WO2020029937A1 - 指示预编码矩阵和确定预编码矩阵的方法以及通信装置 - Google Patents

指示预编码矩阵和确定预编码矩阵的方法以及通信装置 Download PDF

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WO2020029937A1
WO2020029937A1 PCT/CN2019/099351 CN2019099351W WO2020029937A1 WO 2020029937 A1 WO2020029937 A1 WO 2020029937A1 CN 2019099351 W CN2019099351 W CN 2019099351W WO 2020029937 A1 WO2020029937 A1 WO 2020029937A1
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vector
vectors
frequency
pmi
domain
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PCT/CN2019/099351
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English (en)
French (fr)
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王潇涵
金黄平
毕晓艳
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华为技术有限公司
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Priority to EP19846607.0A priority Critical patent/EP3826199B1/en
Publication of WO2020029937A1 publication Critical patent/WO2020029937A1/zh
Priority to US17/171,714 priority patent/US11165483B2/en

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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
    • H04B7/0456—Selection of precoding matrices or codebooks, e.g. using matrices antenna weighting
    • H04B7/0478—Special codebook structures directed to feedback optimisation
    • 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
    • H04B7/06—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station
    • H04B7/0613—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission
    • H04B7/0615—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission of weighted versions of same signal
    • H04B7/0619—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission of weighted versions of same signal using feedback from receiving side
    • H04B7/0636—Feedback format
    • H04B7/0639—Using selective indices, e.g. of a codebook, e.g. pre-distortion matrix index [PMI] or for beam selection
    • 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
    • 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
    • H04B7/046—Selection of precoding matrices or codebooks, e.g. using matrices antenna weighting taking physical layer constraints into account
    • H04B7/0469—Selection of precoding matrices or codebooks, e.g. using matrices antenna weighting taking physical layer constraints into account taking special antenna structures, e.g. cross polarized antennas into account
    • 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
    • H04B7/06—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station
    • H04B7/0613—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission
    • H04B7/0615—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission of weighted versions of same signal
    • H04B7/0619—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission of weighted versions of same signal using feedback from receiving side
    • H04B7/0621—Feedback content
    • H04B7/0626—Channel coefficients, e.g. channel state information [CSI]
    • 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
    • H04B7/06—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station
    • H04B7/0613—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission
    • H04B7/0615—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission of weighted versions of same signal
    • H04B7/0619—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the transmitting station using simultaneous transmission of weighted versions of same signal using feedback from receiving side
    • H04B7/0636—Feedback format
    • H04B7/0645—Variable feedback
    • H04B7/065—Variable contents, e.g. long-term or short-short
    • 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
    • H04B7/10—Polarisation diversity; Directional diversity

Definitions

  • the present application relates to the field of wireless communications, and more particularly, to a method of indicating a precoding matrix, a method of determining a precoding matrix, and a communication device.
  • pre-coding can reduce interference between multiple users and interference between multiple signal streams of the same user, which is beneficial to improve Signal quality, realize space division multiplexing, and improve spectrum utilization.
  • a terminal device can perform channel measurement according to a received reference signal, determine an ideal precoding matrix, and feed back to a network device through a precoding matrix indicator (PMI). .
  • PMI precoding matrix indicator
  • the terminal device may indicate the ideal precoding matrix to the network device through a two-level feedback method of wideband feedback and subband feedback.
  • the terminal device may indicate the quantized value of the selected beam and the wideband amplitude coefficient of each beam through wideband feedback, and may indicate the quantized value of the combination coefficient available to each subband through subband feedback, where the combination coefficient includes, for example, Band amplitude coefficient and subband phase coefficient.
  • the network device can synthesize the information of the wideband feedback and the information of the subband feedback to recover a precoding matrix that is close to the ideal precoding matrix.
  • network equipment can transmit data to terminal equipment through multiple transmission layers.
  • the terminal device performs the wideband feedback and the subband feedback as described above based on each transmission layer, a large feedback overhead may be brought.
  • the present application provides a method for indicating a precoding matrix, a method for determining a precoding matrix, and a communication device, so as to reduce feedback overhead of a PMI.
  • a method for indicating a precoding matrix is provided.
  • the method may be executed by a terminal device, or may be executed by a chip configured in the terminal device.
  • the method includes: determining a precoding matrix indicating PMI, the PMI includes R sets of space frequency information corresponding to R transmission layers, and the R sets of space frequency information are used to determine a precoding matrix corresponding to each subband,
  • the r-th group of space-frequency information in the R-group of space-frequency information is used to indicate: P * L space-domain vectors corresponding to the r-th transmission layer in the R-transmission layers; K frequencies corresponding to the r-th transmission layer A domain vector; and P * L * K coefficients corresponding to the r-th transmission layer; and sending the PMI.
  • the P * L spatial domain vectors are determined by the L beam vectors in each of the P polarization directions and their broadband amplitude coefficients, and each of the P * L * K coefficients is used to indicate P *
  • the linear superposition coefficient of the vector operation result between one spatial domain vector in L spatial domain vectors and one frequency domain vector in K frequency domain vectors; R is the number of transmission layers, P is the number of polarization directions, and R, r, P, L, and K are all positive integers.
  • a method for determining a precoding matrix is provided, and the method may be executed by a network device or a chip configured in the network device.
  • the method includes: receiving a PMI, the PMI including R group of air frequency information corresponding to R transmission layers, and the r group of air frequency information in the R group of air frequency information is used to indicate that: P * L spatial domain vectors corresponding to the rth transmission layer; K frequency domain vectors corresponding to the rth transmission layer; and P * L * K coefficients corresponding to the rth transmission layer; based on the R group space
  • the frequency information determines a precoding matrix corresponding to each subband.
  • P * L spatial domain vectors are determined by the L beam vectors in each of the P polarization directions and their wideband amplitude coefficients, and each of the P * L * K coefficients is used to indicate P *
  • the linear superposition coefficient of the vector operation result between one spatial domain vector in L spatial domain vectors and one frequency domain vector in K frequency domain vectors;
  • R is the number of transmission layers,
  • P is the number of polarization directions, and
  • R, r, P , L, and K are all positive integers.
  • the terminal device can characterize each column vector in the ideal precoding matrix of each subband in the frequency domain by the linear combination of the beam vectors in the spatial domain, and pass the weighting coefficients used in the linear combination of each beam vector through several A linear combination of frequency-domain vectors is described.
  • Each frequency domain vector can be used to represent a variation rule of a weighting coefficient of a linear combination of each beam vector on multiple subbands. Therefore, the linear combination coefficients of the spatial domain vectors of each subband can be described by performing different linear combinations on several frequency domain vectors.
  • the above feedback mode may be referred to as a feedback mode of wideband feedback plus subband joint feedback.
  • the feedback mode of the type II codebook defined in Release 15 (Release 15, R15) of the prior art NR protocol TS38.214 can be referred to as a wideband feedback plus subband independent feedback feedback mode.
  • the spatial domain vector is a column vector with a dimension (P * N tx ) * 1
  • the frequency domain vector is a column vector with a dimension N sb * 1
  • the result of this vector operation includes: the product of the conjugate transpose of the space-domain vector and the frequency-domain vector, or the Kronecker product of the conjugate of the frequency-domain vector and the space-domain vector.
  • N tx is the number of antenna ports in each polarization direction
  • N sb is the number of subbands to be reported
  • N tx and N sb are positive integers.
  • the terminal device determines a PMI, which is used to determine a precoding matrix corresponding to N sb subbands, and the precoding matrix is obtained based on R space frequency matrices corresponding to R transmission layers, and the PMI It includes R group indication information corresponding to the R space frequency matrices, and the r group indication information in the R group indication information is used to indicate: P * L space domain column vectors corresponding to the r th transmission layer; and the r th transmission K frequency-domain column vectors corresponding to the layer; and P * L * K weighting coefficients for determining the r-th space-frequency matrix, each weighting coefficient indicating a space-domain column vector of the P * L space-domain column vectors and The weight of the product of the conjugate transpose of a frequency domain column vector in the K frequency domain column vectors in the r-th space frequency matrix, or the conjugate of a frequency domain column vector and the Krone of a space domain column vector Kerr product weight in r-
  • the network device receives a PMI, which is used to determine a precoding matrix corresponding to N sb subbands.
  • the precoding matrix is obtained based on R space frequency matrices corresponding to R transmission layers, and the PMI includes the The R group indication information corresponding to the frequency matrix, and the r group indication information in the R group indication information is used to indicate: P * L space domain column vectors corresponding to the r th transmission layer; K pieces corresponding to the r th transmission layer Frequency domain column vector; and P * L * K weighting coefficients for determining the r-th space frequency matrix, each weighting coefficient indicating a space domain column vector and K frequency domain columns of P * L space domain column vectors The weight of the product of the conjugate transpose of a frequency domain column vector in the vector in the r-th space frequency matrix, or the Kronecker product of the conjugate of a frequency domain column vector and a space domain column vector in the first Weights in r space-frequency matrices; a
  • R group indication information is also the R group space frequency information mentioned above.
  • the R space frequency matrices can be considered as a possible manifestation of the R group space frequency information.
  • the P * L spatial domain column vectors may be determined by L beam vectors and L wideband amplitude coefficients in each polarization direction of the P polarization directions, and the dimensions of the spatial domain vector may be N tx * 1.
  • the dimension of the frequency domain column vector can be N sb * 1, N tx is the number of antenna ports in each polarization direction, N sb is the number of subbands to be reported, P is the number of polarization directions, 1 ⁇ L ⁇ N tx , 1 ⁇ K ⁇ N sb , and r, k, 1, R, K, L, P, N tx and N sb are all positive integers.
  • the space-frequency matrix is only a concept introduced for ease of understanding, and can be understood as an intermediate value in the process of determining the PMI by the terminal device or the process of determining the precoding matrix by the network device, and should not constitute any limitation to this application.
  • the terminal device may also directly generate the PMI or determine the precoding matrix without generating the space-frequency matrix.
  • the spatial domain vector is a column vector with a dimension (P * N tx ) * 1
  • the frequency domain vector is a row vector with a dimension 1 * N sb
  • the result of the vector operation includes: the product of the spatial domain vector and the frequency domain vector, or the transpose of the frequency domain vector and the Kronecker product of the spatial domain vector.
  • N tx is the number of antenna ports in each polarization direction
  • N sb is the number of subbands to be reported
  • N tx and N sb are positive integers.
  • the spatial domain vector is a row vector with a dimension of 1 * (P * N tx )
  • the frequency domain vector is a row vector with a dimension of 1 * N sb
  • the result of this vector operation includes: the product of the conjugate transposition of the spatial domain vector and the frequency domain vector, or the Kronecker product of the transposition of the frequency domain vector and the conjugate transposition of the space domain vector.
  • N tx is the number of antenna ports in each polarization direction
  • N sb is the number of subbands to be reported
  • N tx and N sb are positive integers.
  • the spatial domain vector is a row vector with a dimension of 1 * (P * N tx ), and the frequency domain vector is a column vector with a dimension of N sb * 1
  • the result of this vector operation includes: the product of the conjugate transpose of the spatial domain vector and the conjugate transpose of the frequency domain vector, or the Kronecker product of the conjugate transposition of the frequency domain vector and the conjugate transposition of the space domain vector.
  • N tx is the number of antenna ports in each polarization direction
  • N sb is the number of subbands to be reported
  • N tx and N sb are positive integers.
  • the spatial domain vector is a column vector with a dimension (P * N tx ) * 1
  • the frequency domain vector is a column vector with a dimension N sb * 1
  • the result of the vector operation includes: a product of the spatial domain vector and the conjugate transpose of the frequency domain vector, or a Kronecker product of the conjugate of the frequency domain vector and the spatial domain vector, where , N tx is the number of antenna ports in each polarization direction, N sb is the number of subbands to be reported, 1 ⁇ L ⁇ N tx , 1 ⁇ K ⁇ N sb , and N tx and N sb are positive integers.
  • the foregoing L beam vectors are taken from a subset of a predefined first vector set, and the PMI further includes indication information of the first subset, The indication information of the first subset is used to indicate a position of each vector in the first subset in the first vector set.
  • the first vector set can be expanded into multiple subsets by an oversampling factor, and the L beam vectors can be taken from one of the subsets.
  • the subset to which the L beam vectors belong is recorded as the first Subset.
  • the terminal device may indicate each beam vector in the first subset through the PMI, so that the network device determines the L beam vectors.
  • the foregoing K frequency-domain vectors are taken from a second subset of a predefined second vector set, and the PMI further includes the second subset.
  • Indication information, and the indication information of the second subset is used to indicate a position of each vector in the second subset in the second vector set.
  • the second vector set can also be expanded into multiple subsets by oversampling factors, and the K frequency-domain vectors can be taken from one of the subsets.
  • the subset to which the K frequency-domain vectors belong is recorded.
  • the terminal device may indicate each frequency domain vector in the second subset through the PMI, so that the network device determines the K frequency domain vectors.
  • the method further includes: receiving first indication information, where the first indication information is used to indicate a value of K.
  • the method further includes: sending first indication information, where the first indication information is used to indicate a value of K.
  • the network device may indicate the number of frequency domain vectors to the terminal device.
  • the number of the frequency domain vectors may also be predefined, such as a protocol definition.
  • the method further includes: receiving second instruction information, where the second instruction information is used to indicate a value of L.
  • the method further includes: sending second instruction information, where the second instruction information is used to indicate a value of L.
  • the network device may indicate the number of beam vectors to the terminal device.
  • the number of the beam vectors may also be predefined, such as a protocol definition.
  • the terminal device may determine L beam vectors from the first vector set based on L and K, and determine K frequency domain vectors from the second vector set, Further, based on the L beam vectors and the K frequency domain vectors, the broadband amplitude coefficients and P * L * K coefficients of each beam vector in the P polarization directions are determined.
  • the spatial domain vector is a column vector with a dimension (P * N tx ) * 1
  • the frequency domain vector is a column vector with a dimension N sb * 1.
