CN105490716A - Dual-hop relay communication system and method - Google Patents

Abstract

The invention discloses a dual-hop relay communication system and method. The dual-hop relay communication system comprises a transmission end, a relay end, a receiving end, a transmission end-relay end transmission channel, and a relay end-receiving end transmission channel, wherein the transmission end comprises a pre-coding matrix P<1> of the transmission end; the relay end comprises a pre-coding matrix P<2> of the relay end; the transmission end-relay end channel comprises a transmission matrix H<1>; and the relay end-receiving end channel comprises a transmission matrix H<2>. Singular value decomposition is performed on the transmission end-relay end transmission matrix H<1> and the relay end-receiving end transmission matrix H<2> respectively, and the pre-coding matrix P<1> of the transmission end and the pre-coding matrix P<2> of the relay end are obtained through the decomposed matrixes. Compared with a conventional technical scheme, the dual-hop relay communication system and method have the advantages that a pre-coder does not need to be generated through a plurality of times of iterative operation, and signal processing of the system becomes easier and quicker, so that signal transmission delay is reduced, and an expression of channel capacity which does not exist in an iterative algorithm can be deduced theoretically.

Description

A kind of relaying double jump communication system and communication means

Technical field

The present invention relates to multiple-input and multiple-output (Multiple-inputMultiple-output is called for short MIMO) relaying double jump (Dual-hoprelay) system in wireless communication transmissions and communication means.

Background technology

MIMO relaying technique significantly can must improve throughput and the transmission coverage rate of wireless communication system, at Long Term Evolution/Long Term Evolution-senior (LTE/LTE-A, LongTermEvolutionAdvanced) in system standard, MIMO relaying technique be a kind of can the technical scheme of remarkable elevator system performance.Relaying technique is mainly divided into amplification also transmission policy and decoding also transmission policy, and compared to the latter, amplification also transmission policy has less propagation delay time and more excellent energy efficiency.In the performance index of wireless system, channel capacity can portray a peak transfer rate when channel reliably transmits data.And when the transmitting terminal of relay system and relay all have accurately channel condition information time, they can carry out precoding processing to signal before transmitting, to reduce the channel relevancy impact of multipath channel in mimo system, thus mimo system is made to obtain more outstanding channel capacity.

At present, a kind of iterative algorithm designing precoder is suggested.In signals transmission, when transmitting terminal and relay obtain instant channel condition information, by the cycle calculations of this iterative algorithm, draw pre-coding matrix.When through-put power one timing, this pre-coding matrix can make the channel capacity of system obtain optimal value.But there is following shortcoming in above-mentioned method for designing:

1., because optimum pre-coding matrix is drawn by iterative algorithm, namely cannot go out instant precoder model with the formal description of analytic solutions, therefore cannot draw the analytic solutions of channel capacity.

2. in order to obtain the system channel capacity using this iterative algorithm, must by a large amount of Computer Simulations (i.e. MonteCarlo method).But when system scale is larger, this simulation process consumes resources is more.

3. in signals transmission, wireless multi-path channels can change in real time, and due to the introducing of iterative algorithm, the acquisition of pre-coding matrix needs the time to calculate.When system scale is larger, this time can not ignore, and therefore this method for designing can increase the propagation delay time of signal undoubtedly and reduce the performance of system.

Therefore, wish that a kind of technical scheme of more simple and effective precoder overcomes or at least alleviates the defect of said method, and still can reach outstanding system performance index.

Summary of the invention

Technical problem to be solved by this invention is the deficiency existed for above-mentioned prior art, and propose a kind of without the need to generating precoder through the interative computation of several times, make the signal transacting of system more simple and quick, thus reduce relaying double jump communication system and the communication means of signal transmission time delay.

For solving the problems of the technologies described above, technical scheme of the present invention is:

A kind of relaying double jump communication system, comprise transmitting terminal, relay, receiving terminal, the transmission channel of transmitting terminal-relay and the transmission channel of relay-receiving terminal, described transmitting terminal comprises the pre-coding matrix P of transmitting terminal ₁, described relay comprises the pre-coding matrix P of relay ₂, the channel of described transmitting terminal-relay comprises transmission matrix H ₁, the channel of described relay-receiving terminal comprises transmission matrix H ₂, the pre-coding matrix P of described transmitting terminal ₁with the pre-coding matrix P of relay ₂be respectively:

P ₁＝(1/k) ^1/2V ₁E _k

$P_2={\left(\frac{1}{{\mathrm{k\&sigma;}}_1^2}\right)}^{\frac{1}{2}}{V}_2{E}_k{(I+\frac{{\mathrm{\&alpha;}}_1{\mathrm{\&rho;}}_1}{{\mathrm{k\&sigma;}}_1^2}{\mathrm{\&Lambda;}}_1)}^{-1/2}{U}_1^H$

Wherein, 1≤k≤m, m=min{n _s, n _r, n _dbe expressed as the minimum value of transmitting terminal antenna number, relay antenna number and receiving terminal antenna number, α ₁represent the path attenuation of transmitting terminal-relay transmission path, ρ ₁represent the signal power of transmitting terminal, represent the variance of the noise in transmitting terminal-relay transmitting procedure, V ₁for the transmission matrix H to described transmitting terminal-relay ₁carry out the right singular vector matrix after singular value decomposition, U ₁for the transmission matrix H to described transmitting terminal-relay ₁carry out the left singular vector matrix after singular value decomposition, V ₂for the transmission matrix H to described relay-receiving terminal ₂carry out the right singular vector matrix after singular value decomposition, I represents a unit matrix, E _kfor Block matrix, Λ ₁for diagonal matrix;

$E_k=\left(\begin{array}{cc}{I}_k& 0\\ 0& 1\end{array}\right)$

${\mathrm{\&Lambda;}}_1={\mathrm{\&Sigma;}}_1{\mathrm{\&Sigma;}}_1^H$

Wherein, Σ ₁for the transmission matrix H to described transmitting terminal-relay ₁carry out the singular value matrix after singular value decomposition, I _krepresent that dimension is the unit matrix of k.

A kind of relaying double jump communication means, is characterized in that, comprise the steps:

Signal, after the precoding processing of transmitting terminal, is sent to repeater:

$r=\sqrt{{\mathrm{\&alpha;}}_1{\mathrm{\&rho;}}_1}{H}_1{P}_{1}x+n_1$

In equation, x represents the signal phasor of transmission, and r represents the signal phasor that repeater receives, n ₁represent the noise vector in transmitting terminal-relay transmitting procedure, α ₁represent the path attenuation of transmitting terminal-relay transmission path, ρ ₁represent the signal power of transmitting terminal, P ₁represent the pre-coding matrix of transmitting terminal, H ₁represent transmitting terminal-relay transmission matrix;

Signal at repeater after treatment, is sent to receiving terminal:

$y=\sqrt{{\mathrm{\&alpha;}}_2{\mathrm{\&rho;}}_2}{H}_2{P}_{2}r+n_2$

In equation, y represents the signal received by receiving terminal, n ₂represent the noise vector in relay-receiving terminal transmitting procedure, P ₂represent the pre-coding matrix of relay, α ₂represent the path attenuation of transmitting terminal-relay transmission path, ρ ₂represent the signal power of transmitting terminal, H ₂represent relay-receiving terminal transmission matrix.

In MIMO relaying double jump communication system, repeater and receiver are half-duplex state, in systems in practice, when transmitting terminal and receiving terminal standoff distance far away time, due to larger path loss, the signal directly arriving receiving terminal from transmitting terminal is negligible, and receiving terminal receives only the signal from repeater transmission.The transmitting procedure of signal can be divided into two steps:

1. signal is after the precoding processing of transmitting terminal, is sent to repeater: in equation, x represents the signal phasor of transmission, and r represents the signal phasor that repeater receives, n ₁represent that the noise vector in transmitting terminal-relay transmitting procedure (supposes n ₁element meet zero-mean and variance is gaussian Profile), α ₁represent the path attenuation of transmitting terminal-relay transmission path, ρ ₁represent the signal power of transmitting terminal, P ₁represent the pre-coding matrix of transmitting terminal, and H ₁represent transmitting terminal-relay transmission matrix.

2. signal is at repeater after treatment, is sent to receiving terminal:

in equation, y represents the signal received by receiving terminal, n ₂represent that the noise vector in transmitting terminal-relay transmitting procedure (supposes n ₂element meet zero-mean and variance is gaussian Profile), α ₂represent the path attenuation of transmitting terminal-relay transmission path, ρ ₂represent the signal power of transmitting terminal, P ₂represent the pre-coding matrix of transmitting terminal, and H ₂represent relay-receiving terminal transmission matrix.

