CN102938686A - Decode-and-forward cooperative communication method with high-order diversity - Google Patents

Abstract

The invention discloses a decode-and-forward cooperative communication method with high-order diversity. The method comprises the following steps: a source node rotates two original symbols so as to obtain two rotation symbol components, and the two rotation symbol components are sent in four stages; in a first stage, the source node sends a first rotation symbol component, and a relay node and a destination node receive the first rotation symbol component; in a second stage, the relay node sets a first cooperative status bit according to whether the correct demodulation can be carried out or not, and sends data to the destination node according to the first cooperative status bit; in a third stage, the source node a second rotation symbol component, and the relay node and the destination node receive the second rotation symbol component; and in a fourth stage, the relay node sets a second cooperative status bit according to whether the correct demodulation can be carried out or not, and sends data to the destination node according to the second cooperative status bit, and the destination node carries out maximum likelihood joint demodulation on the received data so as to recover information sent by the source node. The decode-and-forward cooperative communication method with the high-order diversity has the advantages of high transmission reliability and low bit error rate.

Description

Decoding forward collaboration communication means with high diversity order

Technical field

The invention belongs to wireless communication field, be specifically related to a kind of decoding forward collaboration communication means with high diversity order, be used for the collaboration communication of wireless network.

Background technology

The antenna that cooperative diversity technique can make a plurality of users in the wireless network share each other according to certain rule comes transmission information, obtain space diversity gain thereby form a virtual multiple-input and multiple-output mimo system, to improve the reliability of transmitting under the fading channel.Cooperative diversity technique has been broken through the restriction that traditional MIMO specification requirement network node is equipped many antennas, and the practical new thinking that provides of MIMO technological direction is provided.In traditional cooperation communication system, communication is divided into two stages: the phase I, source node sends information to via node and destination node; Second stage, via node is processed the information that receives, and the information after then will processing is transmitted to destination node.Different to the processing mode of information according to via node, collaboration protocols can be divided into amplification forwarding AF and DF is transmitted in decoding.In the AF agreement, via node is not deciphered to received signal, directly with its amplification and forwarding; And in the DF agreement, relaying will receive first signal interpretation, and then recompile and forwarding.

The modulation diversity technology is another kind of to the anti fading effective ways, and this technology can under the prerequisite that does not increase signal power and bandwidth, be extracted the intrinsic diversity of signal space.In order to obtain modulation diversity, can first symbol to be sent be rotated a certain angle, so that each component of postrotational symbol has carried whole raw information.Then each component of symbol is independently sending in the fading channel after will rotating.Destination node is by carrying out joint demodulation to the information that receives, can the picked up signal space in intrinsic modulation diversity gain.

Traditional cooperation communication system can obtain space diversity gain, compares with direct transmission system, and this cooperative system can improve the reliability of transmission to a certain extent.But traditional cooperation communication system does not consider to extract modulation diversity gain intrinsic in the signal space, so this system and underuse the diversity that contains in the wireless system, the reliability of transmission remains further to be improved.

Summary of the invention

The object of the invention is to for above-mentioned the deficiencies in the prior art, a kind of decoding forward collaboration communication means with high diversity order is proposed, can under the prerequisite that does not increase power and bandwidth, obtain simultaneously the gain of space diversity gain and modulation diversity, further improve the reliability of cooperation communication system transmission.

Realize that technical scheme of the present invention is: source node is rotated operation with symbol to be sent first before transmission information, then two components with postrotational symbol send respectively in the Frame of the separate decline of experience, the data aggregate demodulation of destination node by the source node that receives and via node are sent obtains the gain of space diversity gain and modulation diversity simultaneously.Concrete steps comprise as follows:

1) source node S is rotated operation with two original symbols, obtains two rotation sign component;

Two rotation sign component that 2) will obtain divide four-stage to send:

2a) in the phase I, source node S sends first rotation sign component in the first frame, and via node R and destination node D receive the data that source node S sends;

2b) in second stage, via node R separates the mediation cyclic redundancy check (CRC) successively to the first frame data that receive, if correctly demodulation of cyclic redundancy check (CRC) indication via node R, the status bits that then will cooperate puts 1; Otherwise the status bits that will cooperate sets to 0;

2c) via node R sends data according to the cooperation status bits to destination node D, if the cooperation status bits is 1, first frame data of via node R after with demodulation are modulated again, and the data after will modulating and cooperation status bits are sent to destination node D by data channel and signaling channel respectively; Otherwise via node R only sends the cooperation status bits to destination node D by signaling channel;

