CN102355287B - A kind of the determination method and device of pre-coding matrix - Google Patents
A kind of the determination method and device of pre-coding matrix Download PDFInfo
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Abstract
The invention discloses the determination method and device of a kind of pre-coding matrix, which includes：It determines the first channel matrix between base station and the first user terminal for belonging to base station, is determined according to the first channel matrix and meet the signal for being sent to the first user terminal after making coding in the first matrix that the first upward beamlet of the first subscriber side terminal is signal main lobe；It determines base station and belongs to the second channel matrix of the second user terminal room of the adjacent base station of base station, determined according to second channel matrix and meet the signal for being sent to the first user terminal after making coding in the second matrix that the second upward beamlet of second user terminal side is signal null；According to the first matrix and the second matrix, pre-coding matrix is determined.According to the technical solution, consideration can be compatible with and be sent to the signal quality of the first serviced user terminal and the signal of transmission to the interference problem of other users terminal signaling, improve the signal transmission performance of system.
Description
Technical Field
The present invention relates to the field of wireless communication technologies, and in particular, to a method and an apparatus for determining a precoding matrix.
Background
With the expansion of the wireless communication application range and the rapid increase of users thereof, the problem of user interference among base stations becomes more and more serious, and the existing wireless communication system is difficult to guarantee the reliability of communication while bearing a large amount of services.
Currently, in a 3Gpp Long Term Evolution-Advanced (LTE-a) system, a Coordinated Multiple Point (CoMP) technology realizes reliable transmission of wireless communication of a user served by a base station through Coordinated transmission of transmitting antennas of a plurality of base stations.
Fig. 1 is a schematic structural diagram of a communication system related to CoMP, and as shown in fig. 1, the system includes: first base station (eNB)1) And is attributed to the eNB1Of a first user terminal (UE)1) Second base station (eNB)2) And is attributed to the eNB2Of the second user terminal (UE)2) Wherein: eNB (evolved node B)1And eNB2Is a neighboring base station, H11As an eNB1To the UE1And the channel matrix, H12As an eNB1To the UE2Channel matrix of, H22As an eNB2To the UE2Channel matrix of, H21As an eNB2To the UE1The channel matrix of (2).
The CoMP technology has been widely used in LTE-a because of advantages such as the ability to improve throughput of base station edge data and spectrum utilization efficiency, but since the CoMP technology uses a plurality of base stations to perform joint transmission to a mobile user, there is interference between signals transmitted from the base stations to the user terminals, for example, in the system shown in fig. 1, when eNB is used1To the UE1When transmitting signals, if the eNB1Also to the UE2Transmitting signals or eNB2Also to the UE2Signals are transmitted, which may be to the eNB1Is sent to UE1Cause interference and thus affect the UE1The received signal quality.
In order to solve the above problems, for the purpose of improving the quality of signals received by the terminal, a precoding technique is introduced in the CoMP technique, and the precoding technique is mainly implemented at the base station side, specifically, the precoding processing is performed on the signals to be transmitted before the base station transmits the signals. A typical precoding method mainly includes: an SLNR (signal to Leakage Noise Ratio) criterion, a maximum signal to Noise Ratio criterion, a maximum signal to interference Noise Ratio criterion, and the like. These criteria are actually based on the consideration that: the interference of the signal to the signals transmitted to other users is considered to be reduced only when the condition that the signal transmitted to the currently served user of the base station is good enough is satisfied, that is, such criteria mainly consider the quality of the signal transmitted to the currently served user, and therefore, in practical application, there may be a problem that: in order to satisfy the QoS (quality of service) required by each user, the base station increases the transmission power of the signal transmitted to each user, and thus, the interference of the signal transmitted to the currently served user to the signals of other users increases, which may cause the receiving end to have poor quality of the demodulated signal due to the large interference of the signals of other users, thereby reducing the transmission performance of the entire system.
Therefore, according to the precoding method provided by the prior art, the base station cannot compatibly consider the quality of the signal sent to the served user terminal and the interference problem of the sent signal to the signals of other user terminals, so that the signal sent to the served user terminal may have large interference to the signals of other user terminals, thereby affecting the transmission performance of the system.
Disclosure of Invention
In view of this, embodiments of the present invention provide a method and an apparatus for determining a precoding matrix, where the precoding matrix determined by the technical scheme is used to perform precoding processing on a signal, so that quality of a signal sent to a serving user terminal and interference of the sent signal on signals of other user terminals can be considered compatibly, thereby improving transmission performance of a system.
