier transform IFFT matrix, and obtain a network coding vector from the IFFT matrix according to the precoding vector and the principle of maximizing channel capacity.

而预编码向量生成单元840用于得到预编码向量，反馈单元860用于向中继节点反馈预编码向量和网络编码向量，但是，根据反馈信道类型的不同，上述两个单元的具体作用也有所不同。The precoding vector generation unit 840 is used to obtain the precoding vector, and the feedback unit 860 is used to feed back the precoding vector and the network coding vector to the relay node. However, the specific functions of the above two units are also different according to the type of the feedback channel. different.

当反馈信道为无限反馈信道时：预编码向量生成单元840用于对与中继节点之间的信道衰落矩阵进行奇异值分解来计算每个并行子信道的信噪比，并将将大于预设门限信噪比的特征值所对应的特征向量作为预编码向量。此时反馈单元860是将网络编码向量的序号和预编码向量反馈给中继节点。When the feedback channel is an infinite feedback channel: the precoding vector generation unit 840 is used to perform singular value decomposition on the channel fading matrix with the relay node to calculate the signal-to-noise ratio of each parallel sub-channel, which will be greater than the preset The eigenvector corresponding to the eigenvalue of the threshold signal-to-noise ratio is used as a precoding vector. At this time, the feedback unit 860 feeds back the serial number of the network coding vector and the precoding vector to the relay node.

当反馈信道为有限反馈信道时：预编码向量生成单元840具体用于按照最小错误比特概率的原则从预设的预编码向量集合中选取预编码向量。而反馈单元860则是将网络编码向量的序号和预编码向量的序号反馈给中继节点。When the feedback channel is a limited feedback channel: the precoding vector generation unit 840 is specifically configured to select a precoding vector from a preset precoding vector set according to the principle of minimum error bit probability. The feedback unit 860 feeds back the sequence number of the network coding vector and the sequence number of the precoding vector to the relay node.

如图10所示为本发明实施例提供的系统结构图，该系统包括源节点1001、中继1002和目的节点1003，其中，中继1002通过无线链路分别和源节点1001及目的节点1003相连。As shown in Figure 10 is a system structure diagram provided by the embodiment of the present invention, the system includes a source node 1001, a relay 1002 and a destination node 1003, wherein the relay 1002 is respectively connected to the source node 1001 and the destination node 1003 through a wireless link .

源节点1001在本实施例中可以包括手机、个人数字助理PDA、个人电脑等可以进行无线通信的电子设备，在本实施例中，源节点1001至少包括上述两个设备。In this embodiment, the source node 1001 may include electronic devices capable of wireless communication such as mobile phones, personal digital assistants (PDAs), and personal computers. In this embodiment, the source node 1001 includes at least the above two devices.

中继1002和目的节点1003都为多天线设备，源节点1001通过中继1002向目的节点1003发送信号。具体来说，中继1002可以包括如上述实施例所述的一种中继，而目的节点1003可以包括上述实施例所述的一种装置，比如一种基站。对于该系统的具体工作过程，在前述实施例已经加以描述。Both the relay 1002 and the destination node 1003 are multi-antenna devices, and the source node 1001 sends a signal to the destination node 1003 through the relay 1002 . Specifically, the relay 1002 may include a relay described in the above embodiments, and the destination node 1003 may include an apparatus described in the above embodiments, such as a base station. The specific working process of the system has been described in the foregoing embodiments.

最后通过几个仿真实验来具体说明本发明实施例的有益效果：Finally, the beneficial effects of the embodiments of the present invention are specified through several simulation experiments:

由于本发明实施例将中继节点在T_S个时隙内的估计信号，经过网络预编码处理后在一个时隙内转发完成，因此其吞吐量可以达到T_S/(T_S+1)，可以随T_S的增加而提高，因此本发明实施例具有高吞吐量的优点。Since the embodiment of the present invention forwards the estimated signal of the relay node in T _S time slots after network precoding processing, and completes forwarding in one time slot, the throughput can reach T _S /(T _S +1), It can be increased with the increase of T _S , so the embodiment of the present invention has the advantage of high throughput.

另外，本发明实施例还具有较高编码增益的优点。如图11所示为本发明实施例的网络预编码方案与复数域网络编码的性能比较，其仿真参数如下：In addition, the embodiment of the present invention also has the advantage of higher coding gain. As shown in Figure 11, the performance comparison between the network precoding scheme of the embodiment of the present invention and the complex domain network coding, the simulation parameters are as follows:

(1)网络预编码方案中，两个源节点，一个中继节点和一个目的节点，源节点的天线数为1，中继节点和目的节点天线数为2，预编码向量和网络编码向量的个数均为1，符号个数T_S＝1，即吞吐量为1/2符号/信源/时隙；(1) In the network precoding scheme, two source nodes, one relay node and one destination node, the number of antennas of the source node is 1, the number of antennas of the relay node and the destination node is 2, the precoding vector and the network coding vector The number is 1, the number of symbols T _S =1, that is, the throughput is 1/2 symbol/source/time slot;

