CN102957512A - Code word selecting method on basis of two-jump distributed precoding limited feedback - Google Patents

Abstract

The invention relates to a code word selecting method on the basis of two-jump distributed precoding limited feedback. The integral transmission process is completed in two jumps. In the first jump, firstly, a relay estimates channel response from each antenna to the relay on each subcarrier; secondly, after being processed, a transmitting end signal is sent to the relay by a transmitting end precoding matrix, the relay obtains a transmitting end CSI (Customer Satisfaction Index), carrying out SVD (Singular Value Decomposition) on a channel matrix, using direction information of a right singular vector as a feedback quantity and quantizing the feedback quantity by utilizing a RVQ (Random Vector Quantization) code generated below the line; and finally, using a code word vector with the smallest included angle with the feedback quantity and the maximum inner product as a quantization quantity by utilizing a minimum distance criterion, converting a number of the selected code word vector into a binary code and feeding back the binary code to a transmitting end. The transmitting end regulates a sending strategy according to the code word vector which is fed back so as to adapt to the channel state. According to the invention, the code word selecting time can be obviously reduced; the complexity of code word selection and computing is reduced; and the sum rate performance of a system is also obviously improved.

Description

A kind of codeword selection method based on double bounce distributed precoding Limited Feedback

[technical field]

The invention belongs to wireless communication field, be specifically related to a kind of codeword selection method based on double bounce distributed precoding Limited Feedback.

[background technology]

Collaboration communication refers to, in the multi-user communication environment, share transmissions that cooperate of each other antenna according to certain way between each neighbor node, thereby produce a kind of virtual environment of similar many antennas transmissions, obtain space diversity gain, improve the communication mode of the transmission performance of system.

Introduce the relay station that communicates in cooperative communication network, relay station can be used as the signal forward node of a special use, can accept simultaneously the control signal of base station and the feedback information of travelling carriage.Than common portable terminal, have the characteristics of the high power consumption of standing, to compare with the base station, complexity and cost are far below the base station.

The MIMO relay transmission mainly has following characteristics: 1) Effective Raise power system capacity.By the planning network structure, can be between a plurality of relayings the reasonable distribution resource; 2) promote cell-edge performance, Extended Cell area coverage.Owing to having introduced relaying, can reduce user's transmitting power, greatly degree reduces cochannel interference between neighbor cell, and simultaneously, the middle rotating function of relaying can also be eliminated the blind area that Cellular Networks covers; 3) improve spectrum efficiency.By the employing emission diversity gain, array gain, the spatial reuse gain, the technology such as co-channel interferences suppression can effectively promote spectrum efficiency, improve the system transmissions performance.

The performance of MIMO relay system depends on receiving terminal and the known complete channel condition information of transmitting terminal (CSI), yet under the random fading environment, the time variation of wireless channel causes the acquisition of channel information very difficult.Can directly obtain accurately channel information by pilot tone at receiving terminal, the method that then needs to depend on feedback at transmitting terminal obtains CSI indirectly.If terminal feeds back to transmitting terminal fully with CSI, need great feedback overhead, introduce thus the Limited Feedback technology.Through what quantize, vulgar feedback information is informed the forward link information that transmitting terminal is relevant by rl transmission in system, and transmitting terminal is adjusted sending strategy according to the feedback information that receives, to adapt to forward link.

The at present research of Limited Feedback technology mainly concentrates on the MIMO relay system precoding technique based on code book.At first utilize certain criterion off-line to generate code book, code book is known to receiving terminal and the transmitting terminal simultaneously.Receiving terminal obtains complete CSI according to the pilot frequency information that receives, and chooses optimum code word in default code book, and the sequence number of code word is fed back to transmitting terminal with binary form.The sequence number of transmitting terminal by being received by feedback channel rebuild pre-coding matrix or precoding vector according to default code word.Therefore, the design of code book affects the performance based on the MIMO pre-coding system of code book to a great extent.The design of code book comprises that random vector quantizes (RVQ), Grassmann stream shape etc. at present.With respect to other code books, the RVQ code book is more flexible on using, and more easily analyze on mathematics, and when code book size and number of transmit antennas were larger, its performance and optimum code book is very approaching.