The embodiment of the invention is realized by the following technical scheme:
according to an aspect of the embodiments of the present invention, there is provided a method for determining a precoding matrix, including:
determining a first channel matrix between a base station and a first user terminal belonging to the base station, and determining a first matrix which meets the requirement that a first sub-beam of a coded signal to be sent to the first user terminal in the direction of the first user terminal is a signal main lobe according to the first channel matrix; and
determining a second channel matrix between a base station and a second user terminal belonging to an adjacent base station of the base station, and determining a second matrix which meets the requirement that a second sub-beam of a signal to be sent to the first user terminal after being coded in the direction of the second user terminal is a signal null according to the second channel matrix;
and determining a precoding matrix for precoding a signal to be sent to the first user terminal according to the first matrix and the second matrix.
According to another aspect of the embodiments of the present invention, there is also provided an apparatus for determining a precoding matrix, including:
a first matrix determining unit, configured to determine a first channel matrix between a base station and a first user terminal belonging to the base station, and determine, according to the first channel matrix, a first matrix that satisfies a condition that a first sub-beam, in a direction of the first user terminal, of a signal to be sent to the first user terminal after being encoded is a signal main lobe; and
a second matrix determining unit, configured to determine a second channel matrix between a base station and a second user terminal of an adjacent base station belonging to the base station, and determine, according to the second channel matrix, a second matrix that satisfies a condition that a second sub-beam of a signal to be sent to the first user terminal after being encoded in a direction of the second user terminal is a signal null;
a precoding matrix determining unit, configured to determine, according to the first matrix determined by the first matrix determining unit and the second matrix determined by the second matrix determining unit, a precoding matrix used for precoding a signal to be sent to the first user terminal.
Through at least one of the above technical solutions provided in the embodiments of the present invention, before a base station sends a signal to a first user terminal belonging to the base station, a first channel matrix between the base station and the first user terminal is determined, and the first matrix is determined according to the first channel matrix, the first matrix satisfies that a first sub-beam formed by the encoded signal to be transmitted to the first user terminal in the direction of the first user terminal is a signal main lobe, and the base station determines a second matrix according to the determined second channel matrix of the base station and the second user terminal of the adjacent base station, the second matrix is satisfied to make the second sub-beam formed by the signal to be sent to the first user terminal after coding in the direction of the second user terminal be a signal null, and further convolve the first matrix with the second matrix, to determine a precoding matrix for precoding a signal to be transmitted to the first user terminal. By adopting the precoding matrix to encode the signal to be transmitted to the first user terminal, the base station can compatibly consider the quality of the signal transmitted to the served first user terminal and the interference problem of the transmitted signal to other user terminal signals, the signal to be transmitted to the first user terminal can be equivalent to two sub-beams after being encoded, wherein one sub-beam forms a signal main lobe in the direction of the first user terminal to improve the quality of the transmission signal, and the other sub-beam forms a signal null in the direction of the second user terminal to inhibit the interference to other user signals.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.
Drawings
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention and not to limit the invention. In the drawings:
fig. 1 is a schematic structural diagram of a communication system involved in CoMP in the background art;
fig. 2 is a schematic flowchart of determining a precoding matrix according to an embodiment of the present invention;
FIG. 3 is a diagram illustrating a first matrix W according to an embodiment of the present invention11A schematic flow diagram of (a);
fig. 4 is a schematic flowchart of determining eigenvectors corresponding to the first j large eigenvalues of the third matrix according to the first embodiment of the present invention;
fig. 5 is a schematic flowchart of determining a second matrix according to an embodiment of the present invention;
fig. 6 is a schematic flowchart of determining a precoding matrix according to a second embodiment of the present invention;
fig. 7 is a schematic diagram of a transmission beam formed after a precoding matrix determined by applying the embodiment of the present invention processes a signal to be transmitted according to a second embodiment of the present invention;
fig. 8 is a schematic structural diagram of a device for determining a precoding matrix according to a third embodiment of the present invention.
Detailed Description
In order to provide an implementation scheme for improving the transmission performance of the system, the embodiment of the present invention provides a method and an apparatus for determining a precoding matrix, and the following describes preferred embodiments of the present invention with reference to the drawings in the specification, it should be understood that the preferred embodiments described herein are only used for illustrating and explaining the present invention, and are not used to limit the present invention. And the embodiments and features of the embodiments in the present application may be combined with each other without conflict.
