CN102694628A - Interference suppression method for multi-user MIMO collaborative relay system - Google Patents

Abstract

The invention discloses an interference suppression method for a multi-user MIMO collaborative relay system, mainly solving the problem that each user has multiple antennas in a common-channel multi-user relay system. The interference suppression method comprises the steps that: a user determines a beamforming vector by adopting a signal space alignment method, and sends out a signal after weighting the signal with the beamforming vector in a multiple-access time slot; a relay constructs a precoding matrix based on an orthogonal projection principle, and amplifies and sends the received signal after precoding; the user receives the signal and suppresses interference signals between user pairs by adopting a decoding vector, and conducts a maximum likelihood detection to obtain the needed signal. According to the invention, a network transmission rate and a resource utilization rate are improved, diversity gains of multiple antennas are achieved, channel fading resisting capability of the system is enhanced, and a bit error ratio is decreased. Further, the interference suppression method of the invention can be applied in a transmission mode under centralized management and control of a wireless ad hoc network and base station, wherein data can be exchanged directly through user-relay-user mode.

Description

Disturbance restraining method based on the collaborative relay system of multiuser MIMO

Technical field

The invention belongs to communication technical field, relate to the signal space alignment schemes, particularly a kind of disturbance restraining method to the collaborative relay system of multiuser MIMO can be used for radio communication.

Background technology

In real life, often need use the real-time reliable two-way communication, such as the real-time interactive document between the user, video calling and special-purpose supervisory control system etc.Two-way communication requires the communication two ends can both send and receive signal simultaneously; Because the interval, geographical position or the channel quality that direct transfers are abominable; Expectation realizes user's networking realization reliable communication voluntarily of two-way communication, at this time can utilize relaying to assist to accomplish two-way communication.Relaying generally is divided into two kinds of patterns, promptly deciphers forwarding type DF and amplifies forwarding type AF.Decoding forwarding type relaying is to decipher to the received signal earlier, if receive correctly, then with transmitting behind the signal recompile that receives; Amplifying forwarding type relaying is directly to amplify the back to the received signal to transmit.Compare with decoding forwarding type relaying, amplify forwarding type relaying and have lower signal processing time delay and complexity, more be applicable to real time bidirectional communication.Collaborative relaying technique carries out Combined Treatment communication when accomplishing a plurality of node with the multiple signals that receive, can extended coverage range, improve the spectrum efficiency of wireless transmission.In addition, can effectively reduce error rate of system, enlarge the power system capacity zone, improve systematic function in conjunction with MIMO technique MIMO.

Because the broadcast characteristic of radio communication, the signal that the multi-user launches in similar frequency bands simultaneously certainly leads to common-channel interference, and the introducing of MIMO has also increased the difficulty and the complexity of anti-interference algorithm.The newest fruits of multi-user's common-channel interference is a signal space alignment algorithm; Its core concept is a design beam shaping vector; The interference signal that receiving node is not expected snaps to same signal subspace; And through disturbing the inhibition matrix to be configured to corresponding orthogonal subspaces to desired signal, realize disturbing and suppress.

The patent of Beijing University of Post & Telecommunication's application " a kind of " (number of patent application 201110200566.5, publication No. CN102355291A) based on amplifying the two-way relay transmission method of transmitting of multithread.This patent application has mainly proposed a kind of based on amplifying the two-way relay transmission method of transmitting of multiple-input and multiple-output, and the step of this method is: relaying carries out a day line options through two users' channel matrix; Carry out two-way relay transmission according to the antenna subset of selecting then, it is mutual to accomplish signal.The deficiency that this patent application exists is: under identical running time-frequency resource, relaying can only be realized two information exchanges between the user, can not realize the bidirectional transfer of information that a plurality of users are right, has reduced network transmission speed and power system capacity.

The patent " a kind of network code transmission method " (number of patent application 201010533192.4, publication No. CN101997647A) of Beijing University of Post & Telecommunication's application.This patent application mainly is the collaborative relay transmission method that has proposed a kind of network code; The steps include: that relaying carries out network code according to a plurality of users that get access to respectively to signal, broadcasting was sent after the signal behind then that different user is the right network code superposeed.The deficiency that this patent application exists is: this method only is applicable to that the user disposes the scene of single antenna, and the scene that disposes many antennas for the user is then inapplicable, thereby can not obtain potential diversity gain, the anti-channel fading ability of system a little less than.