  • the precoding matrix corresponding to each subband is determined according to the R group of space frequency information, including: traversing the value of n sb from 1 to N sb , and repeatedly performing the following operations to obtain the Subband corresponding precoding matrix:
  • v l represents the l-th beam vector among the L-beam vectors corresponding to the r-th transmission layer
  • Quantized value representing the amplitude coefficient of v l Represents the n-th sb element in the k-th frequency-domain vector of the K frequency-domain vectors corresponding to the r-th transmission layer
  • Express Conjugate A quantized value representing the magnitude of a linear superposition coefficient corresponding to the lth spatial domain vector in the P * L spatial domain vectors and the kth frequency domain vector in the K frequency domain vectors, Represents quantized values of the phases of the linear superposition coefficients corresponding to the lth spatial vector in the P * L spatial domain vectors and the kth frequency domain vector in the K frequency domain vectors, where k and l are positive integers.
  • the network device may determine a precoding matrix with each subband based on the R group of space frequency information indicated in the PMI.
  • the space domain vector is a column vector with a dimension (P * N tx ) * 1
  • the frequency domain vector is a row vector with a dimension 1 * N sb .
  • the precoding matrix corresponding to each subband is determined according to the R group of space frequency information, including: traversing the value of n sb from 1 to N sb , and repeatedly performing the following operations to obtain the Subband corresponding precoding matrix:
  • the network device may determine a precoding matrix with each subband based on the R group of space frequency information indicated in the PMI.
  • the spatial domain vector is a column vector with a dimension (P * N tx ) * 1
  • the frequency domain vector is a column vector with a dimension N sb * 1.
  • the precoding matrix corresponding to each subband is determined according to the R group of space frequency information, including: traversing the value of n sb from 1 to N sb , and repeatedly performing the following operations to obtain the Subband corresponding precoding matrix:
  • v l represents the l-th column vector of the L-column vectors corresponding to the r-th transmission layer
  • a quantized value representing the amplitude coefficient of v l in the first polarization direction Represents a quantized value of the amplitude coefficient of v l in the second polarization direction
  • u r, k, j represents the n-th sb element in the k-th column vector of the K-th column vector corresponding to the r-th transmission layer
  • a quantized value representing the magnitude of the linear superposition coefficient corresponding to the lth spatial domain vector in the L spatial domain vectors in the first polarization direction and the kth frequency domain vector in the K frequency domain vectors that is, the first A quantized value of the magnitude of the linear superposition coefficients of the vector operation results of v l and u r, k in the polarization direction
  • the network device may determine a precoding matrix with each subband based on the R group of space frequency information indicated in the PMI.
  • the space domain vector is a column vector with a dimension (P * N tx ) * 1
  • the frequency domain vector is a row vector with a dimension 1 * N sb .
  • the precoding matrix corresponding to each subband is determined according to the R group of space frequency information, including: traversing the value of n sb from 1 to N sb , and repeatedly performing the following operations to obtain the Subband corresponding precoding matrix:
  • the network device may determine a precoding matrix with each subband based on the R group of space frequency information indicated in the PMI.
  • a method for indicating a precoding matrix is provided.
  • the method may be executed by a terminal device, or may be executed by a chip configured in the terminal device.
  • the method includes: receiving third instruction information for determining a feedback mode based on type II codebook feedback PMI, the feedback mode being a first feedback mode or a second feedback mode, the first feedback The mode is a mode based on the first vector set feedback PMI, and the second feedback mode is based on the first vector set and the second vector set feedback PMI.
  • the first vector set includes a plurality of vectors with a dimension of N tx
  • the second vector set includes a plurality of vectors with a dimension of N sb .
  • N tx is the number of transmitting antenna ports in each polarization direction
  • N sb is the number of subbands to be reported
  • N tx and N sb are positive integers; based on the feedback mode, PMI is determined and sent.
  • a method for indicating a precoding matrix may be executed by a network device, and may also be executed by a chip configured in the network device.
  • the method includes: generating third instruction information for determining a feedback mode based on type II codebook feedback PMI, the feedback mode being a first feedback mode or a second feedback mode, the first feedback The mode is a mode based on the first vector set feedback PMI, and the second feedback mode is based on the first vector set and the second vector set feedback PMI.
  • the first vector set includes a plurality of vectors with a dimension of N tx
  • the second vector set includes a plurality of vectors with a dimension of N sb .
  • N tx is the number of transmitting antenna ports in each polarization direction
  • N sb is the number of subbands to be reported
  • N tx and N sb are positive integers
  • third indication information is sent
  • PMI is received
  • PMI is based on the feedback mode determine.
  • the terminal device may determine the feedback mode based on the instruction of the network device, or based on the number and / or location of the subbands to be reported, and may use a feedback mode with a smaller feedback overhead to feedback the PMI in some cases.
  • the PMI is fed back through a feedback mode with a small feedback overhead, which can not only ensure high approximation accuracy, but also reduce feedback overhead.
  • both feedback accuracy and feedback overhead can be taken into account, thereby achieving a balance between the two.
  • the second feedback mode provided in the present application can be well compatible with the existing feedback mode, and the existing protocol is changed little and is easy to implement.
  • the second feedback mode is not limited to the wideband feedback plus subband joint feedback disclosed in the present application.
  • the second feedback mode may also be, for example, a feedback mode of a wideband feedback plus a subband partial feedback.
  • the first feedback mode can still be the feedback mode of the type II codebook defined in the NR protocol TS38.214R15. In order to distinguish it from the second feedback mode, the first feedback mode can also be referred to as wideband feedback plus all subband feedback Feedback mode.
  • the third indication information includes indication information of a PMI feedback mode.
  • the network device instructs the terminal device which feedback mode to use to feedback the PMI.
  • the third indication information is used to indicate the number and location of subbands to be reported.
  • the method further includes determining a PMI feedback mode according to a preset rule based on the number of subbands to be reported and / or the position of the subbands to be reported.
  • the terminal device and the network device determine the PMI feedback mode based on the same preset rule. Specifically, the terminal device may determine, based on the number and / or position of the subbands to be reported, a feedback mode based on the feedback mode for the PMI. After the network device determines the feedback mode based on the preset rule, the network device may recover a precoding matrix based on the feedback mode and the PMI.
  • the third indication information is carried in a radio resource control RRC message.
  • the PMI when the feedback mode is the second feedback mode, the PMI includes R sets of space frequency information corresponding to R transmission layers, and the R sets of space frequency information are used for Determine the precoding matrix corresponding to each subband.
  • the r-th group of space-frequency information in the R-group of space-frequency information is used to indicate:
  • P * L spatial domain vectors are determined by the L beam vectors in each of the P polarization directions and their wideband amplitude coefficients, and each of the P * L * K coefficients is used to indicate P * Linear superposition coefficient of vector operation between one spatial domain vector in L spatial domain vectors and one frequency domain vector in K frequency domain vectors; the L beam vectors are taken from the first vector set, and the K frequency domain vectors are taken from The second vector collection.
  • R is the number of transmission layers
  • P is the number of polarization directions
  • R, r, P, L, and K are all positive integers.
  • the terminal device or a chip configured in the terminal device may be used to execute the method in any one of the possible implementation manners of the first aspect
  • the network device or the network device may be configured in the network device.
  • the chip can be used to execute the method in any one of the possible implementation manners in the second aspect.
  • a communication device including each module or unit for performing a method in any one of the possible implementation manners of the first aspect or the third aspect.
  • a communication device including a processor.
  • the processor is coupled to the memory and can be used to execute instructions in the memory to implement the method in any one of the possible implementation manners of the first aspect or the third aspect.
  • the communication device further includes a memory.
  • the communication device further includes a communication interface, and the processor is coupled to the communication interface.
  • the communication device is a terminal device.
  • the communication interface may be a transceiver, or an input / output interface.
  • the communication device is a chip configured in a terminal device.
  • the communication interface may be an input / output interface.
  • the transceiver may be a transceiver circuit.
  • the input / output interface may be an input / output circuit.
  • a communication apparatus including each module or unit for performing the method in any one of the possible implementation manners of the second aspect or the fourth aspect.
  • a communication device including a processor.
  • the processor is coupled to the memory and can be used to execute instructions in the memory to implement the method in any one of the possible implementation manners of the second aspect or the fourth aspect.
  • the communication device further includes a memory.
  • the communication device further includes a communication interface, and the processor is coupled to the communication interface.
  • the communication device is a network device.
  • the communication interface may be a transceiver, or an input / output interface.
  • the communication device is a chip configured in a network device.
  • the communication interface may be an input / output interface.
  • the transceiver may be a transceiver circuit.
  • the input / output interface may be an input / output circuit.
  • a processor including: an input circuit, an output circuit, and a processing circuit.
  • the processing circuit is configured to receive a signal through the input circuit and transmit a signal through the output circuit, so that the processor executes any one of the first aspect to the fourth aspect and any possible implementation manner of the first aspect to the fourth aspect.
  • the processor may be a chip
  • the input circuit may be an input pin
  • the output circuit may be an output pin
  • the processing circuit may be a transistor, a gate circuit, a flip-flop, and various logic circuits.
  • An input signal received by the input circuit may be received and input by, for example, but not limited to, a receiver
  • a signal output by the output circuit may be, for example, but not limited to, output to a transmitter and transmitted by the transmitter
  • the circuits may be the same circuit, which are used as input circuits and output circuits respectively at different times.
  • the embodiments of the present application do not limit specific implementations of the processor and various circuits.
  • a processing device including a processor and a memory.
  • the processor is used to read instructions stored in the memory, and can receive signals through a receiver and transmit signals through a transmitter to execute the first aspect to the fourth aspect and any possible implementation manner of the first aspect to the fourth aspect.
  • processors there are one or more processors, and one or more memories.
  • the memory may be integrated with the processor, or the memory is separately provided from the processor.
  • the memory may be a non-transitory memory, such as a read-only memory (ROM), which may be integrated on the same chip as the processor, or may be separately set in different On the chip, the embodiment of the present application does not limit the type of the memory and the way of setting the memory and the processor.
  • ROM read-only memory
  • sending instruction information may be a process of outputting instruction information from a processor
  • receiving capability information may be a process of receiving input capability information by a processor.
  • the processed output data can be output to the transmitter, and the input data received by the processor can come from the receiver.
  • the transmitter and the receiver may be collectively referred to as a transceiver.
  • the processing device in the tenth aspect may be a chip, and the processor may be implemented by hardware or software.
  • the processor may be a logic circuit, an integrated circuit, or the like.
  • the processor may be a general-purpose processor, which is implemented by reading software codes stored in a memory.
  • the memory may be integrated in the processor, may be located outside the processor, and exist independently.
  • a computer program product includes a computer program (also referred to as code or instructions), and when the computer program is executed, causes a computer to execute the first aspect to The method in the fourth aspect and any one of the possible implementation manners of the first to fourth aspects.
  • a computer program also referred to as code or instructions
  • a computer-readable medium stores a computer program (also referred to as code, or instructions), which when executed on a computer, causes the computer to execute the first aspect to The method in the fourth aspect and any one of the possible implementation manners of the first to fourth aspects.
  • a computer program also referred to as code, or instructions
  • a communication system including the foregoing network device and terminal device.
  • FIG. 1 is a schematic diagram of a communication system applicable to a method for indicating and determining a precoding matrix according to an embodiment of the present application
  • FIG. 2 is a schematic diagram of signal processing provided by an embodiment of the present application.
  • FIG. 3 is a schematic flowchart of a method for indicating and determining a precoding matrix according to an embodiment of the present application
  • FIG. 4 is a schematic diagram of transmitting antennas with different polarization directions according to an embodiment of the present application.
  • FIG. 5 is a schematic flowchart of a method for indicating a precoding matrix according to another embodiment of the present application.
  • FIG. 6 shows several possible situations in which the subbands to be reported are distributed in the frequency domain
  • FIG. 7 is a schematic block diagram of a communication device according to an embodiment of the present application.
  • FIG. 8 is a schematic structural diagram of a terminal device according to an embodiment of the present application.
  • FIG. 9 is a schematic structural diagram of a network device according to an embodiment of the present application.
  • GSM global mobile communication
  • CDMA code division multiple access
  • WCDMA broadband code division multiple access
  • GPRS general packet radio service
  • LTE long term evolution
  • FDD frequency division duplex
  • TDD Time Division Duplex
  • UMTS Universal Mobile Telecommunications System
  • WiMAX Global Interoperability for Microwave Access
  • FIG. 1 is a schematic diagram of a communication system 100 applicable to a method for indicating and determining a precoding matrix according to an embodiment of the present application.
  • the communication system 100 may include at least one network device, such as the network device 110 shown in FIG. 1; the communication system 100 may further include at least one terminal device, such as the terminal device 120 shown in FIG. 1.
  • the network device 110 and the terminal device 120 can communicate through a wireless link.
  • Each communication device, such as the network device 110 or the terminal device 120 can be configured with multiple antennas.
  • the configured multiple antennas may include at least one transmitting antenna for transmitting signals and at least one receiving antenna for receiving signals. Therefore, communication devices in the communication system 100, such as the network device 110 and the terminal device 120, can communicate through multi-antenna technology.
  • the network device in the communication system may be any device having a wireless transceiver function.
  • the network equipment includes but is not limited to: evolved Node B (eNB), radio network controller (RNC), node B (NB), base station controller (BSC) ), Base transceiver station (BTS), home base station (for example, home NodeB, or home NodeB, HNB), baseband unit (BBU), wireless fidelity (Wireless Fidelity, WIFI) system Access point (AP), wireless relay node, wireless backhaul node, transmission point (TP) or transmission and reception point (TRP), etc.
  • eNB evolved Node B
  • RNC radio network controller
  • NB node B
  • BSC base station controller
  • BBU Base transceiver station
  • home base station for example, home NodeB, or home NodeB, HNB
  • BBU baseband unit
  • wireless fidelity Wireless Fidelity, WIFI
  • AP wireless relay node
  • TP transmission point
  • TRP transmission and reception point
  • the gNB may include a centralized unit (CU) and a DU.
  • the gNB may also include a radio frequency unit (radio unit, RU).
  • CU implements some functions of gNB
  • DU implements some functions of gNB, for example, CU implements radio resource control (RRC), packet data convergence layer protocol (PDCP) layer functions, and DU implements wireless chain Functions of radio control (RLC), media access control (MAC) and physical (PHY) layers.
