CN109309517B - Signal transmission method and device, computer readable storage medium, and base station - Google Patents

Signal transmission method and device, computer readable storage medium, and base station Download PDF

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CN109309517B
CN109309517B CN201710635614.0A CN201710635614A CN109309517B CN 109309517 B CN109309517 B CN 109309517B CN 201710635614 A CN201710635614 A CN 201710635614A CN 109309517 B CN109309517 B CN 109309517B
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transmission layers
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right unitary
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CN109309517A (en
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卡尔·兰皮宁
塔帕尼·韦斯特曼
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Spreadtrum Communications Shanghai Co Ltd
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B7/00—Radio transmission systems, i.e. using radiation field
    • H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
    • H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
    • H04B7/0413—MIMO systems
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B7/00—Radio transmission systems, i.e. using radiation field
    • H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
    • H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
    • H04B7/0413—MIMO systems
    • H04B7/0456—Selection of precoding matrices or codebooks, e.g. using matrices antenna weighting

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Abstract

A signal transmission method and device, a computer readable storage medium and a base station are provided, and the signal transmission method comprises the following steps: receiving channel matrixes fed back by all user equipment, and determining the number of transmission layers distributed by each user equipment; performing singular value decomposition on the channel matrixes of all user equipment to obtain first right unitary matrixes of all the user equipment; constructing a first middle matrix of the user equipment according to a first right unitary matrix of other user equipment except the user equipment and the distributed transmission layer number; calculating an effective channel matrix and an effective sub-matrix of the user equipment by using a first middle matrix and a first right unitary matrix of the user equipment; and performing block diagonalization by using the effective channel matrix and the effective sub-matrix to obtain a precoding matrix, and modulating a signal sent to the user equipment by using the precoding matrix. The technical scheme of the invention can improve the signal transmission performance of the MIMO system.

Description

Signal transmission method and device, computer readable storage medium, and base station
Technical Field
The present invention relates to the field of communications technologies, and in particular, to a signal transmission method and apparatus, a computer-readable storage medium, and a base station.
Background
Block Diagonalization (BD) is a linear precoding technique in a Multi-user Multiple-Input Multiple-Output (MU-MIMO) system, which can avoid Multi-user interference by using null space. BD decomposes the multi-user MIM0 downlink channel into multiple parallel independent single-user MIMO downlink channels. BD is more robust to channel estimation errors than non-linear techniques. The signal of each user transmitted at the transmitting end is represented by a modulation matrix which is the null space of the channel matrix of other users, so that the interference of the user to other users is zero.
In the prior art, in a New Radio (NR) system, downlink MU-MIMO transmission is better supported than a Long Term Evolution (LTE) system. One aspect of the improvement is Channel State Information (CSI) feedback. E.g., explicit CSI feedback, representing channel coefficients, covariance matrices, or eigenvectors of a User Equipment (UE) feedback channel. The covariance or eigenvector feedback causes the BD to operate on the eigenvectors, but if full channel information for the channel matrix is available, the channel matrix is used in the BD. In LTE systems, forming nulls requires assuming that each UE applies a water-filling algorithm on all layers to optimize capacity.
However, in an NR system or an LTE system, a practical MIMO system has a limited modulation and coding rate, and a lower or higher modulation and coding rate option may not match the power of the assigned layer, the final signal-to-noise ratio. Therefore, in downlink adaptation, the number of actually allocated layers may be smaller than the maximum number of layers allocated for the UE. In this case, the water filling algorithm efficiency is reduced, resulting in that the interference is amplified and the overall signal-to-noise ratio is reduced, the performance of block diagonalization is reduced, and the signal transmission performance is low.
Disclosure of Invention
The invention solves the technical problem of how to improve the signal transmission performance of the MIMO system.
To solve the foregoing technical problem, an embodiment of the present invention provides a signal transmission method, where the signal transmission method includes: receiving channel matrixes fed back by all user equipment, and determining the number of transmission layers distributed by each user equipment according to the number of the distributed transmission layers, wherein the number of the transmission layers distributed by each user equipment is less than or equal to the maximum number of the transmission layers configured by each user equipment; performing singular value decomposition on the channel matrixes of all user equipment to obtain first right unitary matrixes of all the user equipment; constructing a first middle matrix of the user equipment according to a first right unitary matrix of other user equipment except the user equipment and the distributed transmission layer number; calculating an effective channel matrix and an effective sub-matrix of the user equipment by using a first middle matrix and a first right unitary matrix of the user equipment; and performing block diagonalization by using the effective channel matrix and the effective sub-matrix to obtain a precoding matrix, and modulating a signal sent to the user equipment by using the precoding matrix.
Optionally, the constructing a first intermediate matrix of the user equipment according to the first right unitary matrix of the user equipment except the user equipment and the number of the transmission layers allocated thereto includes: if the number of transmission layers distributed by the other user equipment is smaller than the configured maximum number of transmission layers, selecting a characteristic vector in a first right unitary matrix of the other user equipment; and constructing a first intermediate matrix of the user equipment according to the number of transmission layers distributed by the other user equipment and the eigenvector.
Optionally, the constructing a first intermediate matrix of the user equipment according to the number of transmission layers allocated by the other user equipment and the eigenvector includes: and selecting at least part of elements in the eigenvectors of the other user equipment to construct a first intermediate matrix of the user equipment, wherein the number of columns of the first intermediate matrix of the user equipment is equal to the number of transmission layers distributed by the other user equipment.
Optionally, the selecting at least a part of elements in the feature vectors of the other ue to construct a first intermediate matrix of the ue includes: and selecting the first N rows of elements in the first right unitary matrix of the other user equipment to obtain a first middle matrix of the user equipment, wherein N is equal to the number of transmission layers allocated to the other user equipment.
