CN103249057A - Data transmission method and system as well as relay station - Google Patents

Abstract

The invention provides a data transmission method which comprises the steps as follows; a relay station receives channel state information reported by a first mobile terminal through a first base station and channel state information reported by a second mobile terminal through a second base station; pre-coding matrixes of the first base station and the second base station and a processing matrix of the relay station are determined according to the channel state information reported by the first mobile terminal and the second mobile terminal; the determined pre-coding matrix of the first station and the processing matrix of the relay station are informed to the first station, while the determined pre-coding matrix of the second base station and the processing matrix of the relay station are informed to the second station; signals from the first base station and the second base station are received in a first time slot; and the relay station processes a received signal in a second time slot, and processed mixed signals are broadcasted to the first mobile terminal and the second mobile terminal simultaneously. The invention further provides the relay station and a data transmission system for achieving the method. According to the data transmission method and system as well as the relay station, interference among cells can be effectively reduced, and data rates of the mobile terminals are increased.

Description

A kind of data transmission method, system and relay station

Technical field

The present invention relates to cellular mobile communication technology, particularly the data transmission method in the cell mobile communication systems, system and relay station.

Background technology

In the current cellular mobile communication system, the obtainable data rate of user depends on the residing position of user to a great extent.For example, being in the data rate of the Cell Edge User of cell edge will be well below the data rate of the Cell Center User that is in center of housing estate.Therefore, the data rate that how to improve Cell Edge User is the problem that cell mobile communication systems of new generation need solve.From the propagation characteristic of signal wireless environment as can be known, the user received signal far away apart from the base station, behind the process space loss, its intensity will certainly weaken, and its data rate will reduce.In this case, if by increasing the base station transmitted power of edge customer is overcome the loss of signal strength signal intensity, will cause this base station to the increase of neighbor cell interference, thereby cause the data rate of neighbor cell edge customer.Therefore, wanting to improve the data rate of Cell Edge User, fundamentally is the interference problem that will solve the minizone.

Summary of the invention

Embodiments of the invention provide a kind of data transmission method and relay station, can eliminate the interference of minizone effectively, improve the data rate of Cell Edge User.

The data transmission method that the embodiment of the invention provides comprises: relay station receives the channel condition information that channel condition information that first portable terminal reports by first base station and second portable terminal report by second base station; Relay station is determined the pre-coding matrix of first base station and second base station and the processing array of relay station according to the channel condition information of first portable terminal and second mobile terminal reporting; The pre-coding matrix of first base station that relay station will be determined and the processing array of relay station are notified first base station, and notify second base station with the pre-coding matrix of second base station and the processing array of relay station; At first time slot, relay station receives from first base station and second signal of base station; And at second time slot, relay station is handled the signal that receives, and the mixed signal after will handling is broadcast to first portable terminal and second portable terminal; Wherein, the pre-coding matrix of the base station that first portable terminal and second portable terminal are determined according to relay station respectively and the processing array of relay station carry out joint-detection to what receive at first time slot from first base station and second signal of base station and at the signal from relay station that second time slot receives, and demodulation obtains self required data.

Wherein, relay station is handled the signal that receives and comprised: relay station amplifies to transmit to the signal that receives to be handled.

At this moment, relay station comprises according to determine first base station and the pre-coding matrix of second base station and the processing array of relay station of first portable terminal and second mobile terminal reporting:

A is to h ₁₁Carry out SVD and decompose, will lead right singular vector and be set at the first base station pre-coding matrix initial value P ₁, to h ₂₂Carry out SVD and decompose, will lead right singular vector and be set at the second base station pre-coding matrix initial value P ₂, wherein, h ₁₁Represent first base station to the channel of first portable terminal; h ₂₂Represent second base station to the channel of second portable terminal;

B determines the processing array P of relay station according to following formula _r:

P _r＝unvec{P}

Wherein, P=U (:, m) ^*, U (:, m) ^*Represent the conjugation of the m row of U, U obtains H=USV by the SVD decomposition of H ^H, H is the matrix of the capable n row of m, namely P is the conjugation of left singular vector of the minimum singular value correspondence of H, $H={[\mathrm{\β}(h_{2r}{P}_2\⊗{h_{r1}}^T),(1-\mathrm{\β})(h_{1r}{P}_1\⊗{h_{r2}}^T)]}^T,$ $\mathrm{\β}=\frac{a}{a+b};(1-\mathrm{\β})=\frac{b}{a+b},$ $a={\left[R_{n_1{n}_1}\right]}_{\mathrm{kk}}+{\left|\right|h_{11}{P}_1\left|\right|}^2\·{\left|\right|h_{r1}{P}_r{h}_{2r}{P}_2\left|\right|}^2+{\mathrm{\γ}}_1\·{\left|\right|h_{r1}{P}_r{h}_{1r}{P}_1\left|\right|}^2\·{\left|\right|h_{21}{P}_2\left|\right|}^2,$ $b={\left[R_{n_2{n}_2}\right]}_{\mathrm{kk}}+{\left|\right|h_{22}{P}_2\left|\right|}^2\·{\left|\right|h_{r2}{P}_r{h}_{1r}{P}_1\left|\right|}^2+{\mathrm{\γ}}_2\·{\left|\right|h_{r2}{P}_r{h}_{2r}{P}_2\left|\right|}^2\·{\left|\right|h_{12}{P}_1\left|\right|}^2,$ T is the matrix transpose operation,

Be the Kronecker product, unvec is the vector matrix computing,

With

It is the noise variance matrix $R_{n_1{n}_1}=E\left(N_1{N_1}^{+}\right)=\left[\begin{array}{cc}{\mathrm{\δ}}^2& 0\\ 0& (1+{\left|\right|h_{r1}{P}_r\left|\right|}^2){\mathrm{\δ}}^2\end{array}\right],$ $R_{n_2{n}_2}=E\left(N_2{N_2}^H\right)=\left[\begin{array}{cc}{\mathrm{\δ}}^2& 0\\ 0& (1+{\left|\right|H_{r2}{P}_r\left|\right|}^2){\mathrm{\δ}}^2\end{array}\right],$ δ ²Be the receiving terminal noise power, [R] _KkThe element that the capable k of representing matrix k lists, k represents k data flow, h ₁₁And h ₁₂Represent first base station respectively to the channel of first portable terminal and second portable terminal; h ₂₁And h ₂₂Represent second base station respectively to the channel of first portable terminal and second portable terminal; h _1rAnd h _2rRepresent first base station and second base station respectively to the channel of relay station; h _R1And h _R2Represent relay station respectively to the channel of first portable terminal and second portable terminal;

C determines the pre-coding matrix P of first base station and second base station according to following formula ₁, P ₂:

$P_k={(\underset{l=1}{\overset{K}{\mathrm{\Σ}}}{h}_{\mathrm{lk}}^{+}{w}_l^{+}{w}_l{h}_{\mathrm{lk}}-\frac{1}{b}(\left(\underset{l\≠k}{\mathrm{\Σ}}\mathrm{Tr}\right\{J_l^{\left(k\right)}\}-\mathrm{Tr}\{J_k^{\left(l\right)}\left\}\right)-\mathrm{Tr}\{w_k{R}_{n_k{n}_k}{w}_k^{+}\left\}\right)I)}^{-1}{h}_{\mathrm{kk}}^{+}{w}_k^{+}$

Wherein,

K represents the number of receiving terminal,

Be the noise variance matrix, define the same ,+be the conjugate transpose operation of matrix, Tr be matrix ask the mark operation, b is the maximum transmit power of first base station and second base station.

D judges the processing array P of determined relay station _rAnd the pre-coding matrix P of base station ₁, P ₂Whether restrain, if then obtain the processing array P of relay station _rAnd the pre-coding matrix P of base station ₁, P ₂Optimal solution; Otherwise, return B.