Example one
The first embodiment of the present invention provides a method for determining a precoding matrix, which can be applied to CoMP of an LTE-a system, and includes determining a first matrix according to a channel matrix of a base station and a first user terminal belonging to the base station, where the first matrix satisfies that a first sub-beam formed by a signal to be coded and sent to the first user terminal in a direction of the first user terminal is a signal main lobe, determining a second matrix according to a channel matrix of the base station and a second user terminal adjacent to the base station, where the second matrix satisfies that a second sub-beam formed by a signal to be coded and sent to the first user terminal in a direction of the second user terminal is a signal null, further performing precoding processing on a signal to be sent to the first user terminal according to precoding matrices determined by the first matrix and the second matrix, and equalizing the signal to be sent to the first user terminal into two sub-beams after coding, one of the sub-beams forms a signal main lobe in the direction of the first user terminal to improve the quality of a transmission signal, and the other sub-beam forms a signal null in the direction of the second user terminal to suppress interference to other user signals.
The above scheme may be applied to the system shown in fig. 1, fig. 2 is a schematic diagram illustrating a process of determining a precoding matrix based on the system shown in fig. 1, and as shown in fig. 2, the process of determining a precoding matrix mainly includes the following steps:
step 201, determining eNB1And is attributed to the eNB1Of a first user terminal UE1First channel matrix H in between11And eNB1And is attributed to the eNB1Adjacent base station eNB2Second user terminal UE2Second channel matrix H in between12。
In this step 201, the eNB1And UE1Or UE2The channel matrix between can be determined by the prior art, e.g. using，eNB1Can be achieved by receiving the UE in the served cell1Sending uplink sounding-1 (sounding-1) signal, and estimating the UE according to the sounding-1 signal1Channel matrix H in between11；eNB1Can be achieved by receiving the UE in the served cell2Sending uplink sounding-2 signal, and estimating the UE according to the sounding-2 signal2Channel matrix H in between12. In practical applications, the method for determining the channel matrix between the base station and the user terminal may be flexibly selected, which is only an example and will not be described in detail herein.
Step 202, according to the determined first channel matrix H11Determining whether the coded data is to be transmitted to the UE1At the UE1A first matrix W with a first sub-beam in the direction as the signal main lobe11。
Step 203, according to the determined second channel matrix H12Determining whether the coded data is to be transmitted to the UE1At the UE2Second matrix W with signal nulls for second sub-beam in direction12。
Step 204, according to the first matrix W11And a second matrix W12Determining to be sent to the UE1Is used for precoding the signal of1。
In this step 204, the first matrix W may preferably be set11And a second matrix W12Determining the matrix obtained by convolution as a precoding matrix W1Namely:
at this point, the process of determining the precoding matrix ends.
In the above procedure for determining the precoding matrix, steps 201, 202 and step 203 are not strictly limited in the execution order, and for example, the sequence may be limitedTo determine a first channel matrix H in step 20111Thereafter, step 202 is performed directly, and a second channel matrix H is determined in step 20112Thereafter, step 203 is performed directly, and the first channel matrix H is determined11And a second channel matrix H12Nor is there a strict order of execution.
Determining a precoding matrix W according to the above process corresponding to FIG. 21Then, the precoding matrix W is further adopted1To the transmission to the UE1Is precoded so as to be transmitted to the UE1At the UE1The directional sub-beam S1 is the signal main lobe, causing transmission to the UE1At the UE2The directional beamlet S2 nulls the signal. Therefore, the precoding matrix is adopted to precode the transmitted signals, and the purpose of improving the signal transmission performance of the system is achieved.
The flow corresponding to fig. 2 includes step 202, according to the determined first channel matrix H11Determining whether the coded data is to be transmitted to the UE1At the UE1A first matrix W with a first sub-beam in the direction as the signal main lobe11As shown in fig. 3, the process mainly includes the following steps:
301, according to the first channel matrix H11And determining a third matrix.
In step 301, the third matrix may be the first channel matrix H11And the first channel matrix H11Is multiplied by the conjugate transpose matrix of (b), or is directly the first channel matrix H11Or the first channel matrix H11Preferably, the third matrix may be the first channel matrix H11And the first channel matrix H11The matrix obtained by multiplying the conjugate transpose matrix is a square matrix, so that the subsequent determination of the first matrix W can be reduced11The amount of calculation of (a).
Step 302, determining eigenvectors corresponding to the first j large eigenvalues of the third matrix, wherein j isUE1The number of layers used.
Step 303, determining a matrix comprising eigenvectors corresponding to the first j large eigenvalues as a first matrix W11。
To this end, a first matrix W is determined11The process of (4) is ended.
In step 302 included in the corresponding flow of fig. 3, the eigenvectors corresponding to the first j large eigenvalues of the third matrix are determined according to the following formula:
formula (1)
The third matrix correspondingly determined by the above formula (1) is the first channel matrix H11And the first channel matrix H11The matrix obtained by multiplying the conjugate transpose matrix of (3). Wherein,representing a third matrixThe first j large feature values of the user UE correspond to feature vectors, j is the user UE1Number of layers, matrices usedIs a matrix H11The conjugate transpose matrix of (2).