(2)复数域网络编码中，两个源节点，两个中继节点和一个目的节点，所有节点都是一根天线，吞吐量为1/2符号/信源/时隙；(2) In the complex domain network coding, two source nodes, two relay nodes and one destination node, all nodes are one antenna, and the throughput is 1/2 symbol/source/time slot;

(3)假设信道为对称信道，即源节点到中继节点、源节点到目的节点以及中继节点到目的节点的信道均为独立衰落信道，且假设目的节点和中继节点的接收信噪比相同；(3) Assume that the channel is a symmetric channel, that is, the channels from the source node to the relay node, from the source node to the destination node, and from the relay node to the destination node are all independent fading channels, and assume that the receiving signal-to-noise ratio of the destination node and the relay node same;

(4)源节点和中继节点均采用BPSK调制方式。(4) Both the source node and the relay node adopt BPSK modulation.

由图11可看出，采用网络预编码的方案比复数域网络编码的方案有着明显的编码增益，比如在错误比特率BER＝10-4时，本发明实施例的方案比现有复数域网络编码有近10dB的编码增益。It can be seen from Fig. 11 that the scheme using network precoding has obvious coding gain compared with the scheme of complex domain network coding. For example, when the error bit rate BER=10 The coding has a coding gain of nearly 10dB.

接下来是网络预编码方案在不同吞吐量情况下的性能比较，请参见图12，这里的仿真参数如下：Next is the performance comparison of the network precoding scheme under different throughput conditions. Please refer to Figure 12. The simulation parameters here are as follows:

(1)网络预编码方案中，两个源节点，一个中继节点和一个目的节点，源节点的天线数为1，中继节点和目的节点天线数为2，T_S分别取1，3和4，对应的吞吐量分别为1/2符号/信源/时隙、3/4符号/信源/时隙和4/5符号/信源/时隙；(1) In the network precoding scheme, there are two source nodes, one relay node and one destination node, the number of antennas of the source node is 1, the number of antennas of the relay node and the destination node is 2, and T _S is respectively 1, 3 and 4. The corresponding throughputs are 1/2 symbol/source/time slot, 3/4 symbol/source/time slot and 4/5 symbol/source/time slot;

(2)假设信道为对称信道，即源节点到中继节点、源节点到目的节点以及中继节点到目的节点的信道均为独立衰落信道，且假设目的节点和中继节点的接收信噪比相同；(2) Assume that the channel is a symmetric channel, that is, the channels from the source node to the relay node, from the source node to the destination node, and from the relay node to the destination node are all independent fading channels, and assume that the receiving signal-to-noise ratio of the destination node and the relay node is same;

(3)源节点和中继节点均采用BPSK调制方式。(3) Both the source node and the relay node adopt BPSK modulation.

从图12可以看出，在小信噪比SNR时，随着吞吐量的增加，网络预编码方案的性能逐渐恶化，不过其变化幅度不是很大，随着SNR的逐渐增加，几种方案的性能逐渐趋于一致。It can be seen from Fig. 12 that when the signal-to-noise ratio (SNR) is small, as the throughput increases, the performance of the network precoding scheme gradually deteriorates, but the range of change is not very large. With the gradual increase of the SNR, the performance of several schemes Performance gradually converges.

这是由于在小信噪比时，信道加性噪声(高斯白噪声)的影响较大，目的节点性能的改善很大程度上依赖中继节点提供额外的分集，而在中继节点合并过多数据必然造成较多错误。随着信噪比的增加，信道中产生的错误较少，目的节点仅接收源节点的信息即可恢复原始数据的概率增加，对中继节点的依赖减少，从而使几种方案的性能趋于一致。This is because when the signal-to-noise ratio is small, the channel additive noise (Gaussian white noise) has a greater impact, and the improvement of the performance of the destination node largely depends on the relay node to provide additional diversity, while the relay node combines too much Data will inevitably cause more errors. As the signal-to-noise ratio increases, fewer errors are generated in the channel, the probability that the destination node can restore the original data by only receiving the information from the source node increases, and the dependence on the relay node decreases, so that the performance of several schemes tends to be unanimous.

可见，本方案在具有高吞吐量的同时，还可以将错误比特率的控制在一定的范围之内。It can be seen that, while this solution has high throughput, it can also control the bit error rate within a certain range.

本领域普通技术人员可以理解实现上述实施例方法中的全部或部分流程，可以通过计算机程序来指令相关的硬件来完成，所述的程序可存储于一计算机可读取存储介质中，该程序在执行时，可包括如上述各方法的实施例的流程。其中，所述的存储介质可为磁碟、光盘、只读存储记忆体(Read-Only Memory，ROM)或随机存储记忆体(Random Access Memory，RAM)等。Those of ordinary skill in the art can understand that all or part of the processes in the methods of the above embodiments can be realized by instructing related hardware through a computer program, and the program can be stored in a computer-readable storage medium. During execution, it may include the processes of the embodiments of the above-mentioned methods. Wherein, the storage medium may be a magnetic disk, an optical disk, a read-only memory (Read-Only Memory, ROM) or a random access memory (Random Access Memory, RAM), etc.

