WO2009003423A1 - Method for channel state information feedback and wireless transceiver - Google Patents

Abstract

A method for channel state information feedback and a wireless transceiver in wireless communication field are disclosed. At least two codebooks generated in different rules are used. Receiver selects the pre-code matrix composition, which is the most suitable for the current channel state from codebooks, and then the pre-code matrix composition is sent to transmitter in limited bit feedback. It can improve capability of pre-code process without increasing feedback information quantity, and save the storage space of saving codebooks. A main codebook and an assistant codebook may be used, the assistant codebook can be looked upon a increased disturbance based on the main codebook. The main codebook can be generated in method well known in the art, the assistant codebook can be generated based on Fourier matrix or expand rotation matrix.

Description

 Channel state information feedback method and wireless transceiver

The present invention relates to the field of wireless communications, and in particular, to channel state information feedback techniques. BACKGROUND OF THE INVENTION At present, the application of Multi-Input Multi-Output (MIMO) technology in wireless communication systems is receiving more and more attention, both from the perspective of increasing system capacity and improving system performance. MIMO has its irreplaceable advantages. MIMO is mainly divided into two categories, one is spatial diversity technology for the purpose of maximizing diversity gain, and the other is space division multiplexing technology for the purpose of maximizing data rate. A system based on MIMO spatial division multiplexing technology can significantly improve the spectrum utilization of a system by simultaneously transmitting multiple independent data streams, but the space division multiplexing system is very sensitive to poor channel conditions. For this problem, a more effective way is to first adaptively adjust the number of independent data streams that need to be sent so as not to be larger than the smaller of the number of received antennas and the number of transmitting antennas, and dynamically change according to the rank of the current channel matrix. At the same time, the transmitted data stream is precoded or beamformed, and the design or selection of the precoding matrix or the transmit beam needs to utilize channel information. The basic idea of the precoding system is to design the signal transmission mode by analyzing some form of channel information known by the transmitting end, so that the transmitted signal can adapt to the characteristic structure of the channel matrix, so that the mutual interference between the independent data streams is as small. The precoding system design can utilize different forms of channel information and is designed according to different criteria. When the transmitting end has accurately learned the current channel state information ("CSI"), the precoding system can obtain the maximum gain. In a wireless communication system using Time Division Duplex ("TDD"), when data is transmitted and received It is ensured that during the appropriate ping-pong time, the estimated value of the channel in the receiving mode can be used to estimate the transmission channel, that is, the transmitting end may obtain relatively accurate channel state information, but in frequency division duplex (Frequency

In a wireless communication system of Division Duplex ("FDD"), channel state information can only be transmitted from the receiving end to the transmitting end through the feedback channel. However, since the MIMO channel matrix contains a plurality of parameters, the transmission of these channel parameters exceeds the loadability of the limited feedback channel. Therefore, the manner in which the channel state information is transmitted from the receiving end to the transmitting end through the feedback channel is not feasible in the limited feedback system. Therefore, in order to reduce the amount of feedback information, one of the more effective methods is to adopt a scheme based on precoding matrix or beam codebook, called limited feedback precoding, and the idea is to design a set of available precoding according to the statistical characteristics of the channel. The matrix or the beam vector constitutes a codebook, and the codebook is known at both the transmitting end and the receiving end, and the receiving end selects one codeword in the codebook according to the estimated channel matrix and a certain performance criterion to be used as a pre- The coding matrix or beam vector is fed back to the sender at the sequence number in the codebook. The design of the codebook is a very important part in the design of the precoding system. The design method of the skeleton time constellation proposed by Hochwald et al. It should be noted that, in order to achieve simplicity, each element in the pre-encoded codebook, ie, the codeword F, F _e c ^M ' ^rf satisfies ι^Γ = ΐκ , that is, the precoding matrix F is a matrix orthogonally normalized by columns. Each column acts as a bearer beam for an independent data stream. Specifically, it is assumed that the system can feed back the bits for precoding design. If the precoding codebook is used, the codebook is composed of N = 2 ^S precoding matrices. If each precoding matrix in the codebook (if M = 1 , the matrix degenerates into a beam) is regarded as a subspace formed by columns (if the codeword is degraded into beams, each beam can be regarded as a Line), so the design of the codebook is equivalent to a subspace (or line) stacking process, its goal is to maximize the minimum distance between different subspaces, this method is called Grassmannian subspace stacking, method.

The key to the Grassmannian subspace stacking method is how to define two different subspaces. The distance, theoretical analysis shows that, according to the different codeword selection criteria adopted by the system and the specific receiver model, different subspace distance definitions should be used when designing the codebook. The following is a brief introduction to the various standard codeword selection criteria and the corresponding distance definitions.

(1) Assuming that the receiver uses the maximum likelihood receiver, the system selects a precoding matrix from the codebook to maximize the minimum distance of the received symbol vector (MD Selection) or maximize the instantaneous capacity.

(2) Assuming that the receiver uses a zero-forcing ZF linear receiver, the system selects a precoding matrix from the codebook to maximize the minimum singular value of the equivalent channel matrix HF (SV Selection).

(3) 4 The receiver uses a minimum mean-square error (MMSE) receiver, and the system selects a precoding matrix from the codebook to make the trace of the mean square error matrix (MMSE-trace). Selection ) or MMSE-det Selection is minimized. The specific definitions of the above various codeword selection criteria are shown in Table 1.