Summary of the invention

The objective of the invention is to deficiency to above-mentioned prior art; Propose a kind of disturbance restraining method,, obtained the diversity gain of many antennas to improve network transmission speed and resource utilization based on the collaborative relay system of multiuser MIMO; The anti-channel fading ability of enhanced system reduces the error rate.

The basic ideas that realize the object of the invention are, at first time slot, promptly multiple access access slot user adopts the signal space alignment schemes to confirm the beam shaping vector, and form vector with wave beam and send after with signal weighting to be sent; Relaying obtains pre-coding matrix according to equivalent channel matrix, and the multiple user signals that receives is carried out precoding processing, amplifies the back at second time slot, promptly broadcasts sending time slots and sends; The user receive signal and adopt the decoding vector suppress the user to interference signal, carry out Maximum Likelihood Detection again and obtain required signal.Implementation step comprises as follows:

(1) the definite combinations of pairs that need communicate of each user according to combinations of pairs, adopts the signal space alignment schemes, determines beam shaping vector separately, and obtains the equivalent channel vector of user to relaying;

(2) each user modulates signal to be sent separately, obtains modulation signal, and after the multiple access access slot adopts above-mentioned definite beam shaping vector with the modulation signal weighting, sends;

(3) relaying utilizes the equivalent channel vector of above-mentioned each user to relaying, constructs pre-coding matrix P:

3a) will except that i user to the right equivalent channel vector of K-1 user form the dimension of N * (K-1) matrix U side by side _i=(u ^{[r, 1]}..., u ^{[r, i-1]}, u ^{[r, i+1]}..., u ^{[r, K]}), wherein N is the relaying antenna number, K is the right number of user;

3b) calculate corresponding i the orthogonal intersection cast shadow matrix that the user is right Wherein I is a unit matrix,

Be U _iAssociate matrix;

3c) construct the relaying pre-coding matrix:

according to above-mentioned projection matrix wherein;

is the power normalization factor, || || 2 norms of expression vector;

(4) relaying receives the signal that each user sends, and carries out to the received signal amplifying after the premultiplication with above-mentioned pre-coding matrix P, at the broadcasting sending time slots it is sent then;

(5) user disturbs the retransmit that receives and suppresses and demodulation after detection:

5a) user receives the signal that relaying sends, and uses v ^{[i] H}Carry out premultiplication by following formula to the received signal as the decoding vector:

${\hat{y}}^{\left[i\right]}=v^{\left[i\right]H}{y}^{\left[i\right]}$

Suppress the interference signal between user's group, deciphered out required signal, wherein, v ^{[i] H}Be the corresponding beam shaping vector v of user i ^[i]Conjugate transpose, y ^[i]The signal that receives for user i,

Be the reception signal after suppressing through interference;

5b) to disturbing the reception signal after suppressing to adopt maximum likelihood method to detect;

The signal that 5c) detection is obtained carries out demodulation, obtains the required reception signal of user.

Above-mentioned disturbance restraining method based on the collaborative relay system of multiuser MIMO, wherein the described employing signal space of step (1) alignment schemes is determined beam shaping vector separately, utilizes following signal space aligned condition to confirm:

$\mathrm{span}\left(H^{[r,i]}{v}^{\left[i\right]}\right)=\mathrm{span}\left(H^{[r,i+K]}{v}^{[i+K]}\right)(\∀i=\mathrm{1,2},...,K)$

Wherein, the space that span () expression is opened by matrix column vector, r representes relaying, i and i+K need to represent two right users of i user of exchange message, v ^[i]And v ^[i+K]The beam shaping vector of representing user i and user i+K respectively, H ^{[r, i]}And H ^{[r, i+K]}Be respectively user i and user i+K uplink channel transmission matrix, feed back to each user after above-mentioned Channel Transmission matrix obtains through relaying to relaying.

Above-mentioned disturbance restraining method based on the collaborative relay system of multiuser MIMO, the user in the wherein said step (1) is obtained by following formula to the equivalent channel vector of relaying:

u ^[r,i]＝H ^[r,i]v ^[i]＝H ^[r,i+K]v ^[i+K]

Wherein, u ^{[r, i]}Represent that two users of i user's centering divide the equivalent channel vector that is clipped to relaying.