Optionally, the constructing a first intermediate matrix of the user equipment according to the first right unitary matrix of the user equipment except the user equipment and the number of the transmission layers allocated thereto includes: and if the number of the transmission layers distributed by the other user equipment is the configured maximum number of the transmission layers, selecting the channel matrixes of the other user equipment to construct a first intermediate matrix of the user equipment.
Optionally, the calculating the effective channel matrix of the user equipment by using the first intermediate matrix and the first right unitary matrix of the user equipment includes: performing singular value decomposition on the first intermediate matrix of the user equipment to obtain a second right unitary matrix; selecting a first sub-matrix from the first right unitary matrix, wherein the column number of the first sub-matrix is equal to the number of transmission layers distributed by the user equipment; removing the matrix with the column number being the number of the transmission layers distributed by the user equipment from the second right unitary matrix, and taking the residual matrix as an effective sub-matrix of the user equipment; taking the product of the first sub-matrix and the effective sub-matrix as the effective channel matrix.
Optionally, the performing block diagonalization by using the effective channel matrix to obtain a precoding matrix includes: performing singular value decomposition on the effective channel matrix to obtain a third right unitary matrix; selecting a third sub-matrix corresponding to the user equipment from the third right unitary matrix, wherein the column number of the third sub-matrix is equal to the number of transmission layers distributed by the user equipment; taking the product of the effective sub-matrix and the third sub-matrix as the precoding matrix.
The embodiment of the invention also discloses a signal transmission device, which comprises: the receiving module is suitable for receiving the channel matrixes fed back by all the user equipment and determining the number of the transmission layers distributed by each user equipment according to the number of the distributed transmission layers, wherein the number of the transmission layers distributed by each user equipment according to the number of the distributed transmission layers is less than or equal to the maximum number of the transmission layers configured by each user equipment; the singular value decomposition module is suitable for performing singular value decomposition on the channel matrixes of all the user equipment to obtain first right unitary matrixes of all the user equipment; the matrix construction module is suitable for constructing a first middle matrix of the user equipment according to a first right unitary matrix of other user equipment except the user equipment and the distributed transmission layer number; an effective channel matrix calculation module adapted to calculate an effective channel matrix and an effective sub-matrix of the user equipment using a first intermediate matrix and a first right unitary matrix of the user equipment; and the precoding module is suitable for carrying out block diagonalization by utilizing the effective channel matrix and the effective submatrix to obtain a precoding matrix and modulating a signal sent to the user equipment by utilizing the precoding matrix.
Optionally, the matrix building module includes: a selecting unit, adapted to select a eigenvector in a first right unitary matrix of the other user equipment if the number of transmission layers allocated by the other user equipment is smaller than the configured maximum number of layers; and the matrix construction unit is suitable for constructing a first intermediate matrix of the user equipment according to the number of transmission layers distributed by the other user equipment and the eigenvector.
Optionally, the matrix building unit includes: a matrix construction subunit, adapted to select at least a part of elements in the eigenvectors of the other user equipments to construct a first intermediate matrix of the user equipment, where the number of columns of the first intermediate matrix of the user equipment is equal to the number of transmission layers allocated to the other user equipments.
Optionally, the matrix constructing subunit selects first N rows of elements in the first right unitary matrix of the other user equipment to obtain a first intermediate matrix of the user equipment, where N is equal to the number of transmission layers allocated to the other user equipment.
Optionally, the matrix constructing module selects the channel matrices of the other user equipments to construct the first intermediate matrix of the user equipment when the number of transmission layers allocated to the other user equipments is the configured maximum number of transmission layers.
Optionally, the effective channel matrix calculating module includes: the first singular value decomposition unit is suitable for performing singular value decomposition on a first intermediate matrix of the user equipment to obtain a second right unitary matrix; a first sub-matrix selecting unit, adapted to select a first sub-matrix from the first right unitary matrix, where the number of columns of the first sub-matrix is equal to the number of transmission layers allocated to the user equipment; an effective sub-matrix selecting unit, adapted to remove the matrix whose number of columns is the number of transmission layers allocated to the user equipment from the second right unitary matrix, and use the remaining matrix as an effective sub-matrix of the user equipment; an effective channel matrix calculation unit adapted to take a product of the first sub-matrix and the effective sub-matrix as the effective channel matrix.
Optionally, the precoding module includes: the second singular value decomposition unit is suitable for performing singular value decomposition on the effective channel matrix to obtain a third right unitary matrix; a third sub-matrix selecting unit, adapted to select a third sub-matrix corresponding to the ue from the third right unitary matrix, where the number of columns of the third sub-matrix is equal to the number of transmission layers allocated to the ue; a precoding matrix calculation unit adapted to take a product of the effective sub-matrix and the third sub-matrix as the precoding matrix.
The embodiment of the invention also discloses a computer readable storage medium, wherein computer instructions are stored on the computer readable storage medium, and the computer instructions execute the steps of the signal transmission method when running.
The embodiment of the invention also discloses a base station, which comprises a memory and a processor, wherein the memory is stored with computer instructions capable of running on the processor, and the processor executes the steps of the signal transmission method when running the computer instructions.