2d) in the phase III, source node S sends second rotation sign component in the second frame, and via node R and destination node D receive the data that source node S sends;

2e) in the quadravalence section, via node R separates the mediation cyclic redundancy check (CRC) successively to the second frame data that receive, if correctly demodulation of cyclic redundancy check (CRC) indication via node R, the status bits that then will cooperate puts 1; Otherwise the status bits that will cooperate sets to 0;

2f) via node R sends data according to the cooperation status bits to destination node D, if the cooperation status bits is 1, second frame data of via node R after with demodulation are modulated again, and the data after will modulating and cooperation status bits are sent to destination node D by data channel and signaling channel respectively; Otherwise via node R only sends the cooperation status bits to destination node D by signaling channel;

3) the destination node D data that will in four-stage, receive and the demodulator that is sent to self in the cooperation status bits that second stage and quadravalence section receive;

4) demodulator carries out the maximum likelihood joint demodulation to the data that send, and recovers the information that source node S sends

$[{\hat{x}}_1,{\hat{x}}_2]=\arg \underset{x_1,x_2}{\min }\{{|y_D^{\left(1\right)}-\sqrt{E_S}{h}_{\mathrm{SD},1}{x}_1|}^2+{|y_D^{\left(2\right)}-\sqrt{E_R}{h}_{\mathrm{RD},1}\left({\mathrm{\α}}_1{x}_1\right)|}^2+$

${|y_D^{\left(3\right)}-\sqrt{E_S}{h}_{\mathrm{SD},2}{x}_2|}^2+{|y_D^{\left(4\right)}-\sqrt{E_R}{h}_{\mathrm{RD},2}\left({\mathrm{\α}}_2{x}_2\right)|}^2{\}}^{\′}$

Wherein,

Represent respectively destination node D the first, two, three, the data that the quadravalence section receives, x ₁And x ₂Represent respectively first and second rotation sign component, E _SAnd E _RThe transmitted power that represents respectively source node S and via node R, h _{SD, 1}The channel fading coefficient corresponding with the first frame between expression source node S and the destination node D, h _{SD, 2}The channel fading coefficient corresponding with the second frame between expression source node S and the destination node D, h _{RD, 1}The channel fading coefficient corresponding with the first frame between expression via node R and the destination node D, h _{RD, 2}The channel fading coefficient corresponding with the second frame between expression via node R and the destination node D, α ₁Represent the cooperation status bits corresponding with the first frame, α ₂Represent the cooperation status bits corresponding with the second frame.

The present invention compared with prior art has the following advantages

The present invention introduces cooperation communication system with the modulation diversity technology, before sending, symbol adds rotary manipulation, compare with traditional cooperation communication system, can under the prerequisite that does not increase power and bandwidth, obtain simultaneously the gain of space diversity gain and modulation diversity, can further improve the reliability of transmission, and the bit error rate of decrease system.

Description of drawings

Fig. 1 is the system model figure that the present invention is suitable for;

Fig. 2 is workflow diagram of the present invention;

Fig. 3 is the schematic diagram of information transmit-receive among the present invention;

Fig. 4 is the performance of BER comparison diagram of the solution of the present invention and existing scheme.

Embodiment

With reference to the accompanying drawings and in conjunction with example the present invention is described further.

With reference to Fig. 1, the system model that the present invention adopts is by a source node S, and a via node R and a destination node D form.Suppose the separate flat Rayleigh fading of each internodal channel experience, and the channel fading coefficient remains unchanged in a frame, and fading coefficients corresponding to different pieces of information frame is separate.For representing conveniently channel fading coefficient corresponding with the k frame between node i and the node j to be designated as h _{Ij, k}, it obeys average is zero, variance is

Multiple Gaussian Profile, wherein, i ∈ S, R}, j ∈ R, D}, k ∈ 1,2 ....The reception noise of supposing each node is additive white Gaussian noise, and to obey average be zero, and variance is N ₀Multiple Gaussian Profile.

In this system, each node is all equipped single antenna and modulator-demodulator independently.Source node at first sends Frame to via node and destination node.Can via node adopts the DF mode, first with the data demodulates that receives, again the data communication device after the demodulation is crossed cyclic redundancy check (CRC), then according to correctly separating the adjustment frame data, the cooperation status bits is set.If correctly demodulation, then the data of via node after with demodulation are modulated again, and the data after will modulating and cooperation status bits are sent to destination node by data channel and signaling channel respectively; Otherwise via node only is sent to destination node by the signaling channel status bits that will cooperate.Destination node is recovered the information that source node sends by the data that receive are carried out joint demodulation.