Above-mentioned disturbance restraining method based on the collaborative relay system of multiuser MIMO, the realization condition of signal space alignment schemes is in the wherein said step (1), the relaying antenna number is carried out the user's of signal space alignment antenna sum less than two of each user's centerings.

The above-mentioned disturbance restraining method based on the collaborative relay system of multiuser MIMO, the modulator approach in the wherein said step (2) adopts the binary phase modulator approach.

The above-mentioned disturbance restraining method based on the collaborative relay system of multiuser MIMO, the condition that the pre-coding matrix P in the wherein said step (3) realizes is that the relaying antenna number is more than or equal to the right number of user.

Above-mentioned disturbance restraining method based on the collaborative relay system of multiuser MIMO, wherein said step 5b) maximum likelihood method in is undertaken by following formula:

${\hat{s}}^{[i+K]}=\arg \underset{s^{[i+K]}}{\min }{|{\hat{y}}^{\left[i\right]}-{\mathrm{\α}}_i\mathrm{\β}{\left(P_i{u}^{[r,i]}\right)}^H{u}^{[r,i]}(s^{\left[i\right]}+s^{[i+K]})|}^2$

Wherein,

For user i detects the signal from user i+K that obtains, s ^[i]And s ^[i+K]Be respectively the transmission signal of user i and user i+K,

For user i process is disturbed the reception signal after suppressing, P _iBe step 3b) described in i right orthogonal intersection cast shadow matrix of user of correspondence, u ^{[r, i]}Be the equivalent channel vector of user i to relaying, α _iBe the right power normalization factor of corresponding i user, β is the relaying amplification coefficient, the variate-value when arg min representes to make target function get minimum value, () ^HExpression conjugate transpose operator, || ²The expression modulus of complex number square.

Above-mentioned disturbance restraining method based on the collaborative relay system of multiuser MIMO, wherein said step 5c) demodulation in is adopted and the corresponding demodulation mode of modulation.

The present invention compared with prior art has the following advantages:

The first, because the present invention has adopted the signal space alignment schemes; And utilize orthogonality projection principle to design pre-coding matrix; The user who has suppressed common channel between interference signal; Can make a plurality of users that disposed many antennas to carrying out transfer of data simultaneously, improve resource utilization ratio and network transmission speed.

The second, since in the present invention the user adopted multi-antenna technology, make full use of many antennas and obtained higher diversity gain, improved the reliability of wireless communication system, reduced the error rate.

Three, user-relaying-user of can be applicable under the centralized management control of wireless self-organization network and base station of the present invention directly carries out in the transmission mode of exchanges data.

Description of drawings

The system model sketch map that Fig. 1 is suitable for for the present invention;

Fig. 2 is a flow chart of the present invention;

Fig. 3 is an error rate analogous diagram of the present invention.

Embodiment

Below in conjunction with accompanying drawing the present invention is done and to describe in further detail.

With reference to Fig. 1, in the system model that the present invention is suitable for total K user to a relaying, each user is respectively user i and user i+K to comprising the user that two needs are communicated by letter, wherein, i=1,2 ..., K.Each user configured antenna number is M, and the antenna number of relaying configuration is N.Whole communication process is divided into two time slots, and first time slot is the multiple access access slot, and second time slot is the broadcasting sending time slots.At the multiple access access slot, each user adopts the signal space alignment schemes to retransmit, and wherein user i is H to the uplink channel transmission matrix of relaying r ^{[r, i]}At the broadcasting sending time slots, relaying adopts orthogonality projection principle to carry out to the received signal amplifying broadcasting after the precoding processing, and wherein relaying r is H to the downlink channel transmission matrix of user i ^{[i, r]}User and relaying all communicate with TDD mode, suppose that transmission channel satisfies heterogeneite, i.e. H ^{[i, r]}Be H ^{[r, i]}Associate matrix.Obtain the antenna constraints of following user and relaying by signal space alignment schemes and orthogonality projection principle:

$\left\{\begin{array}{c}2M-N>0\\ N\≥K\end{array}\right.$

According to as above constraints, system can adopt multiple combination of antennas, for example: first kind of combination K=2, M=3, N=2; Second kind of combination K=2, M=2, N=3; The third makes up K=3, M=2, N=3 etc., number of users K=2 in the present embodiment, user's antenna number M=2, the antenna number N=3 of relaying.