  • RRC radio resource control
  • PDCP packet data convergence layer protocol
  • RLC wireless chain Functions of radio control
  • MAC media access control
  • PHY physical
  • the network device may be a CU node, or a DU node, or a device including a CU node and a DU node.
  • the CU can be divided into network equipment in an access network (RAN), or the CU can be divided into network equipment in a core network (CN), which is not limited in this application.
  • RAN access network
  • CN core network
  • the terminal equipment in the wireless communication system may also be referred to as user equipment (UE), access terminal, user unit, user station, mobile station, mobile station, remote station, remote terminal, mobile device, User terminal, terminal, wireless communication device, user agent or user device.
  • the terminal device in the embodiments of the present application may be a mobile phone, a tablet, a computer with a wireless transmitting and receiving function, a virtual reality (VR) terminal device, or an augmented reality (AR) terminal.
  • Equipment wireless terminals in industrial control, wireless terminals in self driving, wireless terminals in remote medical, wireless terminals in smart grid, transportation security ( wireless terminals in transportation, wireless terminals in smart cities, wireless terminals in smart homes, and so on.
  • the embodiment of the present application does not limit the application scenario.
  • FIG. 1 is only a simplified schematic diagram for ease of understanding.
  • the communication system 100 may further include other network devices or other terminal devices, which are not shown in FIG. 1.
  • the signal processing process shown in FIG. 2 may be performed by a network device or a chip configured in the network device; it may be performed by a terminal device or a chip configured in the terminal device .
  • This application does not limit this.
  • hereinafter are collectively referred to as a transmitting device.
  • the transmitting device can process codewords from higher layers on the physical channel.
  • the codeword may be a coded bit that is coded (for example, includes a channel code).
  • the codeword is scrambling to generate scrambled bits.
  • the scrambled bits undergo modulation mapping to obtain modulation symbols.
  • Modulation symbols are mapped to multiple layers through layer mapping.
  • the modulation symbols after layer mapping are precoded to obtain a precoded signal.
  • the pre-encoded signal is mapped to multiple REs after being mapped with resource elements (REs). These REs are then modulated by orthogonal frequency division multiplexing (OFDM) and transmitted through an antenna port.
  • OFDM orthogonal frequency division multiplexing
  • the precoding technology may be to perform a pre-processing on the transmission signal when the transmitting device knows the channel status, that is, to process the to-be-transmitted signal by using a pre-coding matrix that matches the channel resource, so that the pre-processing
  • the encoded signal to be transmitted is adapted to the channel, so that the complexity of the receiving device in eliminating the influence between the channels is reduced. Therefore, by precoding the signals to be transmitted, the received signal quality (such as signal to interference plus noise ratio (SINR)) is improved. Therefore, by adopting the precoding technology, transmission devices and multiple receiving devices can be transmitted on the same time-frequency resource, that is, multiple user multiple input multiple output (MU-MIMO) is realized.
  • SINR signal to interference plus noise ratio
  • the related description of the precoding technology is only used as an example, and is not used to limit the protection scope of the embodiments of the present application.
  • the precoding may also be performed in other ways. For example, when the channel matrix cannot be obtained, precoding is performed by using a precoding matrix or a weighting processing method set in advance. For the sake of brevity, the specific content will not be repeated here.
  • the sending device may perform channel measurement in advance by sending a reference signal to obtain feedback from the receiving device, thereby determining the precoding matrix.
  • the receiving device may perform singular value decomposition on the channel matrix H of each subband or the covariance matrix HH H of the channel matrix.
  • value decomposition (SVD) method to determine the ideal precoding matrix for each subband.
  • U and V H are unitary matrices, and S is a diagonal matrix, and its non-zero elements (ie, elements on the diagonal) are the singular values of the channel matrix H. These singular values can usually be in descending order arrangement.
  • the conjugate transpose V of the right unitary matrix V H is the ideal precoding matrix. In other words, the ideal precoding matrix is the precoding matrix calculated according to the channel matrix H.
  • the receiving device may determine a precoding matrix that is relatively similar to the ideal precoding matrix of each subband, and feedback the precoding matrix that is approximately the ideal precoding matrix on each subband to the sending device through PMI.
  • the transmitting device may determine a precoding matrix that is close to an ideal precoding matrix of each subband according to the PMI. Thereby, the transmitting device can determine a precoding matrix adapted to the channel to perform precoding processing on the signal to be transmitted.
  • the receiving device desires to be able to determine the precoding matrix that is most similar to the ideal precoding matrix to indicate to the transmitting device.
  • the sending device may be a network device or a chip configured in the network device
  • the receiving device may be a terminal device or a chip configured in the terminal device
  • the reference signal may be used for downlink channel measurement.
  • the reference signal is, for example, a channel state information reference signal (CSI-RS).
  • the terminal device can perform CSI measurement according to the received CSI-RS, and feed back the CSI of the downlink channel to the network device.
  • CSI-RS channel state information reference signal
  • the sending device may also be a terminal device or a chip configured in the terminal device
  • the receiving device may be a network device or a chip configured in the network device.
  • the reference signal may be a reference signal for uplink channel measurement. For example, sounding reference signal (SRS).
  • SRS sounding reference signal
  • the network device may perform CSI measurement according to the received SRS, and indicate the CSI of the uplink channel to the terminal device.
  • the CSI may include, for example, a precoding matrix indicator (PMI), a rank indicator (RI), and a channel quality indicator (CQI).
  • PMI precoding matrix indicator
  • RI rank indicator
  • CQI channel quality indicator
  • the codebooks on which the terminal device feeds back the PMI may include two types of codebooks, which are type I and type II.
  • type one is beam selection
  • type two is linear beam combination.
  • the feedback overhead of type 1 is small, but the approximation accuracy is low; the feedback overhead of type 2 is large, but the approximation accuracy is high.
  • the terminal device may use type two to determine the precoding matrix and the feedback PMI. Specifically, the terminal device may indicate the quantized value of the selected beam and the wideband amplitude coefficient of each beam through wideband feedback, and may indicate the quantized value of the combination coefficient available to each subband through subband feedback, where the combination coefficient includes, for example, Band amplitude coefficient and subband phase coefficient.
  • the network device can synthesize the information of the wideband feedback and the information of the subband feedback to recover a precoding matrix that is close to the ideal precoding matrix.
  • the following shows a simple example of a two-level codebook format with a rank of 1.
  • W represents a subband precoding matrix to be fed back on a transport layer
  • W is determined by the wideband feedback.
  • W 2 determined by the sub-band feedback.
  • b 0 to b 3 are beam vectors included in W 1 and can be indicated by an index of a combination of the plurality of beam vectors.
  • p 0 to p 7 are the wideband amplitude coefficients included in W 1 and can be indicated by the quantized values of the wideband amplitude coefficients.
  • c 0 to c 7 are the subband superposition coefficients included in W 2 and may include the subband amplitude coefficients ⁇ 0 to ⁇ 7 and the narrowband phase coefficient to Quantized values of narrow-band amplitude coefficients ⁇ 0 to ⁇ 7 and narrow-band phase coefficients to Quantized value to indicate.
  • network devices can transmit data to terminal devices through multiple transmission layers.
  • the feedback overhead of p 0 to p 7 and c 0 to c 7 will be 4 times that of one transmission layer. That is, if the terminal device performs the wideband feedback and the subband feedback as described above based on each transmission layer, as the number of transmission layers increases, the feedback overhead brought by it will increase exponentially. The greater the number of subbands, the greater the increase in feedback overhead. Therefore, it is desirable to be able to provide a method that can achieve a balance between feedback overhead and approximate accuracy.
  • the present application provides a method for indicating a precoding matrix, which flexibly selects a feedback mode based on the correlation of channels in the frequency domain, and reduces the feedback overhead as much as possible while ensuring the quality of data transmission, while improving the
  • the utilization of spectrum resources improves the data transmission capacity and throughput of communication systems.
  • beam can be understood as the distribution of signal strength formed in a certain direction in space
  • beam vector can be used to characterize “beam”.
  • a plurality of beam vectors may be linearly superimposed by a beamforming technique, so that a transmission beam forms a certain directivity in space.
  • a subband is taken as an example of a frequency domain unit, and a specific method for indicating and determining a precoding matrix is described in detail, but this should not constitute any limitation to the present application.
  • the subband is only one possible form of a frequency domain unit, and the frequency domain unit may also be a subcarrier, a resource block (RB), or the like, which is not limited in this application.
  • the precoding matrix corresponding to the subband in the embodiments of the present application may be understood as a precoding matrix determined based on the channel matrix of the subband. In the embodiments shown below, the meanings expressed by "precoding matrix corresponding to a subband" and “precoding matrix of a subband" may be the same unless otherwise specified.
  • a Kronecker product is a block matrix composed of all elements in a matrix multiplied by another matrix. For example, multiplying the Kronecker product of a k * l-dimensional matrix A and a p * q-dimensional matrix B to obtain a kp * ql-dimensional matrix is as follows:
  • pre-acquisition may include indication or pre-definition by network device signaling, for example, protocol definition.
  • pre-defined can be achieved by pre-saving corresponding codes, forms, or other methods that can be used to indicate related information in devices (for example, terminal devices and network devices), and this application does not make specific implementations thereof. limited.
  • “save” involved in the embodiments of the present application may refer to saving in one or more memories.
  • the one or more memories may be provided separately or integrated in an encoder or a decoder, a processor, or a communication device.
  • the one or more memories may also be partly provided separately and partly integrated in a decoder, a processor, or a communication device.
  • the type of the memory may be any form of storage medium, which is not limited in this application.
  • the "protocols" involved in the embodiments of the present application may refer to standard protocols in the communication field, and may include, for example, the LTE protocol, the NR protocol, and related protocols used in future communication systems, which are not limited in this application.
  • At least one means one or more, and “multiple” means two or more.
  • “And / or” describes the association relationship of related objects, and indicates that there can be three kinds of relationships, for example, A and / or B can represent: the case where A exists alone, A and B exist simultaneously, and B alone exists, where A, B can be singular or plural.
  • the character “/” generally indicates that the related objects are an "or” relationship.
  • “At least one or more of the following” or similar expressions refers to any combination of these items, including any combination of single or plural items.
  • At least one (a) of a, b, and c may represent: a, or, b, or, c, or, a and b, or, a and c, or, b and c, or, a , B, and c, where a, b, and c can be single or multiple.
  • the method provided in the embodiment of the present application may be applied to a communication system that communicates through a multi-antenna technology, for example, the communication system 100 shown in FIG. 1.
  • the communication system may include at least one network device and at least one terminal device. Network equipment and terminal equipment can communicate through multi-antenna technology.
  • the embodiments shown below do not specifically limit the specific structure of the execution subject of the method provided in the embodiments of the present application, as long as the program recorded with the code of the method provided in the embodiments of the present application can be run to
  • the method provided in the embodiment of the application may perform communication.
  • the method provided in the embodiment of the application may be a terminal device or a network device, or a function module in the terminal device or the network device that can call a program and execute the program.
  • the interaction between the network device and the terminal device is taken as an example to describe in detail the method for indicating and determining the precoding matrix provided in the embodiments of the present application.
  • FIG. 3 is a schematic flowchart of a method for indicating and determining a precoding matrix according to an embodiment of the present application, which is shown from the perspective of device interaction. As shown in FIG. 3, the method 300 may include steps 310 to 360. Each step in the method 300 is described in detail below.
  • step 310 the terminal device determines a PMI.
  • the terminal device may determine the PMI according to the ideal precoding matrix of the wideband and the ideal precoding matrix of each subband, and indicate the ideal precoding matrix of each subband to the network device through the PMI.
  • the terminal device may perform channel measurement according to the received reference signal, such as CSI-RS, and determine the PMI according to the measured ideal precoding matrix of the wideband and the ideal precoding matrix of each subband. .
  • the method 300 further includes: step 320, the network device sends a reference signal. Accordingly, the terminal device receives the reference signal.
  • Network devices can send reference signals through multiple transmit antennas.
  • the multiple transmitting antennas may be transmitting antennas of the same polarization direction, or may be transmitting antennas of different polarization directions. This application does not limit this.
  • FIG. 4 is a schematic diagram of transmitting antennas in different polarization directions. Specifically, eight transmitting antennas are shown in the figure, and the eight transmitting antennas correspond to two polarization directions.
  • antenna ports 0, 1, 2, and 3 are antenna ports of the same polarization direction (for example, denoted as the first polarization direction), and can correspond to the same beam vector, for example, denoted as v 1 ;
  • antenna ports 4, 5, and 6 and 7 are antenna ports in the same polarization direction (for example, denoted as the second polarization direction), and can correspond to another same beam vector, for example, denoted as v 2 .
  • v 1 and v 2 may be two orthogonal discrete fourier transform (DFT) vectors, or may be mathematical vectors that characterize the characteristics of space electromagnetic waves, which are not specifically limited in the embodiments of the present application. .
  • DFT discrete fourier transform
  • the terminal device may first estimate the channel matrix of the wideband and each subband according to the received reference signal, and determine the RI, that is, the recommended transmission rank, that is, the recommended number of transmission layers. Thereafter, the terminal device may determine a wideband ideal precoding matrix according to a wideband channel matrix, and may determine a perfect precoding matrix of each subband according to a channel matrix of each subband.
  • the specific process for the terminal device to determine the ideal precoding matrix according to the channel matrix has been described in detail above. For the sake of brevity, it will not be repeated here.
  • the method for the terminal device to determine the ideal precoding matrix is not limited to the above.
  • the terminal device can also determine the ideal precoding matrix according to the channel status.
  • the terminal device can determine the ideal precoding matrix based on the reciprocity of the uplink and downlink channels.
  • the coding matrix and the like are not limited in this application.
  • the determination process of the RI may be the same as that in the prior art, and for brevity, a detailed description of the specific process is omitted here.
  • the embodiment shown below mainly explains the determination process of PMI in detail.
  • the terminal device can determine the PMI according to the ideal precoding matrix of each subband.
  • the precoding matrix of each subband may be determined by the R group of space frequency information corresponding to the R transmission layers.