Compared with the prior art, the technical scheme of the embodiment of the invention has the following beneficial effects:
receiving channel matrixes fed back by all user equipment, and determining the number of transmission layers distributed by each user equipment according to the number of the distributed transmission layers, wherein the number of the transmission layers distributed by each user equipment is less than or equal to the maximum number of the transmission layers configured by each user equipment; performing singular value decomposition on the channel matrixes of all user equipment to obtain first right unitary matrixes of all the user equipment; constructing a first middle matrix of the user equipment according to a first right unitary matrix of other user equipment except the user equipment and the distributed transmission layer number; calculating an effective channel matrix of the user equipment by using the first intermediate matrix of the user equipment; and carrying out block diagonalization by utilizing the effective channel matrix to obtain a precoding matrix, and modulating a signal sent to the user equipment by utilizing the precoding matrix. The technical scheme of the invention calculates the effective channel matrix of the user equipment by utilizing the first intermediate matrix of the user equipment, and the first intermediate matrix of the user equipment is constructed according to the first right unitary matrix of other user equipment except the user equipment and the distributed transmission layer number. Therefore, in the MIMO system, when the number of transmission layers allocated by the ue is less than the configured maximum number of transmission layers, the number of columns of the first intermediate matrix is small, which can reduce the complexity of calculating the effective channel matrix compared to a scheme in the prior art that directly uses the channel matrix to calculate the effective channel matrix. In addition, because the influence of the number of transmission layers allocated by the user equipment on the diagonalization is considered, the technical scheme of the invention can also improve the performance of block diagonalization, improve the signal-to-noise ratio and further improve the signal transmission performance of the MIMO system.
Further, at least a part of elements in the eigenvectors of the other user equipments are selected to construct a first intermediate matrix of the user equipment, and the number of columns of the first intermediate matrix of the user equipment is equal to the number of transmission layers allocated to the other user equipments. According to the technical scheme, at least one part of elements of the characteristic vector in the first right unitary matrix are selected, so that the constructed first middle matrix can be ensured to have better transmission performance, the block diagonalization performance can be improved, and the signal transmission performance of the MIMO system can be improved.
Drawings
Fig. 1 is a flow chart of a signal transmission method according to an embodiment of the present invention;
FIG. 2 is a graph comparing the effect of the embodiment of the present invention with the prior art;
fig. 3 is a schematic structural diagram of a signal transmission apparatus according to an embodiment of the present invention.
Detailed Description
As described in the background, in an NR system or an LTE system, a practical MIMO system has a limited modulation and coding rate, and a modulation and coding rate option that is lower or higher may not match the power of an allocated layer, the final signal-to-noise ratio. Therefore, in downlink adaptation, the number of actually allocated layers may be smaller than the maximum number of layers allocated for the UE. In this case, the water-filling algorithm efficiency is reduced, resulting in that the interference is amplified and the overall signal-to-noise ratio is reduced, reducing the performance of block diagonalization and also making the signal transmission performance low.
The technical scheme of the invention calculates the effective channel matrix of the user equipment by utilizing the first intermediate matrix of the user equipment, and the first intermediate matrix of the user equipment is constructed according to the first right unitary matrix of other user equipment except the user equipment and the distributed transmission layer number; in the MIMO system, when the number of transmission layers allocated to the ue is less than the configured maximum number of transmission layers, the number of columns of the first intermediate matrix is small, which can reduce the complexity of calculating the effective channel matrix compared to the prior art in which the effective channel matrix is calculated by directly using the channel matrix; in addition, the influence of the number of transmission layers allocated to the user equipment on the diagonalization is considered, so that the performance of block diagonalization can be improved, the signal-to-noise ratio is improved, and the signal transmission performance of the MIMO system is further improved.
In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in detail below.
Fig. 1 is a flowchart of a signal transmission method according to an embodiment of the present invention.
The signal transmission method of the present embodiment may be used for a base station side, specifically, may be used for a transmitter of a base station; and can be used for Multi-User Multiple-Input Multiple-Output (MU-MIMO) application scenarios.
The signal transmission method may include the steps of:
step S101: receiving channel matrixes fed back by all user equipment, and determining the number of transmission layers distributed by each user equipment according to the number of the distributed transmission layers, wherein the number of the transmission layers distributed by each user equipment is less than or equal to the maximum number of the transmission layers configured by each user equipment;
step S102: performing singular value decomposition on the channel matrixes of all user equipment to obtain first right unitary matrixes of all the user equipment;
step S103: constructing a first middle matrix of the user equipment according to a first right unitary matrix of other user equipment except the user equipment and the distributed transmission layer number;
step S104: calculating an effective channel matrix of the user equipment by using a first middle matrix and a first right unitary matrix of the user equipment;
step S105: and carrying out block diagonalization by utilizing the effective channel matrix to obtain a precoding matrix, and modulating a signal sent to the user equipment by utilizing the precoding matrix.
In a specific implementation, the base station may perform signal transmission with a multi-User Equipment (UE) at the same time.In step S101, the base station may receive channel matrices fed back by all the user equipments. Wherein the channel matrix may reflect the channel status, and each UE corresponds to one channel matrix, for example, the channel matrix of UE k may be HkThe channel matrix of the UE (k-1) may be represented by Hk-1And (4) showing.
Specifically, the maximum number of transmission layers that the user equipment is configured with may be equal to the number of base station transmit antennas, that is, the number of simultaneously transmitted data streams for the user equipment is maximum to the number of transmit antennas. However, in practical applications, the number of transmission layers allocated by the user equipment may be smaller than the maximum number of transmission layers it is configured to. The number of transmission layers allocated to the user equipment has a certain influence on the precoding matrix of the user equipment, and in order to optimize the precoding matrix, the number of transmission layers allocated to the user equipment may be used to calculate an effective channel matrix.
In step S102, Singular Value Decomposition (SVD) is performed on the channel matrices of all the ues to obtain the first right unitary matrices of all the ues. E.g. channel matrix H for UEkkSingular value decomposition is carried out:
Figure BDA0001363764550000071
wherein the content of the first and second substances,
Figure BDA0001363764550000072
is the first left unitary matrix for UE k,
Figure BDA0001363764550000073
in the form of a diagonal matrix,
Figure BDA0001363764550000074
is the first right unitary matrix for UE k.