以上所述的具体实施方式，对本发明的目的、技术方案和有益效果进行了进一步详细说明，所应理解的是，以上所述仅为本发明的具体实施方式而已，并不用于限定本发明的保护范围，凡在本发明的精神和原则之内，所做的任何修改、等同替换、改进等，均应包含在本发明的保护范围之内。The specific embodiments described above have further described the purpose, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above descriptions are only specific embodiments of the present invention and are not intended to limit the scope of the present invention. Protection scope, within the spirit and principles of the present invention, any modification, equivalent replacement, improvement, etc., shall be included in the protection scope of the present invention.

Claims

1. A data transmission method, characterized in that the method comprises:

receiving source signals sent by at least two source nodes to obtain received signals;

Decoding the received signal to obtain an estimated signal of the source signal;

Perform network precoding on the estimated signal, and send the precoded signal to the destination node.

2. The method according to claim 1, wherein said performing network precoding on said estimated signal comprises:

Receive the sequence number and precoding vector of the network coding vector fed back by the destination node through the infinite feedback channel;

Selecting a network coding vector according to the serial number of the network coding vector;

Perform network precoding on the estimated signal according to the precoding vector and the network coding vector.

3. The method according to claim 1, wherein said performing network precoding on said estimated signal comprises:

Receive the sequence number of the network coding vector and the sequence number of the precoding vector fed back by the destination node through the limited feedback channel;

selecting a network coding vector according to the serial number of the network coding vector, and selecting a precoding vector according to the serial number of the precoding vector;

4. A data transmission method, characterized in that the method comprises:

receiving a precoded signal sent by the relay node, the relay node decodes the received signal obtained according to the source signals sent by the at least two source nodes to obtain an estimated signal, and performs Network precoding is obtained;

Decoding is performed according to the received signal and the precoded signal.

5. The method according to claim 4, further comprising: before receiving the precoded signal sent by the relay node:

Singular value decomposition is performed on the channel fading matrix between the relay node and the signal-to-noise ratio of the parallel sub-channel;

Using the feature vector corresponding to the signal-to-noise ratio greater than the preset threshold as the precoding vector;

Select an inverse fast Fourier transform IFFT matrix, and obtain a network coding vector from the IFFT matrix according to the precoding vector;

Feedback the sequence number of the network coding vector and the precoding vector to the relay node through an infinite feedback channel.

6. The method according to claim 4, characterized in that before receiving the coded signal sent by the relay node after network precoding, the method further includes:

Selecting a precoding vector from a set of precoding vectors;

Select an IFFT matrix, and obtain a network coding vector from the IFFT matrix according to the precoding vector;

Feedback the sequence number of the precoding vector and the sequence number of the network coding vector to the relay node through a limited feedback channel.

7. A relay, characterized in that it comprises:

a source signal receiving unit, configured to receive source signals sent by at least two source nodes to obtain received signals;

a decoding unit, configured to decode the received signal to obtain an estimated signal of the source signal;

A network precoding unit, configured to perform network precoding on the estimated signal;

A sending unit, configured to send the signal precoded by the network precoding unit to a destination node.

8. The relay according to claim 7, wherein the network precoding unit comprises:

The vector receiving module is used to receive the sequence number and precoding vector of the network coding vector fed back by the destination node through the infinite feedback channel;

A vector acquisition module, configured to acquire a network encoding vector according to the serial number of the network encoding vector;

A precoding module, configured to perform network precoding on the estimated signal according to the precoding vector and the network coding vector.

9. The relay of claim 8, wherein

The vector receiving module is also used to receive the sequence number of the network coding vector and the sequence number of the precoding vector fed back by the destination node through a limited feedback channel;

The vector acquiring module is further configured to acquire a precoding vector according to the sequence number of the precoding vector.

10. A device, characterized in that it comprises:

A coded signal receiving unit, configured to receive a precoded signal sent by a relay node, where the relay node decodes a received signal obtained from source signals sent by the at least two source nodes to obtain an estimated signal, and network precoding is performed on the estimated signal to obtain;

A decoding unit, configured to perform decoding according to the received signal and the precoded signal.

11. The apparatus of claim 10, further comprising:

A precoding vector generation unit, configured to perform singular value decomposition on the channel fading matrix between the relay node to calculate the signal-to-noise ratio of each parallel sub-channel, and set the SNR corresponding to the signal-to-noise ratio greater than the preset threshold The feature vector is used as a precoding vector;

A network encoding vector generating unit, configured to select an inverse fast Fourier transform IFFT matrix, and obtain a network encoding vector from the IFFT matrix according to the precoding vector;

A feedback unit, configured to feed back the precoding vector and the network coding vector to the relay node through an infinite feedback channel.

12. The apparatus of claim 10, wherein

The precoding vector generating unit is further configured to select a precoding vector from a precoding vector set;

The feedback unit is further configured to feed back the precoding vector and the network coding vector to the relay node through a limited feedback channel.

13. A data transmission system, comprising the relay according to any one of claims 7-9, the device according to any one of claims 10-12, and at least two source nodes, the source nodes It is used to send data to the relay and the device.