  • Each group of space frequency information in the R group of space frequency information may include space domain information, frequency domain information, and coefficients.
  • the r-th (1 ⁇ r ⁇ R, and r is an integer) group of space-frequency information may be used to indicate:
  • P * L spatial domain vectors are determined by the L beam vectors in each of the P polarization directions and their wideband amplitude coefficients, and each of the P * L * K coefficients is used to indicate P * A linear superposition coefficient of a vector operation result between one spatial domain vector in the L spatial domain vectors and one frequency domain vector in the K frequency domain vectors.
  • the spatial domain vector is a column vector with a dimension (P * N tx ) * 1
  • the frequency domain vector is a column vector with a dimension N sb * 1.
  • the result of the vector operation includes: the spatial domain vector and the frequency The product of the conjugate transpose of the domain vector, or the Kronecker product of the conjugate of the frequency domain vector and the space domain vector.
  • N tx antenna ports each polarization direction, N sb is the number of subbands, 1 ⁇ L ⁇ N tx, 1 ⁇ K ⁇ N sb, and N tx are positive integers and N sb.
  • the spatial domain vector is a column vector with a dimension (P * N tx ) * 1
  • the frequency domain vector is a row vector with a dimension 1 * N sb .
  • the operation result of the vector includes: The product of the frequency domain vector, or the Kronecker product of the transposition of the frequency domain vector and the space domain vector.
  • the space domain vector is a row vector with a dimension of 1 * (P * N tx ), and the frequency domain vector is a row vector with a dimension of 1 * N sb .
  • the operation result of the vector includes: The product of the conjugate transpose and the frequency domain vector, or the Kronecker product of the transposition of the frequency domain vector and the conjugate transposition of the space domain vector.
  • the spatial domain vector is a row vector with a dimension of 1 * (P * N tx ), and the frequency domain vector is a column vector with a dimension of N sb * 1.
  • the operation result of the vector includes: The product of the conjugate transpose and the conjugate transpose of the frequency domain vector, or the Kronecker product of the conjugate transposition of the frequency domain vector and the conjugate transposition of the space domain vector.
  • the spatial domain vector is a column vector with a dimension (P * N tx ) * 1
  • the frequency domain vector is a column vector with a dimension N sb * 1.
  • Those skilled in the art can also determine the corresponding PMI through mathematical transformation or equivalent replacement based on the specific implementation manners shown below, and can determine the precoding matrix of each subband based on the PMI.
  • the R group of space frequency information may be used to determine R space frequency matrices.
  • the space-frequency matrix of the r-th transmission layer may be determined by the space-frequency information of the r-th transmission layer.
  • the spatial information of the r-th transmission layer can be determined by the beam vectors (e.g., L, L ⁇ 1 and integers) of the selected spatial domain on the r-th transmission layer and the L beam vectors in each polarization direction.
  • the frequency domain information of the r-th transmission layer can be determined by the selected frequency-domain base vector on the r-th transmission layer (that is, the frequency-domain vectors described above, for example, K, K ⁇ 1 and Is an integer); the space-frequency matrix of the r-th transmission layer can be determined by the P-L determined by the r-th transmission layer, the L beam vectors in the P polarization directions and their wideband amplitude coefficients, and the K frequency-domain basis vectors.
  • K component matrices are obtained by linear superposition, and the coefficients of the r-th transmission layer can be determined by the linear superposition coefficients of the component matrices.
  • Each column vector in the ideal precoding matrix of each subband in the frequency domain can be characterized by a linear combination of spatial beam vectors, and the weighting coefficients used in the linear combination of each beam vector can be determined by the K frequency-domain base vectors described above. To describe the linear combination.
  • Each frequency-domain base vector can be used to represent a variation rule of the weighting coefficient on multiple sub-bands in the frequency domain.
  • the frequency domain vector taken from the second vector set is referred to as a frequency domain base vector.
  • the frequency domain column vector may be a frequency domain base vector directly determined from the second vector set, or may be a product of the frequency domain base vector and the amplitude coefficient. Therefore, in this embodiment, the dimensions of the frequency domain base vector and the frequency domain column vector may be the same.
  • "frequency-domain base vector" and "frequency-domain vector” have the same meaning. In the following, for the sake of brevity, the description of the same or similar situation is omitted.
  • L and K determine the size of the PMI overhead.
  • the values of L and K can be pre-configured by the network device and indicated to the terminal device; it can also be pre-defined, such as a protocol definition; one of the values can be configured by the network device, and the other value is defined by the protocol;
  • the terminal device is reported to the network device after it is determined; the network device may be configured with multiple candidate values in advance to the terminal device, and the terminal device selects one of the multiple candidate values of the network device and reports it to the network device. This application does not limit this.
  • the method 300 further includes: Step 330: The network device sends first indication information, where the first indication information is used to indicate the value of K. Accordingly, the terminal device receives the first indication information.
  • the method 300 further includes: Step 340: The network device sends second instruction information, where the second instruction information is used to indicate the value of L. Accordingly, the terminal device receives the first indication information.
  • the network device may indicate the values of K and L to the terminal device through the same signaling or different signaling. That is, the first indication information and the second indication information may be carried in the same signaling, or may be carried in different signalings, which is not limited in this application.
  • the first indication information is carried in a radio resource control (radio resource control, RRC) message.
  • RRC radio resource control
  • the second indication information is carried in an RRC message.
  • the network device carrying the first indication information and the second indication information in the RRC message and configuring the terminal device is only one possible implementation manner, and should not constitute any limitation to this application.
  • the network device may also carry the first indication information and / or the second indication information in other signaling, such as MAC, CE, or DCI, which is not limited in this application.
  • the first indication information and the second indication information may be carried in the same signaling, or may be carried in different signaling, which is not limited in this application.
  • the number of polarization directions of the transmitting antenna is P
  • the number of ports of the transmitting antenna in each polarization direction is N tx
  • the number of ports of the receiving antenna is N rx
  • the number of transmission layers is It is R, N tx > 1, N rx ⁇ 1, R ⁇ 1, P ⁇ 1, and R, P, N tx , and N rx are all integers.
  • the space-frequency matrix may be, for example, a matrix having a dimension (P * N tx ) * N sb .
  • Each column vector in the matrix may correspond to a subband.
  • the column vectors of the R dimensions (P * N tx ) * 1 are arranged from left to right in the order of 1 to R of the transmission layer, and a matrix of (P * N tx ) * R can be obtained.
  • the space-frequency matrix may be, for example, a column vector having a dimension (P * N tx * N sb ) * 1.
  • the column vector includes a plurality of groups of elements corresponding to a plurality of subbands. For example, the first element to the P * N tx elements correspond to the first subband, the P * N tx +1 element to the 2P * N tx elements may correspond to the second subband, and so on The last P * N tx elements may correspond to the N sbth subband.
  • R column vectors of (P * N tx ) * 1 dimensions can also be obtained.
  • the column vectors of the R dimensions (P * N tx ) * 1 are arranged from left to right in the order of 1 to R of the transmission layer, and a matrix of (P * N tx ) * R can also be obtained.
  • This matrix is a precoding matrix corresponding to the n sbth subband.
  • the space-frequency matrix described above is an intermediate value in the process of determining the PMI of the terminal device.
  • the terminal device can determine the air-domain information, frequency-domain information, and weighting corresponding to each transmission layer based on the channel matrix of each subband. Coefficients without necessarily generating the space-frequency matrix described above.
  • the terminal device may determine only the column vectors used to generate the above-mentioned space-frequency matrix. After the terminal device obtains the spatial and frequency domain information corresponding to each transmission layer, it can generate a PMI that can be used to determine the precoding matrix of each subband.
  • a column vector of dimension (P * N tx * N sb ) * 1 can be obtained by matrix transformation of (P * N tx ) * N sb .
  • the dimension is (P * N tx * N sb ) * 1
  • the specific process of the column vector is similar to the specific process of determining the matrix with the dimension (P * N tx ) * N sb .
  • Those skilled in the art are in the process of determining the matrix with the dimension (P * N tx ) * N sb . After simple mathematical transformation or replacement, you can get a column vector with dimension (P * N tx * N sb ) * 1.
  • the terminal device determines a wideband ideal precoding matrix according to the channel matrix of each subband.
  • the terminal device may determine the covariance matrix of the channels of each subband according to the channel matrix of each subband, and then add the covariance matrix corresponding to each subband to perform SVD to obtain a wideband ideal precoding matrix.
  • the dimension of the channel matrix H of each subband is (P * N tx ) * N rx .
  • P is the number of polarization directions, P ⁇ 1, and is an integer.
  • the dimension of the covariance matrix HH H of the channel matrix of each subband is determined based on the channel matrix of each subband as (P * N tx ) * (P * N tx ).
  • the SVD can be obtained by adding the covariance matrix of the channel matrix of each subband to obtain a wideband ideal precoding matrix, and its dimension can be (P * N tx ) * R.
  • the ideal precoding matrix of the wideband can correspond to a column vector with dimension (P * N tx ) * 1 in one transmission layer.
  • the column vector with dimension (P * N tx ) * 1 is regarded as an ideal precoding vector of a wide band.
  • the terminal device may determine a corresponding space-frequency matrix based on each transmission layer.
  • the following steps are based on the rth (1 ⁇ r ⁇ R, and r is an integer) transport layer to describe the specific process of the terminal device determining the space-frequency matrix.
  • the terminal device may traverse the values of r from 1 to R, and repeatedly perform the following steps ii to iv to obtain the R group indication information for indicating the R space frequency matrices corresponding to the R transmission layers.
  • the PMI may include R group indication information corresponding to the R transmission layers, and each group of indication information may be used to indicate a space-frequency matrix.
  • the terminal device projects a wideband ideal precoding vector on the r-th transmission layer to the space domain to obtain P * L space-domain column vectors on the r-th transmission layer.
  • the L beam vectors on any two transmission layers in the R transmission layers may be the same as each other or different from each other, which is not limited in this application.
  • the L beam vectors in any two polarization directions of the P polarization directions may be the same as each other or different from each other, which is not limited in this application.
  • the terminal device may first determine The L beam vectors, and then determine the broadband amplitude coefficients of the L beam vectors in the P polarization directions on each transmission layer.
  • the broadband amplitude coefficients of the L beam vectors in the first polarization direction of the r-th transmission layer may be Denote as a 0 , a 1 , ..., a L-1
  • the broadband amplitude coefficients of the L beam vectors in the second polarization direction on the r-th transmission layer can be described as a L , a L + 1 , ... ..., a 2L-1 .
  • the product of the L beam vectors in the P polarization directions on the r-th transmission layer and the corresponding broadband amplitude coefficients is as follows: a 0 v 0 , a 1 v 1 , ..., a L-1 v L -1 , a L v 0 , a L + 1 v 1 , ..., a 2L-1 v L-1 .
  • the product of a beam vector and the corresponding wideband amplitude coefficient is referred to as an intermediate vector in this embodiment.
  • an intermediate vector can be determined by a beam vector and its corresponding wideband amplitude coefficient
  • Vector can be used to determine a spatial column vector.
  • the dimension of the intermediate vector may be N tx * 1
  • the dimension of a spatial domain column vector determined from this may be (P * N tx ) * 1.
  • the terminal device may determine the L beam vectors in the P polarization directions of each transmission layer and the corresponding wideband amplitude coefficient. Similarly, if the L beam vectors in each of the P polarization directions are different from each other, the terminal device may determine the L beam vectors in each polarization direction and the corresponding wideband amplitude coefficient. The manner in which the terminal device determines the L beam vectors in each transmission layer and each polarization direction may be the same.
  • the terminal device may determine the L beam vectors based on a certain transmission layer and a certain polarization direction, and then determine the broadband amplitude coefficients of the L beam vectors in the P polarization directions of the r-th transmission layer.
  • the transmission layer used to determine the L beam vectors may be any one of the R transmission layers.
  • the transmission layer may be the first transmission layer or the Rth transmission layer.
  • the transmission layer used to determine the L beam vectors may be a certain transmission layer specified in advance, such as a protocol definition, or a certain transmission layer indicated by a network device.
  • the r-th transmission layer is taken as an example to describe the specific process of the terminal device determining the L beam vectors and the wideband amplitude coefficients of the L beam vectors.
  • the polarization direction used to determine the L beam vectors may be any one of the P polarization directions, for example, it may be the first polarization direction or the Pth polarization direction.
  • the polarization direction used to determine the L beam vectors may be a certain polarization direction specified in advance, such as a protocol definition, or a certain polarization direction indicated by a network device.
  • the r-th transmission layer and p-th polarization direction are used as examples to explain the specific process of the terminal device determining the L beam vectors, and the r-th transmission layer is used as an example to describe the terminal device determining L.
  • the specific process of the wideband amplitude coefficient of each beam vector in the P polarization directions are used as an example to describe the terminal device determining L.
  • the terminal device can project a wideband ideal precoding vector on the r-th transmission layer into the airspace to obtain the L beam vectors and the wideband amplitude coefficients of the L beam vectors in the airspace.
  • the terminal device may determine the L beam vectors in the spatial domain and the wideband amplitude coefficients of the L beam vectors according to the first vector set and the wideband ideal precoding vector on the r-th transmission layer.
  • the first vector set may include a plurality of column vectors with dimensions N tx * 1, and each column vector is a two-dimensional (2dimension, 2D) -DFT vector or an oversampled 2D-DFT vector.
  • 2D can represent two different directions, such as a horizontal direction and a vertical direction.
  • the first vector set may include N tx column vectors, and any two column vectors in the N tx column vectors are orthogonal to each other.
  • the terminal device may select L column vectors from the N tx column vectors as the selected L beam vectors in the air domain.
  • the terminal device may perform an inner product of an ideal precoding vector in a polarization direction (for example, p-th) of the broadband ideal precoding vector and each column vector in the first vector set to obtain multiple value. It can be understood that the multiple values are plural.
  • the terminal device may further determine, from among the plurality of values, L values having a larger modulus, and the modulus of any one of the L values is greater than the modulus of any one of the remaining N tx -L values.
  • the L column vectors used to generate the L values in the first vector set can be used as the L beam vectors in the spatial domain.