Table 1 According to the above different codeword selection criteria, the following codebook design criteria can be obtained: (1) When ? = oo, it is equivalent to all channel state information known to the transmitting end. At this time, the optimal precoding matrix is composed of the feature vectors corresponding to the M largest eigenvalues of the matrix H ^ff H . If eigenvalue decomposition is performed on H ^ff H, the following form is obtained:

, 则最优预编码矩阵 为：

H = V _H D _H (1 ) where D _H

, then the optimal precoding matrix is:

Where Ϋ _Η denotes a matrix consisting of the first M columns of v _H .

( 3 ) (2) In the limited feedback system, assume ? = l. g ₂ (N). If the determinant is used to achieve the minimum or capacity selection criteria, the codebook design goal is to maximize the distance: min^^^W^.), where (F _;, F) represents the two formed by the matrix _F; The Fribini-Study distance between subspaces is defined as follows: d _FS F _i , Fj)

(3)

(3) Limited feedback system If MMSE-trace, SV or MD codeword selection criteria are used, the codebook design objective is to maximize the distance: _m i _{ni ≤; < ≤ A} ^ ₂ (F _; , F ), where ₂ (F _;, F) represents the projected two-norm distance between the two subspaces formed by the matrix F _; and F., which are defined as follows:

的最小奇异值。 -FF/ || ₂ = ^- _n ( ^F F ( 4 ) where UF3⁄4) represents the matrix

The smallest singular value.

(4) For a finite feedback precoding system that uses orthogonal space-time block codes in combination, the codebook design objective is to maximize the distance: min^.^ ^F^F.), where (F _; , ) represents the matrix F _; and the chordal distance between Zhang Cheng's two subspaces, as defined below:

 The present inventors have found that in the present prior art, the receiving end feeds back the sequence number of the selected codeword (ie, the precoding matrix) in its codebook to the transmitting end, and notifies the transmitting end. The precoding matrix used by the transmitted signal is used to reduce the amount of feedback information. However, the inventors of the present invention have found that, since a relatively low complexity linear receiver is often used in practice, the actually available throughput has a certain loss with respect to the information theory capacity, that is, the receiving end is based on the estimated channel matrix. The codewords selected with certain performance criteria are not accurate enough for the optimal codewords, resulting in a certain performance loss. In addition, each codeword in the current codebook is a large precoding matrix, so the occupied storage space is large. Summary of the invention

 The main technical problem to be solved by the embodiments of the present invention is to provide a channel state information feedback method and a wireless transceiver device, so that the performance of the precoding process can be improved under the condition of the same amount of feedback information.

 To solve the above technical problem, an embodiment of the present invention provides a channel state information feedback method, including the following steps:

 The receiving end selects one precoding matrix from at least two codebooks according to the current channel state, adapts the selected combination of precoding matrices to the current channel state, and transmits information representing the selected precoding matrices to The transmitting end notifies the transmitting end to perform precoding processing on the signal to be transmitted according to the combination of the precoding matrices selected by the receiving end; wherein each codebook in the receiving end is generated by different criteria, in each codebook Contains at least two precoding matrices.

 An embodiment of the present invention further provides a wireless receiving apparatus, including:

 a storage unit, configured to store at least two codebooks, each codebook is generated by different criteria, and each codebook includes at least two precoding matrices;

 a selecting unit, configured to respectively select a precoding matrix from each codebook saved by the storage unit according to a current channel state, so that the selected combination of precoding matrices is adapted to a current channel state;

And a feedback unit, configured to transmit information of each precoding matrix selected by the selection unit to the transmitting end. An embodiment of the present invention further provides a wireless transmitting apparatus, including: a storage unit, configured to store at least two codebooks identical to the sender, each codebook being generated by different criteria, and each codebook includes at least two precoding matrices;

 a receiving unit, which receives a sequence number of at least two precoding matrices selected by the transmitting end in respective codebooks; and a searching unit, configured to respectively find corresponding ones from each codebook in the storage unit according to each serial number received by the receiving unit Precoding matrix

 And a precoding unit, configured to perform precoding processing on the signal to be transmitted by using a combination of precoding matrices found by the searching unit.

 Compared with the prior art, the main effect of the embodiment of the present invention is that the performance of the precoding process can be improved without increasing the amount of feedback information. When multiple codebooks are used without increasing the amount of feedback information, although each codebook becomes smaller, since the codebook is generated by different criteria, it is equivalent to introducing some nonlinear factors. It is proved by simulation (see the corresponding embodiment for the simulation result) that multiple codebooks generated by different criteria can be more adapted to the current channel state than one codebook. Moreover, a plurality of small codebooks occupy less storage space than a large codebook, and can save storage space of the storage codebooks at both ends of the transmission and reception.