In a specific implementation, in step S103, a first middle matrix of the user equipment is constructed according to a first right unitary matrix of other user equipments except the user equipment and the allocated number of transmission layers. That is, for UE k, the second of UE0, UE 1 … UE (k-1), UE (k +1) … other than UE k is utilizedA right unitary matrix and the allocated transmission layer number to construct a first intermediate matrix of UE k
Figure BDA0001363764550000075
Since the number of transmission layers allocated to the user equipment affects the number of columns of the matrix, the smaller the number of columns, the smaller the rank of the matrix, and the larger the null value, compared with the channel matrix of the user equipment, the first intermediate matrix of the user equipment has fewer columns and fewer non-zero eigenvalues, and thus, when an effective channel matrix is calculated by using singular value decomposition in the subsequent process, the calculation complexity can be reduced.
In particular, the following formula may be employed to represent the first intermediate matrix of UE k
Figure BDA0001363764550000076
Figure BDA0001363764550000077
Wherein the content of the first and second substances,
Figure BDA0001363764550000078
is a first right unitary matrix according to UE0 and its allocated number of transmission layers Nl(0) The matrix of the determination is then determined,
Figure BDA0001363764550000079
is a first right unitary matrix according to UE (k-1) and its allocated number of transmission layers Nl(the matrix determined by k-1,
Figure BDA00013637645500000710
is a first right unitary matrix according to UE (k +1) and its allocated number of transmission layers Nl(k +1) determined matrix.
The user equipment referred to in the embodiments of the present invention may be any user equipment in the MIMO system, and the other user equipment is other user equipment except the any user equipment.
It is to be understood that step S103 may be performed on the premise that the number of transmission layers allocated by the other user equipment is less than the configured maximum number of transmission layers, or may be performed on the premise that the number of transmission layers allocated by the other user equipment is equal to the configured maximum number of transmission layers. When the number of transmission layers allocated to other user equipment is equal to the configured maximum number of transmission layers, the first intermediate matrix of the user equipment may also be constructed by directly using the channel matrices of other user equipment, which is not limited in this embodiment of the present invention.
In a specific implementation, in step S104, the effective channel matrix, the effective sub-matrix, and the effective sub-matrix of the user equipment are calculated by using the first middle matrix and the first right unitary matrix of the user equipment. Specifically, a first intermediate matrix of UE k is utilized
Figure BDA0001363764550000081
Calculating an effective channel matrix H 'of UE k'k(i.e., the transmission matrix). In other words, the effective channel matrix is calculated based on the first intermediate matrix.
More specifically, a first intermediate matrix for UE k
Figure BDA0001363764550000082
Singular value decomposition is carried out:
Figure BDA0001363764550000083
wherein the content of the first and second substances,
Figure BDA0001363764550000084
is the second right unitary matrix for UE k,
Figure BDA0001363764550000085
is the second left unitary matrix for UE k,
Figure BDA0001363764550000086
is a diagonal matrix. Second right unitary matrix at UE k
Figure BDA0001363764550000087
In (1), the number of excluded columns is Nl(K) The remaining matrix is used as the effective sub-matrix of UE k
Figure BDA0001363764550000088
Further, in step S105, block diagonalization is performed by using the effective channel matrix and the effective sub-matrix to obtain a precoding matrix, and the base station may modulate a signal transmitted to the user equipment by using the precoding matrix and transmit the modulated signal. Specifically, a signal r received by UE kkThe following formula can be used: r isk＝HkWksk+nkWherein W iskPrecoding matrix for UE k, HkIs the channel matrix, s, of UE kkAnd nkRespectively a transmitted symbol vector and a noise vector.
In this embodiment, a precoding technique based on singular value decomposition is used, and the obtained channel state information is used at the MIMO transmitting end to preprocess the original transmitting signal, so as to eliminate interference between the transmitting data streams, thereby obtaining better system performance. The MIMO channel can be decomposed into r (r is the rank of the channel matrix) parallel single-input single-output sub-channels, and the interference between the MIMO sub-channels is reduced.
The embodiment of the invention calculates the effective channel matrix of the user equipment by utilizing the first intermediate matrix of the user equipment, and the first intermediate matrix of the user equipment is constructed according to the first right unitary matrix of other user equipment except the user equipment and the distributed transmission layer number; in the MIMO system, when the number of transmission layers allocated to the ue is less than the configured maximum number of transmission layers, the number of columns of the first intermediate matrix is small, which can reduce the complexity of calculating the effective channel matrix compared to the prior art in which the effective channel matrix is calculated by directly using the channel matrix; in addition, the influence of the number of transmission layers allocated to the user equipment on the diagonalization is considered, so that the performance of block diagonalization can be improved, the signal-to-noise ratio is improved, and the signal transmission performance of the MIMO system is further improved.
Preferably, step S103 may include the steps of: if the number of transmission layers distributed by the other user equipment is smaller than the configured maximum number of transmission layers, selecting a characteristic vector in a first right unitary matrix of the other user equipment; and constructing a first intermediate matrix of the user equipment according to the number of transmission layers distributed by the other user equipment and the eigenvector. Specifically, after singular value decomposition, the channel matrix may obtain a plurality of eigenvalues and an eigenvector corresponding to each eigenvalue. The eigenvectors may be embodied in a first right unitary matrix, with each column being one eigenvector. Then, when constructing the first intermediate matrix, a matrix with the number of columns being the number of transmission layers allocated to the other user equipment may be selected from the first right unitary matrix. Further, the eigenvector corresponding to the maximum eigenvalue of the number of transmission layers allocated to the other user equipment may be selected.