  • the first vector set may include O 1 * O 2 * N tx column vectors, where O 1 and O 2 are oversampling factors, O 1 ⁇ 1, O 2 ⁇ 1, O 1 and O 2 are not 1 at the same time, and they are both integers.
  • the first basis vector may include O 1 * O 2 subsets, each subset includes N tx column vectors, and any two column vectors in each subset are orthogonal to each other.
  • the terminal device may select a subset from the O 1 * O 2 subsets, and the selected subset includes the selected L beam vectors.
  • the dimensions of the ideal precoding vector due to the wideband in each polarization direction are also N tx * 1.
  • the terminal device can calculate the inner product of the wideband ideal precoding vector in a certain (for example, p) polarization direction and the N tx column vectors in the O 1 * O 2 subset of the first vector set, and obtain O 1 * O 2 sets of values, each set of values includes N tx values.
  • the terminal device can determine L values with a larger modulus from each set of values, and can further compare the L values in the O 1 * O 2 set of values to select a set of values.
  • the modulus of the L values in the selected group of values is greater than the modulus of the L values in any one of the remaining O 1 * O 2 -1 groups of values.
  • the L column vectors used to generate the set of values in the first vector set are the selected L beam vectors in the spatial domain. It can be understood that the L beam vectors belong to a subset of the foregoing O 1 * O 2 subsets, and may be recorded as the first subset, for example.
  • the terminal device can traverse the value of p from 1 to P and repeatedly perform the following operations to obtain L broadbands in each of the P polarization directions.
  • Amplitude coefficient The modulo of the value obtained by inner-producting the ideal precoding vector of the broadband in the p-th polarization direction of the P polarization directions and the L beam vectors determined above can be used as the p-th pole The wideband amplitude coefficients of the L column vectors in the direction of transformation.
  • the terminal device can obtain L wideband amplitude coefficients in each of the P polarization directions, that is, P * L wideband amplitude coefficients.
  • the terminal device can further determine P * L intermediate vectors.
  • the terminal device may traverse the value of p in [1, P] to obtain L intermediate vectors in each of the P polarization directions in turn.
  • the L intermediate vectors in the p-th polarization direction can be obtained by traversing the value of l from 1 to L and repeatedly performing the following operation: combining the l-th beam vector in the L-beam vectors with the p-th Multiply the first broadband amplitude coefficient of the L broadband amplitude coefficients in the polarization direction to obtain the first intermediate vector in the p-th polarization direction.
  • the terminal device can obtain L intermediate vectors in the p-th polarization direction.
  • the terminal device may determine P * L spatial domain column vectors according to the P * L intermediate vectors.
  • the dimensions of each intermediate vector are N tx * 1
  • the dimensions of a matrix formed by L intermediate vectors in each polarization direction can be N tx * L, P * L in P polarization directions.
  • the dimensions of the matrix constructed by the two intermediate vectors can be (P * N tx ) * (P * L).
  • a matrix constructed from P * L intermediate vectors in P polarization directions may be referred to as a space matrix W 1 in the following, and each column vector in the space matrix W 1 is referred to as a space domain column vector.
  • a space matrix W 1 can be constructed as follows:
  • a 0 to a 2L-1 represent wideband amplitude coefficients
  • v 0 to v L-1 represent beam vectors. That is, the elements in the (p-1) * L + 1th to p * Lth columns, and the pth to p * Ntx rows in the space matrix can be L in the pth polarization direction
  • the intermediate vector is determined, which can be obtained by multiplying the L beam vectors by the L wideband amplitude coefficients in the p-th polarization direction.
  • the space matrix may be a representation form of the airspace information of the r-th transmission layer.
  • the terminal device may directly determine the intermediate vectors of different polarization directions according to the L beam vectors and corresponding broadband amplitude coefficients in different polarization directions. For example, the terminal device may determine L intermediate vectors according to the wideband amplitude coefficient of the p-th polarization direction and L beam vectors, and may determine the spatial domain vector according to the dimension of the spatial domain vector.
  • the elements in the p * N tx row are the elements in the above L intermediate vectors, and the elements in other rows may be zero.
  • the terminal device can determine P * L spatial domain column vectors according to the broadband amplitude coefficients in the P polarization directions and the L beam vectors.
  • an inner product of a wideband ideal precoding vector in a certain polarization direction and each column vector in the first vector set is determined to determine L beam vectors, and the L beam vectors are used as P poles.
  • the directional beam vector method is only one possible implementation.
  • the terminal device may also calculate an inner product of the wideband ideal precoding vector in each polarization direction of the P polarization directions and each column vector in the first vector set to determine P * corresponding to the P polarization directions. L beam vectors. This application does not limit this.
  • the weighting coefficient of each spatial domain column vector is determined.
  • the terminal device may determine a corresponding ideal precoding matrix according to a method in the prior art according to a channel matrix of each subband, and a dimension thereof may be (P * N tx ) * R.
  • the ideal precoding matrix of each subband may correspond to a column vector with dimension (P * N tx ) * 1 in one transmission layer.
  • the column vector with dimension (P * N tx ) * 1 is described below as the ideal precoding vector of the subband.
  • the terminal device may perform an inner product based on an ideal precoding vector of one subband and the P * L spatial domain column vectors obtained in step ii above, to obtain P * L values.
  • the value obtained by dividing the P * L values by the P * L wideband amplitude coefficients determined in step ii is a weighting coefficient corresponding to this subband.
  • the weighting coefficient can be understood as: the weighting coefficient of each spatial domain vector when the ideal precoding vector of this subband is characterized by a linear combination of P * L spatial domain column vectors.
  • N sb subbands in the order of the column vectors N sb sequentially arranged from left to right, you can be a dimension (P * L) * N sb matrix.
  • Each column of the matrix corresponds to a subband, and the elements in each column are used to represent the weighting coefficients of the corresponding subbands when they are characterized by a linear combination of P * L spatial domain column vectors.
  • the terminal device determines K frequency-domain basis vectors on the r-th transmission layer.
  • the K frequency-domain base vectors on any two of the R transmission layers may be the same as each other or different from each other, which is not limited in this application. If K frequency-domain base vectors on any two transmission layers on the R transmission layers are the same as each other, the frequency-domain base vectors on the R transmission layers may be K, and the terminal device may determine K based on a certain transmission layer. Frequency-domain base vectors; if K frequency-domain base vectors on each of the R transport layers are different from each other, the frequency-domain base vectors on the R transport layers may be R * K, and the terminal device may be based on Each of the R transmission layers determines K frequency-domain base vectors.
  • the terminal device may determine the K frequency-domain base vectors based on a certain transmission layer.
  • the transmission layer used to determine the K frequency-domain base vectors may be any one of the R transmission layers, for example, it may be the first transmission layer or the R-th transmission layer.
  • the transmission layer used to determine the K frequency-domain base vectors may be a certain transmission layer specified in advance, such as a protocol definition, or a certain transmission layer indicated by a network device.
  • the r-th transport layer is taken as an example to describe the specific process of the terminal device determining the K frequency-domain base vectors.
  • the terminal device may project the superposition coefficients of the subbands on the r-th transmission layer on the second vector set to obtain K frequency-domain base vectors.
  • the second vector set may include multiple column vectors with dimensions N sb * 1, and each column vector is a discrete Fourier transform (DFT) vector or an oversampled DFT vector or discrete Fourier transform. Truncation of vectors or truncation of oversampled DFT vectors.
  • DFT discrete Fourier transform
  • the "truncation" referred to here can be understood as a vector composed of some elements that are truncated from a DFT vector or an oversampled DFT vector.
  • the DFT vector is a 16-dimensional column vector
  • the first 10 elements can be truncated to form a 10-dimensional column vector.
  • the 10-dimensional column vector can be regarded as the truncation of the 16-dimensional DFT vector.
  • the truncated dimension may be N sb * 1.
  • each column vector in the second vector set can be understood as a change rule in the frequency domain.
  • it is hoped that the weighting coefficients of the L beam vectors when the ideal precoding vector of each subband determined in step iii is represented by L beam vectors can pass through several (for example, K) frequencies in the second vector set. It is characterized by a linear combination of the domain basis vectors. Therefore, the K frequency-domain base vectors to be determined in step iv are also several frequency-domain base vectors described above.
  • the second vector set may include N sb column vectors, and any two column vectors in the N sb column vectors are orthogonal to each other.
  • the terminal device may select K column vectors from the N sb column vectors as the K base vectors selected in the frequency domain, that is, K frequency domain base vectors.
  • the terminal device may combine the N sb column vectors into a matrix with dimensions N sb * N sb , for example, F. Thereafter, the terminal device may multiply the matrix having the dimension (P * L) * N sb obtained in step iii with the matrix F to obtain a matrix having the dimension (P * L) * N sb .
  • N sb values can be obtained. From the N sb values, K values having a larger modulus are selected, and the modulus of any one of the K values is greater than the modulus of any one of the remaining N sb -K values.
  • the K columns used to generate the K values in the second vector set may be the K basis vectors selected in the frequency domain.
  • the second vector set may include O 3 * N sb column vectors, where O 3 is an oversampling factor, O 3 ⁇ 1, and is an integer.
  • the second vector set may include O 3 subsets, each subset includes N sb column vectors, and any two column vectors in each subset are orthogonal to each other.
  • the terminal device may select a subset from the O 3 subsets, and the selected subset includes the selected K frequency-domain basis vectors.
  • the terminal device combines the N sb column vectors in each subset into a matrix with dimensions N sb * N sb , for example, F i (1 ⁇ i ⁇ O 3 , and i is an integer), and O 3 dimensions can be obtained.
  • Is a matrix of N sb * N sb .
  • the terminal device may sequentially multiply the matrices of dimension (P * L) * N sb obtained in step iii with the matrices F 1 to F O3 to obtain O 3 matrices of dimension (P * L) * N sb .
  • O 3 groups of values can be obtained, and each group of values includes N sb values.
  • the terminal device can select K values with a larger modulus from each group of values, and can further compare the K values in the O 3 group values to select a group of values.
  • the magnitude of the K values in the selected set of values is greater than the magnitude of the K values in any of the remaining O 3 -1 sets of values.
  • the column vectors used to generate the K values in the second vector set may be K frequency-domain base vectors selected in the frequency domain. It can be understood that the K frequency-domain base vectors belong to a subset of the O 3 subsets, and can be described as the second subset, for example.
  • the terminal device determines P * L * K weighting coefficients.
  • the K frequency-domain base vectors determined by the terminal device in step iv may form a matrix with dimensions N sb * K.
  • the terminal device may determine the matrix of dimension (P * L) * N sb determined in step iii and the matrix of dimension N sb * K, and obtain a matrix of dimension (P * L) * K, for example,
  • the matrix of dimension (P * L) * N sb determined in step iii can be multiplied with a matrix of dimension N sb * K to obtain a matrix of dimension (P * L) * K.
  • This matrix can be called a coefficient matrix.
  • Each element in the coefficient matrix is a weighting coefficient, and each weighting coefficient may include an amplitude coefficient and a phase coefficient.
  • the P * L rows in the coefficient matrix correspond to the P * L columns of the spatial domain column vector
  • the K columns of the coefficient matrix correspond to the K columns of the frequency domain base vector. That is, the coefficients of the P * L rows are weighting coefficients of P * L spatial domain column vectors, and the coefficients of the K column are weighting coefficients of K frequency domain base vectors.
  • the terminal device determines the PMI.
  • the terminal device may be based on the P * L spatial domain column vectors on the r-th transport layer determined in step ii, the K frequency-domain base vectors on the r-th transport layer determined in step iv, and P determined in step v * L * K weighting coefficients to determine R space frequency matrices corresponding to R transmission layers.
  • the space-frequency matrix may be a matrix having a dimension (P * N tx ) * N sb , or a column vector having a dimension (P * N tx * N sb ) * 1.
  • the space-frequency matrix when the space-frequency matrix is a matrix having dimensions (P * N tx ) * N sb , the space-frequency matrix can be expressed as:
  • W 1 is determined by P * L spatial domain column vectors of dimension (P * N tx ) * 1; H is determined by P * L * K weighting coefficients; V 2 is determined by K frequencies of dimension N sb * 1
  • the domain basis vector is determined.
  • W 1 is determined by P * L spatial domain column vectors of dimension (P * N tx ) * 1
  • V 2 is determined by K frequency domain basis vectors and amplitude coefficients of dimension N sb * 1
  • H is determined by P * L * K phase coefficients or P * L * K phase coefficients and amplitude coefficients.
  • the amplitude coefficient may be an amplitude coefficient separated from the weighting coefficient determined in step v.
  • the K frequency-domain base vectors may correspond to the K columns in the coefficient matrix, and an amplitude coefficient may be allocated to the k-th frequency domain base vector in the k-th column, and then the k-th base in the original coefficient matrix may be allocated.
  • the values obtained by dividing the amplitude coefficients in the column by the amplitude coefficients assigned to the k-th frequency-domain base vector are used as the amplitude coefficients in the coefficient matrix.
  • the amplitude coefficient can be retained.
  • H is determined by the amplitude coefficient and the phase coefficient.
  • the amplitude coefficient can also be all set to 1.
  • H is determined by the phase coefficient.
  • W 1 may be a matrix of dimension (P * N tx ) * L
  • H may be a coefficient matrix of dimension (P * L) * K
  • V 2 may be a matrix of dimension N sb * K.
  • the terminal device may determine the PMI based on the space-frequency matrix determined above, or may be based on the P * L spatial domain column vectors on the r-th transmission layer determined in step ii, and on the r-th transmission layer determined in step iv.
  • the K frequency-domain basis vectors and the P * L * K weighting coefficients determined in step v determine the PMI. This application does not limit this.
  • the PMI may include R group indication information corresponding to the R transport layers.
  • the r-th group of indication information in the R-group indication information may be used to indicate:
  • the P * L spatial domain column vectors are determined by the L beam vectors in the first vector set and the L broadband amplitude coefficients in each of the P polarization directions described in step ii. That is, the non-zero elements in the spatial domain vector may be determined by the product of the L beam vectors and the L wideband amplitude coefficients in each polarization direction.
  • the dimension of each spatial domain column vector can be (P * N tx ) * 1.
