Signal sending method and apparatus
A signal sending method and a related apparatus are disclosed. In the signal sending method, an access network device obtains a channel information sample, determines M′ frequency domain units in M frequency domain units in an (x+T) th time unit based on the channel information sample, and sends one or more measurement pilots to a terminal in the M′ frequency domain units. The one or more measurement pilots are used to measure CSI, and the channel information sample includes channel information in an x th time unit to an (x+T−1) th time unit, where M′<M. In the method, the access network device may determine the M′ frequency domain units in the M frequency domain units in the (x+T) th time unit to send the one or more measurement pilots, to implement frequency-domain dimension reduction of the one or more measurement pilots.
1 . A signal sending method, comprising:
obtaining a channel information sample, wherein the channel information sample comprises channel information in an x th time unit to an (x+T−1) th time unit, and both x and T are integers greater than or equal to 1;
determining M′ frequency domain units in M frequency domain units in an (x+T) th time unit based on the channel information sample, wherein the M′ frequency domain units are used to send one or more measurement pilots for measuring channel state information (CSI), both M′ and M are integers greater than or equal to 1, and M′<M; and
sending the one or more measurement pilots to a terminal in the M′ frequency domain units,
wherein the one or more measurement pilots sent in each of the M′ frequency domain units are precoded by using a fourth matrix, the fourth matrix being configured to perform space-domain dimension reduction on the one or more measurement pilots, wherein a seventh matrix is obtained by multiplying the fourth matrix by a third matrix, the third matrix being configured to sparsely represent channel information, and column coherence of the seventh matrix is the smallest.
2 . The method according to claim 1 , further comprising:
sending first indication information to the terminal, wherein the first indication information indicates location information of the M′ frequency domain units.
3 . The method according to claim 1 , wherein the sending the one or more measurement pilots to a terminal in the M′ frequency domain units comprises:
sending one or more measurement pilots of N′ ports to the terminal in each of the M′ frequency domain units based on the channel information sample, and sending second indication information to the terminal, wherein the second indication information indicates a value of N′, and N′ is an integer greater than or equal to 1.
4 . The method according to claim 1 , further comprising:
receiving feedback information from the terminal, wherein the feedback information indicates information about a measurement pilot signal received by the terminal in the (x+T) th time unit; and
determining a downlink channel matrix in the (x+T) th time unit based on the feedback information.
5 . The method according to claim 1 , further comprising:
calculating a downlink channel matrix in an (x+T+1) th time unit by using channel information in p time units as a channel information sample, wherein p is an integer greater than or equal to 1 and less than or equal to x+T.
6 . The method according to claim 1 , wherein a downlink channel matrix in a time unit indicates channel information in the time unit, and the downlink channel matrix in each time unit is an N*M matrix, wherein N is an integer greater than or equal to 1; and an F-norm of a matrix difference between a product of the third matrix and a fifth matrix and a sixth matrix is the smallest, wherein
the sixth matrix is an N* (M*T) matrix, column vectors in the sixth matrix comprise all column vectors in downlink channel matrices in the x th time unit to the (x+T−1) th time unit, column vectors in the fifth matrix correspond one-to-one to the column vectors in the sixth matrix, a column vector in the fifth matrix is a sparse representation of a corresponding column vector in the sixth matrix, and a quantity of non-zero elements in each column vector in the fifth matrix is equal to S 1 , wherein S 1 is an integer greater than or equal to 1 and less than N.
7 . The method according to claim 1 , wherein the M′ frequency domain units are determined by using a second matrix, column coherence of a matrix obtained by multiplying the second matrix by a first matrix is the smallest; and the second matrix is a row-extracted matrix, each row in the second matrix has only one non-zero element, and non-zero elements in different rows are in different locations;
an F-norm of a matrix difference between a product of the first matrix and an eighth matrix and a conjugate transposition matrix of a ninth matrix is the smallest, wherein
the ninth matrix is determined based on the channel information sample and the fourth matrix, an m th column vector in the ninth matrix comprises T column vectors arranged in a top-to-bottom sequence, an s th column vector in the T column vectors is a product of an m th column in an s th downlink channel matrix and the fourth matrix, and the s th downlink channel matrix is a downlink channel matrix in an (x+s−1) th time unit in the x th time unit to the (x+T−1) th time unit, wherein m is an integer greater than or equal to 1 and less than or equal to M, and s is an integer greater than or equal to 1 and less than or equal to T; and
column vectors in the eighth matrix correspond one-to-one to column vectors in the conjugate transposition matrix of the ninth matrix, a column vector in the eighth matrix is a sparse representation of a corresponding column vector in the conjugate transposition matrix of the ninth matrix, and a quantity of non-zero elements in each column vector in the eighth matrix is equal to S 2 , wherein S 2 is an integer greater than or equal to 1 and less than M.
