CN103391167A - New method of improving sum rate of multipoint-to-multipoint MIMO relay system - Google Patents

Abstract

The invention relates to the field of wireless communication, in particular to a multipoint-to-multipoint MIMO relay system and a method of improving the sum rate of the multipoint-to-multipoint MIMO relay system. Particularly, the method aims to resolve the problems that in a multipoint-to-multipoint MIMO communication system, inter-symbol interference among different nodes (users) also exists except for background noise, and when a zero forcing or minimum mean-squared error relay precoder is adopted, sum rate performance of the system will be very poor under the condition of a low signal to noise ratio. Therefore, how to design an appropriate relay precoder is achieved, wherein the appropriate relay precoder is used for improving the sum rate of the multipoint-to-multipoint MIMO relay system under the condition of the low signal to noise ratio and also has the characteristics of simplicity and implementation easiness like the zero forcing precoder and others. The relay precoder designed in the method can greatly improve the sum rate of the multipoint-to-multipoint MIMO relay system under the condition of the low signal to noise ratio, achieves lower complexity, and has higher practical value.

Description

A kind of new method that improves multi-multipoint MIMO relay system and speed

Technical field

The present invention relates to wireless communication field, be specifically related to multi-multipoint MIMO relay system and improve it and the method for speed.

Background technology

Wireless relaying technique take collaboration communication (cooperative communication) as representative is the effective ways of antagonism channel path loss and shadow fading, is one of study hotspot of present wireless communication field.MIMO technology (multiple-input multiple-output) is the key technology of high-speed radiocommunication system of future generation (B3G/4G), configure many antennas and design suitable relaying strategy on relaying, can realize effective combination of MIMO technology and relaying technique.In multi-multipoint communication system, and speed is to weigh an important indicator of systematic function.To improve multi-multipoint MIMO relay system and effective way speed and suitable relaying precoder (precoder) is set.Consider the complexity that system realizes, tend in actual applications adopt the relaying precoder of low complex degree, ZF (zero forcing) precoder for example, least mean-square error (minimum mean-squared error) precoder etc.But in multi-multipoint communication system, except background noise, also there is the symbol-interference between different nodes (user), when adopting above-mentioned relaying precoder, system can be very poor under the condition of low signal-to-noise ratio with rate capability, therefore must take measures the performance of improvement system under the condition of low signal-to-noise ratio.

Summary of the invention

For improve multi-multipoint MIMO relay system under Low SNR and speed, have simultaneously the characteristics that are simple and easy to realize of the precoders such as ZF, the present invention proposes a kind of method for designing of new relaying precoder.

The present invention is applicable to high-speed radiocommunication system of future generation (B3G/4G).Its system model as shown in Figure 1.System comprises K to information source-information destination node pair, and each information source and the stay of two nights are furnished with single antenna; And via node of being furnished with N root antenna.Between information source and the stay of two nights due to apart from too far away and do not have a direct link.K information source is shown complex vector h to the channel table of relaying _k∈ C ^{N * 1}, the channel table that is relayed to k the stay of two nights is shown complex vector g _k∈ C ^{N * 1}The noise of relay is additive white Gaussian noise n _r∈ C ^{N * 1}, its average is that zero covariance is

K (k=1,2 ..., K) noise of individual stay of two nights end is similarly additive white Gaussian noise n _k, its average is that zero variance is

The relaying strategy is amplification forwarding, and message transmitting procedure is divided into two time slots.First time slot, K information source is simultaneously to the repeat transmitted signal, and the emission symbolic representation of k information source is s _k, emitted energy is E{|s _k| ²}=p _kRelay reception to signal phasor be expressed as y ∈ C ^{N * 1}The relaying precoder W ∈ C that designs ^{N * N}With receive signal y and multiply each other, then launch to K the stay of two nights when second time slot, and to make emitted energy be E{||Wy|| ²}=P _r

Detailed design algorithmic procedure of the present invention is as described below:

(1) be calculated as follows parameter matrix: $C=[{\mathrm{\Σ}}_k{p}_k{\left(h_j{h}_j^H\right)}^T+{\mathrm{\σ}}_r^2{I}_N]\⊗I_N;$

$U_k=C^{-\frac{1}{2}}[p_k{\left(h_k{h}_k^H\right)}^T\⊗\left(g_k{g}_k^H\right)]C^{-\frac{1}{2}};$

$V_k=C^{-\frac{1}{2}}\left\{\right[{\mathrm{\&Sigma;}}_{j\&NotEqual;k}{p}_j{\left(h_j{h}_j^H\right)}^T+{\mathrm{\&sigma;}}_r^2{I}_N]\&CircleTimes;\left(g_k{g}_k^H\right)\}{C}^{-\frac{1}{2}}+\frac{{\mathrm{\&sigma;}}_d^2}{P_{\mathrm{<figure-callout\; id="2"\; label="r\; I\; N"\; filenames="HSA00000715215800012.png,HSA00000715215800021.png"\; state="\{\{state\}\}">r</figure-callout>}}}{I}_{N^{}}{{}^2}_{}.$ K=1 wherein, 2 ..., K; Oeprator

Expression Kronecker product (Kronecker product).