  • the K frequency domain column vectors may be determined by the K frequency domain base vectors of the frequency domain described in step iv, and the P * L * K weighting coefficients may be determined by the weighting coefficients described in step v. That is, the frequency-domain column vector may be K frequency-domain base vectors determined by the second vector set. Alternatively, the K frequency-domain column vectors may be determined by the K frequency-domain base vectors of the frequency domain described in step iv and the amplitude coefficients in the weighting coefficients described in step v, and P * L * K weighting coefficients may be determined by step v
  • the phase coefficients of the weighting coefficients described are determined. That is, the frequency-domain column vector may be K column vectors determined by a product of the K frequency-domain base vectors and the amplitude coefficients of the respective frequency-domain base vectors.
  • the dimension of each frequency domain column vector can be N sb * 1.
  • the K frequency-domain column vectors may be the K frequency-domain base vectors selected from the second vector set described above.
  • the P * L * K weighting coefficients may include the K beam vectors. Amplitude and phase coefficients.
  • the K frequency-domain column vectors may also be frequency-domain column vectors formed by the product of K frequency-domain base vectors and K amplitude coefficients. In this case, the P * L * K weighting coefficients may include only the K frequencies. Phase coefficient of the domain basis vector.
  • Each weighting factor can be used to indicate that the product of one spatial domain vector out of P * L spatial domain column vectors and one frequency domain column vector of K frequency domain column vectors is in the rth space frequency matrix The weight of the conjugate of a frequency domain column vector and the Kronecker product of a space domain column vector in the r-th space frequency matrix.
  • the weighting factors g l, k can be expressed Weights in the r-th space-frequency matrix, or, Weights in the r-th space-frequency matrix.
  • the L beam vectors of any two transmission layers may be the same or different from each other; the K frequency-domain base vectors of any two transmission layers may be the same as each other, and May be different from each other.
  • the L beam vectors of any two transmission layers are the same as each other, and the K frequency domain base vectors of any two transmission layers are the same as each other, the L beam vectors and the K frequency domain base vectors may not be indicated in each group. Repeat instructions.
  • the PMI may specifically include:
  • each group of broadband amplitude coefficients in the R group includes P * L coefficients
  • each group of weighting coefficients in the R group includes P * L * K coefficients.
  • the L beam vectors and K frequency domain base vectors may also be in each group
  • the instructions are indicated separately.
  • the PMI may include group R instruction information
  • the group r instruction information in the group R instruction information may specifically include:
  • the specific content contained in the PMI listed above is only an example, and should not be construed as any limitation to this application.
  • the L beam vectors of any two transmission layers may be the same as each other, and the K frequency-domain base vectors of any two transmission layers may be different from each other.
  • the PMI may include: an index of the L beam vectors, and Indexes of K frequency-domain base vectors corresponding to the R transmission layers on a one-to-one basis. This application does not limit this.
  • the first vector set can be extended to O 1 * O 2 * N tx column vectors by oversampling factors, and the selected L beam vectors in the spatial domain can be taken from the O 1 * O 2 * N tx A subset of the column vectors, the first subset described above. Therefore, the PMI may further include indication information for indicating the first subset, so as to indicate a position of each column vector in the first subset in the first vector set.
  • the first vector set may include O 1 * O 2 groups, each group being a subset.
  • the L beam vectors may be taken from any one of the above O 1 * O 2 groups.
  • the indication information of the first subset may be, for example, an index of a group in which L beam vectors are located in O 1 * O 2 groups.
  • the second vector set can also be extended to O 3 * N sb column vectors by oversampling factors, and the K frequency-domain base vectors selected in the frequency domain can be taken from the O 3 * N sb columns A subset of the vector, the second subset described above. Therefore, the PMI may further include indication information for indicating the second subset, so as to indicate a position of each column vector in the second subset in the second vector set.
  • the second vector set may include O 3 groups, each group being a subset.
  • the K beam vectors may be taken from any one of the O 3 groups.
  • the indication information of the second subset may be, for example, an index of a group in which K beam vectors are located in O 3 groups.
  • the P * L wideband amplitude coefficients corresponding to the r-th transmission layer may be indicated by a normalization manner.
  • the terminal device may first determine a maximum value among the P * L wideband amplitude coefficients. Based on this maximum value, the ratio of the remaining P * L-1 wideband amplitude coefficients to this maximum value is obtained.
  • the indication information of the P * L wideband amplitude coefficients may include an index of a quantized value of the maximum value and an index of a quantized value of a ratio of the remaining P * L-1 wideband amplitude coefficients to the maximum value.
  • the terminal device may also indicate the index of the quantized value of the P * L wideband amplitude coefficients, or indicate the P * L wideband amplitude coefficients in a differential manner. This application does not limit the specific method for the terminal device to indicate the P * L wideband amplitude coefficients.
  • the foregoing P * L * K weighting coefficients may be expressed in the form of a matrix, for example, may be a matrix having a dimension (P * L) * K.
  • a matrix composed of P * L * K weighting coefficients may be referred to as a coefficient matrix.
  • the P * L rows in the coefficient matrix may correspond to P * L column vectors in the spatial domain
  • the K columns in the coefficient matrix may correspond to the K column vectors in the frequency domain.
  • the P * L * K weighting coefficients corresponding to the r-th transmission layer may be indicated by a normalization manner.
  • the terminal device may determine the weighting coefficient with the largest amplitude (for example, recorded as the maximum coefficient) from the P * L * K weighting coefficients, and indicate the position of the maximum coefficient in the coefficient matrix (for example, the The maximum number of rows and columns in the coefficient matrix).
  • the terminal device may further indicate the relative value of the weighting coefficient with the largest amplitude in each row of the coefficient matrix (for example, recorded as the maximum coefficient in the row) relative to the above-mentioned maximum coefficient, and other weighting factors of each row relative to the in-line maximum of the same row The relative value of the coefficient; or the terminal device may further indicate the relative value of the weighting coefficient with the largest amplitude in each column of the coefficient matrix (such as the maximum coefficient in the column) relative to the above-mentioned maximum coefficient, and other weighting coefficients for each column Relative value of the largest coefficient in a column relative to the same column.
  • the terminal device may determine the weighting coefficient with the largest amplitude (that is, the above-mentioned maximum coefficient) from the P * L * K weighting coefficients, and indicate the position of the maximum coefficient in the coefficient matrix (for example, the The maximum number of rows and columns in the coefficient matrix). Then, the terminal device may further indicate relative values of other weighting coefficients in the coefficient matrix with respect to the maximum coefficient.
  • the terminal device may also directly indicate the index of the quantized value of the P * L * K weighting coefficients, or indicate the P * L * K weighting coefficients in a differential manner. This application does not limit the specific method for the terminal device to indicate the P * L * K weighting coefficients.
  • Each of the P * L * K weighting coefficients may include an amplitude coefficient and a phase coefficient.
  • the feedback overhead of each amplitude coefficient may be the same.
  • the terminal device may use t 0 (t 0 ⁇ 1, and t 0 is an integer) to feedback the amplitude coefficient.
  • the feedback overhead of each phase coefficient may also be the same.
  • the terminal device may use b 0 (b 0 ⁇ 1, and b 0 is an integer) bit feedback amplitude coefficient.
  • the terminal device may also allocate different feedback overheads to different amplitude coefficients, and / or allocate different feedback overheads to different phase coefficients.
  • the terminal device may use more bits to quantize the rows in the coefficient matrix corresponding to the spatial domain vector with a larger wide-band amplitude coefficient, for example, t 1 (t 1 > t 0 , and t 1 is an integer) Bit feedback amplitude coefficients, and / or b 1 (b 1 > b 0 , and b 1 is an integer) bit feedback phase coefficients; it is also possible to change the Rows use fewer bits to quantify, for example, t 2 (0 ⁇ t 2 ⁇ t 0 , where t 2 is an integer) bit feedback amplitude coefficient, and / or b 2 (0 ⁇ b 2 ⁇ b 0 And b 2 is an integer) number of bit feedback phase coefficients.
  • the terminal device uses more bits to quantize certain rows in the coefficient matrix, more bits may be used to quantify the amplitude coefficient, or phase coefficient, or the amplitude coefficient and phase coefficient; when the terminal device pairs the coefficients, When some columns in the matrix are quantized with fewer bits, fewer bits may be used to quantize the amplitude coefficient, or phase coefficient, or the amplitude coefficient and phase coefficient, which is not limited in this application.
  • M columns with larger wide-band amplitude coefficients can be determined, and the number of quantized bits corresponding to the M rows in the coefficient matrix can be greater than the remaining P * LM rows Number of quantization bits.
  • the value of M may be indicated by the network device, or may be predefined, such as a protocol definition, or may be determined by the terminal device and fed back to the network device, which is not limited in this application.
  • the number of frequency-domain base vectors corresponding to at least two of the L beam vectors is different.
  • the L beam vectors may correspond to L rows in the coefficient matrix
  • the K frequency-domain base vectors may correspond to K columns in the coefficient matrix.
  • the l-th beam vector in the L beam vectors corresponds to the l-th row in the coefficient matrix
  • the k coefficients in the l-th row correspond to the K frequency-domain base vectors.
  • the number of frequency-domain base vectors corresponding to different beam vectors may be different. For example, there are K frequency-domain base vectors corresponding to the l-th beam vector, and K '(1 ⁇ K' ⁇ K) frequency-domain base vectors corresponding to the (l + 1) -th beam vector.
  • the number of frequency-domain base vectors corresponding to the frequency domain can be larger; for a beam vector with a smaller wide-band amplitude coefficient, The number of frequency-domain base vectors corresponding to the frequency domain may be smaller. Because the beam vector with a larger broadband amplitude coefficient occupies a larger weight in the linear combination, it also has a greater impact on the approximation accuracy.
  • the beam vectors in the L spatial domain can be controlled by This is achieved by the number of non-zero elements in the row vector in the coefficient matrix.
  • M columns with larger wide-band amplitude coefficients can be determined from P * L spatial domain column vectors.
  • the M columns correspond to M rows in the coefficient matrix, and the elements in the M rows can all be non- Zero elements, and each of the remaining P * LM rows can include one or more zero elements. If an element in the coefficient matrix is zero, it indicates that the sequence number of the column of the zero element in the coefficient matrix (for example, the mth column) may correspond to the column sequence number in the K frequency domain column vectors, that is, the K The m-th column vector of the frequency-domain column vectors is not used, so that the effect of controlling the number of frequency-domain base vectors can be achieved.
  • the number of beam vectors of at least two transmission layers among the R transmission layers is different.
  • the number of beam vectors of the first transmission layer may be configured as L
  • the number of beam vectors of other transmission layers may be configured as L ', 1 ⁇ L' ⁇ L, and L 'is an integer.
  • the number of frequency domain column vectors of at least two transmission layers among the R transmission layers is different.
  • the number of frequency domain column vectors of the first transmission layer may be configured as K
  • the number of frequency domain column vectors of other transmission layers may be configured as K ', 1 ⁇ K' ⁇ K, and K 'is an integer.
  • the number of beam vectors of at least two transmission layers in the R transmission layers is different, and the number of frequency domain column vectors of at least two transmission layers in the R transmission layers is different.
  • the number of beam vectors of the first transmission layer is configured as L
  • the number of frequency domain column vectors is configured as K
  • the number of beam vectors of other transmission layers is configured as L '
  • the number of frequency domain column vectors is configured.
  • the configuration is K ', 1 ⁇ L' ⁇ L, 1 ⁇ K ' ⁇ K, and L' and K are integers.
  • the terminal device determines an ideal precoding matrix of each subband according to a channel matrix of each subband.
  • the terminal device may determine a corresponding ideal precoding matrix according to a method in the prior art according to a channel matrix of each subband, and a dimension thereof may be (P * N tx ) * R.
  • the ideal precoding matrix of each subband may correspond to a column vector with dimension (P * N tx ) * 1 in one transmission layer.
  • the column vector with dimension (P * N tx ) * 1 is described below as the ideal precoding vector of the subband.
  • the terminal device determines P * L beam vectors, K frequency-domain base vectors, and P * L * K weighting coefficients corresponding to the r-th transmission layer.
  • the L beam vectors of any two of the R transmission layers may be the same as each other, and the L beam vectors of each transmission layer may also be different from each other. If the L beam vectors on any two of the R transmission layers are the same as each other, the terminal device may determine the L beam vectors based on a certain transmission layer; if the L beam vectors on any two of the R transmission layers are The beam vectors are different from each other, and the terminal device may determine corresponding L beam vectors based on each transmission layer. It should be understood that the specific process in which the terminal device determines the L beam vectors based on one transmission layer may be the same.
  • the L beam vectors in any two polarization directions among the P polarization directions may be the same as each other, and the L beam vectors in each polarization direction may also be different from each other. If the L beam vectors in any two polarization directions of the P polarization directions are the same as each other, the terminal device can determine the L beam vectors based on a certain polarization direction; if the polarization directions of the P polarization directions are each The L beam vectors are different from each other, and the terminal device may determine the L beam vectors based on each polarization direction.
  • the terminal device may determine the L beam vectors based on a certain polarization direction.
  • the determination of the L beam vectors by the terminal device based on which polarization direction may be predefined, such as a protocol definition, or may be indicated by a network device, which is not limited in this application.
  • the K frequency-domain base vectors of any two of the R transmission layers may be the same as each other, and the K beam vectors of each transmission layer may also be different from each other. If K frequency-domain base vectors on any two of the R transmission layers are the same as each other, the terminal device may determine K frequency-domain base vectors based on a certain transmission layer; if any two of the R transmission layers transmit The K frequency-domain base vectors on the layer are different from each other, and the terminal device may determine the corresponding K frequency-domain base vectors based on each transmission layer, respectively. It should be understood that the specific process in which the terminal device determines the K frequency-domain base vectors based on each transmission layer may be the same.
  • the terminal device may determine the L beams based on a certain transmission layer Vector and K frequency-domain basis vectors.
  • the terminal device specifically determines the L beam vectors and K frequency-domain base vectors based on which transmission layer can be predefined, such as a protocol definition, or can be indicated by a network device, which is not limited in this application.