8 . A signal sending method, comprising:
receiving a measurement pilot signal;
determining feedback information, wherein the feedback information indicates information about the measurement pilot signal, the measurement pilot signal comprises N′*M′*R elements, each element represents the measurement pilot signal received on one of N′ ports for sending one or more measurement pilots, in one of M′ frequency domain units for sending the one or more measurement pilots, and on one of R ports for receiving the measurement pilot signal, and R, N′, and M′ are all integers greater than or equal to 1; and
sending the feedback information to an access network device,
wherein the M′ frequency domain units are determined from M frequency domain units in an (x+T) th time unit based on a channel information sample and by using a second matrix, the channel information sample comprises channel information in an x th time unit to the (x+T−1) th time unit, both x and T are integers greater than or equal to 1, M is a positive integer, M′<M, and column coherence of a matrix obtained by multiplying the second matrix by a first matrix is the smallest, the first matrix being determined based on the channel information sample.
9 . The method according to claim 8 , wherein the measurement pilot signal comprises a plurality of groups of elements, each group of elements comprises more than one element, and the feedback information indicates amplitude information and phase information of each group of elements.
10 . The method according to claim 8 , further comprising:
receiving first indication information and second indication information from the access network device, wherein the first indication information indicates location information of the M′ frequency domain units for sending the one or more measurement pilots, and the second indication information indicates a value of N′; and
the receiving a measurement pilot signal comprises: receiving the measurement pilot signal on N′ ports in each of the M′ frequency domain units.
11 . A signal sending apparatus, comprising:
at least one processor; and
a memory storing programming instructions that, when executed by the at least one processor, cause the signal sending apparatus to perform operations comprising:
obtaining a channel information sample, wherein the channel information sample comprises channel information in an x th time unit to an (x+T−1) th time unit, and both x and T are integers greater than or equal to 1;
determining M′ frequency domain units in M frequency domain units in an (x+T) th time unit based on the channel information sample, wherein the M′ frequency domain units are used to send one or more measurement pilots for measuring channel state information (CSI), both M′ and M are integers greater than or equal to 1, and M′<M; and
sending the one or more measurement pilots to a terminal in the M′ frequency domain units,
wherein the one or more measurement pilots sent in each of the M′ frequency domain units are precoded by using a fourth matrix, the fourth matrix being configured to perform space-domain dimension reduction on the one or more measurement pilots, wherein a seventh matrix is a matrix obtained by multiplying the fourth matrix by a third matrix, the third matrix being configured to sparsely represent channel information, and column coherence of the seventh matrix is the smallest.
12 . The apparatus according to claim 11 , wherein the operations further comprise:
sending first indication information to the terminal, wherein the first indication information indicates location information of the M′ frequency domain units.
13 . The apparatus according to claim 11 , wherein the sending the one or more measurement pilots to a terminal in the M′ frequency domain units comprises:
sending one or more measurement pilots of N′ ports to the terminal in each of the M′ frequency domain units based on the channel information sample, and sending second indication information to the terminal, wherein the second indication information indicates a value of N′, and N′ is an integer greater than or equal to 1.
14 . The apparatus according to claim 11 , wherein the operations further comprise:
receiving feedback information from the terminal, wherein the feedback information indicates information about a measurement pilot signal received by the terminal in the (x+T) th time unit; and
determining a downlink channel matrix in the (x+T) th time unit based on the feedback information.