(2) compute matrix And normalized main characteristic vector w.

(3) designed relaying precoder is Unvec wherein _{M, n}(a) expression changes into m * n matrix to the vectorial a of mn element by the preferential order of row.

That machine simulation results show as calculated, the relaying precoder of the present invention's design can increase substantially multi-multipoint MIMO relay system under Low SNR and speed.Designed relaying precoder W has the expression formula of sealing, and its computation complexity is O (KN ⁶), therefore implementation complexity of the present invention is lower, has higher practical value.

Description of drawings

Fig. 1 is system block diagram used in the present invention.

In following each figure, the transmitting power of information source is defined as The transmitting power of relaying is defined as ${\mathrm{<figure-callout\; id="2"\; label="SNR"\; filenames="HSA00000715215800012.png,HSA00000715215800021.png"\; state="\{\{state\}\}">SNR</figure-callout>}}_2=P_r/\left({\mathrm{N\&sigma;}}_d^2\right).$ System be configured to K=N=4.

The transmitting power SNR of Fig. 2 information source ₁=-10dB, relaying precoder of the present invention and other the traditional comparison diagram of relaying precoder on system and rate capability.

The transmitting power SNR of Fig. 3 information source ₁=-5dB, relaying precoder of the present invention and other the traditional comparison diagram of relaying precoder on system and rate capability.

The transmitting power SNR of Fig. 4 information source ₁=0dB, relaying precoder of the present invention and other the traditional comparison diagram of relaying precoder on system and rate capability.

The transmitting power SNR of Fig. 5 information source ₁=5dB, relaying precoder of the present invention and other the traditional comparison diagram of relaying precoder on system and rate capability.

Fig. 6 is the basic flow sheet of emulation experiment of the present invention.

Embodiment

The basic procedure of emulation experiment of the present invention is with reference to Fig. 6, and concrete step is: (1) arrange system parameters: N, K,

P _r, p _k(2) produce Rayleigh channel: h _k∈ C ^{N * 1}And g _k∈ C ^{N * 1}(3) compute matrix parameter: $C=[{\mathrm{\&Sigma;}}_k{p}_k{\left(h_j{h}_j^H\right)}^T+{\mathrm{\&sigma;}}_r^2{I}_N]\&CircleTimes;I_N$ With $U_k=C^{-\frac{1}{2}}[p_k{\left(h_k{h}_k^H\right)}^T\&CircleTimes;\left(g_k{g}_k^H\right)]C^{-\frac{1}{2}}$ And $V_k=C^{-\frac{1}{2}}\left\{\right[{\mathrm{\&Sigma;}}_{j\&NotEqual;k}{p}_j{\left(h_j{h}_j^H\right)}^T+{\mathrm{\&sigma;}}_r^2{I}_N]\&CircleTimes;\left(g_k{g}_k^H\right)\}{C}^{-\frac{1}{2}}+\frac{{\mathrm{\&sigma;}}_d^2}{P_r}{I}_{{\mathrm{<figure-callout\; id="2"\; label="N"\; filenames="HSA00000715215800012.png,HSA00000715215800021.png"\; state="\{\{state\}\}">N</figure-callout>}}^2}.$ (4) compute matrix $T=\underset{k=1}{\overset{K}{\mathrm{\&Sigma;}}}{V}_k^{-1}{U}_k$ And normalized main characteristic vector w.(5) calculating the relaying precoder is

(6) calculating and speed: $R_{\mathrm{sum}}=\frac{1}{2}\underset{k=1}{\overset{k}{\mathrm{\&Sigma;}}}\log (1+{\mathrm{SINR}}_k),$ Wherein ${\mathrm{SINR}}_k=\frac{p_k{\left|g_k^H{\mathrm{Wh}}_k\right|}^2}{{\mathrm{\&Sigma;}}_{j\&NotEqual;k}{p}_j{\left|g_k^H{\mathrm{Wh}}_j\right|}^2+{\mathrm{\&sigma;}}_{\mathrm{<figure-callout\; id="2"\; label="r"\; filenames="HSA00000715215800012.png,HSA00000715215800021.png"\; state="\{\{state\}\}">r</figure-callout>}}^2{\left|\right|g_k^{H}W\left|\right|}^2+{\mathrm{\&sigma;}}_{\mathrm{<figure-callout\; id="2"\; label="d"\; filenames="HSA00000715215800012.png,HSA00000715215800021.png"\; state="\{\{state\}\}">d</figure-callout>}}^2}.$

Claims (1)

1. a new method that improves multi-multipoint MIMO relay system and speed, the steps include:

(1) be calculated as follows parameter matrix:

K=1 wherein, 2 ..., K; Oeprator Expression Kronecker product (Kroneckerproduct);

(2) compute matrix

And normalized main characteristic vector w;

(3) designed relaying precoder is

Unvec wherein _{M, n}(a) expression changes into m * n matrix to the vectorial a of mn element by the preferential order of row.

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