Wherein, relay station comprises according to determine first base station and the pre-coding matrix of second base station and the processing array of relay station of first portable terminal and second mobile terminal reporting:

To equivalent channel matrix

Carry out SVD and decompose, the right singular vector of the master who obtains is as the pre-coding matrix P of first base station ₁Right

Carry out SVD and decompose, the right singular vector of the master who obtains is as the pre-coding matrix P of second base station ₂And determine the processing array P of relay station according to following formula _r:

P _r＝unvec{P}

Wherein, P=U (:, m) ^*, U (:, m) ^*Represent the conjugation of the m row of U, U obtains H=USV by the SVD decomposition of H ^H, H is the matrix of the capable n row of m, namely P is the conjugation of left singular vector of the minimum singular value correspondence of H, $H={[\mathrm{\β}(h_{2r}{P}_2\⊗{h_{r1}}^T),(1-\mathrm{\β})(h_{1r}{P}_1\⊗{h_{r2}}^T)]}^T,$ $\mathrm{\β}=\frac{a}{a+b};(1-\mathrm{\β})=\frac{b}{a+b},$ $a={\left[R_{n_1{n}_1}\right]}_{\mathrm{kk}}+{\left|\right|h_{11}{P}_1\left|\right|}^2\·{\left|\right|h_{r1}{P}_r{h}_{2r}{P}_2\left|\right|}^2+{\mathrm{\γ}}_1\·{\left|\right|h_{r1}{P}_r{h}_{1r}{P}_1\left|\right|}^2\·{\left|\right|h_{21}{P}_2\left|\right|}^2,$ $b={\left[R_{n_2{n}_2}\right]}_{\mathrm{kk}}+{\left|\right|h_{22}{P}_2\left|\right|}^2\·{\left|\right|h_{r2}{P}_r{h}_{1r}{P}_1\left|\right|}^2+{\mathrm{\γ}}_2\·{\left|\right|h_{r2}{P}_r{h}_{2r}{P}_2\left|\right|}^2\·{\left|\right|h_{12}{P}_1\left|\right|}^2,$ T is the matrix transpose operation,

Be the Kronecker product, unvec is the vector matrix computing,

With

It is the noise variance matrix $R_{n_1{n}_1}=E\left(N_1{N_1}^{+}\right)=\left[\begin{array}{cc}{\mathrm{\δ}}^2& 0\\ 0& (1+{\left|\right|h_{r1}{P}_r\left|\right|}^2){\mathrm{\δ}}^2\end{array}\right],$ $R_{n_2{n}_2}=E\left(N_2{N_2}^H\right)=\left[\begin{array}{cc}{\mathrm{\δ}}^2& 0\\ 0& (1+{\left|\right|H_{r2}{P}_r\left|\right|}^2){\mathrm{\δ}}^2\end{array}\right],$ δ ²Be the receiving terminal noise power, [R] _KkThe element that the capable k of representing matrix k lists, k represents k data flow, $r_1=\frac{{\left[R_{n_1{n}_1}\right]}_{22}}{{\left[R_{n_1{n}_1}\right]}_{11}},$ $r_2=\frac{{\left[R_{n_2{n}_2}\right]}_{22}}{{\left[R_{n_2{n}_2}\right]}_{11}},$ ${\tilde{H}}_{11}=\left[\begin{array}{c}{h}_{11}\\ {\mathrm{\αh}}_{r1}{P}_r{h}_{1r}\end{array}\right],$ ${\tilde{H}}_{22}=\left[\begin{array}{c}{h}_{22}\\ {\mathrm{\αh}}_{r2}{P}_r{h}_{2r}\end{array}\right],$ h ₁₁And h ₁₂Represent first base station respectively to the channel of first portable terminal and second portable terminal; h ₂₁And h ₂₂Represent second base station respectively to the channel of first portable terminal and second portable terminal; h _1rAnd h _2rRepresent first base station and second base station respectively to the channel of relay station; h _R1And h _R2Represent relay station respectively to the channel of first portable terminal and second portable terminal.

In addition, relay station is handled the signal that receives and comprised: relay station detects earlier to do to transmit to the signal that receives again and handles.

At this moment, relay station comprises according to determine first base station and the pre-coding matrix of second base station and the processing array of relay station of first portable terminal and second mobile terminal reporting:

The pre-coding matrix P of first base station and second base station of following formula is satisfied in search in the hunting zone of pre-coding matrix ₁, P ₂Processing array P with relay station _R1, P _R2:

$\underset{\{P_1,P_2,P_{r1},P_{r2}\}}{\max }\frac{{\left|\right|h_{11}{P}_1\left|\right|}^2+{\left|\right|h_{r1}{P}_{r1}\left|\right|}^2}{{\mathrm{\δ}}^2+{\left|\right|h_{21}{P}_2\left|\right|}^2+{\left|\right|h_{r1}{P}_{r2}\left|\right|}^2}+\frac{{\left|\right|h_{22}{P}_2\left|\right|}^2+{\left|\right|h_{r2}{P}_{r2}\left|\right|}^2}{{\mathrm{\δ}}^2+{\left|\right|h_{12}{P}_1\left|\right|}^2+{\left|\right|h_{r2}{P}_{r1}\left|\right|}^2}$

Wherein, h ₁₁And h ₁₂Represent first base station respectively to the channel of first portable terminal and second portable terminal; h ₂₁And h ₂₂Represent second base station respectively to the channel of first portable terminal and second portable terminal; h _R1And h _R2Represent relay station respectively to the channel of first portable terminal and second portable terminal; δ ²Be the receiving terminal noise power.

The hunting zone of above-mentioned pre-coding matrix comprises:

The first base station pre-coding matrix P ₁The hunting zone be h ₁₁Carry out first row and the h of the right singular matrix V after SVD decomposes ₁₂Carry out last row of the right singular matrix V after SVD decomposes;

The second base station pre-coding matrix P ₂The hunting zone be h ₂₂Carry out first row and the h of the right singular matrix V after SVD decomposes ₂₁Carry out last row of the right singular matrix V after SVD decomposes;

Relay station processing array P _R1The hunting zone be h _R1Carry out first row and the h of the right singular matrix V after SVD decomposes _R2Carry out last row of the right singular matrix V after SVD decomposes; And

Relay station processing array P _R2The hunting zone be h _R2Carry out first row and the h of the right singular matrix V after SVD decomposes _R1Carry out last row of the right singular matrix V after SVD decomposes.

Embodiments of the invention also provide a kind of relay station, comprising:

The channel condition information receiving element for the channel condition information that receives first mobile terminal reporting from first base station, receives the channel condition information of second mobile terminal reporting from second base station;

The matrix determining unit is used for determining the pre-coding matrix of first base station and second base station and the processing array of relay station according to the channel condition information of first portable terminal and second mobile terminal reporting;

The matrix notification unit is used for first base station that will determine and the pre-coding matrix of second base station and the processing array of relay station and is notified to first base station and second base station respectively; And

Retransmission unit be used for according to the processing array of relay station the mixed signal from first base station and second base station that receives being handled, and the signal after will handling is sent to first portable terminal and second portable terminal.

Data transmission system comprises:

The first adjacent base station and second base station, be positioned over the relay station between first base station and second base station, second portable terminal that is positioned at first portable terminal of first base station range and is positioned at second base station range; Wherein,

First portable terminal reports first base station BS, 1, the second portable terminal with self channel status indication information self channel condition information is reported second base station;

Relay station is notified with the channel condition information of first portable terminal and second mobile terminal reporting respectively in first base station and second base station;

Relay station is determined the pre-coding matrix of first base station and second base station and the processing array of relay station according to the channel condition information of first portable terminal and second mobile terminal reporting, and the processing array of the pre-coding matrix of first base station that will determine and relay station notifies first base station, and notifies second base station with the pre-coding matrix of second base station and the processing array of relay station;

First portable terminal is notified with self pre-coding matrix and relay station processing array in first base station, and second portable terminal is notified with self pre-coding matrix and relay station processing array in second base station;

At first time slot, first base station is treated the data that are sent to first portable terminal according to the pre-coding matrix of self and is carried out precoding, and the data after precoding are sent to relay station and first portable terminal and second portable terminal, second base station is treated the data that are sent to second portable terminal according to the pre-coding matrix of self and is carried out precoding, and the data after precoding are sent to relay station and first portable terminal and second portable terminal;

At second time slot, relay station is handled the mixed signal from first base station and second base station that receives according to the processing array of self, and the mixed signal after will handling is broadcast to first portable terminal and second portable terminal; And

First portable terminal and second portable terminal carry out joint-detection according to the pre-coding matrix of base station and the processing array of relay station to the mixed signal that receives respectively in first time slot and second time slot, demodulation obtains self required data.

The described interference elimination method of the embodiment of the invention and relay station are by having introduced relay station between adjacent base station, and adopt the data transmission scheme of two time slots, can reduce the interference of minizone effectively, improve the particularly data rate of Cell Edge User of user.

Description of drawings

Fig. 1 is the basic structure schematic diagram of the described cell mobile communication systems of the embodiment of the invention;

Fig. 2 is the flow chart of the described data transmission method of the embodiment of the invention;

Fig. 3 (a) and (b) be respectively the broadcast segment that obtains after the described cell mobile communication systems of the embodiment of the invention decomposed and disturb and eliminate part;

Fig. 4 determines the method for base station pre-coding matrix and relay station processing array for the described relay station of the embodiment of the invention;

Fig. 5 is the internal structure schematic diagram of the described relay station of the embodiment of the invention; And

Fig. 6 is the basic structure schematic diagram of the described another kind of cell mobile communication systems of the embodiment of the invention.