Further, the constructing a first intermediate matrix of the user equipment according to the number of transmission layers allocated to the other user equipment and the eigenvector includes: and selecting at least part of elements in the eigenvectors of the other user equipment to construct a first intermediate matrix of the user equipment, wherein the number of columns of the first intermediate matrix of the user equipment is equal to the number of transmission layers distributed by the other user equipment.
In particular, a first intermediate matrix for UE k
Figure BDA0001363764550000091
Figure BDA0001363764550000092
Wherein the content of the first and second substances,
Figure BDA0001363764550000093
the number of columns selected for the first right unitary matrix of UE0 is Nl(the matrix of 0. the matrix of,
Figure BDA0001363764550000094
the number of columns selected for the first right unitary matrix of UE (k-1) is Nl(k-1) of a matrix of,
Figure BDA0001363764550000095
for the number of columns selected in the first right unitary matrix of UE (k +1) is NlA matrix of (k + 1).
In this embodiment, before the effective channel matrix is obtained, the eigenvectors corresponding to the layer number in the first right unitary matrix are obtained through SVD decomposition, and the effective channel matrix is calculated on the basis. Since each eigenvector corresponds to a spatial direction, the fewer directions to avoid when transmitting signals, the easier it is to return to zero, which can enable the user equipment to correctly receive the intended signal.
Further, the selecting at least a part of elements in the feature vectors of the other user equipments to construct a first intermediate matrix of the user equipment includes: and selecting the first N rows of elements in the first right unitary matrix of the other user equipment to obtain a first middle matrix of the user equipment, wherein N is equal to the number of transmission layers allocated to the other user equipment.
In particular, a first intermediate matrix for UE k
Figure BDA0001363764550000101
For the first N selected in the first right unitary matrix of UE0l(the matrix of the 0 columns,
Figure BDA0001363764550000102
for the first N selected in the first right unitary matrix of the UE (k-1)lA matrix of (k-1) columns,
Figure BDA0001363764550000103
for the first N selected in the first right unitary matrix of UE (k +1)lA matrix of (k +1) columns.
Further, the number of transmission layers N allocated to UE kl(k) And if the number is 1, selecting the eigenvector corresponding to the maximum singular value. Specifically, a first right unitary matrix at UE k
Figure BDA0001363764550000104
The first column is selected as the matrix
Figure BDA0001363764550000105
To construct a first intermediate matrix for other UEs.
In particular, the magnitude of the singular value may measure the health of the degrees of freedom supported by the channel. The smaller the singular value, the closer the degree of freedom is to the degraded edge; the larger the singular value, the better the channel state. Therefore, when selecting the eigenvector, the embodiment of the present invention selects the eigenvector corresponding to the largest singular value, or selects the eigenvectors corresponding to the largest N singular values, where N is the number of layers allocated for user equipment transmission.
Preferably, step S103 may include the steps of: and if the number of the transmission layers distributed by the other user equipment is the configured maximum number of the transmission layers, selecting the channel matrixes of the other user equipment to construct a first intermediate matrix of the user equipment.
In this embodiment, if the number of transmission layers allocated to the other user equipment is the configured maximum number of transmission layers, the first intermediate matrix of the user equipment is directly constructed by using the channel matrix of the user equipment. For example, if the number of transmission layers allocated to UE0 is the maximum number of transmission layers configured for UE k, the first intermediate matrix of UE k
Figure BDA0001363764550000106
Can be expressed as:
Figure BDA0001363764550000107
wherein the content of the first and second substances,
Figure BDA0001363764550000108
is a channel matrix for the UE0 and,
Figure BDA0001363764550000109
is a first right unitary matrix according to UE (k-1) and its allocated number of transmission layers Nl(k-1) determining a matrix of the image,
Figure BDA00013637645500001010
is a first right unitary matrix according to UE (k +1) and its allocated number of transmission layers Nl(k +1) determined matrix.
It can be appreciated that the first intermediate matrix for UE k
Figure BDA00013637645500001011
Or any other practicable combination, e.g.The number of transmission layers allocated to UE (k-1) or UE (k +1) is the maximum number of layers configured for the UE, which is not limited in the embodiment of the present invention.
Preferably, step S104 may include the steps of: performing singular value decomposition on the first intermediate matrix of the user equipment to obtain a second right unitary matrix; selecting a first sub-matrix from the first right unitary matrix, wherein the column number of the first sub-matrix is equal to the number of transmission layers distributed by the user equipment; removing the matrix with the column number being the number of the transmission layers distributed by the user equipment from the second right unitary matrix, and taking the residual matrix as an effective sub-matrix of the user equipment; taking the product of the first sub-matrix and the effective sub-matrix as the effective channel matrix.
In particular, a first intermediate matrix for UE k
Figure BDA0001363764550000111
Singular value decomposition is carried out:
Figure BDA0001363764550000112
wherein the content of the first and second substances,
Figure BDA0001363764550000113
is the second right unitary matrix for UE k,
Figure BDA0001363764550000114
is the second left unitary matrix for UE k,
Figure BDA0001363764550000115
is a diagonal matrix. According to the number N of transmission layers distributed by UE kl(K) First right unitary matrix at UE k
Figure BDA0001363764550000116
Selecting a first sub-matrix
Figure BDA0001363764550000117
A first sub-matrix
Figure BDA0001363764550000118
The number of columns is Nl(K) (ii) a Further, a first right unitary matrix may be selected
Figure BDA0001363764550000119
Middle front Nl(K) The column being a first sub-matrix
Figure BDA00013637645500001110
Second right unitary matrix at UE k
Figure BDA00013637645500001111
In (1), the number of excluded columns is Nl(K) The remaining matrix is used as the effective sub-matrix of UE k
Figure BDA00013637645500001112
Further still, the second right unitary matrix may be eliminated
Figure BDA00013637645500001113
Middle front Nl(K) Column, residual matrix as the effective sub-matrix for UE K
Figure BDA00013637645500001114
Then the effective channel matrix H 'of UE k'kIs a sub-matrix
Figure BDA00013637645500001115
And the effective sub-matrix
Figure BDA00013637645500001116
Product of, i.e.