DRAWINGS

 1 is a flowchart of a channel state information feedback method according to a first embodiment of the present invention;

 2 is a schematic diagram of performance simulation of a dual codebook scheme and a single codebook scheme according to a first embodiment of the present invention;

 3 is a schematic diagram of performance simulation of a dual codebook scheme and a single codebook scheme according to a second embodiment of the present invention;

 4 is a schematic diagram of performance simulation of a dual codebook scheme and a single codebook scheme according to a third embodiment of the present invention;

 5 is a schematic diagram of performance simulation of a dual codebook scheme and a single codebook scheme according to a fourth embodiment of the present invention;

 6 is a schematic structural diagram of a wireless receiving apparatus according to a fifth embodiment of the present invention;

 Figure 7 is a schematic structural view of an embodiment of the selection unit of Figure 6;

FIG. 8 is a schematic structural diagram of a wireless transmitting apparatus according to a sixth embodiment of the present invention. detailed description

In order to make the objects, the technical solutions and the advantages of the present invention more apparent, the embodiments of the present invention will be further described in detail below. A first embodiment of the present invention relates to a channel state information feedback method. In this embodiment, a receiving end selects a precoding from two codebooks (ie, a primary codebook and an auxiliary codebook) according to a current channel state. a matrix, the selected combination of precoding matrices is adapted to the current channel state, and the sequence numbers of the selected precoding matrices in the respective codebooks are transmitted to the transmitting end, and the transmitting end is notified according to the selected end of the receiving end. The combination of precoding matrices performs precoding processing on the signals that need to be transmitted. The main codebook is generated and selected according to the prior art scheme, and the auxiliary codebook can be regarded as adding a disturbance to the main codebook. The specific process is shown in FIG. In step 110, the receiving end selects a precoding matrix in the main codebook according to the current channel state. Specifically, assume that the main codebook is represented as = {F _P F ₂ , ..., } , which is the complex matrix of Μ, χ Μ dimension. After obtaining the current channel state information, the receiving end selects a precoding matrix F from the codebook F according to the first criterion according to the current channel state. The first criterion may be one of the criteria types in Table 1, such as Capacity Selection or MMSE-trace Selection. Next, proceeding to step 120, the receiving end selects a precoding matrix in the auxiliary codebook according to the current channel state. Specifically, it is assumed that the auxiliary codebook is represented as {U l^ , ..., !^} , U, which is an M-dimensional matrix. After obtaining the current channel state information, the receiving end selects a precoding matrix U from the codebook G according to the current channel state. The combination of the precoding matrix selected in step 110 and the precoding matrix selected in this step satisfies the second criterion. The auxiliary codebook in this embodiment is an auxiliary codebook generated based on a Fourier matrix, and its form is: WD _M , _{g =} o,, G-1 Where D _M ={d _kl ,k,l = 0,...,Ml},d _kl = , M is the precoding matrix

Dimension, A^^ _g (l, exp( ,...,exp(^ - ^1)g )) .

The combination of the precoding matrix ι ^ selected by the MG MG receiving end in the auxiliary codebook G and the precoding matrix Ϊ selected in step 110 satisfies the second criterion. From the perspective of throughput maximization, the second criterion is:

= argmmn +-^FH ^ff HF _j , )- ¹ V ^H \ _k where M is the dimension of the precoding matrix, [^ is the precoding matrix in the selected auxiliary codebook, I _M is the M-dimensional unit matrix , F _p is the precoding matrix in the selected main codebook, U is the precoding matrix in the auxiliary codebook, and H is the channel matrix. Then, proceeding to step 130, the receiving end transmits the sequence numbers of the selected precoding matrices in the respective codebooks to the transmitting end, and notifies the transmitting end to send according to the combination of the precoding matrices selected by the receiving end. The signal is precoded. Compared with the traditional method of using a codebook alone (such as the method using the Grassmannian codebook), the method of using the primary codebook + the auxiliary codebook in this embodiment will require additional feedback on the precoding matrix selected in the auxiliary codebook. The serial number, that is, the total number of bits that the receiver needs to feed back is l. g ₂ (N) + l. g ₂ (G;). Since in the actual system, the number of feedback bits B for indicating the selected precoding matrix is often fixed in advance, the total number of bits that the receiving end needs to feed back is log ₂ (N) ₊ log ₂ (G), which needs to be The fixed feedback bit number B is equal. Where N is the number of precoding matrices included in the main codebook, and G is the number of precoding matrices included in the auxiliary codebook. Since the total number of bits that need to be fed back is fixed in advance, such as 6 bits, if a codebook (such as a Grassmannian codebook) is used alone, the length of the Grassmannian codebook is 64 (ie, the packet) 64 precoding matrices are included; if 2 codebooks are used, the length of the first codebook can be set to 16 (that is, 16 precoding matrices are included), and the length of the second codebook can be set to 4 ( That is, four precoding matrices are included, and it can be seen that the storage space of the storage codebooks at both ends of the transmitting and receiving is reduced as compared with the case of using one codebook alone. Moreover, since the receiving end can select the preferred precoding matrix by using the sequential search method after using the dual codebook, the computational complexity of the search can be significantly reduced compared to the conventional Grassmannian codebook based precoding method. After receiving the feedback bits indicating the sequence numbers from the receiving end, the transmitting end respectively finds corresponding precoding matrices from the same codebooks as the receiving end, to find the combined signals of the precoding matrices to be sent. Perform precoding processing. Of course, in this embodiment, the transmitting end needs to save the specific information of the primary codebook and the auxiliary codebook that are the same as the receiving end. Since only the sequence numbers of the precoding matrices in the respective codebooks are transmitted, the combination of the precoding matrices used by the transmitting end for the transmitted signals can be notified, so that the amount of information transmitted can be effectively reduced. It should be noted that the criteria for selecting the precoding matrix from the primary codebook and the auxiliary codebook twice before and after the receiving end need to be matched. For example, in this embodiment, the first criterion of the precoding matrix is selected in the primary codebook. The second criterion that needs to be met when selecting the precoding matrix in the auxiliary codebook needs to be from the capacity point of view. Assume that the transmitting end (base station) of the communication system is configured with four antennas, and the receiving end (terminal) is configured with two antennas, the antennas are arranged in a uniform line array, the antenna distance at the base station is = 10 1 , and the antenna distance at the terminal is = 0.5/1; The angle at which the extension is AS=2, the angular spread at the terminal is AS=60; and it is assumed that the exit angle (AoD) at the base station is evenly distributed at -60. And 60. The angle of incidence (AoA) at the terminal is fixed at zero. , take 10,000 channel implementations. The performance of the dual codebook scheme using the primary codebook and the auxiliary codebook based on the Fourier matrix of the present embodiment is compared with the performance of the conventional scheme using a codebook (such as a Grassmannian codebook). 2 is shown. In FIG. 2, the abscissa indicates the average signal-to-noise ratio (SignalNoise ratio, referred to as "SNR"), and the ordinate indicates the system throughput size. Two data streams are transmitted at the transmitting end, and the MMSE receiver is used at the receiving end. When the dual codebook scheme is used (the length of the auxiliary codebook is 4), the system throughput has a gain of about 0.3 bits/Hz, indicating that the auxiliary codebook can effectively compensate the capacity loss of the linear receiver. It should also be noted that when the length of the primary codebook (ie, the Grassmannian codebook) is taken as 16, and the length of the secondary codebook is taken as 4, it is necessary to feed back 6 bits of information, which is different from the 64-length Grassmannian codebook. The single-code scheme has the same amount of feedback information. As shown in the figure, both have almost the same average throughput performance, but with a dual codebook scheme, with lower computational complexity and smaller codebook storage space. The second embodiment of the present invention relates to a channel state information feedback method, which is substantially the same as the first embodiment, except that in the first embodiment, the auxiliary codebook used by the receiving end is generated based on the Fourier matrix. Auxiliary codebook; and in this embodiment, the form of the auxiliary codebook used by the receiving end