Embodiment

In order to reduce presence of intercell interference, improve the data rate of Cell Edge User, in an embodiment of the present invention, between adjacent base station, put into an intermediate node, be called relay station (RS, Relay Station).Fig. 1 has shown the basic structure of the described cell mobile communication systems of the embodiment of the invention.As shown in Figure 1, between adjacent two base station BSs 1 and BS2, put into a relay station RS.Embodiments of the invention adopt the data transmission scheme of two time slots, namely at first time slot, first base station BS 1 and second base station BS 2 adopt the beam forming mode, respectively the data of first mobile terminal UE 1 and second mobile terminal UE 2 of giving to be sent are sent to relay station RS, first mobile terminal UE 1 and second mobile terminal UE 2 also can receive data simultaneously, but be mixed signal because first mobile terminal UE 1 and second mobile terminal UE 2 receive, therefore, can't from the mixed signal that receives, demodulate self required data in first time slot, first mobile terminal UE 1 and second mobile terminal UE 2; At second time slot, relay station RS will handle from the mixed signal that first base station BS 1 and second base station BS 2 receive, and be forwarded to first mobile terminal UE 1 and second mobile terminal UE 2 then; First mobile terminal UE 1 and second mobile terminal UE 2 demodulate self required data by two mixed signals that receive are carried out Combined Treatment in two time slots.Describe the data transmission method that the embodiment of the invention provides in detail below in conjunction with accompanying drawing.

Fig. 2 has shown the flow process of the described data transmission method of the embodiment of the invention.As shown in Figure 2, this method mainly comprises the steps:

Step 101, first mobile terminal UE 1 report self channel status indication information (CSI) serving BS of self---first base station BS, 1, the second mobile terminal UE 2 reports self CSI the serving BS of self---second base station BS 2;

The CSI notice relay station RS that step 102, first base station BS 1 and second base station BS 2 report first mobile terminal UE 1 and second mobile terminal UE 2 respectively;

Step 103, the CSI that relay station RS reports according to first mobile terminal UE 1 and second mobile terminal UE 2 determines the pre-coding matrix P of first base station BS 1 and second base station BS 2 ₁, P ₂Processing array P with relay station RS _R1And P _R2(P _R1And P _R2May be identical or different, P when relay station has signal testing function _R1And P _R2Different), and the pre-coding matrix P of first base station that will determine ₁Processing array P with relay station RS _R1Notify first base station BS 1, and with the pre-coding matrix P of second base station ₂Processing array P with relay station RS _R2Notify second base station BS 2;

Step 104, first base station BS 1 is with the pre-coding matrix P of self ₁And relay station RS processing array P _R1Notify the pre-coding matrix P of first mobile terminal UE, 1, the second base station BS 2 with self ₂And relay station RS processing array P _R2Notify second mobile terminal UE 2;

Step 105, at first time slot, first base station BS 1 is according to the pre-coding matrix P of self ₁Treat the data that are sent to first mobile terminal UE 1 and carry out precoding, and the data after precoding are sent to relay station RS and first mobile terminal UE 1 and second mobile terminal UE, 2, the second base station BSs 2 according to the pre-coding matrix P of self ₂Treat the data that are sent to second mobile terminal UE 2 and carry out precoding, and the data after precoding are sent to relay station RS and first mobile terminal UE 1 and second mobile terminal UE 2;

Step 106, at second time slot, relay station RS is according to the processing array P of self _R1And P _R2The mixed signal from first base station BS 1 and second base station BS 2 that receives is handled, and the mixed signal after will handling is broadcast to first mobile terminal UE 1 and second mobile terminal UE 2;

Step 107, first mobile terminal UE 1 and second mobile terminal UE 2 are carried out joint-detection according to the pre-coding matrix of base station and the processing array of relay station RS to the mixed signal that receives respectively in first time slot and second time slot, demodulation obtains self required data.

In said method, relay station at first receives the channel condition information that channel condition information that first portable terminal reports by first base station and second portable terminal report by second base station; Determine the pre-coding matrix of first base station and second base station and the processing array of relay station according to the channel condition information of first portable terminal and second mobile terminal reporting then; The pre-coding matrix of first base station that will determine again and the processing array of relay station are notified first base station, and notify second base station with the pre-coding matrix of second base station and the processing array of relay station; At first time slot, relay station receives from first base station and second signal of base station; And at second time slot, the signal that receives is handled, and the signal after will handling is sent to first portable terminal and second portable terminal.

Particularly, at above-mentioned first time slot, first base station BS 1 and second base station BS 2 utilize the pre-coding matrix P of self respectively ₁, P ₂To the data X that needs separately to send ₁, X ₂Carry out precoding processing, obtain signal P to be sent ₁X ₁, P ₂X ₂, and simultaneously signal is sent to first mobile terminal UE 1, second mobile terminal UE 2 and relay station RS.In this case, first mobile terminal UE 1, second mobile terminal UE 2 and relay station RS receive that mixed signal will distinguish shown in following formula (1), (2) and (3):

$Y_1\left(1\right)=h_{11}{P}_1{X}_1+h_{21}{P}_2{X}_2+N_1^1---\left(1\right)$

$Y_2\left(1\right)=h_{22}{P}_2{X}_2+h_{12}{P}_1{X}_1+N_2^1---\left(2\right)$

Y _r＝h _1rP ₁X ₁+h _2rP ₂X ₂+N _r (3)

Wherein,

It is the receiver noise of first time slot, first mobile terminal UE 1;

It is the receiver noise of first time slot, second mobile terminal UE 2; N _rIt is the first time slot relay station RS receiver noise; h ₁₁And h ₁₂Represent the channel of first base station BS, 1 to first mobile terminal UE 1 and second mobile terminal UE 2 respectively; h ₂₁And h ₂₂Represent the channel of second base station BS, 2 to first mobile terminal UE 1 and second mobile terminal UE 2 respectively; h _1rAnd h _2rRepresent the channel of first base station BS 1 and second base station BS 2 to relay station RS respectively.

At second time slot, relay station RS is according to processing array P _R1And P _R2To the mixed signal Y that receives _rHandle, obtain X _r, then, will generate signal and be sent to first mobile terminal UE 1 and second mobile terminal UE 2.Particularly, relay station RS can adopt two kinds of methods that received mixed signal is handled, and comprising: method 1, and amplify and transmit; Method 2 detects and transmits.

Under the situation that adopts the amplification shown in the said method 1 to transmit, the processing array P of relay station RS _R1And P _R2Be identical, be designated as P _rAt this moment, the mixed signal Y of relay station RS to receiving _rAmplify processing, be the mixed signal that receives is multiplied by a power normalization factor-alpha, wherein, the arranging of α can only be satisfied relaying also can consider the power of terminal simultaneously to the restriction of power, realizes the optimal power allocation between portable terminal and the relay station; Utilize processing array P then _r, generate X _r=α P _rY _r, and then with the signal X that generates _rBe broadcast to first mobile terminal UE 1 and second mobile terminal UE 2.In this case, first mobile terminal UE 1 and second mobile terminal UE 2 receive that mixed signal will distinguish shown in following formula (4) and (5):

$Y_1\left(2\right)={\mathrm{\αh}}_{r1}{P}_r{Y}_r+N_1^2---\left(4\right)$

$Y_2\left(2\right)={\mathrm{\αh}}_{r2}{P}_r{Y}_r+N_2^2---\left(5\right)$

Wherein,

It is the receiver noise of second time slot, first mobile terminal UE 1;

It is the receiver noise of second time slot, second mobile terminal UE 2; h _R1And h _R2Represent relay station RS respectively to the channel of first mobile terminal UE 1 and second mobile terminal UE 2.

Also namely, after through two time slots, first mobile terminal UE 1 and second mobile terminal UE 2 have been received two mixed signals respectively, shown in following formula (6) and (7):

$\left\{\begin{array}{c}{Y}_1\left(1\right)=h_{11}{P}_1{X}_1+h_{21}{P}_2{X}_2+N_1^1\\ Y_1\left(2\right)={\mathrm{\αh}}_{r1}{P}_r{h}_{1r}{P}_1{X}_1+{\mathrm{\αh}}_{r1}{P}_r{h}_{2r}{P}_2{X}_2+{\mathrm{\αh}}_{r1}{P}_r{N}_r+N_1^2\end{array}\right.---\left(6\right)$

$\left\{\begin{array}{c}{Y}_2\left(1\right)=h_{22}{P}_2{X}_2+h_{12}{P}_1{X}_1+N_2^1\\ Y_2\left(2\right)={\mathrm{\αh}}_{r2}{P}_r{h}_{2r}{P}_2{X}_2+{\mathrm{\αh}}_{r2}{P}_r{h}_{1r}{P}_1{X}_1+{\mathrm{\αh}}_{r2}{P}_r{N}_r+N_2^2\end{array}\right.---\left(7\right)$

At this moment, first mobile terminal UE 1 and second mobile terminal UE 2 just can be carried out joint-detection to these two mixed signals, for example adopt the least mean-square error detection algorithm, obtain self required data.