Figure BDA00013637645500001117
It is understood that other user equipments, such as UE0, UE (k-1), and UE (k +1), may also use the above process to calculate the effective channel matrix, and will not be described herein again.
Preferably, step S105 may include the steps of: performing singular value decomposition on the effective channel matrix to obtain a third right unitary matrix; selecting a third sub-matrix corresponding to the user equipment from the third right unitary matrix, wherein the column number of the third sub-matrix is equal to the number of transmission layers distributed by the user equipment; taking the product of the effective sub-matrix and the third sub-matrix as the precoding matrix.
Specifically, the effective channel matrix H 'for UE k'kSingular value decomposition is carried out:
Figure BDA00013637645500001118
wherein the content of the first and second substances,
Figure BDA00013637645500001119
is a third right unitary matrix, U 'of UE k'kThird left unitary matrix, Σ "" for UE kkIs a diagonal matrix. According to the number N of transmission layers distributed by UE kl(K) Third right unitary matrix at UE k
Figure BDA00013637645500001120
Selecting a third sub-matrix
Figure BDA00013637645500001121
Third sub-matrix
Figure BDA00013637645500001122
The number of columns is Nl(K) (ii) a Further, a third right unitary matrix can be selected
Figure BDA00013637645500001123
Middle front Nl(K) Column as the third sub-matrix
Figure BDA00013637645500001124
Precoding matrix H' of UE kkAs an effective sub-matrix
Figure BDA00013637645500001125
And the third sub-matrix
Figure BDA00013637645500001126
Product of (2)
Figure BDA00013637645500001127
The precoding matrix H "is utilizedkModulating the signal r transmitted to the user equipmentkThe following formula can be used:
Figure BDA0001363764550000121
wherein HkChannel matrix, s, for UEkkAnd nkRespectively a transmitted symbol vector and a noise vector. Signal rkAnd is also the signal received by UE k.
It is understood that other user equipments, such as UE0, UE (k-1), and UE (k +1), may also use the above procedure to calculate the precoding matrix, and will not be described herein again.
Fig. 2 is a graph comparing the effect of the embodiment of the present invention with the prior art.
Fig. 2 shows the difference between the embodiment of the present invention and the prior art signal transmission scheme in rayleigh fading (rayleigh fading), which is embodied in the difference of signal-to-noise ratio. In an application scenario of this embodiment, the MIMI system includes two UEs, and the number of layers allocated for transmission of each UE is 1.
In fig. 2, the horizontal axis represents Signal to Interference plus noise ratio (SINR), and the vertical axis represents Cumulative Density Function (CDF). Curve 1 shows the variation curve of SINR with CDF in the prior art, and curve 2 shows the variation curve of SINR with CDF in the embodiment of the present invention. Comparing the curve 1 and the curve 2, the SINR of the embodiment of the present invention is higher under the same CDF.
Fig. 3 is a schematic structural diagram of a signal transmission apparatus according to an embodiment of the present invention.
The signal transmission device may be used on the base station side. In particular, it can be used on the transmitter side of the base station.
The signal transmission apparatus 30 shown in fig. 3 may include a receiving module 301, a singular value decomposition module 302, a matrix construction module 303, an effective channel matrix calculation module 304, and a precoding module 305.
The receiving module 301 is adapted to receive the channel matrices fed back by all the user equipments, and determine the number of transmission layers allocated to each user equipment for the number of transmission layers allocated, where the number of transmission layers allocated to each user equipment for the number of transmission layers allocated is less than or equal to the maximum number of transmission layers allocated to each user equipment; the singular value decomposition module 302 is adapted to perform singular value decomposition on the channel matrices of all the user equipments to obtain first right unitary matrices of all the user equipments; the matrix construction module 303 is adapted to construct a first intermediate matrix of the user equipment according to a first right unitary matrix of other user equipments except the user equipment and the number of allocated transmission layers; the effective channel matrix calculation module 304 is adapted to calculate an effective channel matrix and an effective sub-matrix of the user equipment using a first intermediate matrix and a first right unitary matrix of the user equipment; the precoding module 305 is adapted to perform block diagonalization using the effective channel matrix and the effective sub-matrix to obtain a precoding matrix, and modulate a signal transmitted to the user equipment using the precoding matrix.
The embodiment of the invention calculates the effective channel matrix of the user equipment by utilizing the first intermediate matrix of the user equipment, and the first intermediate matrix of the user equipment is constructed according to the first right unitary matrix of other user equipment except the user equipment and the distributed transmission layer number; in the MIMO system, when the number of transmission layers allocated to the ue is less than the configured maximum number of transmission layers, the number of columns of the first intermediate matrix is small, which can reduce the complexity of calculating the effective channel matrix compared to the prior art in which the effective channel matrix is calculated by directly using the channel matrix; in addition, the influence of the number of transmission layers allocated to the user equipment on the diagonalization is considered, so that the performance of block diagonalization can be improved, the signal-to-noise ratio is improved, and the signal transmission performance of the MIMO system is further improved.
Preferably, the matrix construction module 303 may include a selection unit 3031 and a matrix construction unit 3032. Wherein the selecting unit 3031 is adapted to select the eigenvector in the first right unitary matrix of the other user equipment if the number of transmission layers allocated by the other user equipment is less than the configured maximum number of layers; the matrix construction unit 3032 is adapted to construct a first intermediate matrix of the user equipment according to the number of transmission layers allocated by the other user equipment and the eigenvector.