In the MIMO relay system, comparatively common codeword selection scheme comprises centralized codeword selection and distributed codeword selection scheme, in the centralized codeword selection scheme, the selection of code word is generally carried out according to the criterion of system and speed maximization or BER best performance, code word choose the channel matrix that depends on double bounce, computation complexity is very high; In the distributed codeword selection scheme, the suppose relay end is the defeated channel of known the first jump set only, receiving terminal is the defeated channel of known the second jump set only, and the code word of double bounce is chosen according to channel condition information separately, and computation complexity is compared centralized codeword selection obvious improvement.

But still exist the higher problem of codeword selection complexity in the existing distributed codeword selection, how to utilize lower computation complexity to select the most suitable code book, can reduce the time delay of feedback, have very important realistic meaning.

[summary of the invention]

Technical problem to be solved by this invention is to provide a kind of codeword selection method based on double bounce distributed precoding Limited Feedback, can effectively reduce the codebook selecting complexity, and can improvement system and speed.

The present invention solves the problems of the technologies described above by the following technical solutions:

A kind of codeword selection method based on double bounce distributed precoding Limited Feedback comprises the steps:

Step 1: transmitting terminal is to the relay pilot signal transmitted, and channel estimating is carried out to pilot signal in the relay, obtains the first channel matrix H of jumping ₁

Step 2: to the described first channel matrix H of jumping ₁Carry out SVD and decompose, have

U wherein ₁Left singular matrix, D ₁Diagonal matrix,

It is right singular matrix; First global optimum's precoding vector of jumping is

Wherein

Be expressed as corresponding to H ₁The matrix that the characteristic vector of a front K eigenvalue of maximum forms, when K=1,

Be expressed as corresponding to eigenvalue of maximum characteristic of correspondence vector;

Step 3: select

Directional information as feedback quantity,

Directional information be

Utilize random vector to quantize RVQ code book pair

Quantize, adopt minimum distance criterion to carry out codeword selection, choose with

Angle minimum, the codeword vector of inner product maximum, the codeword selection criterion is

$f_1=\underset{f_i\∈F_1}{\arg \max }\left|{\tilde{V}}_1^T{f}_i^{*}\right|$

F wherein _iBe CDI code book F ₁In code word, F ₁Preset code book for generating under the line, and simultaneously known by relay and transmitting terminal;

Convert the numbering of selected codeword vector to binary code, feed back to transmitting terminal, transmitting terminal designs transmitting terminal pre-coding matrix W according to the code word that feeds back to ₁

Step 4: transmitting terminal adopts even power distribution strategies to relaying transmitting terminal signal, and transmitting power is P ₁

Step 5: relay receiving end/sending end information, this moment, the reception signal of relay was

$y_r=\sqrt{\frac{P_1}{K}}{H}_1{W}_{1}s+n_1$

Wherein,

Channel matrix when expression first is jumped, s are transmitted signal stream, W ₁Be transmitting terminal pre-coding matrix, n ₁Be the relay noise, being expressed as average is 0, and variance is

White Gaussian noise;

Step 6: the relay is to the receiving terminal pilot signal transmitted, and receiving terminal carries out channel estimating to pilot signal, obtains the second channel matrix H that jumps ₂

Step 7: to the second channel matrix H that jumps ₂Carry out SVD and decompose, have U wherein ₂Left singular matrix, D ₂Diagonal matrix,

It is right singular matrix; Second global optimum's precoding vector of jumping is

Wherein

For corresponding to H ₂The matrix that the characteristic vector of a front K eigenvalue of maximum forms, during K=1,

Be expressed as corresponding to eigenvalue of maximum characteristic of correspondence vector, ρ is relaying Power Limitation coefficient;

Step 8: select

Directional information as feedback quantity,

Directional information be

Utilize RVQ code book pair

Quantize, adopt minimum distance criterion to carry out codeword selection, choose with

Angle minimum, the codeword vector of inner product maximum, the codeword selection criterion is

${\mathrm{<figure-callout\; id="2"\; label="f"\; filenames="HDA00002401299400031.png,HDA00002401299400041.png"\; state="\{\{state\}\}">f</figure-callout>}}_2=\underset{f_j\&Element;{\mathrm{<figure-callout\; id="2"\; label="F"\; filenames="HDA00002401299400031.png,HDA00002401299400041.png"\; state="\{\{state\}\}">F</figure-callout>}}_2}{\arg \max }\left|{\tilde{V}}_2^T{f}_j^{*}\right|$

F wherein _jBe CDI code book F ₂In code word, F ₂Be default code book, and simultaneously known by relay and transmitting terminal;

Convert the numbering of selected codeword vector to binary code, feed back to the relay, relay pre-coding matrix W is designed according to the code word that feeds back in the relay ₂