Under the situation that adopts the detection shown in the said method 2 to transmit, relay station RS at first carries out noise to the mixed signal from first base station BS 1 and second base station BS 2 that receives at first time slot to be eliminated, for example utilizing the least mean-square error detection algorithm to carry out noise eliminates, and then treat the signal that is forwarded to first mobile terminal UE 1 and second mobile terminal UE 2 respectively according to the processing array of self and handle, the signal after will handling again at last is forwarded to first mobile terminal UE 1 and second mobile terminal UE 2.

Particularly, at first, at first time slot, relay station RS receive from the mixed signal of first base station BS 1 and second base station BS 2 shown in following formula:

At second time slot, relay station RS is to above-mentioned mixed signal Y _rHandle, detect earlier, utilize MMSE to receive detection algorithm, can be in the hope of receiving matrix

So $X_r=W_r\·Y_r=H_r^{+}{(H_r{H}_r^{+}+{\mathrm{\σ}}^{2}I)}^{-1}(H_r\left[\begin{array}{c}{X}_1\\ X_2\end{array}\right]+N_r).$ In the ideal case, MMSE detect can be complete the noise that removes, obtain complete X ₁And X ₂Information, i.e. X _r=[X ₁X ₂] ^TThen, the signal X after relay station RS will detect _r=[X ₁X ₂] ^TMultiply by the processing array P of relay station RS respectively _r=[P _R1P _R2], obtain the signal P that gives portable terminal to be sent _rX _r=[P _R1P _R2] [X ₁X ₂] ^T, be broadcast to first mobile terminal UE 1 and second mobile terminal UE 2 then.In this case, the signal received at second time slot of first mobile terminal UE 1 and second mobile terminal UE 2 can be distinguished shown in the following formula:

$Y_1\left(2\right)=h_{r1}{P}_r{X}_r+N_1^2=h_{r1}{P}_{r1}{X}_1+h_{r1}{P}_{r2}{X}_2+N_1^2$

$Y_2\left(2\right)=h_{r2}{P}_r{X}_r+N_2^2=h_{r2}{P}_{r2}{X}_2+h_{r2}{P}_{r1}{X}_1+N_1^2$

After through two time slots, first mobile terminal UE 1 and second mobile terminal UE 2 have been received two mixed signals respectively, can for example adopt the least mean-square error detection algorithm by the joint-detection to these two mixed signals, obtain self required data.

By above-mentioned analysis as can be seen, no matter which kind of retransmission method relay station RS adopts, and how to determine that the pre-coding matrix of base station and the processing array of relay station RS are to reduce presence of intercell interference, improves the key of Cell Edge User data rate.

In the time of will being described in detail in relay station RS employing distinct methods below, in the above-mentioned steps 103, the CSI that relay station RS reports according to first mobile terminal UE 1 and second mobile terminal UE 2 determines the concrete grammar of the processing array of the pre-coding matrix of first base station BS 1 and second base station BS 2 and relay station RS.

As previously mentioned, when relay station RS adopted the described amplification retransmission method of said method 1, first mobile terminal UE 1 and second mobile terminal UE 2 will be shown in above-mentioned formula (6) and (7) in two mixed signals receiving in two time slots.

After being derived, above-mentioned formula (6) obtains, shown in the following formula of mixed signal (8) that first mobile terminal UE 1 receives in two time slots:

Wherein, Be the equivalent channel matrix of first base station BS 1 to first mobile terminal UE 1 of two time slot channel matrixes after comprehensive, Be the equivalent channel matrix of second base station BS 2 to first mobile terminal UE 1 of two time slot channel matrixes after comprehensive,

Be useful signal,

Be interference signal,

Be noise.

In like manner, after being derived, above-mentioned (7) obtain, shown in the following formula of mixed signal (9) that second mobile terminal UE 2 receives in two time slots:

Wherein,

Be the equivalent channel matrix of first base station BS 1 to second mobile terminal UE 2 of two time slot channel matrixes after comprehensive,

Be the equivalent channel matrix of second base station BS 2 to second mobile terminal UE 2 of two time slot channel matrixes after comprehensive,

Be useful signal,

Be interference signal, Be noise.

According to above-mentioned formula (8), consider channel matrix H ₁, the mean square error of k data flow of first mobile terminal UE 1 can be expressed as $\mathrm{MMSE}{\left(1\right)}_k={\left[{(R_1+{H_1}^{+}{H}_1)}^{-1}\right]}_{\mathrm{kk}}\·{\left[R_{n_1{n}_1}\right]}_{\mathrm{kk}}.$ Wherein ,+operate for matrix being asked conjugate transpose, $R_{n_1{n}_1}=E\left(N_1{H_1}^{+}\right)=\left[\begin{array}{cc}{\mathrm{\δ}}^2& 0\\ 0& (1+{\left|\right|h_{r1}{P}_r\left|\right|}^2){\mathrm{\δ}}^2\end{array}\right],$ δ ²Be the receiving terminal noise power.

Equally, in above-mentioned formula (9), consider channel matrix H ₂, k data flow mean square error of second mobile terminal UE 2 can be expressed as

Wherein, $R_{n_2{n}_2}=E\left(N_2{N_2}^{+}\right)=\left[\begin{array}{cc}{\mathrm{\δ}}^2& 0\\ 0& (1+{\left|\right|h_{r2}{P}_r\left|\right|}^2){\mathrm{\δ}}^2\end{array}\right].$

When portable terminal adopted the least mean-square error detection algorithm that two received mixed signals are carried out Combined Treatment, the optimization objective function of setting was receiving end signal mean square error minimum, namely shown in the following calculating formula (10):

$\underset{P_1,P_2,P_r}{\min }\underset{i=1}{\overset{K}{\mathrm{\Σ}}}\mathrm{MMSE}\left(i\right)$ $\left(10\right)$

$s.t.\mathrm{tr}\{P_i\·P_i^{+}\}\≤b$

$\mathrm{tr}\left\{\right[P_r\·(h_{1r}{P}_1+h_{2r}{P}_2)]\·{[P_r\·(h_{1r}{P}_1+h_{2r}{P}_2)]}^{+}\}+{\mathrm{\δ}}^2{P}_r\·P_r^{+}\}\≤b$

Suppose A ₁=R ₁+ H ₁ ⁺H ₁, utilize matrixing with A ₁Be transformed to

Wherein, a _kBe matrix A ₁K row, a _{K (k)}Be a _kRemove k the vector behind the element, A _{(k ,-k)}Be matrix A ₁Remove the capable and k of k and be listed as remaining matrix.Above-mentioned matrix A has following characteristic: ${\left[A^{-1}\right]}_{\mathrm{ii}}={\left[{\tilde{A}}^{-1}\right]}_{11}={(A_{\mathrm{ii}}-a_{i(-i)}^{+}{\left(A_{(-i,-i)}\right)}^{-1}{a}_{i(-i)})}^{-1}.$

So optimization objective function (10) can be derived as following formula (11):

$\mathrm{MMSE}\left(1\right)+\mathrm{MMSE}\left(2\right)=\left(\frac{{\left[R_{n_1{n}_1}\right]}_{(-k,-k)}+{\left|\right|h_{21}{P}_2\left|\right|}^2+{\left|\right|h_{r1}{P}_r{h}_{2r}{P}_2\left|\right|}^2}{{\left[R_{n_1{n}_1}\right]}_{(-k,-k)}+{\left|\right|h_{11}{P}_1\left|\right|}^2\·{\left|\right|h_{r1}{P}_r{h}_{2r}{P}_2\left|\right|}^2+{\mathrm{\γ}}_1\·{\left|\right|h_{r1}{P}_r{h}_{1r}{P}_1\left|\right|}^2\·{\left|\right|h_{21}{P}_2\left|\right|}^2}\right)$ (11)

$+\left(\frac{{\left[R_{n_2{n}_2}\right]}_{(-k,-k)}+{\left|\right|h_{12}{P}_1\left|\right|}^2+{\left|\right|h_{r2}{P}_r{h}_{1r}{P}_1\left|\right|}^2}{{\left[R_{n_2{n}_2}\right]}_{(-k,-k)}+{\left|\right|H_{22}{P}_2\left|\right|}^2\·{\left|\right|h_{r2}{P}_r{h}_{1r}{P}_1\left|\right|}^2\text{+}{\mathrm{\γ}}_2\·{\left|\right|h_{r2}{P}_r{h}_{2r}{P}_2\left|\right|}^2\·{\left|\right|h_{12}{P}_1\left|\right|}^2}\right)$

Wherein, $r_1=\frac{{\left[R_{n_1{n}_1}\right]}_{(-k,-k)}}{{\left[R_{n_1{n}_1}\right]}_{(k,k)}}.$

And hypothesis $a={\left[R_{n_1{n}_1}\right]}_{\mathrm{kk}}+{\left|\right|h_{11}{P}_1\left|\right|}^2\·{\left|\right|h_{r1}{P}_r{h}_{2r}{P}_2\left|\right|}^2+{\mathrm{\γ}}_1\·{\left|\right|h_{r1}{P}_r{h}_{1r}{P}_1\left|\right|}^2\·{\left|\right|h_{21}{P}_2\left|\right|}^2;$