Further, the matrix construction unit 3032 may include a matrix construction subunit 30321, and the matrix construction subunit 30321 is adapted to select at least a part of elements in the eigenvector of the other user equipment to construct a first intermediate matrix of the user equipment, where the number of columns of the first intermediate matrix of the user equipment is equal to the number of transmission layers allocated to the other user equipment.
Further, the matrix constructing subunit 30321 selects the first N columns of elements in the first right unitary matrix of the other user equipment to obtain a first intermediate matrix of the user equipment, where N is equal to the number of transmission layers allocated to the other user equipment.
Preferably, the matrix constructing module 303 selects the channel matrix of the other user equipment to construct the first intermediate matrix of the user equipment when the number of transmission layers allocated to the other user equipment is the configured maximum number of transmission layers.
Preferably, the effective channel matrix calculation module 304 may include a first singular value decomposition unit 3041, a first sub-matrix selection unit 3042, an effective sub-matrix selection unit 3043 and an effective channel matrix calculation unit 3044.
The first singular value decomposition unit 3041 is adapted to perform singular value decomposition on the first intermediate matrix of the user equipment to obtain a second right unitary matrix; the first sub-matrix selecting unit 3042 is adapted to select a first sub-matrix from the first right unitary matrix, where the number of columns of the first sub-matrix is equal to the number of transmission layers allocated to the ue; the effective sub-matrix selecting unit 3043 is adapted to remove the matrix whose columns are the number of transmission layers allocated to the user equipment from the second right unitary matrix, and use the remaining matrix as the effective sub-matrix of the user equipment; the effective channel matrix calculation unit 3044 is adapted to take the product of the first sub-matrix and the effective sub-matrix as the effective channel matrix.
Preferably, the precoding module 305 may include a second singular value decomposition unit 3051, a third sub-matrix extracting unit 3052, and a precoding matrix calculating unit 3053.
The second singular value decomposition unit 3051 is adapted to perform singular value decomposition on the effective channel matrix to obtain a third right unitary matrix; the third sub-matrix selecting unit 3052 is adapted to select, from the third right unitary matrix, a third sub-matrix corresponding to the ue, where the number of columns of the third sub-matrix is equal to the number of transmission layers allocated to the ue; the precoding matrix calculation unit 3053 is adapted to take a product of the effective sub-matrix and the third sub-matrix as the precoding matrix.
For more details of the operation principle and the operation mode of the signal transmission device 30, reference may be made to the description of fig. 1 to fig. 2, which is not repeated here.
The embodiment of the invention also discloses a readable storage medium, which stores computer instructions, and when the computer instructions are executed, the steps of the signal transmission method shown in fig. 1 can be executed. The storage medium may include ROM, RAM, magnetic or optical disks, etc.
The embodiment of the invention also discloses a base station, and the user equipment can comprise a memory and a processor, wherein the memory stores computer instructions capable of running on the processor. The processor, when executing the computer instructions, may perform the steps of the signal transmission method shown in fig. 1. The user equipment includes but is not limited to a mobile phone, a computer, a tablet computer and other terminal equipment.
Although the present invention is disclosed above, the present invention is not limited thereto. Various changes and modifications may be effected therein by one skilled in the art without departing from the spirit and scope of the invention as defined in the appended claims.

Claims (14)

1. A signal transmission method, comprising:
receiving channel matrixes fed back by all user equipment, and determining the number of transmission layers distributed by each user equipment, wherein the number of the transmission layers distributed by each user equipment is less than or equal to the maximum number of the transmission layers configured by the user equipment;
performing singular value decomposition on the channel matrixes of all user equipment to obtain first right unitary matrixes of all the user equipment;
constructing a first middle matrix of the user equipment according to a first right unitary matrix of other user equipment except the user equipment and the number of transmission layers distributed by the other user equipment;
calculating an effective channel matrix and an effective sub-matrix of the user equipment by using a first middle matrix and a first right unitary matrix of the user equipment;
block diagonalizing the effective channel matrix and the effective submatrix to obtain a precoding matrix, and modulating a signal transmitted to the user equipment by using the precoding matrix,
wherein calculating the effective channel matrix and the effective sub-matrix of the user equipment by using the first middle matrix and the first right unitary matrix of the user equipment comprises: performing singular value decomposition on the first intermediate matrix of the user equipment to obtain a second right unitary matrix;
selecting a first sub-matrix from the first right unitary matrix, wherein the column number of the first sub-matrix is equal to the number of transmission layers distributed by the user equipment;
removing the matrix with the column number being the number of the transmission layers distributed by the user equipment from the second right unitary matrix, and taking the residual matrix as an effective sub-matrix of the user equipment;
taking the product of the first sub-matrix and the effective sub-matrix as the effective channel matrix;
the obtaining a precoding matrix by performing block diagonalization by using the effective channel matrix and the effective submatrix includes:
performing singular value decomposition on the effective channel matrix to obtain a third right unitary matrix;
selecting a third sub-matrix corresponding to the user equipment from the third right unitary matrix, wherein the column number of the third sub-matrix is equal to the number of transmission layers distributed by the user equipment;
taking the product of the effective sub-matrix and the third sub-matrix as the precoding matrix.
2. The signal transmission method according to claim 1, wherein said constructing the first intermediate matrix of the user equipment according to the first right unitary matrix of the user equipment other than the user equipment and the allocated number of transmission layers comprises:
if the number of transmission layers distributed by the other user equipment is smaller than the configured maximum number of transmission layers, selecting a characteristic vector in a first right unitary matrix of the other user equipment;
and constructing a first intermediate matrix of the user equipment according to the number of transmission layers distributed by the other user equipment and the eigenvector.