If the third matrix is directly H11Then, the above formula (1) is expressed as:if the third matrix is directly H11The above equation (1) is expressed as:
in step 302 included in the corresponding flow of fig. 3, a specific process of determining eigenvectors corresponding to the first j large eigenvalues of the third matrix mainly includes the following steps, as shown in fig. 4:
step 401, feature vectors corresponding to the non-zero feature roots of the third matrix are constructed.
In this step 401, the number of constructed feature vectors corresponds to the number of feature roots, for example, the third matrix has two feature roots, each of which is λ1And λ2Then the following feature vector can be constructed:
wherein, SV1Is a characteristic root λ1Corresponding feature vector, SV2Is a characteristic root λ2A corresponding feature vector.
Step 402, then for each constructed feature vector, determining the SV according to the feature vector formula1And SV2。
In this step 402, the feature vector formula is:
(A-λiI)SVi0 formula (2)
Wherein:
a is a third matrix, I is an identity matrix, SViIs a sum of the characteristic value λiA corresponding feature vector.
And ending the process of determining the eigenvectors corresponding to the first j large eigenvalues of the third matrix.
The flow corresponding to fig. 2 includes step 203, according to the determined second channel matrix H12Determining whether the coded data is to be transmitted to the UE1At the UE2Second matrix W with signal nulls for second sub-beam in direction12As shown in fig. 5, the process mainly includes the following steps:
step 501, according to the second channel matrix H12And determining a fifth matrix.
In step 501, the fifth matrix may be the second channel matrix H12And the second channel matrix H12Is multiplied by the conjugate transpose matrix of (a), or directly is the second channel matrix H12Or the second channel matrix H12Preferably, the fifth matrix may be the second channel matrix H12And the second channel matrix H12The matrix obtained by multiplying the conjugate transpose matrix is a square matrix, so that the subsequent determination of the first matrix W can be reduced12The amount of calculation of (a).
Step 502, determining eigenvectors corresponding to the first j large eigenvalues of the inverse matrix of the fifth matrix, wherein j is UE2The number of layers used.
In step 502, the basic principle of determining the feature vectors corresponding to the first j large eigenvalues of the inverse matrix of the fifth matrix is consistent with the basic principle of determining the feature vectors corresponding to the first j large eigenvalues of the third matrix in step 302, and details are not repeated here.
Step 503, determining the matrix including the eigenvectors corresponding to the first j large eigenvalues as a second matrix W12。
To this end, a first matrix W is determined12The process of (4) is ended.
In step 502 included in the corresponding flow of fig. 5, the feature vectors corresponding to the first j large feature values of the inverse matrix of the fifth matrix are determined according to the following formula:
formula (3)
The fifth matrix correspondingly determined by the above formula (3) is the second channel matrix H12And the second channel matrix H12Is multiplied by a conjugate transpose matrix to obtainIn the case of a matrix of (c). Wherein,means for inverting the fifth matrixThe first j large feature values of (1) are corresponding feature vectors, j is UE2Number of layers, matrices usedIs a matrixThe inverse matrix of (c).
If the fifth matrix is directly H12Then, the above formula (3) is expressed as:if the third matrix is directly H12The above equation (3) is expressed as:
example two
The second embodiment of the present invention provides a specific application scenario of the technical solution provided in the first embodiment.
Fig. 6 is a schematic flow chart illustrating a method for determining a precoding matrix in a specific application scenario according to an embodiment of the present invention, where an adjacent base station eNB is configured1And eNB2The number of transmitting antennas is 4, respectively, and the user terminal UE1Attribution to base station eNB1User terminal UE2Attribution to base station eNB2，UE1And UE2Receive antennas are 2, respectively, and UE1And UE2The number of used layers is 2, as shown in fig. 6, the step of determining the precoding matrix includes:
step 601, determining base station eNB1And user UE in local base station1Of the channel matrix H11And base station eNB1With adjacent base station user UE2Inter channel matrix H12。
In this step 601, the base station eNB1By receiving the user UE of the base station1Transmitted uplink sounding-1 signal, determining base station eNB1With the user UE of the base station1Channel matrix H in between11：
Matrix H11Element h of11，mnWhere m is 1 or 2, denotes a receiving antenna of the user terminal, and n is 1, 2, 3, or 4, denotes a transmitting antenna of the base station, e.g., element h11，12For the UE11 st receiving antenna and eNB1Channel transfer function between the 2 nd transmit antennas, h11，22For the UE12 nd receiving antenna and eNB1Channel transfer function between the 2 nd transmit antennas.