Next, by H ₁and H ₂singular value decomposition, can obtain Σ ₁and Σ ₂be diagonal matrix and diagonal element is respectively matrix H ₁and matrix H ₂singular value, establish simultaneously ${\mathrm{\&Lambda;}}_1={\mathrm{\&Sigma;}}_1{\mathrm{\&Sigma;}}_1^H=diag\left\{{\mathrm{\&lambda;}}_{1j}\right\},{\mathrm{\&Lambda;}}_2={\mathrm{\&Sigma;}}_2{\mathrm{\&Sigma;}}_2^H=diag\left\{{\mathrm{\&lambda;}}_{2j}\right\},$ Λ in equation ₁and Λ ₂be diagonal matrix, and λ _1jand λ _2jbe respectively matrix H ₁and matrix H ₂characteristic value, j=1 ... m; U ₁and V ₁be respectively H ₁left unitary matrix and right unitary matrix, U ₂and V ₂be respectively H ₂left unitary matrix and right unitary matrix.

The pre-coding matrix P of transmitting terminal ₁with the pre-coding matrix P of relay ₂can be expressed as: P ₁=V ₁d ₁with d in equation ₁and D ₂be diagonal matrix.In existing iterative algorithm, D ₁and D ₂generation all need to draw through series of iterations loop computation,

And the P that the present invention provides ₁and P ₂be expressed as

P ₁＝(1/k) ^1/2V ₁E _k

$P_2={\left(\frac{1}{{\mathrm{k\&sigma;}}_1^2}\right)}^{\frac{1}{2}}{V}_2{E}_k{(I+\frac{{\mathrm{\&alpha;}}_1{\mathrm{\&rho;}}_1}{{\mathrm{k\&sigma;}}_1^2}{\mathrm{\&Lambda;}}_1)}^{-1/2}{U}_1^H$

1≤k in equation≤m, k is an adjustable numeric parameter, m=min{n _s, n _r, n _dbeing expressed as the minimum value of transmitting terminal antenna number, relay antenna number and receiving terminal antenna number, I represents a unit matrix, and

$E_k=\left(\begin{array}{cc}{I}_k& 0\\ 0& 1\end{array}\right)$

So far the pre-coding matrix P of transmitting terminal ₁with the pre-coding matrix P of relay ₂draw, during according to such scheme signal transmission, regulate the value of k according to network environment, signal can be made to be broken down into several independent parallel channels and transmit.

The advantage of the present invention compared with prior art is: the present invention is by the transmission matrix H to transmitting terminal-relay ₁with the transmission matrix H of relay-receiving terminal ₂carry out singular value decomposition respectively, then obtained the pre-coding matrix P of transmitting terminal by the matrix after decomposition ₁with the pre-coding matrix P of relay ₂.Generate precoder without the need to the interative computation through several times, make the signal transacting of system more simple and quick, thus reduce the time delay of signal transmission, also can derive theoretically draws the expression formula of the channel capacity that iterative algorithm does not possess.

Accompanying drawing explanation

The theory diagram of Fig. 1 communication system of the present invention;

Fig. 2 is the system transfer rate emulation schematic diagram of the present invention under different transmission power;

Fig. 3 is the present invention in order to the emulation schematic diagram of the system total power reaching nominal transmission speed and need.

Embodiment

Below in conjunction with specific embodiment, the present invention is elaborated:

In Simulation Test Environment, we simulate community, the actual cities multiple antennas relaying download channels model in LTE system, and the parameter supposed all meets LTE system protocol specification.If reflector-channel of repeater and repeater-receiver channels all meet Rayleigh fading model, the operable bandwidth of Signal transmissions is B=20MHz, and the minimum value of transmitting terminal antenna number, relay antenna number and receiving terminal antenna number is m=4, and the variance of noise is the fading channel of two channels is α ₁=α ₂=-90dB.

In MIMO relaying double jump communication system, repeater and receiver are half-duplex state, in systems in practice, when transmitting terminal and receiving terminal standoff distance far away time, due to larger path loss, the signal directly arriving receiving terminal from transmitting terminal is negligible, and receiving terminal receives only the signal from repeater transmission.The transmitting procedure of signal can be divided into two steps:

1. signal is after the precoding processing of transmitting terminal, is sent to repeater: in equation, x represents the signal phasor of transmission, and r represents the signal phasor that repeater receives, n ₁represent that the noise vector in transmitting terminal-relay transmitting procedure (supposes n ₁element meet zero-mean and variance is gaussian Profile), α ₁represent the path attenuation of transmitting terminal-relay transmission path, ρ ₁represent the signal power of transmitting terminal, P ₁represent the pre-coding matrix of transmitting terminal, and H ₁represent transmitting terminal-relay transmission matrix.