With reference to Fig. 2, performing step of the present invention is as follows:

Step 1: source node S is modulated raw information, and the original symbol that obtains is rotated operation, obtains rotation sign component to be sent.

1a) source node S is carried out binary phase shift keying BPSK modulation with raw information, then gets two BPSK symbol s in the data after modulation ₁And s ₂Form a two-dimensional symensional symbol vector s=[s ₁s ₂] ^T, wherein, [] ^TRepresent matrix transpose operation;

1b) set 28.65 ° of anglec of rotation θ=0.5rad ≈, so that the bit error rate of destination node demodulation is minimum; According to this anglec of rotation θ, the unit's of obtaining spin matrix $\mathrm{\Θ}=\left(\begin{array}{cc}\cos \mathrm{\θ}& -\sin \mathrm{\θ}\\ \sin \mathrm{\θ}& \cos \mathrm{\θ}\end{array}\right);$

1c) the above-mentioned two-dimensional symensional symbol vector s spin matrix Θ of the unit of multiply by is rotated counterclockwise, obtains two rotation sign component x ₁And x ₂

Step 2: two rotation sign component that will obtain divide four-stage to send.

With reference to Fig. 3, being implemented as follows of this step:

2a) in the phase I, source node S is with first rotation sign component x ₁Send in the first frame, via node R and destination node D receive the data that source node S sends,

The data that via node R and destination node D receive can be expressed as respectively:

$y_R^{\left(1\right)}=\sqrt{E_S}{h}_{\mathrm{SR},1}{x}_1+n_R^{\left(1\right)},---\left(1\right)$

$y_D^{\left(1\right)}=\sqrt{E_S}{h}_{\mathrm{SR},1}{x}_1+n_D^{\left(1\right)},---\left(2\right)$

Wherein,

With

Represent respectively the data that node R and D received in the phase I,

With

Represent respectively the noise that node R and D received in the phase I, h _{SR, 1}The channel fading coefficient corresponding with the first frame between expression source node S and the via node R, h _{SD, 1}The channel fading coefficient corresponding with the first frame between expression source node S and the destination node D, E _SThe transmitted power of expression source node S;

2b) in second stage, via node R separates the mediation cyclic redundancy check (CRC) successively to the first frame data that receive, if correctly demodulation of cyclic redundancy check (CRC) indication via node R, the status bits that then will cooperate is put α ₁Put 1, i.e. α ₁=1; Otherwise, the status bits that will cooperate α ₁Set to 0, i.e. α ₁=0;

2c) via node R is according to cooperation status bits α ₁Send data to destination node D, if the cooperation status bits is 1, first frame data of via node R after with demodulation are modulated again, and the data after will modulate and the status bits that cooperates are sent to destination node D by data channel and signaling channel respectively; Otherwise via node R only sends the cooperation status bits to destination node D by signaling channel,

The data that destination node D receives can be expressed as:

$y_D^{\left(2\right)}=\sqrt{E_R}{h}_{\mathrm{RD},1}\left({\mathrm{\α}}_1{x}_1\right)+n_D^{\left(2\right)},---\left(3\right)$

Wherein,

The data that expression destination node D receives in second stage,

The noise that expression destination node D receives in second stage, h _{RD, 1}The channel fading coefficient corresponding with the first frame between expression via node R and the destination node D, E _RThe transmitted power of expression via node R;

2d) in the phase III, source node S is with second rotation sign component x ₂Send in the second frame, via node R and destination node D receive the data that source node S sends.

The data that via node R and destination node D receive are expressed as respectively:

$y_R^{\left(3\right)}=\sqrt{E_S}{h}_{\mathrm{SR},2}{x}_2+n_R^{\left(3\right)},---\left(4\right)$

$y_D^{\left(3\right)}=\sqrt{E_S}{h_{\mathrm{SD},2}{x}_2+n}_D^{\left(3\right)},---\left(5\right)$

Wherein, With

Represent respectively the data that node R and D received in the phase III,

With

Represent respectively the noise that node R and D received in the phase III, h _{SR, 2}The channel fading coefficient corresponding with the second frame between expression source node S and the via node R, h _SD2The channel fading coefficient corresponding with the second frame between expression source node S and the destination node D, E _SThe transmitted power of expression source node S;