Base station eNB1 receives user UE in a neighboring base station2Sounding-2 signal of transmitted uplink, determining eNB1And UE2Channel matrix H in between12：
Matrix H12Element h in (1)12，mnWhere m is 1 or 2, denotes a receiving antenna of the user terminal, and n is 1, 2, 3, or 4, denotes a transmitting antenna of the base station, e.g., element h12，12For the UE21 st receiving antenna and eNB1Channel transfer function between the 2 nd transmit antennas, h12，22For the UE22 nd receiving antenna and eNB12 nd transmitting between antennasThe track transfer function.
Step 602, according to base station eNB1And user UE in local base station1Of the channel matrix H11Determining a first matrix W11。
In this step 602, a first matrix W is determined by the above equation (1)11。
Step 603, according to eNB1And UE1Of the channel matrix H12Determining a second matrix W12。
In this step 603, a second matrix W is determined by the above equation (3)12。
Step 604, according to the first matrix W11And a second matrix W12Determining a precoding matrix W1。
From step 601 to step 604, the same can be determined for the base station eNB2Precoding matrix W of signals to be sent to user UE2 in local base station2And according to the determined precoding matrix W2To eNB2Pre-sent to UE2Signal X of2And carrying out precoding processing.
So far, the process of determining the precoding matrix provided in the second embodiment is ended.
In the above step 602, the first matrix W is determined according to the formula (1)11The process of (2) is as follows:
in the formula (1), it is assumed thatIs characterized by a characteristic root of1And λ2Then the structure is respectively corresponding to the λ1And λ2Corresponding feature vector SV1And SV2The following were used:
SV1＝[1，y21，y31，y41]T
SV2＝[-1，y22，y32，y42]T
wherein, SV1＝[1，y21，y31，y41]TIs a matrix [1, y21，y31，y41]The transposed matrix of (2); matrix SV2＝[-1，y22，y32，y42]TIs a matrix [ -1, y22，y32，y42]The transposed matrix of (2).
Matrix arrayIs a fourth order hermitian matrix with a characteristic root of lambda1，λ2，0，0。
Solving SV1The process of (2) is as follows:
substituting A into the above feature vector equation (2) (A- λ)iI)SViWhen the ratio is 0, the following is obtained:
(A-λ1I)SV1＝0
wherein I is an identity matrix:
further obtaining:
(A-λ1I)[1 y21y31y41]T＝0
further obtaining:
further obtaining:
it can thus be determined that:
wherein, the upper corner mark "-1" represents the inversion operation, and SV can be obtained by solving according to the above process1。
Solving SV2The process of (2) is as follows:
substituting A into the above feature vector equation (2) (A- λ)iI)SViWhen the ratio is 0, the following is obtained:
(A-λ2I)SV2＝0
wherein I is an identity matrix:
further obtaining:
(A-λ2I)[-1 y22y32y42]T＝0
further obtaining:
further obtaining:
SV can be obtained by solving according to the process2。
According to the above process, SV in the feature vector is determined1、SV2Respectively as follows:
in summary, the feature vector SV determined according to the above steps1、SV2Determining a base station eNB1For the user UE of the base station1First matrix W of11Comprises the following steps:
to this end, in step 602, the first matrix W is determined according to formula (1)11The process of (4) is ended.
Similarly, in step 603, according to the eNB1And UE1Of the channel matrix H12Determining a second matrix W12The process is basically the same as the above process, and is not described herein again.
After determining the precoding matrix according to the above technical solution provided by the second embodiment of the present invention, processing a signal to be transmitted by using the precoding matrix, fig. 7 shows a schematic diagram of a transmission beam formed after processing the signal to be transmitted by using the precoding matrix determined by the second embodiment of the present invention, as shown in fig. 7, an eNB1Is sent to UE1At the UE1Directional sub-beam S1 at UE1Forming a signal main lobe in a direction, and at the UE2Directional sub-beam S2 at UE2Forming signal nulls in the direction; also, eNB2Is sent to UE2At the UE2In the direction ofBeam S3 at the UE2Forming a signal main lobe in a direction, and at the UE1Directional sub-beam S4 at UE1Signal nulls are formed in the direction.
EXAMPLE III
The third embodiment of the present invention provides a device for determining a precoding matrix, where the device may be applied to a signal transmission device, such as a base station.