2. signal is at repeater after treatment, is sent to receiving terminal: in equation, y represents the signal received by receiving terminal, P ₂represent the pre-coding matrix of relay, the statement of other parameters is similar to a process, but all belongs to relay-receiving terminal transmitting procedure.

When signal is transferred to relay from transmitting terminal, except the data of required transmission, also can transmit a pilot signal, this pilot signal can be used for obtaining the instant channel state information of institute's transmission channel, so transmitting terminal can obtain the transmission matrix H comprising channel condition information of transmitting terminal-relay in such a system ₁, and relay can obtain the transmission matrix H comprising channel condition information of transmitting terminal-relay ₁, and the transmission matrix H comprising channel condition information of relay-receiving terminal ₂.

Next, by H ₁and H ₂singular value decomposition, can obtain Σ ₁and Σ ₂be diagonal matrix and diagonal element is respectively matrix H ₁and matrix H ₂singular value, establish simultaneously ${\mathrm{\&Lambda;}}_1={\mathrm{\&Sigma;}}_1{\mathrm{\&Sigma;}}_1^H=diag\left\{{\mathrm{\&lambda;}}_{1j}\right\},{\mathrm{\&Lambda;}}_2={\mathrm{\&Sigma;}}_2{\mathrm{\&Sigma;}}_2^H=diag\left\{{\mathrm{\&lambda;}}_{2j}\right\},$ Λ in equation ₁and Λ ₂be diagonal matrix, and λ _1jand λ (j=1..m) _{2j (j=1..m)}be respectively matrix H ₁and matrix H ₂characteristic value.U ₁and V ₁be respectively H ₁left unitary matrix and right unitary matrix, U ₂and V ₂be respectively H ₂left unitary matrix and right unitary matrix.

The pre-coding matrix P of transmitting terminal ₁with the pre-coding matrix P of relay ₂be expressed as:

P ₁＝(1/k) ^1/2V ₁E _k

$P_2={\left(\frac{1}{{\mathrm{k\&sigma;}}_1^2}\right)}^{\frac{1}{2}}{V}_2{E}_k{(I+\frac{{\mathrm{\&alpha;}}_1{\mathrm{\&rho;}}_1}{{\mathrm{k\&sigma;}}_1^2}{\mathrm{\&Lambda;}}_1)}^{-1/2}{U}_1^H$

1≤k in equation≤m and k is a tunable integers parameter, m=min{n _s, n _r, n _dbeing expressed as the minimum value of transmitting terminal antenna number, relay antenna number and receiving terminal antenna number, I represents a unit matrix, and

$E_k=\left(\begin{array}{cc}{I}_k& 0\\ 0& 1\end{array}\right)$

So far the pre-coding matrix P of transmitting terminal ₁with the pre-coding matrix P of relay ₂draw, during according to such scheme signal transmission, regulate the value of k according to network environment, signal can be made to be broken down into several independent parallel channels and transmit.

Simulated effect of the present invention is as follows:

First group of emulation, the power transmitted of transmitting terminal and relay has all been set up maximum, corresponding different transmitting powers, by regulating the value of k, the peak transfer rate that observing system can reach.Namely

$\underset{k}{\max }{R}^k({\mathrm{\&rho;}}_1,{\mathrm{\&rho;}}_2)s.t.{\mathrm{\&rho;}}_1\&le;\stackrel{\&OverBar;}{{\mathrm{\&rho;}}_1}{\mathrm{and\&rho;}}_2\&le;\stackrel{\&OverBar;}{{\mathrm{\&rho;}}_2}$

The increase of through-put power, will cause the increase of peak transfer rate, therefore suppose in simulations simulation result as shown in Figure 2, Fig. 2 hollow core round dot " iteration precoder " represents that using iterative algorithm draws the peak transfer rate that the system of precoder obtains, black circle " without precoder " represents the peak transfer rate that the system not applying precoder obtains, and what " this programme precoder " represented is the peak transfer rate that the system applying the precoder that the present invention proposes obtains.Can find out by observing, along with the increase of transmitting power, the peak transfer rate that system obtains also enlarges markedly, in the scheme that application is proposed by the invention, and the value also corresponding increase of required k.And the performance that the technical scheme of the systematic function that the scheme that the present invention proposes reaches and iterative algorithm reaches is about the same, but the solution of the present invention is more simple effectively.