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

Step 1, the user confirms the beam shaping vector.

1a) the definite combinations of pairs that need communicate of each user; According to combinations of pairs; Adopt the signal space alignment schemes, right two paths of signals snaps to same signal subspace with belonging to same user in the signal to be sent, determines beam shaping vector separately.

The concrete implementation of signal space alignment is carried out according to formula in the embodiment of the invention:

$\mathrm{span}\left(H^{[r,i]}{v}^{\left[i\right]}\right)=\mathrm{span}\left(H^{[r,i+K]}{v}^{[i+K]}\right)(\∀i=\mathrm{1,2},...,K),$

Wherein, the space that span () expression is opened by matrix column vector, r representes relaying, i and i+K need to represent two right users of i user of switching signal, H ^{[r, i]}And H ^{[r, i+K]}Be respectively user i and user i+K uplink channel transmission matrix, feed back to each user, v after above-mentioned Channel Transmission matrix obtains through relaying to relaying ^[i]And v ^[i+K]The beam shaping vector of representing user i and user i+K respectively; Above-mentioned beam shaping vector is existed; Provide the condition that antenna must satisfy among the document A novel signaling on the MIMO Y channel signal pace alignment for network coding, promptly the relaying number of antennas must be carried out the user's of signal space alignment antenna sum less than two of each user's centerings: 2M-N＞0;

1b) after the signal space alignment, two users of i user's centering divide the equivalent channel vector that is clipped to relaying to be: u ^{[r, i]}=H ^{[r, i]}v ^[i]=H ^{[r, i+K]}v ^[i+K]

Step 2, the user sends signal

Each user is to separately signal W to be sent ^[i]Modulate, obtain modulation signal s ^[i], modulator approach adopts binary phase modulation or quaternary phase modulated or quadrature amplitude modulation, adopts the binary phase modulation in the embodiment of the invention.

At the multiple access access slot, the to be sent signal of each user after to modulation adopts step 1a) in this user's beam shaping vector v ^[i]Carry out weighting, the to be sent signal of all users after with weighting sends simultaneously.

Step 3, relaying structure pre-coding matrix

Relaying generates the right orthogonal intersection cast shadow matrix of corresponding different user according to the equivalent channel vector, again all orthogonal intersection cast shadow matrixs is obtained the relaying pre-coding matrix through addition behind the power normalization, and to being example, its precoding constitution step is following with i user:

3a) utilize except that i user to the right equivalent channel vector u of K-1 user ^{[r, 1]}..., u ^{[r, i-1]}, u ^{[r, i+1]}..., u ^{[r, K]}Open into Space L, and this forms the dimension of N * (K-1) matrix U side by side with K-1 equivalent channel vector _i=(u ^{[r, 1]}..., u ^{[r, i-1]}, u ^{[r, i+1]}..., u ^{[r, K]}), for making the orthogonal intersection space L of Space L ^⊥Exist, then L ^⊥Dimension must be more than or equal to 1, promptly the relaying antenna number satisfies N>=K;

3b) by matrix U _iGenerating the right orthogonal intersection cast shadow matrix of corresponding i user does

Wherein I is a unit matrix, () ^HExpression conjugate transpose operator;

Character according to orthogonal intersection cast shadow matrix can be known P _i=P _i ^H, and for i user to beyond the right equivalent channel vector u of K-1 user ^{[r, 1]}..., u ^{[r, i-1]}, u ^{[r, i+1]}..., u ^{[r, K]}, P is all arranged _iu ^{[r, j]}=0, u ^{[r, j]}Represent j the equivalent channel vector that the user is right, j=1 ... .K, j ≠ i, and for i the equivalent channel vector u that the user is right ^{[r, i]}, P is arranged _iu ^{[r, i]}≠ 0;

3c) all K user is obtained P to pairing orthogonal intersection cast shadow matrix through addition behind the power normalization, is the relaying pre-coding matrix:

$P=\underset{i=1}{\overset{K}{\mathrm{\Σ}}}{\mathrm{\α}}_i{P}_i$

Wherein,

is corresponding to i the power normalization factor that the user is right, wherein || || 2 norms of expression vector.

Step 4, the relaying precoding is also amplified and is transmitted.