Step 9: the relay is the amplification forwarding relaying, and the relay receives after the transmission information, through relay pre-coding matrix W ₂After send to receiving terminal, this moment receiving terminal the reception signal be

$y_u=\sqrt{\frac{P_1}{K}}{H}_2{W}_2{H}_1{W}_{1}s+H_2{W}_2{n}_1+{\mathrm{<figure-callout\; id="2"\; label="n"\; filenames="HDA00002401299400031.png,HDA00002401299400041.png"\; state="\{\{state\}\}">n</figure-callout>}}_2$

Wherein

The channel matrix that expression second is jumped, n ₂Be the receiving terminal noise, being expressed as average is 0, and variance is

White Gaussian noise.

Further, in the described step 4, the concrete process of transmitting of transmitting terminal is: data symbol at first becomes multiplex data stream through serial to parallel conversion, to realize the output of many antennas, then passes through transmitting terminal pre-coding matrix W ₁Afterwards, signal is sent.

The invention has the advantages that: the present invention proposes a kind of new double bounce relaying distributed precoding codeword selection method.Whole transmission course is finished in double bounce.During the first jumping, at first relaying estimates that at each subcarrier each antenna is to the channel response of relaying; Secondly, the transmitting terminal signal sends to relaying through after processing by the transmitting terminal pre-coding matrix, relaying obtains transmitting terminal CSI, channel matrix is carried out SVD decompose, select the directional information of right singular vector as feedback quantity, utilize the RVQ code book that generates under the line that it is quantized; At last, utilize minimum distance criterion to select with the feedback quantity angle minimum, the codeword vector of inner product maximum is as the quantification amount, and converts the codeword vector numbering of choosing to binary code, feeds back to transmitting terminal.Transmitting terminal is adjusted sending strategy, with the adaptive channel situation according to the codeword vector that feeds back to.The present invention compares with the distributed codeword selection scheme of existing double jump, has proposed a kind of new code word Quantitatively Selecting scheme, works as N _s=4, N _r=4, N _u=2, during K=1, each codeword selection of the present invention approximately needs 200 floating-point operations, code word of the every selection of prior art scheme then needs about 400 floating-point operations, when code word size is larger, can significantly reduce the time of codeword selection, reduce the complexity that codeword selection calculates, simultaneously there has been obvious improvement in system with rate capability.

[description of drawings]

The invention will be further described in conjunction with the embodiments with reference to the accompanying drawings.

Fig. 1 is communication system architecture figure of the present invention.

Fig. 2 is method flow schematic diagram of the present invention.

Fig. 3 is among the present invention in the situation that the relay signal to noise ratio is certain, the simulation curve that system and rate capability change with the receiving terminal signal to noise ratio;

Fig. 4 is among the present invention in the situation that the relay signal to noise ratio is certain, the simulation curve that the BER performance of system changes along with the receiving terminal signal to noise ratio.

[embodiment]

As shown in Figure 1, the structure of communication system of the present invention comprises a transmitting terminal, antenna one-way junction end more than and a receiving terminal.Transmitting terminal, relay and receiving terminal number of antennas are respectively N _s, N _r, N _u, transmit simultaneously K=1 data flow.This relay is half-duplex amplification forwarding relaying.

Embodiments of the invention disclose a kind of double bounce relaying distributed precoding codeword selection method, and a complete communication process is finished in double bounce.Jump first, transmitting terminal passes through the transmitting terminal pre-coding matrix to retransmit; Second jumps, and relaying passes through the relay pre-coding matrix to the receiver transmission information.As shown in Figure 2, the concrete steps of the method are as follows:

Step 1: transmitting terminal is to the relay pilot signal transmitted, and channel estimating is carried out to pilot signal in the relay, obtains the first channel matrix H of jumping ₁

Step 2: to the described first channel matrix H of jumping ₁Carry out SVD and decompose, have

U wherein ₁Left singular matrix, D ₁Diagonal matrix,

It is right singular matrix; First global optimum's precoding vector of jumping is

Wherein

Be expressed as corresponding to H ₁The matrix that the characteristic vector of a front K eigenvalue of maximum forms, when K=1,

Be expressed as corresponding to eigenvalue of maximum characteristic of correspondence vector;

Step 3: select

Directional information as feedback quantity, Directional information be

Utilize random vector to quantize RVQ code book pair

Quantize, adopt minimum distance criterion to carry out codeword selection, choose with