Fig. 8 is a schematic structural diagram of a device for determining a precoding matrix according to a third embodiment of the present invention, and as shown in fig. 8, the device for determining a precoding matrix mainly includes:
first matrix determining section 801, second matrix determining section 802, and precoding matrix determining section 803;
wherein:
a first matrix determining unit 801, configured to determine a first channel matrix between a base station and a first user terminal belonging to the base station, and determine, according to the first channel matrix, a first matrix that satisfies that a first sub-beam of a signal to be sent to the first user terminal after being encoded in a direction of the first user terminal is a signal main lobe;
a second matrix determining unit 802, configured to determine a second channel matrix between the base station and a second user terminal of an adjacent base station belonging to the base station, and determine, according to the second channel matrix, a second matrix that satisfies the requirement that a second sub-beam of a signal to be sent to the first user terminal after being coded in the direction of the second user terminal is a signal null;
a precoding matrix determining unit 803, configured to determine, according to the first matrix determined by the first matrix determining unit and the second matrix determined by the second matrix determining unit, a precoding matrix used for precoding a signal to be sent to the first user terminal.
In a preferred implementation manner provided in the third embodiment of the present invention, the apparatus shown in fig. 8 includes a first matrix determining unit 801, which is specifically configured to:
determining a third matrix according to the first channel matrix;
determining eigenvectors corresponding to the first j large eigenvalues of the third matrix, wherein j is the number of layers used by the first user terminal;
and determining a matrix comprising eigenvectors corresponding to the first j large eigenvalues as a first matrix.
In a preferred implementation manner provided in the third embodiment of the present invention, the apparatus shown in fig. 8 includes a first matrix determining unit 801, which is specifically configured to:
determining a matrix obtained by multiplying the first channel matrix and the conjugate transpose matrix of the first channel matrix as a third matrix; or
Determining the first channel matrix as a third matrix; or
And determining a conjugate transpose matrix of the first channel matrix as a third matrix.
In a preferred implementation manner provided in the third embodiment of the present invention, the apparatus shown in fig. 8 includes a first matrix determining unit 801, which is specifically configured to:
constructing feature vectors respectively corresponding to the non-zero feature roots of the third matrix;
for each feature vector constructed, determining:
subtracting the product of the first characteristic root of the third matrix and the identity matrix from the third matrix to obtain a fourth matrix; and are
And determining the feature vector with the product of the fourth matrix being zero as the feature vector corresponding to the first feature root.
In a preferred implementation manner provided in the third embodiment of the present invention, the apparatus shown in fig. 8 includes a second matrix determining unit 802, which is specifically configured to:
determining a fifth matrix according to the second channel matrix;
determining eigenvectors corresponding to the first j large eigenvalues of the inverse matrix of the fifth matrix, wherein j is the number of layers used by the second user terminal;
and determining a matrix comprising eigenvectors corresponding to the first j large eigenvalues as a second matrix.
In a preferred implementation manner provided in the third embodiment of the present invention, the apparatus shown in fig. 8 includes a second matrix determining unit 802, which is specifically configured to:
a matrix obtained by multiplying the second channel matrix by the conjugate transpose matrix of the second channel matrix is determined as a fifth matrix; or
Determining the second channel matrix as a fifth matrix; or
And determining a conjugate transpose matrix of the second channel matrix as a fifth matrix.
In a preferred implementation manner provided in the third embodiment of the present invention, the apparatus shown in fig. 8 includes a second matrix determining unit 802, which is specifically configured to:
constructing feature vectors corresponding to feature roots, which are not zero, of an inverse matrix of the fifth matrix respectively;
for each feature vector constructed, determining:
subtracting the product of the first characteristic root of the inverse matrix of the fifth matrix and the identity matrix from the inverse matrix of the fifth matrix to obtain a sixth matrix;
and determining the feature vector with the product of the sixth matrix being zero as the feature vector corresponding to the first feature root.
In a preferred implementation manner provided in the third embodiment of the present invention, the apparatus shown in fig. 8 includes a precoding matrix determining unit 803, which is specifically configured to:
and determining a matrix obtained by convolving the first matrix and the second matrix as a precoding matrix for precoding a signal to be sent to the first user terminal.
It should be understood that the above apparatus for determining a precoding matrix includes only units that are logically divided according to the functions implemented by the apparatus, and in practical applications, the above units may be overlapped or separated. The functions implemented by the device for determining a precoding matrix provided in the third embodiment correspond to the method flows for determining a precoding matrix provided in the first and second embodiments one to one, and for the more detailed processing flows implemented by the device, detailed descriptions have been made in the method embodiments, and detailed descriptions are omitted here.
Moreover, the determining apparatus of the precoding matrix in the third embodiment further has functional modules capable of implementing the schemes in the first to second embodiments, and details are not repeated here.