  • the terminal device uses the terminal device to determine L beam vectors and K frequency-domain base vectors based on the r-th transmission layer as an example to illustrate the specific process. It can be understood that if the L beam vectors on any two transmission layers in the R transmission layers are different from each other, or the K frequency domain base vectors on any two transmission layers in the R transmission layers are different from each other, the terminal device may be based on the same To determine L beam vectors or K frequency-domain base vectors corresponding to each transmission layer.
  • the terminal device may arrange the ideal precoding vectors of each subband on the r-th transmission layer determined in step i from left to right in the order of subbands from 1 to N sb , and obtain a dimension of (P * N tx ) * N sb matrix, for example, written as W.
  • the matrix W is an example of the space-frequency matrix described above.
  • the space-frequency matrix may be P component matrices corresponding to the P polarization directions.
  • the component matrix in the p-th polarization direction in the matrix W can be written as W p
  • the dimension of W p is N tx * N sb .
  • p is any integer value from 1 to P.
  • the terminal device projects the component matrix in a certain polarization direction in the space domain and the frequency domain to determine the L beam vectors selected in the space domain and the K basis vectors selected in the frequency domain.
  • the component matrix may be a component matrix in a first polarization direction, or a component matrix in a P-th polarization direction, which is not limited in this application.
  • the component matrix of which polarization direction is used may be indicated by the network device to the terminal device, or may be defined in advance, such as a protocol definition, which is not limited in this application.
  • the terminal device projects the component matrix in the p-th polarization direction on a matrix composed of a first vector set and a matrix composed of a second vector set to determine L beam vectors and K basis vectors.
  • the first vector set includes N tx column vectors of dimension N tx * 1, and arrange the N tx column vectors in order from left to right to obtain a matrix of dimension N tx * N tx .
  • the second group comprises a vector of dimension N sb column vector of N sb * 1, the N sb column vectors in order from left to right are sequentially arranged obtained dimension N sb * N sb A matrix of, for example, B f .
  • the terminal device projects the component matrix W p in the p-th polarization direction on B s and B f , which can be achieved by transposing W p by the conjugate of B s to the left and right by B f , that is,
  • the matrix obtained after the projection is, for example, written as Y p , then
  • the dimension of the matrix Y p may be N tx * N sb . It can be understood that the matrix is a matrix corresponding to the p-th polarization direction.
  • the strongest L rows and the strongest K columns are determined.
  • the terminal device can respectively modulate the N tx rows in the matrix Y p and select L rows with a larger modulus; and can separately modulate the N sb columns in the matrix Y p and choose a larger modulus K columns.
  • the selected L column vectors are determined from the first vector set according to the sequence numbers of the L rows having a large modulus, and the sequence numbers of the columns in which the L column vectors are located are the sequence numbers of the L rows and the L column vectors. It may be the selected L beam vectors.
  • the selected K column vectors are determined from the second vector set according to the sequence numbers of the K columns having a larger modulus.
  • the sequence numbers of the columns in which the K column vectors are located are the sequence numbers of the above K columns, and the K column vectors are also It can be the selected K frequency-domain basis vectors.
  • the terminal device can extract the L columns selected from the first vector set and arrange them in order from left to right to obtain a matrix with dimensions N tx * L, for example, denoted as U 1, p , U 1, p
  • a second terminal device can be extracted from the vector set selected out of the K columns arranged in order from left to right is obtained for the dimension N sb * K matrix, for example, referred to as U 2, U 2 K in columns It can be K frequency-domain basis vectors.
  • L * K coefficients in each polarization direction of the P polarization directions can be obtained, that is, P * L * K coefficients: the matrix U 1
  • the conjugate transpose of p and the matrix U 2 are projected on the space-frequency matrix W p in the p-th polarization direction, for example, multiplying W p to the left Multiply U 2 by right to get L * K coefficients.
  • the L * K coefficients are coefficients in the p-th polarization direction.
  • P * L * K coefficients in the P polarization directions can be obtained, and the P * L * K coefficients can form a matrix having a dimension (P * L) * K, for example, denoted as X.
  • U 1 is determined by L beam vectors
  • U 2 is determined by K frequency-domain base vectors
  • X is determined by P * L * K weighting coefficients. Therefore, U 1 may be a matrix of dimension (P * N tx ) * L, X may be a coefficient matrix of dimension (P * L) * K, and U 2 may be a matrix of dimension N sb * K.
  • space-frequency matrix and the space-frequency matrix in the first implementation manner can be equivalent, or it can be interchanged.
  • each coefficient in the coefficient matrix X includes an amplitude coefficient and a phase coefficient.
  • the wideband amplitude coefficients of the L beam vectors in each polarization direction can be further determined, or the wideband amplitude coefficients of the L beam vectors in each polarization direction and the K frequency domain base vectors can be further determined Amplitude coefficient in each polarization direction.
  • the terminal device may extract a coefficient of the largest modulus in each row of the P * L rows in the matrix with the dimension (P * L) * K, to obtain P * L coefficients.
  • the terminal device may use the amplitude coefficients among the P * L coefficients as the broadband amplitude coefficients of the L beam vectors in the P polarization directions. From this, P * L intermediate vectors can be obtained, and the dimensions of each intermediate vector are N tx * 1.
  • the P * L intermediate vectors can be constructed to obtain a matrix with dimensions (P * N tx ) * (P * L), in which (p-1) * L + 1 to p * L columns,
  • the elements from line p to p * N tx can be determined for the L intermediate vectors in the p-th polarization direction, that is, the L beam vectors can be compared with the L broadband amplitude coefficients in the p-th polarization direction, respectively. Multiplied, this matrix is also W 1 in the space-frequency matrix.
  • the terminal device can then find the relative values of the coefficients in each row.
  • the relative value of each coefficient in the first row can be represented by the ratio of the modulus of each coefficient in the first row to the modulus of the wideband amplitude coefficient taken from the first row.
  • the relative value of each coefficient is the weighting coefficient, and the matrix formed by each weighting coefficient with the dimension (P * L) * K is the coefficient matrix, that is, the coefficient matrix H in the space-frequency matrix.
  • the terminal device may extract the coefficient with the largest modulus in each row of the P * L rows in the matrix with the dimension (P * L) * K, to obtain P * L coefficients.
  • the amplitude coefficients of the P * L coefficients can be used as the wideband amplitude coefficients of the L beam vectors in the P polarization directions. From this, P * L space domain column vectors can be obtained, and W in the space frequency matrix can also be obtained. 1 .
  • the terminal device can further extract the coefficient with the largest modulus in each of the K columns to obtain K coefficients.
  • the amplitude coefficients of the K coefficients can be used as the amplitude coefficients of the K frequency-domain base vectors, thereby obtaining K frequency-domain column vectors, that is, V 2 in the space-frequency matrix.
  • the terminal device can determine the coefficient matrix H in the space-frequency matrix.
  • the dimension of the coefficient matrix H is (P * L) * K.
  • the elements h i, j in the coefficient matrix H may be the elements in the matrix of (P * L) * K described above divided by the maximum modulus and The maximum modulus of the j column is obtained, or it can be determined directly based on the phase coefficients in the original matrix X.
  • the terminal device determines the PMI.
  • the terminal device may determine the PMI based on the space-frequency matrix determined above, or may also be based on the P * L space-domain column vectors, K frequency-domain column vectors, and (P * L) corresponding to the r-th transmission layer determined in step ii. ) * K weighting coefficient to determine PMI. This application does not limit this.
  • step 350 the terminal device sends a PMI. Accordingly, the network device receives the PMI.
  • the PMI may be carried in CSI.
  • the terminal device may send the CSI to the network device through, for example, a physical uplink control channel (PUCCH) or a physical uplink shared channel (PUSCH), so that the network device can recover the CSI based on the PMI in the CSI.
  • Precoding matrix Precoding matrix.
  • step 360 the network device determines a precoding matrix corresponding to each subband according to the PMI.
  • the network device may determine the precoding matrix corresponding to each subband according to the R space frequency information corresponding to the R transmission layers, or determine the space frequency matrix based on the R space frequency information, and then A precoding matrix corresponding to each subband is determined.
  • the spatial domain vector is a column vector with a dimension (P * N tx ) * 1
  • the frequency domain vector is a column vector with a dimension N sb * 1
  • the number of polarization directions is 1.
  • v l represents the l-th beam vector among the L-beam vectors corresponding to the r-th transmission layer
  • Quantized value representing the amplitude coefficient of v l Represents the n-th sb element in the k-th frequency-domain vector of the K frequency-domain vectors corresponding to the r-th transmission layer
  • Express Conjugate A quantized value representing the magnitude of a linear superposition coefficient corresponding to the lth spatial domain vector in the P * L spatial domain vectors and the kth frequency domain vector in the K frequency domain vectors, Represents a quantized value of the phase of a linear superposition coefficient corresponding to the first spatial domain vector in the P * L spatial domain vectors and the kth frequency domain vector in the K frequency domain vectors.
  • a precoding vector corresponding to the number of R transmission layers and the n sb subband is determined, so as to determine a precoding matrix corresponding to the n sb subband, so as to determine a precoding matrix of the N sb subband.
  • the spatial domain vector is a column vector with a dimension (P * N tx ) * 1
  • the frequency domain vector is a column vector with a dimension N sb * 1
  • the number of polarization directions is 2.
  • v l represents the l-th column vector of the L-column vectors corresponding to the r-th transmission layer, A quantized value representing the amplitude coefficient of v l in the first polarization direction. A quantized value representing the amplitude coefficient of v l in the second polarization direction.
  • u r, k, j represents the n-th sb element in the k-th column vector of the K-th column vector corresponding to the r-th transmission layer, Express Conjugate.
  • a quantized value representing the magnitude of the linear superposition coefficient corresponding to the lth spatial domain vector in the L spatial domain vectors in the second polarization direction and the kth frequency domain vector in the K frequency domain vectors that is, the second A quantized value of the magnitude of the linear superposition coefficients of the vector operation results of v l and u r, k in the polarization direction.
  • a quantized value of the phase of the linear superposition coefficients of the vector operation results of u and k .
  • a precoding vector corresponding to the number of R transmission layers and the n sb subband is determined, so as to determine a precoding matrix corresponding to the n sb subband, so as to determine a precoding matrix of the N sb subband.
  • the network device may also determine R space frequency matrices based on the PMI, and further determine a precoding matrix corresponding to N sb subbands based on the R space frequency matrices.
  • the network device can obtain the R space frequency matrices corresponding to the R transmission layers according to the PMI recovery.
  • the space-frequency matrix can be a matrix with dimensions (P * N tx ) * N sb , or a column vector with dimensions (P * N tx * N sb ) * 1.
  • Network equipment can recover R space-frequency matrices based on different forms, respectively. Thereafter, the network device may also recover the column vectors corresponding to the r-th transmission layer and the n- sb- th subband based on the formulas listed above.
  • the column vector Corresponds to the nth sb column vector of a matrix of dimension (P * N tx ) * N sb , or it can correspond to the (P * th) of a column vector of dimension (P * N tx * N sb ) * 1 Ntx) * (n sb -1) +1 to (P * Ntx) * n sb element column vector.
  • N sb by the first column vector in the R transmission layer may determine a precoding matrix of n sb subbands.
  • first vector set and second vector set may both be column vector sets, but it should be understood that the first vector set and the second vector set are not only It is limited to the forms listed in the above embodiment.
  • each vector in the second vector set can also be mathematically transformed, such as taking the conjugate of each vector to form a new second vector set.
  • the network device can still use the above formula 3 or formula 4 to determine Precoding matrix.
  • the first vector set may be a column vector set
  • the second vector set may be a row vector set.
  • each row vector in the second vector set may be obtained by mathematically transforming each column vector in the second vector set listed in the foregoing embodiments, such as taking the transpose of each vector or the conjugate transpose to form a new Second vector collection. This application does not limit this.
  • the network device may use the above formula 1 or formula 2 to determine the precoding matrix; when taking each column vector in the second vector set, When the conjugate transpose obtains a new second vector set, the network device may continue to use the foregoing formula 3 or formula 4 to determine the precoding matrix.
  • the space-frequency matrix is a column vector of dimension (P * N tx * N sb ) * 1
  • the space-frequency matrix can be obtained by linearly superposing the above P * L * K component matrices, and the component matrix can be obtained by K A Kronecker product of a conjugate vector of one frequency domain column vector among one frequency domain column vector and one space domain column vector among P * L space domain column vectors.
  • the network device can still recover the column vector corresponding to the n sbth subband in the space-frequency matrix of the rth transmission layer based on the formula described above.
  • the column vector It can be the (n sb -1) * (P * N tx ) +1 to the n sb * (P * N tx ) th element in a column vector of dimension (P * N tx * N sb ) * 1 Composed column vector.
  • the network device determines a precoding matrix corresponding to the N sbth subband according to the R space frequency matrices corresponding to the R transmission layers.
  • the network device can obtain R space-frequency matrices corresponding to the R transmission layers.
  • Each space-frequency matrix includes a column vector corresponding to N sb subbands.
  • the network device can extract the column vector corresponding to the n sb subband in each space-frequency matrix to obtain R column vectors corresponding to the n sb subband.
  • the dimension of each column vector can be (P * N tx )*1.
  • a matrix having a dimension (P * N tx ) * R can be obtained, and the matrix is a precoding matrix corresponding to the n sbth subband.
  • the space-frequency matrix may be a matrix having a dimension (P * N tx ) * N sb , or a column vector having a dimension (P * N tx * N sb ) * 1.
  • the network device may determine a column vector corresponding to each subband on each transmission layer based on different forms, and then determine a precoding matrix corresponding to each subband.
  • the space-frequency matrix is a matrix having a dimension (P * N tx ) * N sb
  • the N sb column vectors in the matrix correspond to the N sb subbands one-to-one.
  • the network device can extract the n sb- th column of each space-frequency matrix in the R space-frequency matrices to obtain R column vectors with dimensions (P * N tx ) * 1, and the R column vectors are determined according to the transmission layer.
  • the order from 1 to R is arranged from left to right, and after normalization processing, a matrix with a dimension (P * N tx ) * R can be obtained, which is also a precoding matrix corresponding to the n sbth subband. .