4a) relaying receives the signal that each user sends:

$y^{\left[r\right]}=\underset{i=1}{\overset{K}{\mathrm{\Σ}}}(H^{[r,i]}{v}^{\left[i\right]}{s}^{\left[i\right]}+H^{[r,i+K]}{v}^{[i+K]}{s}^{[i+K]})+n^{\left[r\right]}$

$=\underset{i=1}{\overset{K}{\mathrm{\Σ}}}\left(u^{[r,i]}(s^{\left[i\right]}+s^{[i+K]})\right)+n^{\left[r\right]},$

Wherein, H ^{[r, i]}And H ^{[r, i+K]}Be respectively the Channel Transmission matrixes of two users of i user's centering to relaying, v ^[i]And v ^[i+K]The beam shaping vector of representing two users of i user's centering respectively, s ^[i]And s ^[i+K]The transmission signal of representing two users of i user's centering respectively, u ^{[r, i]}Two users that represent i user's centering divide the equivalent channel vector that is clipped to relaying, n ^[r]Be the multiple Gaussian noise vector of relaying;

4b) relaying sends signal with above-mentioned pre-coding matrix P to the user who receives and carries out premultiplication, and amplifies according to the signal of relaying power constraint after to precoding, obtains relaying signal x to be sent ^[r], and when the broadcasting sending time slots, it is sent,

x ^[r]=βPy ^[r]，

Wherein,

Be relaying amplification coefficient, P _rBe relaying transmitted power, P _nBe the relaying received noise power, || || _FThe F norm of representing matrix.

Step 5, the user receives signal and decoding detects.

With user i is example, and it is following to receive signal processing:

5a) user i receives the signal that relaying sends, and this reception signal indication is:

y ^[i]＝H ^[i，r]x ^[r]+n ^[i,r]

，

＝H ^[r，i]Hx ^[r]+n ^[i,r]

Wherein, x ^[r]Be the signal that relaying sends, n ^{[i, r]}Be the white complex gaussian noise vector that the user receives, H ^{[i, r]}For being relayed to the Channel Transmission matrix of user i, H ^{[r, i]}Be the Channel Transmission matrix of user i to relaying;

5b) user i adopts its beam shaping vector v ^[i]Conjugate transpose v ^{[i] H}As deciphering vector y to received signal ^[i]Carry out premultiplication decoding, completion is disturbed and is suppressed, and obtains decoded signal and is:

${\hat{y}}^{\left[i\right]}=v^{\left[i\right]H}{y}^{\left[i\right]}$

$=v^{\left[i\right]H}{H}^{[r,i]H}\mathrm{\β}\underset{j=1}{\overset{K}{\mathrm{\Σ}}}{\mathrm{\α}}_j{P}_j{u}^{[r,j]}(s^{\left[j\right]}+s^{[j+K]})+n^{\left[i\right]}$

$={\left(H^{[r,i]}{v}^{\left[i\right]}\right)}^H\mathrm{\β}\underset{j=1}{\overset{K}{\mathrm{\Σ}}}{\mathrm{\α}}_j{P}_j{u}^{[r,j]}(s^{\left[j\right]}+s^{[j+K]})+n^{\left[i\right]},$

$=u^{[r,i]H}\mathrm{\β}\underset{j=1}{\overset{K}{\mathrm{\Σ}}}{\mathrm{\α}}_j{P_j}^H{u}^{[r,j]}(s^{\left[j\right]}+s^{[j+K]})+n^{\left[i\right]}$

$={\mathrm{\α}}_i\mathrm{\β}{\left(P_i{u}^{[r,i]}\right)}^H{u}^{[r,i]}(s^{\left[i\right]}+s^{[i+K]})+\mathrm{\β}\underset{j=1,j\≠i}{\overset{K}{\mathrm{\Σ}}}{\mathrm{\α}}_j{\left(P_j{u}^{[r,i]}\right)}^H{u}^{[r,j]}(s^{\left[j\right]}+s^{[j+K]})+n^{\left[i\right]}$

Wherein, y ^[i]Be the reception signal of user i, s ^[i]And s ^[i+K]Be respectively the transmission signal of user i and user i+K, s ^[j]And s ^[j+K]Be respectively the transmission signal of user j and user j+K, P _iBe corresponding i the orthogonal intersection cast shadow matrix that the user is right, Ρ _jBe corresponding j the orthogonal intersection cast shadow matrix that the user is right, u ^{[r, i]}Be the equivalent channel vector of user i to relaying, u ^{[r, j]}Be the equivalent channel vector of user j to relaying, v ^[i]Be the beam shaping vector of user i, α _iBe the right power normalization factor of corresponding i user, α _jBe the right power normalization factor of corresponding j user, β is the relaying amplification coefficient, n ^[i]For deciphering the integrated noise of back user i, () ^HExpression conjugate transpose operator.