Through at least one of the above technical solutions provided in the embodiments of the present invention, before a base station sends a signal to a first user terminal belonging to the base station, a first channel matrix between the base station and the first user terminal is determined, and the first matrix is determined according to the first channel matrix, the first matrix satisfies that a first sub-beam formed by the encoded signal to be transmitted to the first user terminal in the direction of the first user terminal is a signal main lobe, and the base station determines a second matrix according to the determined second channel matrix of the base station and the second user terminal of the adjacent base station, the second matrix is satisfied to make the second sub-beam formed by the signal to be sent to the first user terminal after coding in the direction of the second user terminal be a signal null, and further convolve the first matrix with the second matrix, to determine a precoding matrix for precoding a signal to be transmitted to the first user terminal. By adopting the precoding matrix to encode the signal to be transmitted to the first user terminal, the base station can compatibly consider the quality of the signal transmitted to the served first user terminal and the interference problem of the transmitted signal to other user terminal signals, the signal to be transmitted to the first user terminal can be equivalent to two sub-beams after being encoded, wherein one sub-beam forms a signal main lobe in the direction of the first user terminal to improve the quality of the transmission signal, and the other sub-beam forms a signal null in the direction of the second user terminal to inhibit the interference to other user signals.
While the preferred embodiments of the present application have been described, additional variations and modifications in those embodiments may occur to those skilled in the art once they learn of the basic inventive concepts. Therefore, it is intended that the appended claims be interpreted as including preferred embodiments and all alterations and modifications as fall within the scope of the application.
It will be apparent to those skilled in the art that various changes and modifications may be made in the present invention without departing from the spirit and scope of the invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include such modifications and variations.
Claims (14)
1. A method for determining a precoding matrix, comprising:
determining a first channel matrix between a base station and a first user terminal belonging to the base station, and determining a first matrix which meets the requirement that a first sub-beam of a coded signal to be sent to the first user terminal in the direction of the first user terminal is a signal main lobe according to the first channel matrix; and
determining a second channel matrix between a base station and a second user terminal belonging to an adjacent base station of the base station, and determining a second matrix which meets the requirement that a second sub-beam of a signal to be sent to the first user terminal after being coded in the direction of the second user terminal is a signal null according to the second channel matrix;
determining a precoding matrix for precoding a signal to be sent to the first user terminal according to the first matrix and the second matrix;
wherein, the determining, according to the first channel matrix, a first matrix that satisfies that a first sub-beam of a coded signal to be sent to the first user terminal in the direction of the first user terminal is a signal main lobe includes: determining a third matrix according to the first channel matrix; determining eigenvectors corresponding to the first j large eigenvalues of the third matrix, wherein j is the number of layers used by the first user terminal; determining a matrix comprising eigenvectors corresponding to the first j large eigenvalues as the first matrix; the eigenvectors corresponding to the first j large eigenvalues of the third matrix are determined by the following formula:wherein,representing a third matrixThe eigenvectors, matrices corresponding to the first j large eigenvalues ofIs a matrix H11The conjugate transpose matrix of (2).
2. The method of claim 1, wherein determining a third matrix from the first channel matrix comprises:
determining a matrix obtained by multiplying the first channel matrix by a conjugate transpose matrix of the first channel matrix as a third matrix; or
Determining the first channel matrix as a third matrix; or
And determining a conjugate transpose matrix of the first channel matrix as a third matrix.
3. The method of claim 1, wherein determining eigenvectors corresponding to the first j large eigenvalues of the third matrix comprises:
constructing feature vectors respectively corresponding to the feature roots of the third matrix, which are not zero;
for each feature vector constructed, determining:
subtracting the product of the first characteristic root of the third matrix and the identity matrix from the third matrix to obtain a fourth matrix; and are
And determining the feature vector with the product of the fourth matrix being zero as the feature vector corresponding to the first feature root.
4. The method of claim 1, wherein said determining a second matrix satisfying signal nulls for a second sub-beam of the encoded signal to be transmitted to the first user terminal in the direction of the second user terminal based on the second channel matrix comprises:
determining a fifth matrix according to the second channel matrix;
determining eigenvectors corresponding to the first j large eigenvalues of the inverse matrix of the fifth matrix, wherein j is the number of layers used by the second user terminal;
and determining a matrix comprising eigenvectors corresponding to the first j large eigenvalues of the inverse matrix of the fifth matrix as the second matrix.
5. The method of claim 4, wherein determining a fifth matrix from the second channel matrix comprises:
determining a matrix obtained by multiplying the second channel matrix by a conjugate transpose matrix of the second channel matrix as a fifth matrix; or
Determining the second channel matrix as a fifth matrix; or
And determining a conjugate transpose matrix of the second channel matrix as a fifth matrix.