$b={\left[R_{n_2{n}_2}\right]}_{\mathrm{kk}}+{\left|\right|h_{22}{P}_2\left|\right|}^2\·{\left|\right|h_{r2}{P}_r{h}_{1r}{P}_1\left|\right|}^2+{\mathrm{\γ}}_2\·{\left|\right|h_{r2}{P}_r{h}_{2r}{P}_2\left|\right|}^2\·{\left|\right|h_{12}{P}_1\left|\right|}^2;$ And

$\mathrm{\β}=\frac{a}{a+b};(1-\mathrm{\β})=\frac{b}{a+b}.$

By observing above-mentioned formula (11) as can be seen, finding the solution of above-mentioned optimization objective function is too complicated, be difficult to substantially find the solution, so in the present embodiment optimization objective function that can this is complicated find the solution PROBLEM DECOMPOSITION.Specifically radio honeycomb communication system shown in Figure 1 can be decomposed into as Fig. 3 (a) and two subsystems (b): (Interference cancellation) part is eliminated in broadcast BC (Broadcast) part and interference, the PROBLEM DECOMPOSITION of finding the solution with optimization objective function is two subproblems simultaneously: first subproblem: consider that relay station RS to the link of portable terminal, finds the solution the processing array P of relay station RS _rSecond subproblem: consider base station and relay station RS to the link of portable terminal, find the solution the pre-coding matrix P of place, base station ₁P ₂

For above-mentioned first subproblem, if can pre-determine the pre-coding matrix P of first base station and second base station ₁, P ₂, the problem reduction of finding the solution that then can above-mentioned optimization objective function is the new optimization aim function shown in the following formula (12):

Wherein, T is matrix transpose operation, and vec is for to change matrix into vector operations,

Be the Kronecker product, P is relay station RS processing array P _rVectorization.

Shown in the following formula of vectorization (13) of a m * n matrix M:

A＝vec{M}＝[m ₁₁m ₂₁...m _m1m ₁₂...m _m2...m _1n...m _mn] ^T (13)

In like manner, the matrix of vectorial A turns to shown in the following formula (14):

$M=\mathrm{umvec}\left\{A\right\}=\left[\begin{array}{cccc}{m}_{11}& m_{12}& \·\·\·& m_{1n}\\ m_{21}& m_{22}& \·\·\·& m_{2n}\\ \·& \·& & \·\\ \·& \·& & \·\\ \·& \·& & \·\\ m_{m1}& m_{m2}& \·\·\·& m_{\mathrm{mn}}\end{array}\right]---\left(14\right)$

In addition, the Kronecker product is defined as that the Kronecker of matrix N of the matrix M of a m * n and a p * q is long-pending to be $M\⊗N=\left[m_{\mathrm{ij}}N\right]=\left[\begin{array}{cccc}{m}_{11}N& n_{12}N& \·\·\·& m_{1n}N\\ m_{21}N& m_{22}N& \·\·\·& m_{2n}N\\ \·& \·& & \·\\ \·& \·& & \·\\ \·& \·& & \·\\ m_{n1}N& m_{m2}N& \·\·\·& m_{\mathrm{mn}}N\end{array}\right].$

In above-mentioned formula (12), $H=[(H_{1r}\⊗H_{r1}^T),(H_{2r}\⊗H_{r2}^T)],$ H is SVD decomposes H=USV ^H, the processing array P of relay station RS _rVectorization be exactly the conjugation of last row of above-mentioned U, i.e. P _r=unvec{P}, wherein, * is the Matrix Conjugate operation.So as can be known, at the pre-coding matrix P that determines the base station ₁, P ₂The time, can calculate the processing array P of relay station RS _rParticularly, at the pre-coding matrix P that determines the base station ₁, P ₂The time, can determine the processing array of relay station RS by following formula (15):

P _r＝unvec{P}(15)

Wherein, P=U (:, m) ^*, U (:, m) ^*Represent the conjugation of the m row of U.U obtains H=USV by the SVD decomposition of H ^H, H is the matrix of the capable n row of m, namely P is the conjugation of left singular vector of the minimum singular value correspondence of H, $H={[\mathrm{\β}(h_{2r}{P}_2\⊗{h_{r1}}^T),(1-\mathrm{\β})(h_{1r}{P}_1\⊗{h_{r2}}^T)]}^T,$ $\mathrm{\β}=\frac{a}{a+b};(1-\mathrm{\β})=\frac{b}{a+b},$ $a={\left[R_{n_1{n}_1}\right]}_{\mathrm{kk}}+{\left|\right|h_{11}{P}_1\left|\right|}^2\·{\left|\right|h_{r1}{P}_r{h}_{2r}{P}_2\left|\right|}^2+{\mathrm{\γ}}_1\·{\left|\right|h_{r1}{P}_r{h}_{1r}{P}_1\left|\right|}^2\·{\left|\right|h_{21}{P}_2\left|\right|}^2,$ $b={\left[R_{n_2{n}_2}\right]}_{\mathrm{kk}}+{\left|\right|h_{22}{P}_2\left|\right|}^2\·{\left|\right|h_{r2}{P}_r{h}_{1r}{P}_1\left|\right|}^2+{\mathrm{\γ}}_2\·{\left|\right|h_{r2}{P}_r{h}_{2r}{P}_2\left|\right|}^2\·{\left|\right|h_{12}{P}_1\left|\right|}^2,$ T is the matrix transpose operation,

Be the Kronecker product, unvec is the vector matrix computing,

With

It is the noise variance matrix $R_{n_1{n}_1}=E\left(N_1{N_1}^{+}\right)=\left[\begin{array}{cc}{\mathrm{\δ}}^2& 0\\ 0& (1+{\left|\right|h_{r1}{P}_r\left|\right|}^2){\mathrm{\δ}}^2\end{array}\right],$ $R_{n_2{n}_2}=E\left(N_2{N_2}^H\right)=\left[\begin{array}{cc}{\mathrm{\δ}}^2& 0\\ 0& (1+{\left|\right|H_{r2}{P}_r\left|\right|}^2){\mathrm{\δ}}^2\end{array}\right],$ δ ²Be the receiving terminal noise power, [R] _KkThe element that the capable k of representing matrix k lists, k represents k data flow; $r_1=\frac{{\left[R_{n_1{n}_1}\right]}_{22}}{{\left[R_{n_1{n}_1}\right]}_{11}},$ $r_2=\frac{{\left[R_{n_2{n}_2}\right]}_{22}}{{\left[R_{n_2{n}_2}\right]}_{11}}.$

For above-mentioned second subproblem, finding the solution base station pre-coding matrix P ₁, P ₂The time, suppose w _kBe the reprocessing matrix of k portable terminal, suppose that received signal power is 1, i.e. E{xk xk '=1, receiving terminal mean square error MSE covariance matrix can be shown in following formula (16) so.

${\mathrm{\ϵ}}_k=E\left\{(x_k-w_k{y}_k){(x_k-w_k{y}_k)}^{+}\right\}$

$=I-P_k^{+}{h}_{\mathrm{kk}}^{+}{w}_k^{+}-w_k{h}_{\mathrm{kk}}{P}_k+---\left(16\right)$

$w_k{h}_{\mathrm{kk}}{P}_k{P}_k^{+}{h}_{\mathrm{kk}}^{+}{w}_k^{+}+\underset{l\≠k}{\mathrm{\Σ}}{w}_k{h}_{\mathrm{kl}}{P}_l{P}_l^{+}{h}_{\mathrm{kl}}^{+}{w}_k^{+}+w_k{R}_k{w}_k^{+}$

Wherein,

$R_k=R_{n_1{n}_1}+\underset{l\≠k}{\mathrm{\Σ}}{h}_{\mathrm{kl}}{P}_l{P}_l^T{h}_{\mathrm{kl}}^T.$

In this case, the problem of finding the solution of above-mentioned optimization objective function can be reduced to the first new optimization aim shown in the following formula (17):

$\min \underset{k=1}{\overset{2}{\mathrm{\Σ}}}\mathrm{Tr}\left\{E\right[(x_k-w_k{y}_k){(x_k-w_k{y}_k)}^{+}\left]\right\}---\left(17\right)$

$s.t.\mathrm{Tr}\left\{P_k^{+}{P}_k\right\}=b$

Utilize Lagrangian that above-mentioned formula (17) is found the solution and can obtain following formula (18):

$J\left(\right\{P_k,{\mathrm{\λ}}_k\left\}\right)=\underset{k=1}{\overset{2}{\mathrm{\Σ}}}\mathrm{Tr}\left\{{\mathrm{\ϵ}}_k\right\}-{\mathrm{\λ}}_k\left(\mathrm{Tr}\right\{P_k^T{P}_k\}-b)---\left(18\right)$

Pass through above-mentioned formula (18) differentiate again, and order

Just can find the solution and obtain:

${\mathrm{\λ}}_k=\underset{l\≠k}{\mathrm{\Σ}}\mathrm{Tr}\left\{w_l{h}_{\mathrm{lk}}{P}_k{\left(w_l{h}_{\mathrm{lk}}{P}_k\right)}^T\right\}-\underset{l\≠k}{\mathrm{\Σ}}\mathrm{Tr}\left\{w_k{h}_{\mathrm{kl}}{P}_l{\left(w_k{h}_{\mathrm{kl}}P\right)}^T\right\}-\left(\mathrm{Tr}\right\{w_k{R}_{n_k}{w}_k\left\}\right)---\left(19\right)$

$P_k={(\underset{l=1}{\overset{K}{\mathrm{\Σ}}}{h}_{\mathrm{lk}}^{+}{w}_l^{+}{w}_l{h}_{\mathrm{lk}}-\frac{1}{b}(\left(\underset{l\≠k}{\mathrm{\Σ}}\mathrm{Tr}\right\{J_l^{\left(k\right)}\}-\mathrm{Tr}\{J_k^{\left(l\right)}\left\}\right)-\mathrm{Tr}\{w_k{R}_{n_1{n}_1}{w}_k^{+}\left\}\right)I)}^{-1}{h}_{\mathrm{kk}}^{+}{w}_k^{+}---\left(20\right)$

Wherein, K represents the number of receiving terminal,

Be the noise variance matrix, definition is the same ,+be the conjugate transpose operation of matrix, Tr is that the mark of asking of matrix is operated, b is the maximum transmit power of first base station and second base station.

Can be seen by above analysis, finding the solution first subproblem, namely find the solution P _rThe time, need to determine P ₁, P ₂Value, and finding the solution second subproblem, namely find the solution P ₁, P ₂The time, need to determine P _rValue, therefore, present embodiment has provided a kind of iterative algorithm can find the solution optimal solution, this iterative algorithm mainly comprises the steps: as shown in Figure 4

Step 201 is to h ₁₁Carry out SVD and decompose, will lead right singular vector and be set at the first base station pre-coding matrix initial p ₁, to h ₂₂Carry out SVD and decompose, will lead right singular vector and be set at the second base station pre-coding matrix initial value P ₂

Step 202 is determined the processing array P of relay station RS according to above-mentioned formula (15) _r

Step 203 is determined the pre-coding matrix P of first base station and second base station according to above-mentioned formula (20) ₁, P ₂

Step 204 is judged the processing array P of determined relay station RS _rAnd the pre-coding matrix P of first base station and second base station ₁, P ₂Whether restrain, if then obtain the processing array P of relay station RS _rAnd the pre-coding matrix P of first base station and second base station ₁, P ₂Optimal solution, and finish this iterative algorithm; Otherwise, return step 202.

By above-mentioned iterative algorithm, can obtain the processing array P of relay station RS _rAnd the pre-coding matrix P of first base station and second base station ₁, P ₂Optimal solution.And, can determine that by emulation under 90% above situation, iterations can not surpass the processing array P of 10 relay station RS _rAnd the pre-coding matrix P of first base station and second base station ₁, P ₂Just can restrain.

Because above-mentioned algorithm need carry out repeatedly iteration, amount of calculation is higher relatively, so embodiments of the invention have also proposed a kind of heuritic approach of simplification.It is two subproblems that this method is found the solution optimization objective function PROBLEM DECOMPOSITION equally, namely at the pre-coding matrix P that determines the base station ₁, P ₂Situation under find the solution the processing array P of relay station RS _rAnd at the processing array P that determines relay station RS _rSituation under find the solution the pre-coding matrix P of base station ₁, P ₂Wherein, finding the solution of first subproblem can namely utilize formula (15) to finish with reference to said method.To describe the method for solving of second subproblem below in detail.

Two the mixed signal expression formulas (8) that in two time slots, received by first mobile terminal UE 1 and second mobile terminal UE 2 and (9) as can be seen, at equivalent matrix

In, if determine the processing array P of relay station RS _rValue, just the complicated interference channel that contains relay station RS can be reduced to common multiple-input and multiple-output (MIMO) interference channel, then to equivalent channel matrix

Carry out SVD and decompose, the right singular vector of the master who obtains is as the pre-coding matrix P of first base station ₁, right again

Carry out SVD and decompose, the right singular vector of the master who obtains is as the pre-coding matrix P of second base station ₂Namely can be at first to equivalent channel matrix

With

Carry out SVD and decompose the pre-coding matrix P that determines the base station ₁And P ₂, determine the processing array P of relay station then according to formula (15) _r

When relay station RS adopts the described detection retransmission method of said method 2, two mixed signals that first mobile terminal UE 1 receives can following formula (21) shown in:

Wherein, H _P1Be the equivalent channel matrix of first base station BS 1 to first mobile terminal UE 1 of two time slot channel matrixes after comprehensive, G _P1Be the equivalent channel matrix of second base station BS 2 to first mobile terminal UE 1 of two time slot channel matrixes after comprehensive, H _P1P ₁X ₁Be useful signal, G _P1P ₂X ₂Be interference signal, first mobile terminal UE 1 can be regarded interference signal as noise and handles, and also interference signal can be handled as useful signal.

In like manner, two mixed signals receiving of second mobile terminal UE 2 can following formula (22) shown in:

Wherein, H _P2Be the equivalent channel matrix of first base station BS 1 to first mobile terminal UE 1 of two time slot channel matrixes after comprehensive, G _P2Be the equivalent channel matrix of second base station BS 2 to first mobile terminal UE 1 of two time slot channel matrixes after comprehensive, H _P2P ₂X ₂Be useful signal, G _P2P ₁X ₁Be interference signal, second mobile terminal UE 2 can be regarded interference signal as noise and handles, and also interference signal can be handled as useful signal.

In this case, the optimization aim of receiving terminal is maximization receiving terminal Signal to Interference plus Noise Ratio sum, since too complicated to finding the solution of optimization objective function, therefore, in the present embodiment, also adopt the heuritic approach of simplifying to find the solution the processing array P of relay station RS _rAnd the pre-coding matrix P of base station ₁, P ₂

Employing is transmitted the mode of similarly finding the solution with above-mentioned amplification, introduces matrixing, finds the solution to obtain shown in the following formula of target function (23): (maximization receiving terminal Signal to Interference plus Noise Ratio sum)

$\underset{\{P_1,P_2,P_{r1},P_{r2}\}}{\max }\frac{{\left|\right|h_{11}{P}_1\left|\right|}^2+{\left|\right|h_{r1}{P}_{r1}\left|\right|}^2}{{\mathrm{\δ}}^2+{\left|\right|h_{21}{P}_2\left|\right|}^2+{\left|\right|h_{r1}{P}_{r2}\left|\right|}^2}+\frac{{\left|\right|h_{22}{P}_2\left|\right|}^2+{\left|\right|h_{r2}{P}_{r2}\left|\right|}^2}{{\mathrm{\δ}}^2+{\left|\right|h_{12}{P}_1\left|\right|}^2+{\left|\right|h_{r2}{P}_{r1}\left|\right|}^2}---\left(23\right)$

Can find P by observing above-mentioned formula (23) ₁, P ₂, P _R1, P _R2Only relevant with relevant channel separately, not influence each other, therefore, can adopt the method for traversal to propose a kind of simple searching algorithm and try to achieve optimal solution, also namely in the hunting zone of pre-coding matrix search satisfy the pre-coding matrix P of first base station and second base station of formula (23) ₁, P ₂Processing array P with relay station _R1, P _R2Following table 1 has shown the hunting zone of each pre-coding matrix.As shown in table 1 below, travel through the scope shown in the following table 1, be met the P of above-mentioned formula (23) ₁, P ₂, P _R1, P _R2

Table 1

Corresponding above-mentioned data transmission method, embodiments of the invention also provide the relay station of carrying out said method, and its internal structure mainly comprises as shown in Figure 5:

Channel condition information receiving element 501 for the channel condition information that receives first mobile terminal reporting from first base station, receives the channel condition information of second mobile terminal reporting from second base station;

Matrix determining unit 502 is used for determining the pre-coding matrix of first base station and second base station and the processing array of relay station according to the channel condition information of first portable terminal and second mobile terminal reporting;

Matrix notification unit 503 is used for first base station that will determine and the pre-coding matrix of second base station and the processing array of relay station and is notified to first base station and second base station respectively; And

Retransmission unit 504 be used for according to the processing array of relay station the mixed signal from first base station and second base station that receives being handled, and the signal after will handling is sent to first portable terminal and second portable terminal.