2e) in the quadravalence section, via node R separates the mediation cyclic redundancy check (CRC) successively to the second frame data that receive, if correctly demodulation of cyclic redundancy check (CRC) indication via node R, the status bits that then will cooperate is put α ₂Put 1, i.e. α ₂=1; Otherwise, the status bits that will cooperate α ₂Set to 0, i.e. α ₂=0;

2f) via node R is according to cooperation status bits α ₂Send data to destination node D, if the cooperation status bits is 1, second frame data of via node R after with demodulation are modulated again, and the data after will modulate and the status bits that cooperates are sent to destination node D by data channel and signaling channel respectively; Otherwise via node R only sends the cooperation status bits to destination node D by signaling channel,

The data that destination node D receives are expressed as:

$y_D^{\left(4\right)}=\sqrt{E_R}{h}_{\mathrm{RD},2}\left({\mathrm{\α}}_2{x}_2\right)+n_D^{\left(4\right)},---\left(6\right)$

Wherein,

The data that expression destination node D receives in the quadravalence section,

The noise that expression destination node D receives in the quadravalence section, h _{RD, 2}The channel fading coefficient corresponding with the second frame between expression via node R and the destination node D, E _RThe transmitted power of expression via node R.

The data that step 3: destination node D will receive in four-stage and the demodulator that is sent to self in the cooperation status bits that second stage and quadravalence section receive.

Step 4: demodulator carries out the maximum likelihood joint demodulation to the data that send, and recovers the information that source node S sends

$[{\hat{x}}_1,{\hat{x}}_2]=\arg \underset{x_1,x_2}{\min }\{{|y_D^{\left(1\right)}-\sqrt{E_S}{h}_{\mathrm{SD},1}{x}_1|}^2+{|y_D^{\left(2\right)}-\sqrt{E_R}{h}_{\mathrm{RD},1}\left({\mathrm{\α}}_1{x}_1\right)|}^2+$ (7)

${|y_D^{\left(3\right)}-\sqrt{E_S}{h}_{\mathrm{SD},2}{x}_2|}^2+{|y_D^{\left(4\right)}-\sqrt{E_R}{h}_{\mathrm{RD},2}\left({\mathrm{\α}}_2{x}_2\right)|}^2{\}}^{\′}$

Wherein,

Represent respectively destination node D the first, two, three, the data that the quadravalence section receives, x ₁And x ₂Represent respectively first and second rotation sign component, E _SAnd E _RThe transmitted power that represents respectively source node S and via node R, h _{SD, 1}The channel fading coefficient corresponding with the first frame between expression source node S and the destination node D, h _{SD, 2}The channel fading coefficient corresponding with the second frame between expression source node S and the destination node D, h _{RD, 1}The channel fading coefficient corresponding with the first frame between expression via node R and the destination node D, h _{RD, 2}The channel fading coefficient corresponding with the second frame between expression via node R and the destination node D, α ₁Represent the cooperation status bits corresponding with the first frame, α ₂Represent the cooperation status bits corresponding with the second frame.

Effect of the present invention can further specify by following emulation:

1, simulation parameter is set:

Suppose the separate flat Rayleigh fading of each internodal channel experience.The average signal-to-noise ratio that defines each channel is:

Г wherein ₀=E _Tot/ N ₀Be the transmission signal to noise ratio of each symbol, E _Tot=E _S+ E _RFor the total transmitted power of each symbol, be without loss of generality, suppose that source node S and via node R divide total transmitted power, i.e. E equally _S=E _R=E _Tot2.Adopt the BPSK modulation, comprise the information of 80 bits in each frame.

2, simulation result:

The present invention and existing traditional collaboration method carry out the simulation comparison of bit error rate, and simulation result as shown in Figure 4.

As can be seen from Figure 4, the channel between S → R is unavailable, namely

The time, two systems all can not obtain space diversity gain.In this case, traditional collaboration method can only obtain a diversity order, and the present invention still can obtain the second order modulation diversity.Channel between S → R can be used, namely

The time, traditional collaboration method can obtain the second order space diversity, and the present invention can obtain space diversity and modulation diversity simultaneously, namely can obtain fourth-order order diversity.In addition, at Г ₀Under the condition of 20dB, the channel quality of the present invention between S → R is general, namely

The time, can meet and exceed the ideal cooperation of conventional method, namely Performance.

It should be noted that the present invention and traditional collaboration method have identical band efficiency.Therefore, compare with traditional collaboration method, the present invention can obtain the more diversity gain of high-order under the prerequisite that does not increase power and bandwidth, thereby has effectively improved the reliability of transmission and the bit error rate of decrease system.