Can find out decoded signal from following formula Form by 3 parts, comprise useful signal α for user i _iβ (P _iu ^{[r, i]}) ^Hu ^{[r, i]}(s ^[i]+ s ^[i+K]), interference signal

With noise signal n ^[i]

Character by orthogonal intersection cast shadow matrix can be known P _ju ^{[r, i]}=0, j ≠ i, i.e. decoded signal

In interference signal

Be 0, therefore, in the reception signal of user i, the right signal of other users can be eliminated the interference of the right signal of i user:

${\hat{y}}^{\left[i\right]}={\mathrm{\α}}_i\mathrm{\β}{\left(P_i{u}^{[r,i]}\right)}^H{u}^{[r,i]}(s^{\left[i\right]}+s^{[i+K]})+n^{\left[i\right]};$

5c) user i detects decoded signal with maximum likelihood method, obtains the signal that user i+K sends

${\hat{s}}^{[i+K]}=\arg \underset{s^{[i+K]}}{\min }{|{\hat{y}}^{\left[i\right]}-{\mathrm{\α}}_i\mathrm{\β}{\left(P_i{u}^{[r,i]}\right)}^H{u}^{[r,i]}(s^{\left[i\right]}+s^{[i+K]})|}^2,$

Wherein,

For user i detects the signal from user i+K that obtains,

Be the decoded signal of user i, s ^[i]And s ^[i+K]Be respectively the transmission signal of user i and user i+K, P _iBe step 3b) described in i right orthogonal intersection cast shadow matrix of user of correspondence, u ^{[r, i]}Be the equivalent channel vector of user i to relaying, α _iBe the right power normalization factor of corresponding i user, β is the relaying amplification coefficient, the variate-value when arg min representes to make target function get minimum value, || ²The expression modulus of complex number square;

5d) user i signal

that detection is obtained carries out demodulation, obtains the required reception signal of user

The corresponding demodulation mode of modulation in demodulation employing and the step 2.The binary phase demodulation mode is adopted in demodulation in the embodiment of the invention.

Effect of the present invention can further specify through simulation result:

1. simulating scenes and condition

Fig. 1 is the simulating scenes of the inventive method, and wherein user antenna is counted M=2, and it is that 0 variance is 1 multiple Gaussian distribution that relaying antenna number N=3, user's logarithm K=2, each element in the Channel Transmission matrix obey average.

2. emulation content and simulation result

The present invention is carried out the emulation contrast of the error rate based on the single antenna user with the network code transmission method that disturbs arrangement with existing, and simulation result is as shown in Figure 3, and wherein curve A is the ber curve of existing method, and curve B is a ber curve of the present invention.Fig. 3 shows, has reduced error rate of system effectively after employing this method, has improved the anti-channel fading ability and the noiseproof feature of system.

Claims (8)

1. disturbance restraining method based on the collaborative relay system of multiuser MIMO comprises that step is following:

(1) the definite combinations of pairs that need communicate of each user according to combinations of pairs, adopts the signal space alignment schemes, determines beam shaping vector separately, and obtains the equivalent channel vector of user to relaying;

(2) each user modulates signal to be sent separately, obtains modulation signal, and after the multiple access access slot adopts above-mentioned definite beam shaping vector with the modulation signal weighting, sends;

(3) relaying utilizes the equivalent channel vector of above-mentioned each user to relaying, constructs pre-coding matrix P:

3a) will except that i user to the right equivalent channel vector of K-1 user form the dimension of N * (K-1) matrix U side by side _i=(u ^{[r, 1]}..., u ^{[r, i-1]}, u ^{[r, i+1]}..., u ^{[r, K]}), wherein N is the relaying antenna number, K is the right number of user;

3b) calculate corresponding i the orthogonal intersection cast shadow matrix that the user is right

Wherein I is a unit matrix,

Be U _iAssociate matrix;