In addition, embodiments of the invention also provide the execution system for carrying out said process, and its structure can be with reference to figure 1.This system mainly comprises: the first adjacent base station and second base station, be positioned over the relay station between first base station and second base station, second portable terminal that is positioned at first portable terminal of first base station range and is positioned at second base station range; Wherein,

First portable terminal reports first base station BS, 1, the second portable terminal with self channel status indication information self channel condition information is reported second base station;

Relay station is notified with the channel condition information of first portable terminal and second mobile terminal reporting respectively in first base station and second base station;

Relay station is determined the pre-coding matrix of first base station and second base station and the processing array of relay station according to the channel condition information of first portable terminal and second mobile terminal reporting, and the processing array of the pre-coding matrix of first base station that will determine and relay station notifies first base station, and notifies second base station with the pre-coding matrix of second base station and the processing array of relay station;

First portable terminal is notified with self pre-coding matrix and relay station processing array in first base station, and second portable terminal is notified with self pre-coding matrix and relay station processing array in second base station;

At first time slot, first base station is treated the data that are sent to first portable terminal according to the pre-coding matrix of self and is carried out precoding, and the data after precoding are sent to relay station and first portable terminal and second portable terminal, second base station is treated the data that are sent to second portable terminal according to the pre-coding matrix of self and is carried out precoding, and the data after precoding are sent to relay station and first portable terminal and second portable terminal;

At second time slot, relay station is handled the mixed signal from first base station and second base station that receives according to the processing array of self, and the mixed signal after will handling is broadcast to first portable terminal and second portable terminal; And

First portable terminal and second portable terminal carry out joint-detection according to the pre-coding matrix of base station and the processing array of relay station to the mixed signal that receives respectively in first time slot and second time slot, demodulation obtains self required data.

From the described data transmission method of the embodiment of the invention and relay station as can be seen, because present embodiment has been introduced relay station RS between adjacent base station, and adopt the data transmission scheme of two time slots, therefore, can reduce the interference of minizone effectively, improve the particularly data rate of Cell Edge User of user.In addition, because in the embodiments of the invention, taken into full account interference signal when the processing array of the pre-coding matrix of determining the base station and relay station, making an uproar than sum with least mean-square error or maximum Shinkansen is optimum target, thereby can obtain extraordinary transfer of data effect.

In addition, need to prove, though embodiments of the invention all are to be that example describes with the model of placing relay station between two adjacent base stations, but, those skilled in the art will appreciate that method of the present invention and relay station, can also be applied in other models, for example, be applied between three adjacent base stations, place in the model of a relay station.Fig. 6 has shown the basic structure of cell mobile communication systems under this application.In this model, user's channel condition information is determined the pre-coding matrix of these three base stations and the processing array of self in its coverage that relay station can report according to three base stations that are adjacent, and notifies each user in each base station range with the pre-coding matrix of the base station self determined and the processing array of self by the base station.And relay station adopts the described method of present embodiment that the mixed signal that receives is handled, and then is broadcast to each user after the mixed signal that receives from each adjacent base station.Like this, each user just can carry out joint-detection to the mixed signal that successively receives according to the pre-coding matrix of its serving BS and the processing array of relay station in two time slots, obtain self required signal, has reduced the interference of minizone effectively.

The above only is preferred embodiment of the present invention, and is in order to limit the present invention, within the spirit and principles in the present invention not all, any modification of making, is equal to replacement, improvement etc., all should be included within the scope of protection of the invention.

Claims (9)

1. a data transmission method is characterized in that, comprising:

Relay station receives the channel condition information that channel condition information that first portable terminal reports by first base station and second portable terminal report by second base station;

Relay station is determined the pre-coding matrix of first base station and second base station and the processing array of relay station according to the channel condition information of first portable terminal and second mobile terminal reporting;

The pre-coding matrix of first base station that relay station will be determined and the processing array of relay station are notified first base station, and notify second base station with the pre-coding matrix of second base station and the processing array of relay station;

At first time slot, relay station receives from first base station and second signal of base station; And

At second time slot, relay station is handled the signal that receives, and the mixed signal after will handling is broadcast to first portable terminal and second portable terminal; Wherein,

The pre-coding matrix of the base station that first portable terminal and second portable terminal are determined according to relay station respectively and the processing array of relay station carry out joint-detection to what receive at first time slot from first base station and second signal of base station and at the signal from relay station that second time slot receives, and demodulation obtains self required data.

2. data transmission method according to claim 1 is characterized in that, described relay station is handled the signal that receives and comprised: relay station amplifies to transmit to the signal that receives to be handled.

3. data transmission method according to claim 2 is characterized in that, described relay station comprises according to determine first base station and the pre-coding matrix of second base station and the processing array of relay station of first portable terminal and second mobile terminal reporting:

A is to h ₁₁Carry out SVD and decompose, will lead right singular vector and be set at the first base station pre-coding matrix initial value P ₁, to h ₂₂Carry out SVD and decompose, will lead right singular vector and be set at the second base station pre-coding matrix initial value P ₂, wherein, h ₁₁Represent first base station to the channel of first portable terminal; h ₂₂Represent second base station to the channel of second portable terminal;

B determines the processing array P of relay station according to following formula _r:

P _r＝unvec{P}

Wherein, P=U (:, m) ^*, U (:, m) ^*Represent the conjugation of the m row of U, U obtains H=USV by the SVD decomposition of H ^H, H is the matrix of the capable n row of m, namely P is the conjugation of left singular vector of the minimum singular value correspondence of H, $H={[\mathrm{\β}(h_{2r}{P}_2\⊗{h_{r1}}^T),(1-\mathrm{\β})(h_{1r}{P}_1\⊗{h_{r2}}^T)]}^T,$ $\mathrm{\β}=\frac{a}{a+b};(1-\mathrm{\β})=\frac{b}{a+b},$ $a={\left[R_{n_1{n}_1}\right]}_{\mathrm{kk}}+{\left|\right|h_{11}{P}_1\left|\right|}^2\·{\left|\right|h_{r1}{P}_r{h}_{2r}{P}_2\left|\right|}^2+{\mathrm{\γ}}_1\·{\left|\right|h_{r1}{P}_r{h}_{1r}{P}_1\left|\right|}^2\·{\left|\right|h_{21}{P}_2\left|\right|}^2,$ $b={\left[R_{n_2{n}_2}\right]}_{\mathrm{kk}}+{\left|\right|h_{22}{P}_2\left|\right|}^2\·{\left|\right|h_{r2}{P}_r{h}_{1r}{P}_1\left|\right|}^2+{\mathrm{\γ}}_2\·{\left|\right|h_{r2}{P}_r{h}_{2r}{P}_2\left|\right|}^2\·{\left|\right|h_{12}{P}_1\left|\right|}^2,$ T is the matrix transpose operation,

Be the Kronecker product, unvec is the vector matrix computing,

With

It is the noise variance matrix $R_{n_1{n}_1}=E\left(N_1{N_1}^{+}\right)=\left[\begin{array}{cc}{\mathrm{\δ}}^2& 0\\ 0& (1+{\left|\right|h_{r1}{P}_r\left|\right|}^2){\mathrm{\δ}}^2\end{array}\right],$ $R_{n_2{n}_2}=E\left(N_2{N_2}^H\right)=\left[\begin{array}{cc}{\mathrm{\δ}}^2& 0\\ 0& (1+{\left|\right|H_{r2}{P}_r\left|\right|}^2){\mathrm{\δ}}^2\end{array}\right],$ δ ²Be the receiving terminal noise power, [R] _KkThe element that the capable k of representing matrix k lists, k represents k data flow, h ₁₁And h ₁₂Represent first base station respectively to the channel of first portable terminal and second portable terminal; h ₂₁And h ₂₂Represent second base station respectively to the channel of first portable terminal and second portable terminal; h _1rAnd h _2rRepresent first base station and second base station respectively to the channel of relay station; h _R1And h _R2Represent relay station respectively to the channel of first portable terminal and second portable terminal;

C determines the pre-coding matrix P of first base station and second base station according to following formula ₁, P ₂:

$P_k={(\underset{l=1}{\overset{K}{\mathrm{\Σ}}}{h}_{\mathrm{lk}}^{+}{w}_l^{+}{w}_l{h}_{\mathrm{lk}}-\frac{1}{b}(\left(\underset{l\≠k}{\mathrm{\Σ}}\mathrm{Tr}\right\{J_l^{\left(k\right)}\}-\mathrm{Tr}\{J_k^{\left(l\right)}\left\}\right)-\mathrm{Tr}\{w_k{R}_{n_k{n}_k}{w}_k^{+}\left\}\right)I)}^{-1}{h}_{\mathrm{kk}}^{+}{w}_k^{+}$

Wherein,

K represents the number of receiving terminal, Be the noise variance matrix, define the same ,+be the conjugate transpose operation of matrix, Tr be matrix ask the mark operation, b is the maximum transmit power of first base station and second base station.

D judges the processing array P of determined relay station _rAnd the pre-coding matrix P of base station ₁, P ₂Whether restrain, if then obtain the processing array P of relay station _rAnd the pre-coding matrix P of base station ₁, P ₂Optimal solution; Otherwise, return B.