Cos θ _χ - sin θ _χ

u ₂ =

 Sin θ, cos θ,

For:

U _M/2 'cos -U _M/2 -sin3⁄4

, M = 2 ^k , k = 2, ..., K

θ_κ。 具体地说，从补偿容量损失角度出发， 最优的扰动矩阵 U 为矩阵 H^ffHF_p 的特征向量组成的酉阵， 即 1^ Η"Η 1^为对角矩阵， I ^的作用相当于通过 相似变换对

进行对角化。工程矩阵理论已表明，对于两维的实对称矩阵 U _M/2 'sin U _M/2 'cos where M is the dimension of the precoding matrix and K is an integer greater than 1.

θ _κ . Specifically, from the perspective of compensation capacity loss, the optimal perturbation matrix U is a matrix of eigenvectors of the matrix H ^ff HF _p , that is, 1^ Η"Η 1^ is a diagonal matrix, and the action of I ^ is equivalent. Pairwise transformation

Diagonalize. Engineering matrix theory has shown that for two-dimensional real symmetric matrices

A , there is a rotation matrix U , so that

V ^H AV = diag(A _l , ₂ ) (6) Cos^ -sin^

 Sin Θ cos Θ (7) The rotation angle e has a value range of [_ r/4, r/4]. If the auxiliary codebook is constructed in the form of equation (7), only the degree of rotation is one degree of freedom, and the auxiliary codebook can be easily generated by quantizing the form of S, ie

Cos 6 _g - sin 0 _f

 (8) sin θ„ cos θ„ π

Where =- because the matrix FH ^ff HF „ which needs to be diagonalized here belongs to the complex space,

其中 和 分别表示矩阵 Α的实部和虚部， 需要指出的是， 由于 A为 4 2(G-1) The degree of diagonalization of the new matrix obtained by similarly changing the Hermitian matrix 1^1^ using the perturbation matrix of the form shown in equation (7) will be analyzed. For the convenience of expression, order

Where and respectively represent the real and imaginary parts of the matrix ,, it should be pointed out that since A is

。 很容易证明： 当 In the Hermitian matrix, the diagonal elements are all real numbers, so the diagonal elements of A, are all zero. In addition, when the precoding matrix is selected from the codebook F, when N = 2 ^s →, there is j → = Ϋ _Η , so Α is a diagonally dominant matrix in the high probability sense, which also means

. It is easy to prove: when

^丄_arctan 3⁄4l _e[ _ , ] (^ (. ₁₂₎ indicates retelling. The real part of ₁₂ ),

2 a _x j - ₂₂ 4 4

U ^ff AU = U ^ff A _s U + j - U ^ff A ₇ U = A _R +j- U ^ff A ₇ U where Λ _Λ denotes a diagonal matrix, and