Angle minimum, the codeword vector of inner product maximum, the codeword selection criterion is

$f_1=\underset{f_i\&Element;F_1}{\arg \max }\left|{\tilde{V}}_1^T{f}_i^{*}\right|$

F wherein _iBe CDI code book F ₁In code word, F ₁Preset code book for generating under the line, and simultaneously known by relay and transmitting terminal;

Convert the numbering of selected codeword vector to binary code, feed back to transmitting terminal, transmitting terminal designs transmitting terminal pre-coding matrix W according to the code word that feeds back to ₁

Step 4: transmitting terminal adopts even power distribution strategies to relaying transmitting terminal signal, and transmitting power is P ₁The concrete process of transmitting of transmitting terminal is: data symbol at first becomes multiplex data stream through serial to parallel conversion, to realize the output of many antennas, then passes through transmitting terminal pre-coding matrix W ₁Afterwards, signal is sent;

Step 5: relay receiving end/sending end information, this moment, the reception signal of relay was

$y_r=\sqrt{\frac{P_1}{K}}{H}_1{W}_{1}s+n_1$

Wherein,

Channel matrix when expression first is jumped, s are transmitted signal stream, W ₁Be transmitting terminal pre-coding matrix, n ₁Be the relay noise, being expressed as average is 0, and variance is

White Gaussian noise;

Step 6: the relay is to the receiving terminal pilot signal transmitted, and receiving terminal carries out channel estimating to pilot signal, obtains the second channel matrix H that jumps ₂

Step 7: to the second channel matrix H that jumps ₂Carry out SVD and decompose, have

U wherein ₂Left singular matrix, D ₂Diagonal matrix, It is right singular matrix; Second global optimum's precoding vector of jumping is

Wherein

For corresponding to H ₂The matrix that the characteristic vector of a front K eigenvalue of maximum forms, during K=1,

Be expressed as corresponding to eigenvalue of maximum characteristic of correspondence vector, ρ is relaying Power Limitation coefficient;

Step 8: select

Directional information as feedback quantity,

Directional information be Utilize RVQ code book pair

Quantize, adopt minimum distance criterion to carry out codeword selection, choose with

Angle minimum, the codeword vector of inner product maximum, the codeword selection criterion is

${\mathrm{<figure-callout\; id="2"\; label="f"\; filenames="HDA00002401299400031.png,HDA00002401299400041.png"\; state="\{\{state\}\}">f</figure-callout>}}_2=\underset{f_j\&Element;{\mathrm{<figure-callout\; id="2"\; label="F"\; filenames="HDA00002401299400031.png,HDA00002401299400041.png"\; state="\{\{state\}\}">F</figure-callout>}}_2}{\arg \max }\left|{\tilde{V}}_2^T{f}_j^{*}\right|$

F wherein _jBe CDI code book F ₂In code word, F ₂Be default code book, and simultaneously known by relay and transmitting terminal;

Convert the numbering of selected codeword vector to binary code, feed back to the relay, relay pre-coding matrix W is designed according to the code word that feeds back in the relay ₂

Step 9: the relay is the amplification forwarding relaying, and the relay receives after the transmission information, through relay pre-coding matrix W ₂After send to receiving terminal, this moment receiving terminal the reception signal be

$y_u=\sqrt{\frac{P_1}{K}}{H}_2{W}_2{H}_1{W}_{1}s+H_2{W}_2{n}_1+{\mathrm{<figure-callout\; id="2"\; label="n"\; filenames="HDA00002401299400031.png,HDA00002401299400041.png"\; state="\{\{state\}\}">n</figure-callout>}}_2$

Wherein

The channel matrix that expression second is jumped, n ₂Be the receiving terminal noise, being expressed as average is 0, and variance is

White Gaussian noise.

Fig. 3 has provided in the relaying signal to noise ratio fixedly the time, system with rate capability and BER performance at the simulation curve of receiving terminal signal to noise ratio in 0～20dB scope.By simulation result as seen, of the present invention among Fig. 3 and rate capability is better than existing double jump distributed precoding selection scheme.Work as N _s=4, N _r=4, N _uDuring=2, K=1, each codeword selection of the present invention approximately needs 200 floating-point operations, and code word of the every selection of prior art then needs about 400 floating-point operations, and computation complexity of the present invention reduces far away by contrast, reduces the time delay of feedback; BER performance of the present invention and existing scheme maintain an equal level among Fig. 4, work as N _s=2, N _r=2, N _uDuring=1, K=1, each codeword selection of the present invention probably needs 50 floating-point operations, and existing each codeword selection of scheme probably needs 100 floating-point operations, and computation complexity of the present invention reduces feedback delay far below existing scheme.