15 . The apparatus according to claim 11 , wherein the operations further comprise:
calculating a downlink channel matrix in an (x+T+1) th time unit by using channel information in p time units as a channel information sample, wherein p is an integer greater than or equal to 1 and less than or equal to x+T.
16 . The apparatus according to claim 11 , wherein a downlink channel matrix in a time unit indicates channel information in the time unit, and the downlink channel matrix in each time unit is an N*M matrix, wherein N is an integer greater than or equal to 1; and an F-norm of a matrix difference between a product of the third matrix and a fifth matrix and a sixth matrix is the smallest, wherein
the sixth matrix is an N* (M*T) matrix, column vectors in the sixth matrix comprise all column vectors in downlink channel matrices in the x th time unit to the (x+T−1) th time unit, column vectors in the fifth matrix correspond one-to-one to the column vectors in the sixth matrix, a column vector in the fifth matrix is a sparse representation of a corresponding column vector in the sixth matrix, and a quantity of non-zero elements in each column vector in the fifth matrix is equal to S 1 , wherein S 1 is an integer greater than or equal to 1 and less than N.
17 . The apparatus according to claim 11 , wherein the M′ frequency domain units are determined by using a second matrix, column coherence of a matrix obtained by multiplying the second matrix by a first matrix is the smallest; and the second matrix is a row-extracted matrix, each row in the second matrix has only one non-zero element, and non-zero elements in different rows are in different locations;
an F-norm of a matrix difference between a product of the first matrix and an eighth matrix and a conjugate transposition matrix of a ninth matrix is the smallest, wherein
the ninth matrix is determined based on the channel information sample and the fourth matrix, an m th column vector in the ninth matrix comprises T column vectors arranged in a top-to-bottom sequence, an s th column vector in the T column vectors is a product of an m th column in an s th downlink channel matrix and the fourth matrix, and the s th downlink channel matrix is a downlink channel matrix in an (x+s−1) th time unit in the x th time unit to the (x+T−1) th time unit, wherein m is an integer greater than or equal to 1 and less than or equal to M, and s is an integer greater than or equal to 1 and less than or equal to T; and
column vectors in the eighth matrix correspond one-to-one to column vectors in the conjugate transposition matrix of the ninth matrix, a column vector in the eighth matrix is a sparse representation of a corresponding column vector in the conjugate transposition matrix of the ninth matrix, and a quantity of non-zero elements in each column vector in the eighth matrix is equal to S 2 , wherein S 2 is an integer greater than or equal to 1 and less than M.
18 . A signal sending apparatus, comprising:
at least one processor; and
a memory storing programming instructions that, when executed by the at least one processor, cause the signal sending apparatus to perform operations comprising:
receiving a measurement pilot signal;
determining feedback information, wherein the feedback information indicates information about the measurement pilot signal, the measurement pilot signal comprises N′*M′*R elements, each element represents the measurement pilot signal received on one of N′ ports for sending one or more measurement pilots, in one of M′ frequency domain units for sending the one or more measurement pilots, and on one of R ports for receiving the measurement pilot signal, and R, N′, and M′ are all integers greater than or equal to 1; and
sending the feedback information to an access network device,
wherein the M′ frequency domain units are determined from M frequency domain units in an (x+T) th time unit based on a channel information sample and by using a second matrix, the channel information sample comprises channel information in an x th time unit to the (x+T−1) th time unit, both x and T are integers greater than or equal to 1, M is a positive integer, M′<M, and column coherence of a matrix obtained by multiplying the second matrix by a first matrix is the smallest, the first matrix being determined based on the channel information sample.
19 . The apparatus according to claim 18 , wherein the measurement pilot signal comprises a plurality of groups of elements, each group of elements comprises more than one element, and the feedback information indicates amplitude information and phase information of each group of elements.
20 . The apparatus according to claim 18 , wherein the operations further comprise:
receiving first indication information and second indication information from the access network device, wherein the first indication information indicates location information of the M′ frequency domain units for sending the one or more measurement pilots, and the second indication information indicates a value of N′; and
the receiving a measurement pilot signal comprises: receiving the measurement pilot signal on N′ ports in each of the M′ frequency domain units.