6. The method of claim 4, wherein determining the eigenvectors corresponding to the first j large eigenvalues of the inverse of the fifth matrix comprises:
constructing feature vectors respectively corresponding to feature roots of the inverse matrix of the fifth matrix, which are not zero;
for each feature vector constructed, determining:
subtracting the product of the first characteristic root of the inverse matrix of the fifth matrix and the identity matrix from the inverse matrix of the fifth matrix to obtain a sixth matrix;
and determining the feature vector with the product of the sixth matrix being zero as the feature vector corresponding to the first feature root.
7. The method of claim 1, wherein determining a precoding matrix for precoding a signal to be transmitted to the first user terminal based on the first matrix and the second matrix comprises:
and determining a matrix obtained by convolving the first matrix and the second matrix as a precoding matrix for precoding a signal to be sent to the first user terminal.
8. An apparatus for determining a precoding matrix, comprising:
a first matrix determining unit, configured to determine a first channel matrix between a base station and a first user terminal belonging to the base station, and determine, according to the first channel matrix, a first matrix that satisfies a condition that a first sub-beam, in a direction of the first user terminal, of a signal to be sent to the first user terminal after being encoded is a signal main lobe;
a second matrix determining unit, configured to determine a second channel matrix between a base station and a second user terminal of an adjacent base station belonging to the base station, and determine, according to the second channel matrix, a second matrix that satisfies a condition that a second sub-beam of a signal to be sent to the first user terminal after being encoded in a direction of the second user terminal is a signal null;
a precoding matrix determining unit, configured to determine, according to the first matrix determined by the first matrix determining unit and the second matrix determined by the second matrix determining unit, a precoding matrix used for precoding a signal to be sent to the first user terminal;
the first matrix determining unit is specifically configured to: determining a third matrix according to the first channel matrix; determining eigenvectors corresponding to the first j large eigenvalues of the third matrix, wherein j is the number of layers used by the first user terminal; determining a matrix comprising eigenvectors corresponding to the first j large eigenvalues as the first matrix; the eigenvectors corresponding to the first j large eigenvalues of the third matrix are determined by the following formula:wherein,representing a third matrixThe eigenvectors, matrices corresponding to the first j large eigenvalues ofIs a matrix H11The conjugate transpose matrix of (2).
9. The apparatus of claim 8, wherein the first matrix determination unit is specifically configured to:
determining a matrix obtained by multiplying the first channel matrix by a conjugate transpose matrix of the first channel matrix as a third matrix; or
Determining the first channel matrix as a third matrix; or
And determining a conjugate transpose matrix of the first channel matrix as a third matrix.
10. The apparatus of claim 8, wherein the first matrix determination unit is specifically configured to:
constructing feature vectors respectively corresponding to the feature roots of the third matrix, which are not zero;
for each feature vector constructed, determining:
subtracting the product of the first characteristic root of the third matrix and the identity matrix from the third matrix to obtain a fourth matrix; and are
And determining the feature vector with the product of the fourth matrix being zero as the feature vector corresponding to the first feature root.
11. The apparatus of claim 8, wherein the second matrix determination unit is specifically configured to:
determining a fifth matrix according to the second channel matrix;
determining eigenvectors corresponding to the first j large eigenvalues of the inverse matrix of the fifth matrix, wherein j is the number of layers used by the second user terminal;
and determining a matrix comprising eigenvectors corresponding to the first j large eigenvalues of the inverse matrix of the fifth matrix as the second matrix.
12. The apparatus of claim 11, wherein the second matrix determination unit is specifically configured to:
determining a matrix obtained by multiplying the second channel matrix by a conjugate transpose matrix of the second channel matrix as a fifth matrix; or
Determining the second channel matrix as a fifth matrix; or
And determining a conjugate transpose matrix of the second channel matrix as a fifth matrix.
13. The apparatus of claim 11, wherein the second matrix determination unit is specifically configured to:
constructing feature vectors respectively corresponding to feature roots of the inverse matrix of the fifth matrix, which are not zero;
for each feature vector constructed, determining:
subtracting the product of the first characteristic root of the inverse matrix of the fifth matrix and the identity matrix from the inverse matrix of the fifth matrix to obtain a sixth matrix;
and determining the feature vector with the product of the sixth matrix being zero as the feature vector corresponding to the first feature root.
14. The apparatus of claim 8, wherein the precoding matrix determination unit is specifically configured to:
and determining a matrix obtained by convolving the first matrix and the second matrix as a precoding matrix for precoding a signal to be sent to the first user terminal.
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| CN102025464A (en) * | 2010-12-21 | 2011-04-20 | 中兴通讯股份有限公司 | Method and system for precoding coordination of downlink multi-base station multi-input and multi-output |
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