Claims (2)

1. the codeword selection method based on double bounce distributed precoding Limited Feedback is characterized in that: comprise the steps:

Step 1: transmitting terminal is to the relay pilot signal transmitted, and channel estimating is carried out to pilot signal in the relay, obtains the first channel matrix H of jumping ₁

Step 2: to the described first channel matrix H of jumping ₁Carry out SVD and decompose, have

U wherein ₁Left singular matrix, D ₁Diagonal matrix,

It is right singular matrix; First global optimum's precoding vector of jumping is

Wherein

Be expressed as corresponding to H ₁The matrix that the characteristic vector of a front K eigenvalue of maximum forms, when K=1,

Be expressed as corresponding to eigenvalue of maximum characteristic of correspondence vector;

Step 3: select

Directional information as feedback quantity, Directional information be

Utilize random vector to quantize RVQ code book pair

Quantize, adopt minimum distance criterion to carry out codeword selection, choose with

Angle minimum, the codeword vector of inner product maximum, the codeword selection criterion is

$f_1=\underset{f_i\&Element;F_1}{\arg \max }\left|{\tilde{V}}_1^T{f}_i^{*}\right|$

F wherein _iBe CDI code book F ₁In code word, F ₁Preset code book for generating under the line, and simultaneously known by relay and transmitting terminal;

Convert the numbering of selected codeword vector to binary code, feed back to transmitting terminal, transmitting terminal designs transmitting terminal pre-coding matrix W according to the code word that feeds back to ₁

Step 4: transmitting terminal adopts even power distribution strategies to relaying transmitting terminal signal, and transmitting power is P ₁

Step 5: relay receiving end/sending end information, this moment, the reception signal of relay was

$y_r=\sqrt{\frac{P_1}{K}}{H}_1{W}_{1}s+n_1$

Wherein,

Channel matrix when expression first is jumped, s are transmitted signal stream, W ₁Be transmitting terminal pre-coding matrix, n ₁Be the relay noise, being expressed as average is 0, and variance is

White Gaussian noise;

Step 6: the relay is to the receiving terminal pilot signal transmitted, and receiving terminal carries out channel estimating to pilot signal, obtains the second channel matrix H that jumps ₂

Step 7: to the second channel matrix H that jumps ₂Carry out SVD and decompose, have U wherein ₂Left singular matrix, D ₂Diagonal matrix,

It is right singular matrix; Second global optimum's precoding vector of jumping is

Wherein

For corresponding to H ₂The matrix that the characteristic vector of a front K eigenvalue of maximum forms, during K=1,

Be expressed as corresponding to eigenvalue of maximum characteristic of correspondence vector, ρ is relaying Power Limitation coefficient;

Step 8: select

Directional information as feedback quantity, Directional information be

Utilize RVQ code book pair Quantize, adopt minimum distance criterion to carry out codeword selection, choose with

Angle minimum, the codeword vector of inner product maximum, the codeword selection criterion is

$f_2=\underset{f_j\&Element;F_2}{\arg \max }\left|{\tilde{V}}_2^T{f}_j^{*}\right|$

F wherein _jBe CDI code book F ₂In code word, F ₂Be default code book, and simultaneously known by relay and transmitting terminal;

Convert the numbering of selected codeword vector to binary code, feed back to the relay, relay pre-coding matrix W is designed according to the code word that feeds back in the relay ₂

Step 9: the relay is the amplification forwarding relaying, and the relay receives after the transmission information, through relay pre-coding matrix W ₂After send to receiving terminal, this moment receiving terminal the reception signal be

$y_u=\sqrt{\frac{P_1}{K}}{H}_2{W}_2{H}_1{W}_{1}s+H_2{W}_2{n}_1+n_2$

Wherein The channel matrix that expression second is jumped, n ₂Be the receiving terminal noise, being expressed as average is 0, and variance is

White Gaussian noise.

2. a kind of codeword selection method based on double bounce distributed precoding Limited Feedback as claimed in claim 1, it is characterized in that: in the described step 4, the concrete process of transmitting of transmitting terminal is: data symbol at first becomes multiplex data stream through serial to parallel conversion, to realize the output of many antennas, then pass through transmitting terminal pre-coding matrix W ₁Afterwards, signal is sent.

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