3. The signal transmission method according to claim 2, wherein the constructing the first intermediate matrix of the user equipment according to the number of transmission layers allocated to the other user equipment and the eigenvector comprises:
and selecting at least part of elements in all the eigenvectors of the other user equipment to construct a first intermediate matrix of the user equipment, wherein the number of columns of the first intermediate matrix of the user equipment is equal to the number of transmission layers distributed by the other user equipment.
4. The signal transmission method according to claim 3, wherein said selecting at least a portion of elements in the eigenvectors of the other user equipments to construct a first intermediate matrix of the user equipment comprises:
and selecting the first N rows of elements in the first right unitary matrix of the other user equipment to obtain a first middle matrix of the user equipment, wherein N is equal to the number of transmission layers allocated to the other user equipment.
5. The signal transmission method according to claim 3, wherein said selecting at least a portion of elements in the eigenvectors of the other user equipments to construct a first intermediate matrix of the user equipment comprises:
and selecting N eigenvectors corresponding to the N maximum eigenvalues in the first right unitary matrix of the other user equipment to obtain a first intermediate matrix of the user equipment, wherein N is equal to the number of transmission layers distributed by the other user equipment.
6. The signal transmission method according to claim 1, wherein said constructing the first intermediate matrix of the user equipment according to the first right unitary matrix of the user equipment other than the user equipment and the allocated number of transmission layers comprises:
and if the number of the transmission layers distributed by the other user equipment is the configured maximum number of the transmission layers, selecting the channel matrixes of the other user equipment to construct a first intermediate matrix of the user equipment, wherein the singular value decomposition is carried out on the channel matrixes to obtain a first right unitary matrix.
7. A signal transmission apparatus, comprising:
the receiving module is suitable for receiving the channel matrixes fed back by all the user equipment and determining the number of the transmission layers distributed by each user equipment, wherein the number of the transmission layers distributed by each user equipment is less than or equal to the maximum number of the transmission layers configured by each user equipment;
the singular value decomposition module is suitable for performing singular value decomposition on the channel matrixes of all the user equipment to obtain first right unitary matrixes of all the user equipment;
the matrix construction module is suitable for constructing a first middle matrix of the user equipment according to a first right unitary matrix of other user equipment except the user equipment and the number of transmission layers distributed by the other user equipment;
an effective channel matrix calculation module adapted to calculate an effective channel matrix and an effective sub-matrix of the user equipment using a first intermediate matrix and a first right unitary matrix of the user equipment;
a precoding module, adapted to perform block diagonalization by using the effective channel matrix and the effective sub-matrix to obtain a precoding matrix, and modulate a signal transmitted to the user equipment by using the precoding matrix;
wherein the effective channel matrix calculation module comprises: the first singular value decomposition unit is suitable for performing singular value decomposition on a first intermediate matrix of the user equipment to obtain a second right unitary matrix;
a first sub-matrix selecting unit, adapted to select a first sub-matrix from the first right unitary matrix, where the number of columns of the first sub-matrix is equal to the number of transmission layers allocated to the user equipment;
an effective sub-matrix selecting unit, adapted to remove the matrix whose number of columns is the number of transmission layers allocated to the user equipment from the second right unitary matrix, and use the remaining matrix as an effective sub-matrix of the user equipment;
an effective channel matrix calculation unit adapted to take a product of the first sub-matrix and the effective sub-matrix as the effective channel matrix;
the precoding module includes:
the second singular value decomposition unit is suitable for performing singular value decomposition on the effective channel matrix to obtain a third right unitary matrix;
a third sub-matrix selecting unit, adapted to select a third sub-matrix corresponding to the ue from the third right unitary matrix, where the number of columns of the third sub-matrix is equal to the number of transmission layers allocated to the ue;
a precoding matrix calculation unit adapted to take a product of the effective sub-matrix and the third sub-matrix as the precoding matrix.
8. The signal transmission apparatus of claim 7, wherein the matrix construction module comprises:
a selecting unit, adapted to select a eigenvector in a first right unitary matrix of the other user equipment if the number of transmission layers allocated by the other user equipment is smaller than the configured maximum number of layers;
and the matrix construction unit is suitable for constructing a first intermediate matrix of the user equipment according to the number of transmission layers distributed by the other user equipment and the eigenvector.
9. The signal transmission apparatus according to claim 8, wherein the matrix construction unit includes:
a matrix construction subunit, adapted to select at least a part of elements in all eigenvectors of the other user equipment to construct a first intermediate matrix of the user equipment, where the number of columns of the first intermediate matrix of the user equipment is equal to the number of transmission layers allocated to the other user equipment.
10. The apparatus of claim 9, wherein the matrix construction subunit selects first N columns of elements in the first right unitary matrix of the other ue to obtain a first middle matrix of the ue, where N is equal to the number of transmission layers allocated to the other ue.
11. The apparatus of claim 9, wherein the matrix construction subunit selects N eigenvectors corresponding to N largest eigenvalues in the first right unitary matrix of the other user equipment to obtain the first intermediate matrix of the user equipment, where N is equal to the number of transmission layers allocated by the other user equipment.
12. The apparatus according to claim 7, wherein the matrix constructing module selects the channel matrices of the other ue to construct the first intermediate matrix of the ue when the number of transmission layers allocated to the other ue is the configured maximum number of transmission layers.
13. A computer-readable storage medium, on which computer instructions are stored, characterized in that the computer program executes the steps of the signal transmission method according to one of claims 1 to 6.
14. A base station comprising a memory and a processor, the memory having stored thereon a computer program operable on the processor, wherein the processor, when executing the computer program, performs the steps of the signal transmission method of any of claims 1 to 6.
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