3c) construct the relaying pre-coding matrix:

according to above-mentioned projection matrix wherein; is the power normalization factor, || || 2 norms of expression vector;

(4) relaying receives the signal that each user sends, and carries out to the received signal amplifying after the premultiplication with above-mentioned pre-coding matrix P, at the broadcasting sending time slots it is sent then;

(5) user disturbs the retransmit that receives and suppresses and demodulation after detection:

5a) user receives the signal that relaying sends, and uses v ^{[i] H}Carry out premultiplication by following formula to the received signal as the decoding vector:

${\hat{y}}^{\left[i\right]}=v^{\left[i\right]H}{y}^{\left[i\right]}$

Suppress the interference signal between user's group, deciphered out required signal, wherein, v ^{[i] H}Be the corresponding beam shaping vector v of user i ^[i]Conjugate transpose, y ^[i]The signal that receives for user i,

Be the reception signal after suppressing through interference;

5b) to disturbing the reception signal after suppressing to adopt maximum likelihood method to detect;

The signal that 5c) detection is obtained carries out demodulation, obtains the required reception signal of user.

2. the disturbance restraining method based on the collaborative relay system of multiuser MIMO according to claim 1, wherein the described employing signal space of step (1) alignment schemes is determined beam shaping vector separately, utilizes following signal space aligned condition to confirm:

$\mathrm{span}\left(H^{[r,i]}{v}^{\left[i\right]}\right)=\mathrm{span}\left(H^{[r,i+K]}{v}^{[i+K]}\right)(\∀i=\mathrm{1,2},...,K)$

Wherein, the space that span () expression is opened by matrix column vector, r representes relaying, i and i+K need to represent two right users of i user of exchange message, v ^[i]And v ^[i+K]The beam shaping vector of representing user i and user i+K respectively, H ^{[r, i]}And H ^{[r, i+K]}Be respectively user i and user i+K uplink channel transmission matrix, feed back to each user after above-mentioned Channel Transmission matrix obtains through relaying to relaying.

3. the disturbance restraining method based on the collaborative relay system of multiuser MIMO according to claim 1, the user in the wherein said step (1) is obtained by following formula to the equivalent channel vector of relaying:

u ^[r,i]＝H ^[r,i]v ^[i]＝H ^[r,i+K]v ^[i+K]

Wherein, u ^{[r, i]}Represent that two users of i user's centering divide the equivalent channel vector that is clipped to relaying.

4. the disturbance restraining method based on the collaborative relay system of multiuser MIMO according to claim 1; The realization condition of signal space alignment schemes is in the wherein said step (1), and the relaying antenna number is carried out the user's of signal space alignment antenna sum less than two of each user's centerings.

5. the disturbance restraining method based on the collaborative relay system of multiuser MIMO according to claim 1, the modulator approach in the wherein said step (2) adopts the binary phase modulator approach.

6. the disturbance restraining method based on the collaborative relay system of multiuser MIMO according to claim 1, the condition that the pre-coding matrix P in the wherein said step (3) realizes is that the relaying antenna number is more than or equal to the right number of user.

7. the maximum likelihood method the disturbance restraining method based on the collaborative relay system of multiuser MIMO according to claim 1, wherein said step 5b) is undertaken by following formula:

${\hat{s}}^{[i+K]}=\arg \underset{s^{[i+K]}}{\min }{|{\hat{y}}^{\left[i\right]}-{\mathrm{\α}}_i\mathrm{\β}{\left(P_i{u}^{[r,i]}\right)}^H{u}^{[r,i]}(s^{\left[i\right]}+s^{[i+K]})|}^2$

Wherein,

For user i detects the information from user i+K that obtains, s ^[i]And s ^[i+K]Be respectively the transmission information of user i and user i+K,

For user i process is disturbed the reception signal after suppressing, P _iBe step 3b) described in i right orthogonal intersection cast shadow matrix of user of correspondence, u ^{[r, i]}Be the equivalent channel vector of user i to relaying, α _iBe the right power normalization factor of corresponding i user, β is the relaying amplification coefficient, the variate-value when arg min representes to make target function get minimum value, () ^HExpression conjugate transpose operator, || ²The expression modulus of complex number square.

8. the demodulation the disturbance restraining method based on the collaborative relay system of multiuser MIMO according to claim 1, wherein said step 5c) is adopted and the corresponding demodulation mode of modulation.

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