对角元素的值决定的， 其中 在使用 MMSE (最小 均方差估计）接收机时值为 1 , «在使用 ZF (迫零 )接收机时值为 0。 与从容量 角度考察不同的是， 此时的最优扰动矩阵 U。_pi是使

所有的对角元 素都相等， 若仍然用式 （7 ) 限定的模式来表示扰动矩阵， 很容易证明， 当U ^H A _r U|L=|l A _r |L«||A _B |L=|IA Therefore, the complex matrix A can be converted into a quasi-diagonal matrix by the similar transformation described above, which means that there must be one codeword (ie, precoding matrix) in the auxiliary codebook constructed by equation (8), which can approximate the system. The optimal capacity u, the larger the codebook scale G, the higher the degree of approximation. The codebook construction method is analyzed from the perspective of compensation capacity. If the error rate performance is used, the function of an optimal disturbance is to balance the signal-to-noise ratio of each signal stream, so that the channel condition is the worst one. The noise ratio is maximized. Since the signal-to-noise ratio of each signal stream is determined by the matrix

The value of the diagonal element is determined by the value of 1 when using the MMSE (Minimum Mean Square Error Estimation) receiver, and the value is 0 when using the ZF (forcing zero) receiver. The difference from the capacity perspective is the optimal perturbation matrix U at this time. _Pi is made

All diagonal elements are equal. If the perturbation matrix is still represented by the pattern defined by equation (7), it is easy to prove that when

^丄_arctan ^l ^ _{e [} — , ] when, there is

2 2Re( ₁₂ ) 4 4

U ^ff AU = ^X

上式表明： 当辅助码本采用式（8 ) 的构造方式， 必存在一个码字逼近使系统误码率最优的扰动矩阵， 码本尺度 G 越大， 则逼近的程度越高。 上述分析表明， 无论从容量最大或者误码率最小的角度考虑， 均可以采用 旋转矩阵的形式构造辅助码本， 由于该形式只有单维的自由度， 可以采用对旋 转角度等间隔量化的方式生成码本。 当 > 2时， 可通过下面的方式扩展旋转矩 阵的形式： U* x where

The above formula shows that: When the auxiliary codebook adopts the construction method of equation (8), there must be a perturbation matrix in which the codeword approximation makes the system error rate optimal. The larger the codebook scale G is, the higher the degree of approximation. The above analysis shows that the auxiliary codebook can be constructed in the form of a rotation matrix from the perspective of maximum capacity or minimum bit error rate. Since this form has only a single-dimensional degree of freedom, it can be generated by equally calculating the rotation angle. Codebook. When > 2, the form of the rotation matrix can be extended in the following way: U

U _M/2 'cos -U _M/2 -sin3⁄4

M = 2 ^k , k = 2, ..., K

。 而在本实施例中， 接收端从优化误码率角U _M/2 'sin U _M/2 -cos3⁄4 where M is the dimension of the precoding matrix, and K is an integer greater than 1. In order to reduce the degree of freedom that needs to be quantized, it can be seen that this can be seen. The difference between an embodiment is that the generation manner of the auxiliary codebook is different, so that the effect of the first embodiment can also be achieved, for example, the storage space of the storage codebook at both ends of the transmission and reception can be saved. The performance of the dual codebook scheme using the primary codebook and the auxiliary codebook obtained by extending the rotation matrix in this embodiment is compared with the conventional performance simulation using a codebook (such as a Grassmannian codebook), as shown in FIG. The simulation results are similar to the simulation results shown in Figure 2, and will not be described here. A third embodiment of the present invention relates to a channel state information feedback method. This embodiment is substantially the same as the first embodiment. The difference is that, in the first embodiment, the receiving end starts from the perspective of throughput maximization. The combination of the precoding matrix selected in the codebook and the auxiliary codebook satisfies the second criterion:

. In this embodiment, the receiving end optimizes the error rate angle.

= argmmn [ ^υ (^ +-^FH ^ff HF _j , )- ¹ V ^H _k degrees, that is, to maximize the signal-to-noise ratio of the signal channel with the worst channel conditions. Therefore, the second criterion that satisfies is:

U _? =argmmmax[U(I ₊ FHF _p ) - where M is the dimension of the precoding matrix, [^ is the precoding matrix in the selected auxiliary codebook, I _M is the M dimension unit matrix, is selected The precoding matrix in the main codebook, U is the precoding matrix in the auxiliary codebook, and H is the channel matrix. The criteria of the array need to be matched. In this embodiment, the first criterion for selecting the precoding matrix in the primary codebook is from the perspective of optimizing the error rate. Therefore, when the precoding matrix is selected in the auxiliary codebook, it is required. The second criterion that is met also needs to be optimized from the perspective of optimizing the bit error rate. It is not difficult to find that the difference between this embodiment and the first embodiment is that the second criterion that needs to be met when the precoding matrix is selected in the auxiliary codebook is different. The second criterion that needs to be satisfied in this embodiment starts from optimizing the bit error rate. Improve the performance of the precoding process without increasing the amount of feedback information. When multiple codebooks are used without increasing the amount of feedback information, although each codebook becomes smaller, since the codebook is generated by different criteria, it is equivalent to introducing some nonlinear factors. It is proved by simulation that a plurality of codebooks generated by different criteria can be more adapted to the current channel state than a codebook. Of course, as in the first embodiment, the purpose of saving the codebook storage space at both ends of the transmission and reception can also be achieved. Assume that the transmitting end (base station) of the communication system is configured with four antennas, and the receiving end (terminal) is configured with two antennas, the antennas are arranged in a uniform line array, the antenna distance at the base station is = 10 1 , and the antenna distance at the terminal is = 0.5/1; The angle at which the extension is AS=2, the angular spread at the terminal is AS=60; and it is assumed that the exit angle (AoD) at the base station is evenly distributed at -60. And 60. The angle of incidence (AoA) at the terminal is fixed at zero. , take 10,000 channel implementations. The performance simulation using the dual codebook scheme using the primary codebook and the auxiliary codebook based on the Fourier matrix of this embodiment, and the performance simulation using the conventional scheme using a codebook (such as a Grassmannian codebook) are shown in FIG. In Fig. 4, the abscissa indicates the ratio of the received energy per bit to the noise power spectral density (Eb/No), and the ordinate indicates the bit error rate (BBER), which is not difficult to find, at low BER. In the case of the region, when the value of Eb/No is the same, the scheme using the dual codebook has a lower bit error rate than the scheme using the single codebook, and the system has a gain of about ldB. In other words, the party using the double codebook The case has higher performance in bit error rate. The fourth embodiment of the present invention relates to a channel state information feedback method, which is substantially the same as the third embodiment, and is different in the third embodiment, the auxiliary codebook used by the receiving end and the first embodiment. The auxiliary codebook in the same is the auxiliary codebook generated based on the Fourier matrix; in the embodiment, the auxiliary codebook used by the receiving end has the form: cos θ _χ - sin θ _χ

u

 Sin θ, cos θ,

U _M/2 ' cos -U _M/2 - sin3⁄4

, M = 2 ^k , k = 2, ..., K

U _M/2 ' sin U _M/2 ' cos where M is the dimension of the precoding matrix, K is an integer greater than 1, θ, = θ _Ί - . = θ _κ . It is not difficult to find that the difference between this embodiment and the third embodiment is that the generation manner of the auxiliary codebook is different, so that the effect of the third embodiment can also be achieved, for example, the current channel state can be more adapted to one codebook, and the transmission and reception can be saved. The storage space of the storage codebook at the end. The performance of the dual codebook scheme using the primary codebook and the auxiliary codebook obtained by extending the rotation matrix in this embodiment is compared with the conventional performance simulation using a codebook (such as a Grassmannian codebook), as shown in FIG. The simulation results are similar to the simulation results shown in FIG. 4, and are not described here. A fifth embodiment of the present invention relates to a wireless receiving apparatus 1, as shown in FIG. 6, comprising: a storage unit 10, configured to store at least two codebooks, each generated by a different criterion, each The codebook includes at least two precoding matrices, and the selecting unit 12 is configured to respectively select a precoding matrix from each codebook saved by the storage unit 10 according to the current channel state, so that the selected precoding matrices are respectively selected. The combination is most adapted to the current channel state; the feedback unit 14 is configured to pass information representing each precoding matrix selected by the selection unit 12 to the transmitting end. The codebook saved by the storage unit 10 includes a primary codebook and an auxiliary codebook, and the information of each precoding matrix selected by the selection unit 12 is selected for each precoding matrix. The serial number from the code book. The auxiliary codebook is in the form of one of the following:

, M is the dimension of the precoding matrix,

cos θ_χ - sin θ_χ

Cos θ _χ - sin θ _χ

 U.

 Sin θ, cos θ,

 (2)

U _M/2 'cos -U _M/2 -sin3⁄4

M = 2 ^k , k = 2, ..., K

或 者 ， 该 第 二 准 则 为U _M/2 -sin U _M/2 'cos where M is the dimension of the precoding matrix, K is an integer greater than 1, θ, =θ _Ί -. = θ _κ . As shown in FIG. 7, the selecting unit 12 in this embodiment further includes: a primary codebook selecting subunit 120, configured to select a precoding matrix from the primary codebook by using a first criterion; and an auxiliary codebook selecting subunit 122, For selecting a precoding matrix from the auxiliary codebook, the combination of the precoding matrix and the precoding matrix selected by the primary codebook selection subunit 120 satisfies the second criterion. The second criterion is:

Or, the second criterion is

选的辅助码本中的预编码矩阵， /_M是M维单位矩阵， 是所选的主码本中的预 编码矩阵， U是辅助码本中的预编码矩阵， Η是信道矩阵。 在本实施例中， 使用了至少两个以不同准则生成的码本， 接收端从各码本 中选出最适应当前信道状态的预编码矩阵的组合， 并将该预编码矩阵的组合以 有限比特反馈给发送端， 可以在不增加反馈信息量的条件下提高预编码处理的 性能。 由于码本是以不同的准则生成的， 所以相当于引入了一些非线性的因素， 经仿真证明， 多个以不同准则生成的码本可以比一个码本更适应当前信道状态。 而且， 能够节省收发两端的存储码本的存储空间。 本发明的第六实施例涉及一种无线发送装置 2, 如图 8所示， 包括： 存贮单 元 20, 用于保存与发送端相同的至少两个码本， 每个码本分别以不同的准则生 成， 每个码本中包含至少两个预编码矩阵； 接收单元 22, 接收发送端所选的至 少两个预编码矩阵在各自码本中的序号； 查找单元 24, 用于根据该接收单元 22 收到的各序号分别从该存贮单元 20中各码本内找到对应的各预编码矩阵； 预编 码单元 26,用于以该查找单元 24找到的各预编码矩阵的组合对需要发送的信号 进行预编码处理。 综上所述， 在本发明的实施例中， 使用至少两个以不同准则生成的码本， 接收端从各码本中选出最适应当前信道状态的预编码矩阵的组合， 并将该预编 码矩阵的组合以有限比特反馈给发送端， 可以在不增加反馈信息量的条件下提 高预编码处理的性能。 在不增加反馈信息量的条件下， 使用多个码本时， 虽然 每个码本都变小了， 但由于码本是以不同的准则生成的， 所以相当于引入了一 些非线性的因素， 经仿真证明 （仿真结果见相应实施例）， 多个以不同准则生成 的码本可以比一个码本更适应当前信道状态。 而且， 能够节省收发两端的存储 码本的存储空间。 在发送端和接收端预置相同的码本， 只传各预编码矩阵在各自码本中的序 号， 可以有效地减少传输的信息量。 本发明实施例提出了一种典型的情况， 即使用两个码本， 一个可称为主码 本， 另一个可称为辅助码本， 其中主码本按现有技术的方案生成和选择， 辅助 码本可以看作在主码本的基础上增加一个扰动。 本发明实施例提出了两种实用 的辅助码本形式， 一种是基于 Fourier矩阵生成的， 另一种是扩展旋转矩阵生成 = argmmn [ ^υ (^ + ]* U _?

The precoding matrix in the selected auxiliary codebook, / _M is an M-dimensional unit matrix, which is a precoding matrix in the selected main codebook, U is a precoding matrix in the auxiliary codebook, and Η is a channel matrix. In this embodiment, at least two codebooks generated by different criteria are used, and the receiving end selects a combination of precoding matrices that best fits the current channel state from each codebook, and combines the precoding matrices with The finite bit is fed back to the transmitting end, and the performance of the precoding process can be improved without increasing the amount of feedback information. Since the codebook is generated by different criteria, it is equivalent to introducing some nonlinear factors. It is proved by simulation that a plurality of codebooks generated by different criteria can be more adapted to the current channel state than a codebook. Moreover, the storage space of the storage codebook at both ends of the transmission and reception can be saved. A sixth embodiment of the present invention relates to a wireless transmitting apparatus 2, as shown in FIG. 8, comprising: a storage unit 20, configured to store at least two codebooks identical to a transmitting end, each codebook being different The criterion is generated, each codebook includes at least two precoding matrices; the receiving unit 22 receives the sequence numbers of the at least two precoding matrices selected by the transmitting end in the respective codebooks; the searching unit 24 is configured to use the receiving unit according to the receiving unit The received sequence numbers respectively find corresponding precoding matrices from each codebook in the storage unit 20; the precoding unit 26 is configured to use the combination of precoding matrices found by the searching unit 24 to be sent. The signal is precoded. In summary, in the embodiment of the present invention, using at least two codebooks generated by different criteria, the receiving end selects, from each codebook, a combination of precoding matrices that best fits the current channel state, and The combination of the coding matrices is fed back to the transmitting end with limited bits, and the performance of the precoding processing can be improved without increasing the amount of feedback information. When multiple codebooks are used without increasing the amount of feedback information, although each codebook becomes smaller, since the codebook is generated by different criteria, it is equivalent to introducing some nonlinear factors. It is proved by simulation (see the corresponding embodiment for the simulation result) that multiple codebooks generated by different criteria can be more adapted to the current channel state than one codebook. Moreover, the storage space of the storage codebook at both ends of the transmission and reception can be saved. Presetting the same codebook on the transmitting end and the receiving end only transmits the sequence numbers of the precoding matrices in the respective codebooks, which can effectively reduce the amount of information transmitted. The embodiment of the present invention proposes a typical case, that is, using two codebooks, one may be called a master code The other can be called an auxiliary codebook, wherein the main codebook is generated and selected according to the prior art scheme, and the auxiliary codebook can be regarded as adding a perturbation based on the main codebook. The embodiments of the present invention propose two practical auxiliary codebook forms, one is generated based on a Fourier matrix, and the other is an extended rotation matrix generation.

It can be understood that those skilled in the art can understand that all or part of the process of implementing the above embodiments can be completed by a program to instruct related hardware, and the program can be stored in a computer readable storage medium. Wherein, the program, when executed, may include the flow of an embodiment of the methods as described above. The storage medium may be a magnetic disk, an optical disk, a read-only memory (ROM), or a random access memory (RAM). Obviously, the movements and variations do not depart from the spirit and scope of the invention. Thus, it is intended that the present invention cover the modifications and variations of the inventions