Claims (3)

1. decoding forward collaboration communication means with high diversity order may further comprise the steps:

1) source node S is rotated operation with two original symbols, obtains two rotation sign component;

Two rotation sign component that 2) will obtain divide four-stage to send:

2a) in the phase I, source node S sends first rotation sign component in the first frame, and via node R and destination node D receive the data that source node S sends;

2b) in second stage, via node R separates the mediation cyclic redundancy check (CRC) successively to the first frame data that receive, if correctly demodulation of cyclic redundancy check (CRC) indication via node R, the status bits that then will cooperate puts 1; Otherwise the status bits that will cooperate sets to 0;

2c) via node R sends data according to the cooperation status bits to destination node D, if the cooperation status bits is 1, first frame data of via node R after with demodulation are modulated again, and the data after will modulating and cooperation status bits are sent to destination node D by data channel and signaling channel respectively; Otherwise via node R only sends the cooperation status bits to destination node D by signaling channel;

2d) in the phase III, source node S sends second rotation sign component in the second frame, and via node R and destination node D receive the data that source node S sends;

2e) in the quadravalence section, via node R separates the mediation cyclic redundancy check (CRC) successively to the second frame data that receive, if correctly demodulation of cyclic redundancy check (CRC) indication via node R, the status bits that then will cooperate puts 1; Otherwise the status bits that will cooperate sets to 0;

2f) via node R sends data according to the cooperation status bits to destination node D, if the cooperation status bits is 1, second frame data of via node R after with demodulation are modulated again, and the data after will modulating and cooperation status bits are sent to destination node D by data channel and signaling channel respectively; Otherwise via node R only sends the cooperation status bits to destination node D by signaling channel;

3) the destination node D data that will in four-stage, receive and the demodulator that is sent to self in the cooperation status bits that second stage and quadravalence section receive;

4) demodulator carries out the maximum likelihood joint demodulation to the data that send, and recovers the information that source node S sends

$[{\hat{x}}_1,{\hat{x}}_2]:$

$[{\hat{x}}_1,{\hat{x}}_2]=\arg \underset{x_1,x_2}{\min }\{{|y_D^{\left(1\right)}-\sqrt{E_S}{h}_{\mathrm{SD},1}{x}_1|}^2+{|y_D^{\left(2\right)}-\sqrt{E_R}{h}_{\mathrm{RD},1}\left({\mathrm{\α}}_1{x}_1\right)|}^2+$

${|y_D^{\left(3\right)}-\sqrt{E_S}{h}_{\mathrm{SD},2}{x}_2|}^2+{|y_D^{\left(4\right)}-\sqrt{E_R}{h}_{\mathrm{RD},2}\left({\mathrm{\α}}_2{x}_2\right)|}^2{\}}^{\′}$

Wherein,

Represent respectively destination node D the first, two, three, the data that the quadravalence section receives, x ₁And x ₂Represent respectively first and second rotation sign component, E _SAnd E _RThe transmitted power that represents respectively source node S and via node R, h _{SD, 1}The channel fading coefficient corresponding with the first frame between expression source node S and the destination node D, h _{SD, 2}The channel fading coefficient corresponding with the second frame between expression source node S and the destination node D, h _{RD, 1}The channel fading coefficient corresponding with the first frame between expression via node R and the destination node D, h _{RD, 2}The channel fading coefficient corresponding with the second frame between expression via node R and the destination node D, α ₁Represent the cooperation status bits corresponding with the first frame, α ₂Represent the cooperation status bits corresponding with the second frame.

2. the decoding forward collaboration communication means with high diversity order according to claim 1, wherein the described source node S of step 1) is rotated operation with original symbol, obtains two rotation sign component, carries out as follows:

2a) get two adjacent in initial data frame symbols, form a two-dimensional symensional symbol vector;

2b) set anglec of rotation θ, so that the bit error rate of destination node demodulation is minimum; According to this anglec of rotation θ,

The unit's of obtaining spin matrix $\mathrm{\Θ}=\left(\begin{array}{cc}\cos \mathrm{\θ}& -\sin \mathrm{\θ}\\ \sin \mathrm{\θ}& \cos \mathrm{\θ}\end{array}\right);$

2c) the above-mentioned two-dimensional symensional symbol vector spin matrix Θ of the unit of multiply by is rotated counterclockwise, obtains two rotation sign component.

3. the decoding forward collaboration communication means with high diversity order according to claim 1, step 2c wherein) and 2f) data of described via node R after with demodulation are modulated again, refer to that via node R adopts the data after the modulation system identical with source node S modulated own demodulation again.

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