Second group of emulation, supposes to meet the requirements of system transfer rate, the transmitting power summation required for observing system.Namely

$\underset{{\mathrm{\&rho;}}_1,{\mathrm{\&rho;}}_2}{\min }{\mathrm{\&rho;}}_1+{\mathrm{\&rho;}}_2\underset{k}{\max }{R}^k({\mathrm{\&rho;}}_1,{\mathrm{\&rho;}}_2)\&GreaterEqual;\stackrel{\&OverBar;}{R}$

The system transfer rate reached needed for supposing is can see in figure 3, the gross power required for technical scheme of the scheme that the present invention proposes and iterative algorithm is about the same, is all obviously better than the scheme without precoder.

Claims (2)

1. a relaying double jump communication system, comprise transmitting terminal, relay, receiving terminal, the transmission channel of transmitting terminal-relay and the transmission channel of relay-receiving terminal, described transmitting terminal comprises the pre-coding matrix P of transmitting terminal ₁, described relay comprises the pre-coding matrix P of relay ₂, the channel of described transmitting terminal-relay comprises transmission matrix H ₁, the channel of described relay-receiving terminal comprises transmission matrix H ₂, it is characterized in that: the pre-coding matrix P of described transmitting terminal ₁with the pre-coding matrix P of relay ₂be respectively:

P ₁＝(1/k) ^1/2V ₁E _k

$P_2={\left(\frac{1}{{\mathrm{k\&sigma;}}_1^2}\right)}^{\frac{1}{2}}{V}_2{E}_k{(I+\frac{{\mathrm{\&alpha;}}_1{\mathrm{\&rho;}}_1}{{\mathrm{k\&sigma;}}_1^2}{\mathrm{\&Lambda;}}_1)}^{-1/2}{U}_1^H$

Wherein, 1≤k≤m, m=min{n _s, n _r, n _dbe expressed as the minimum value of transmitting terminal antenna number, relay antenna number and receiving terminal antenna number, α ₁represent the path attenuation of transmitting terminal-relay transmission path, ρ ₁represent the signal power of transmitting terminal, represent the variance of the noise in transmitting terminal-relay transmitting procedure, V ₁for the transmission matrix H to described transmitting terminal-relay ₁carry out the right singular vector matrix after singular value decomposition, U ₁for the transmission matrix H to described transmitting terminal-relay ₁carry out the left singular vector matrix after singular value decomposition, V ₂for the transmission matrix H to described relay-receiving terminal ₂carry out the right singular vector matrix after singular value decomposition, I represents a unit matrix, E _kfor Block matrix, Λ ₁for diagonal matrix;

$E_k=\left(\begin{array}{cc}{I}_k& 0\\ 0& 1\end{array}\right)$

${\mathrm{\&Lambda;}}_1={\mathrm{\&Sigma;}}_1{\mathrm{\&Sigma;}}_1^H$

Wherein, Σ ₁for the transmission matrix H to described transmitting terminal-relay ₁carry out the singular value matrix after singular value decomposition, I _krepresent that dimension is the unit matrix of k.

2., based on a communication means for relaying double jump communication system according to claim 1, it is characterized in that, comprise the steps:

Signal, after the precoding processing of transmitting terminal, is sent to repeater:

$r=\sqrt{{\mathrm{\&alpha;}}_1{\mathrm{\&rho;}}_1}{H}_1{P}_{1}x+n_1$

In equation, x represents the signal phasor of transmission, and r represents the signal phasor that repeater receives, n ₁represent the noise vector in transmitting terminal-relay transmitting procedure, α ₁represent the path attenuation of transmitting terminal-relay transmission path, ρ ₁represent the signal power of transmitting terminal, P ₁represent the pre-coding matrix of transmitting terminal, H ₁represent the transmission matrix of transmitting terminal-relay;

Signal at repeater after treatment, is sent to receiving terminal:

$y=\sqrt{{\mathrm{\&alpha;}}_2{\mathrm{\&rho;}}_2}{H}_2{P}_{2}r+n_2$

In equation, y represents the signal received by receiving terminal, n ₂represent the noise vector in relay-receiving terminal transmitting procedure, P ₂represent the pre-coding matrix of relay, α ₂represent the path attenuation of transmitting terminal-relay transmission path, ρ ₂represent the signal power of transmitting terminal, H ₂represent the transmission matrix of relay-receiving terminal.