Claims

Rights request A channel state information feedback method, comprising the steps of:  The receiving end selects one precoding matrix from at least two codebooks according to the current channel state, adapts the selected combination of precoding matrices to the current channel state, and transmits information representing the selected precoding matrices to The transmitting end notifies the transmitting end to perform precoding processing on the signal to be transmitted according to the combination of the precoding matrices selected by the receiving end; wherein each codebook in the receiving end is generated by different criteria, each code The book contains at least two precoding matrices.  The channel state information feedback method according to claim 1, wherein the information representing each of the selected precoding matrices is a sequence number of each of the selected precoding matrices in a respective codebook;  It also includes the following steps:  The transmitting end finds corresponding precoding matrices from the same codebooks as the receiving end according to the sequence numbers, and performs precoding processing on the signals to be transmitted by using the combination of the found precoding matrices.  The channel state information feedback method according to claim 1, wherein the codebook comprises a primary codebook and an auxiliary codebook;  The step of selecting a precoding matrix from at least two codebooks respectively, and adapting the selected combination of precoding matrices to the current channel state comprises the following substeps:  A precoding matrix is selected from the primary codebook in a first criterion, and a precoding matrix is selected from the secondary codebook such that the combination of the two precoding matrices satisfies the second criterion.  The channel state information feedback method according to claim 3, wherein the auxiliary codebook has the following form: U = Λ - D _M , g = 0,..., G - l where , , Μ is the precoding matrix

Dimension, = ^ _g (l, exp( ^),...,exp(^" ⁽ ^ - ^1)g )).  g MG MG The channel state information feedback method according to claim 3, wherein the auxiliary codebook has the following form: Cos ^ - sin θ _χ  U =  Sin cos 9. U _M/2 ' cos -U _M/2 - sin3⁄4 u M = 2 ^k , k = 2, ..., K U _M/2 ' sin U _M/2 ' cos where M is the dimension of the precoding matrix and K is an integer greater than 1, = The channel state information feedback method according to any one of claims 3 to 5, wherein the second criterion is:

: argniin]^[[U(I +— FH ^w HF _p 'U where M is the dimension of the precoding matrix, which is the precoding matrix in the selected auxiliary codebook, I is the M-dimensional unit matrix, is The precoding matrix in the selected primary codebook, U is the precoding matrix in the auxiliary codebook, and H is the channel matrix. The channel state information feedback method according to any one of claims 3 to 5, wherein the second criterion is:

Where M is the dimension of the precoding matrix, ^ is the precoding matrix in the selected auxiliary codebook, I _M is the M-dimensional unit matrix, is the precoding matrix in the selected main codebook, U is the auxiliary code In the precoding matrix herein, H is a channel matrix.  The channel state information feedback method according to any one of claims 3-5, wherein the master codebook is a codebook designed by using a Grassmanian subspace stacking method;  The first criterion is a precoding matrix selection criterion in the Grassmanian subspace stacking method. A wireless receiving device, comprising:  a storage unit, configured to store at least two codebooks, each codebook is generated by different criteria, and each codebook includes at least two precoding matrices; a selecting unit, configured to select a precoding matrix from each codebook saved by the storage unit according to a current channel state, so that the selected combination of precoding matrices is adapted to a current channel state; Send the end.  10. The radio receiving apparatus according to claim 9, wherein the information representing each precoding matrix selected by the selecting unit is a sequence number of each precoding matrix selected in a respective codebook.  The wireless receiving device according to claim 9, wherein the codebook comprises a primary codebook and an auxiliary codebook;  The selecting unit further includes:  a primary codebook selection subunit, configured to select a precoding matrix from the primary codebook by using a first criterion; and an auxiliary codebook selection subunit, configured to select a precoding matrix from the auxiliary codebook, so that the precoding The combination of the coding matrix and the precoding matrix selected by the primary codebook selection subunit satisfies the second criterion.  The wireless receiving device according to claim 11, wherein the auxiliary codebook has the form of one of the following: , M is the precoding matrix

Dimension, = ^ _g (l,exp( ^),...,exp(^" ⁽ ^- ^1)g )) , g MG MG or, cos θ _χ - sin θ _χ  u.  Sin θ cos θ U _M/2 'cos -U _M/2 -sin3⁄4 M = 2 ^k , k = 2, ..., K U _M/2 -sin U _M/2 'cos where M is the dimension of the precoding matrix and K is an integer greater than 1, ' The wireless receiving device according to claim 11 or 12, wherein the first criterion is one of the following:

= argmmn[U(I _M ] or, U _? = argmmmax[U(I + -F^H ^H HF _p y ¹ V ^H ] _kk where M is the dimension of the precoding matrix, ^ is the precoding matrix in the selected auxiliary codebook, ^ is M The dimension unit matrix is the precoding matrix in the selected main codebook, U is the precoding matrix in the auxiliary codebook, and H is the channel matrix.  The wireless receiving device according to claim 11 or 12, characterized in that  The main codebook is a codebook designed by using a Grassmanian subspace stacking method;  The first criterion is a precoding matrix selection criterion in the Grassmanian subspace stacking method. A wireless transmitting device, comprising:  a storage unit, configured to store at least two codebooks identical to the sender, each codebook being generated by different criteria, and each codebook includes at least two precoding matrices;  Receiving unit, receiving a sequence number of at least two precoding matrices selected by the transmitting end in respective codebooks;  a searching unit, configured to find corresponding precoding matrices from each codebook in the storage unit according to each serial number received by the receiving unit;  And a precoding unit, configured to perform precoding processing on the signal to be transmitted by using a combination of precoding matrices found by the searching unit.