4. data transmission method according to claim 2 is characterized in that, described relay station comprises according to determine first base station and the pre-coding matrix of second base station and the processing array of relay station of first portable terminal and second mobile terminal reporting:

To equivalent channel matrix Carry out SVD and decompose, the right singular vector of the master who obtains is as the pre-coding matrix P of first base station ₁Right

Carry out SVD and decompose, the right singular vector of the master who obtains is as the pre-coding matrix P of second base station ₂And determine the processing array P of relay station according to following formula _r:

P _r＝unvec{P}

Wherein, P=U (:, m) ^*, U (:, m) ^*Represent the conjugation of the m row of U, U obtains H=USV by the SVD decomposition of H ^H, H is the matrix of the capable n row of m, namely P is the conjugation of left singular vector of the minimum singular value correspondence of H, $H={[\mathrm{\β}(h_{2r}{P}_2\⊗{h_{r1}}^T),(1-\mathrm{\β})(h_{1r}{P}_1\⊗{h_{r2}}^T)]}^T,$ $\mathrm{\β}=\frac{a}{a+b};(1-\mathrm{\β})=\frac{b}{a+b},$ $a={\left[R_{n_1{n}_1}\right]}_{\mathrm{kk}}+{\left|\right|h_{11}{P}_1\left|\right|}^2\·{\left|\right|h_{r1}{P}_r{h}_{2r}{P}_2\left|\right|}^2+{\mathrm{\γ}}_1\·{\left|\right|h_{r1}{P}_r{h}_{1r}{P}_1\left|\right|}^2\·{\left|\right|h_{21}{P}_2\left|\right|}^2,$ $b={\left[R_{n_2{n}_2}\right]}_{\mathrm{kk}}+{\left|\right|h_{22}{P}_2\left|\right|}^2\·{\left|\right|h_{r2}{P}_r{h}_{1r}{P}_1\left|\right|}^2+{\mathrm{\γ}}_2\·{\left|\right|h_{r2}{P}_r{h}_{2r}{P}_2\left|\right|}^2\·{\left|\right|h_{12}{P}_1\left|\right|}^2,$ T is the matrix transpose operation,

Be the Kronecker product, unvec is the vector matrix computing,

With

It is the noise variance matrix $R_{n_1{n}_1}=E\left(N_1{N_1}^{+}\right)=\left[\begin{array}{cc}{\mathrm{\δ}}^2& 0\\ 0& (1+{\left|\right|h_{r1}{P}_r\left|\right|}^2){\mathrm{\δ}}^2\end{array}\right],$ $R_{n_2{n}_2}=E\left(N_2{N_2}^H\right)=\left[\begin{array}{cc}{\mathrm{\δ}}^2& 0\\ 0& (1+{\left|\right|H_{r2}{P}_r\left|\right|}^2){\mathrm{\δ}}^2\end{array}\right],$ δ ²Be the receiving terminal noise power, [R] _KkThe element that the capable k of representing matrix k lists, k represents k data flow, $r_1=\frac{{\left[R_{n_1{n}_1}\right]}_{22}}{{\left[R_{n_1{n}_1}\right]}_{11}},$ $r_2=\frac{{\left[R_{n_2{n}_2}\right]}_{22}}{{\left[R_{n_2{n}_2}\right]}_{11}},$ ${\tilde{H}}_{11}=\left[\begin{array}{c}{h}_{11}\\ {\mathrm{\αh}}_{r1}{P}_r{h}_{1r}\end{array}\right],$ ${\tilde{H}}_{22}=\left[\begin{array}{c}{h}_{22}\\ {\mathrm{\αh}}_{r2}{P}_r{h}_{2r}\end{array}\right],$ h ₁₁And h ₁₂Represent first base station respectively to the channel of first portable terminal and second portable terminal; h ₂₁And h ₂₂Represent second base station respectively to the channel of first portable terminal and second portable terminal; h _1rAnd h _2rRepresent first base station and second base station respectively to the channel of relay station; h _R1And h _R2Represent relay station respectively to the channel of first portable terminal and second portable terminal.

5. data transmission method according to claim 1 is characterized in that, described relay station is handled the signal that receives and comprised: relay station detects earlier to do to transmit to the signal that receives again and handles.

6. data transmission method according to claim 5 is characterized in that, described relay station comprises according to determine first base station and the pre-coding matrix of second base station and the processing array of relay station of first portable terminal and second mobile terminal reporting:

The pre-coding matrix P of first base station and second base station of following formula is satisfied in search in the hunting zone of pre-coding matrix ₁, P ₂Processing array P with relay station _R1, P _R2:

$\underset{\{P_1,P_2,P_{r1},P_{r2}\}}{\max }\frac{{\left|\right|h_{11}{P}_1\left|\right|}^2+{\left|\right|h_{r1}{P}_{r1}\left|\right|}^2}{{\mathrm{\δ}}^2+{\left|\right|h_{21}{P}_2\left|\right|}^2+{\left|\right|h_{r1}{P}_{r2}\left|\right|}^2}+\frac{{\left|\right|h_{22}{P}_2\left|\right|}^2+{\left|\right|h_{r2}{P}_{r2}\left|\right|}^2}{{\mathrm{\δ}}^2+{\left|\right|h_{12}{P}_1\left|\right|}^2+{\left|\right|h_{r2}{P}_{r1}\left|\right|}^2}$

Wherein, h ₁₁And h ₁₂Represent first base station respectively to the channel of first portable terminal and second portable terminal; h ₂₁And h ₂₂Represent second base station respectively to the channel of first portable terminal and second portable terminal; h _R1And h _R2Represent relay station respectively to the channel of first portable terminal and second portable terminal; δ ²Be the receiving terminal noise power.

7. data transmission method according to claim 6 is characterized in that, the hunting zone of described pre-coding matrix comprises:

The first base station pre-coding matrix P ₁The hunting zone be h ₁₁Carry out first row and the h of the right singular matrix V after SVD decomposes ₁₂Carry out last row of the right singular matrix V after SVD decomposes;

The second base station pre-coding matrix P ₂The hunting zone be h ₂₂Carry out first row and the h of the right singular matrix V after SVD decomposes ₂₁Carry out last row of the right singular matrix V after SVD decomposes;

Relay station processing array P _R1The hunting zone be h _R1Carry out first row and the h of the right singular matrix V after SVD decomposes _R2Carry out last row of the right singular matrix V after SVD decomposes; And

Relay station processing array P _R2The hunting zone be h _R2Carry out first row and the h of the right singular matrix V after SVD decomposes _R1Carry out last row of the right singular matrix V after SVD decomposes.

8. a relay station is characterized in that, comprising:

The channel condition information receiving element for the channel condition information that receives first mobile terminal reporting from first base station, receives the channel condition information of second mobile terminal reporting from second base station;

The matrix determining unit is used for determining the pre-coding matrix of first base station and second base station and the processing array of relay station according to the channel condition information of first portable terminal and second mobile terminal reporting;

The matrix notification unit is used for first base station that will determine and the pre-coding matrix of second base station and the processing array of relay station and is notified to first base station and second base station respectively; And

Retransmission unit be used for according to the processing array of relay station the mixed signal from first base station and second base station that receives being handled, and the signal after will handling is sent to first portable terminal and second portable terminal.

9. data transmission system comprises:

The first adjacent base station and second base station, be positioned over the relay station between first base station and second base station, second portable terminal that is positioned at first portable terminal of first base station range and is positioned at second base station range; Wherein,

First portable terminal reports first base station BS, 1, the second portable terminal with self channel status indication information self channel condition information is reported second base station;

Relay station is notified with the channel condition information of first portable terminal and second mobile terminal reporting respectively in first base station and second base station;

Relay station is determined the pre-coding matrix of first base station and second base station and the processing array of relay station according to the channel condition information of first portable terminal and second mobile terminal reporting, and the processing array of the pre-coding matrix of first base station that will determine and relay station notifies first base station, and notifies second base station with the pre-coding matrix of second base station and the processing array of relay station;

First portable terminal is notified with self pre-coding matrix and relay station processing array in first base station, and second portable terminal is notified with self pre-coding matrix and relay station processing array in second base station;

At first time slot, first base station is treated the data that are sent to first portable terminal according to the pre-coding matrix of self and is carried out precoding, and the data after precoding are sent to relay station and first portable terminal and second portable terminal, second base station is treated the data that are sent to second portable terminal according to the pre-coding matrix of self and is carried out precoding, and the data after precoding are sent to relay station and first portable terminal and second portable terminal;

At second time slot, relay station is handled the mixed signal from first base station and second base station that receives according to the processing array of self, and the mixed signal after will handling is broadcast to first portable terminal and second portable terminal; And

First portable terminal and second portable terminal carry out joint-detection according to the pre-coding matrix of base station and the processing array of relay station to the mixed signal that receives respectively in first time slot and second time slot, demodulation obtains self required data.

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