  • the normalization process can be performed by multiplying each element of each column vector in the R column vectors by the normalization coefficient of each column, so that the sum of the power of each element is equal to 1. Multiply the global normalization coefficient so that the sum of the powers of the column vectors is equal to one.
  • the space-frequency matrix is a column vector of (P * N tx * N sb ) * 1, each P * N tx consecutive element in the column vector corresponds to a subband.
  • the network device may follow the arrangement order of the N tx * N sb elements, take each P * N tx consecutive elements as a column, and may extract N sb columns, and the N sb columns from 1 to 1 according to the transmission layer.
  • the order of R is arranged from left to right, and a matrix having a dimension (P * N tx ) * N sb can be obtained.
  • the N sb column vectors in the matrix have one-to-one correspondence with N sb subbands.
  • the network device may recover the precoding matrix corresponding to the n sbth subband according to the method described above.
  • n sb traverse N sb 1 to repeatedly perform the above operation, the network device will be able to recover the pre-coding matrix corresponding to N sb subbands.
  • the method for recovering the precoding matrix by the network device listed above is only one possible implementation manner, and should not constitute any limitation to this application.
  • the space-frequency matrix may not be generated as an intermediate value for restoring the precoding matrix.
  • This application does not limit the specific implementation manner for the network device to recover the precoding matrix based on the PMI.
  • the terminal device can characterize each column vector in the ideal precoding matrix of each subband in the frequency domain by a linear combination of spatial beam vectors, and pass the weighting coefficients used when linearly combining each beam vector through several It is described by linear combination of frequency-domain basis vectors.
  • each frequency-domain base vector can be used to represent a variation rule on multiple subbands. Therefore, different linear combinations of several frequency-domain base vectors can be used to describe the changing law of the combination coefficients of the spatial-domain column vectors of each subband. Because multiple frequency domain base vectors are used to describe different changes in the frequency domain, the relationship between subbands is fully explored.
  • the continuity in the frequency domain can be used to describe the changes of all subbands with fewer frequency domain base vectors Law to compress the feedback overhead.
  • the feedback overhead brought by the subband feedback can be greatly reduced, and the approximate accuracy of the type II codebook can also be guaranteed.
  • the first vector set may comprise at least one of: the dimension N tx 2D-DFT vector transpose dimension 2D-DFT N tx of vector, of dimension N tx of 2D-DFT vector conjugated dimension conjugated 2D-DFT vector N tx transpose, of dimension N tx oversampling 2D-DFT vector, of dimension N tx oversampling 2D-DFT vector transpose, of dimension N tx
  • the conjugate of the oversampled 2D-DFT vector and the conjugate transpose of the oversampled 2D-DFT vector with dimension N tx are conjugate of the oversampled 2D-DFT vector with dimension N tx .
  • the first vector may further include truncation of the 2D-DFT vector, truncation of the transposition of the 2D-DFT vector, truncation of the conjugate of the 2D-DFT vector, truncation of the conjugate transposition of the 2D-DFT vector, and oversampling Truncation of DFT vector, transposition of oversampled 2D-DFT vector, truncation of conjugate of oversampled 2D-DFT vector with dimension N tx , truncation of conjugate transpose of oversampled 2D-DFT vector, and truncation
  • the dimension can be N tx .
  • Said second vector set may comprise at least one of: the DFT dimension N sb vector transpose DFT dimension N sb vector of dimension conjugated N sb vector of DFT, the DFT dimension N sb vector transpose conjugate transpose, of dimension N sb oversampling DFT vector of dimension N sb oversampled DFT vectors of dimension N sb oversampled DFT vectors conjugate and of dimension N sb oversampled DFT vectors Conjugate transpose.
  • the second vector set may also include truncation of the DFT vector, truncation of the DFT vector transposition, truncation of the conjugate transposition of the DFT vector, truncation of the conjugate transposition of the DFT vector, truncation of the oversampled DFT vector, and oversampling of the DFT vector.
  • At least one of the truncation of the transposition, the truncation of the conjugate of the oversampled DFT vector, and the truncation of the conjugate of the oversampled DFT vector, and the truncated dimension may be N sb .
  • the first vector set can provide multiple beam vectors with dimensions of N tx
  • the second vector set can provide multiple frequency-domain base vectors with dimensions of N sb .
  • the method for indicating a precoding matrix is particularly applicable to a case where there are a large number of subbands and continuous subbands. This method can make full use of the correlation between the subbands, compress the feedback overhead, and reduce The huge overhead brought by independent feedback of multiple subbands. However, in some cases, the number of subbands is not large, or the subbands are not continuous. If the existing combination of wideband feedback and subband feedback is used to feedback PMI, it may not bring much Feedback overhead. And in the case of discontinuous subbands, independent approximation of subbands can ensure high approximation accuracy. Therefore, this application further provides a method for indicating a precoding matrix, which can combine different scenarios and feed back the PMI using a feedback mode, which can not only ensure approximate accuracy, but also save feedback overhead.
  • FIG. 5 is a schematic flowchart illustrating a precoding matrix according to another embodiment of the present application, which is shown from the perspective of device interaction. As shown in FIG. 5, the method 400 may include steps 410 to 440. The steps in the method 400 are described in detail below.
  • step 410 the network device generates third indication information, where the third indication information is used to determine a feedback mode based on the type II codebook feedback PMI.
  • the feedback mode based on the type II codebook feedback PMI may include at least two types, and the feedback mode determined by the terminal device based on the third instruction information may be a first feedback mode or a second feedback mode.
  • the first feedback mode is a mode based on the first vector set feedback PMI
  • the second feedback mode is a mode based on the first vector set and the second vector set feedback PMI.
  • the first set of vectors may include at least one of: the dimension N tx 2D-DFT vector transpose dimension 2D-DFT vector N tx, dimensions conjugated 2D-DFT vector of N tx, of dimension N tx of 2D-DFT vector conjugate transpose of dimension N tx oversampling 2D-DFT vector, of dimension N tx oversampling 2D-DFT vector transpose, of dimension N tx oversampling 2D Conjugate of -DFT vector and conjugate transpose of oversampled 2D-DFT vector of dimension N tx .
  • the first vector may further include truncation of the 2D-DFT vector, truncation of the transposition of the 2D-DFT vector, truncation of the conjugate of the 2D-DFT vector, truncation of the conjugate transposition of the 2D-DFT vector, and oversampling of 2D- Truncation of DFT vector, transposition of oversampled 2D-DFT vector, truncation of conjugate of oversampled 2D-DFT vector with dimension N tx , truncation of conjugate transpose of oversampled 2D-DFT vector, and truncation
  • the dimension can be N tx .
  • Said second vector set may comprise at least one of: the DFT dimension N sb vector transpose DFT dimension N sb vector of dimension conjugated N sb vector of DFT, the DFT dimension N sb vector transpose conjugate transpose, of dimension N sb oversampling DFT vector of dimension N sb oversampled DFT vectors of dimension N sb oversampled DFT vectors conjugate and of dimension N sb oversampled DFT vectors Conjugate transpose.
  • the second vector set may also include truncation of the DFT vector, truncation of the DFT vector transposition, truncation of the conjugate transposition of the DFT vector, truncation of the conjugate transposition of the DFT vector, truncation of the oversampled DFT vector, and At least one of the truncation of the transposition, the truncation of the conjugate of the oversampled DFT vector, and the truncation of the conjugate of the oversampled DFT vector, and the truncated dimension may be N sb .
  • the first vector set may provide multiple spatial domain beam vectors
  • the second vector set may provide multiple frequency domain base vectors.
  • the first feedback mode may be, for example, a feedback mode of a type II codebook defined in NR protocol TS38.214 version 15 (Release 15, R15), which may specifically be a combination of broadband feedback and subband independent feedback. Feedback mode.
  • the second feedback mode may be, for example, the feedback mode described above in connection with the method 300. Compared with the first feedback mode, the second feedback mode may be understood as a feedback mode in which broadband feedback and sub-band joint feedback are combined. Based on the description above, it can be seen that the second feedback mode is based on the continuity in the frequency domain and uses the relationship between the subbands to jointly feedback multiple subbands. Compared with the first feedback mode, the feedback is greatly reduced. Overhead.
  • the third indication information may be used to indicate any one of the following information:
  • the network device When the third instruction information is used to indicate a), that is, the network device directly instructs the PMI feedback mode through the third instruction information.
  • the third indication information may reuse existing signaling.
  • the network device may indicate the number of subbands to be reported and the position in the frequency band to the terminal device through the parameter configuration information. The number and / or position of the subbands to be reported may be used to determine the feedback mode of the PMI.
  • the third instruction information may be the same information as the first instruction information described above.
  • the number of frequency domain column vectors may be equal to the number of frequency domain base vectors. If the number K of the frequency-domain base vectors is 0, it can be used to implicitly indicate that the first feedback mode is adopted, and the number K of the frequency-domain column vectors greater than 0 can be used to implicitly indicate that the second feedback mode is adopted.
  • step 420 the network device sends the third instruction information. Accordingly, the terminal device receives the third instruction information.
  • the third indication information may be carried in an RRC message, a MAC CE, or a DCI.
  • the terminal device may determine a PMI feedback mode according to the third instruction information.
  • step 430 the terminal device determines a feedback mode based on the third instruction information, and determines a PMI based on the feedback mode.
  • step 430 specifically includes:
  • Step 4301 The terminal device may determine a feedback mode based on the third instruction information.
  • Step 4302 The terminal device determines the PMI based on the feedback mode.
  • Step 4301 is described in detail below.
  • the terminal device may determine the PMI according to the feedback mode indicated by the third instruction information.
  • the terminal device may determine a PMI feedback mode based on a preset rule according to the number and / or position of the subbands indicated by the third instruction information.
  • the network device may also determine the PMI feedback mode based on the same preset rule, so that based on the determined feedback mode, the precoding matrix is restored according to the PMI that is subsequently fed back by the terminal device.
  • the subband to be reported may be indicated by, for example, a bitmap.
  • the number of subbands is 10, and 10 bits may be used to correspond to the 10 subbands one-to-one.
  • the bit corresponding to the sub-band to be reported may be set to "1", and the bit corresponding to the sub-band to be reported may be set to "0"; or, the bit corresponding to the sub-band to be reported may be set to "0",
  • the bit corresponding to the unreported subband can be set to "1". This application does not limit this.
  • bitmap to indicate the subbands to be reported is only one possible implementation manner, and should not constitute any limitation to this application. This application does not limit the specific manner in which the network device indicates the subbands to be reported. For example, the network device may also directly indicate the number of the subband to be reported to the terminal device.
  • the preset rule is: when the number of subbands to be reported is less than a preset first threshold, a first feedback mode is adopted; when the number of subbands to be reported is greater than or equal to the first threshold, a second feedback is used mode.
  • the feedback overhead caused by independent sub-band feedback is small, and the first feedback mode can be adopted; when the number of sub-bands to be reported is large, the feedback brought by independent sub-band feedback The overhead is large, and the second feedback mode can be adopted.
  • the first threshold may be pre-configured by the network device to the terminal device, or may be pre-defined, such as a protocol definition, or may be determined by the terminal device and reported to the network device, which is not limited in this application.
  • the preset rule is: when the number of subbands to be reported is greater than or equal to a predefined threshold, a second feedback mode is used; when the number of subbands to be reported is less than a predefined threshold, a first feedback mode is used.
  • the predefined threshold may be defined by a protocol, may be fixed, or may change with the total number of subbands, and the protocol may define thresholds corresponding to different numbers of subbands.
  • the number of subbands is 10 and the threshold is 5. That is, a total of 10 subbands, when the number of subbands to be reported is greater than or equal to 5, the second feedback mode is adopted, and when the number of subbands to be reported is less than 5, the first feedback mode is used; for another example, the number of subbands is 20, The threshold is 10. That is, there are a total of 20 subbands.
  • the second feedback mode is adopted; when the number of subbands to be reported is less than 10, the first feedback mode is used.
  • the preset rule is: when the subbands to be reported are not continuous, the first feedback mode is adopted; when the subbands to be reported are continuous, the second feedback mode is used.
  • the approximate accuracy of the precoding matrix recovered by the PMI fed back through the second feedback mode may be lower than the first feedback mode, so the first feedback mode may be preferentially adopted;
  • the approximate accuracy of the precoding matrix recovered by the PMI fed back by the second feedback mode may be basically the same as that of the first feedback mode. Therefore, a second Feedback mode.
  • the subband to be reported is indicated by a bitmap, and the subband to be reported is indicated by "1", and the subband to be reported is indicated by "0", if multiple consecutive bits in the bitmap are “1” , And if there is no "0" between any two consecutive "1s", the subband to be reported is considered to be continuous. If there is a "0" between two adjacent "1s" in the bitmap, the subbands to be reported are considered discontinuous.
  • the preset rule is: when the subbands to be reported are discontinuous, but are regularly arranged in the frequency domain, the second feedback mode is adopted; the subbands to be reported are discontinuous and are arranged in the frequency domain When irregular, the first feedback mode is used.
  • the sub-bands to be reported are not continuous, but are regularly arranged in the frequency domain, for example, there are one or more sub-bands between two adjacent sub-bands to be reported; for example, the sub-bands to be reported
  • the numbers are all odd or even.
  • a second feedback mode can be used.
  • a first feedback mode may be used.
  • whether the subbands to be reported are continuous can be determined in the following manner.
  • the preset rule is: when the number of subbands to be reported is greater than or equal to the first threshold, and the subbands to be reported are continuous, the second feedback mode is adopted; otherwise, the first feedback mode is adopted.
  • a second feedback mode with a smaller feedback overhead may be preferentially adopted.
  • the first feedback mode may be adopted.
  • the approximate accuracy of the precoding matrix recovered by the PMI fed back through the second feedback mode may be lower than the first feedback mode, so the first feedback mode may be adopted.
  • FIG. 6 shows several possible situations in which the subbands to be reported are distributed in the frequency domain.
  • each square can represent a sub-band, where the shaded sub-band represents the sub-band to be reported.
  • the above-mentioned second feedback mode may be used to feed back PMI.
  • the number of subbands to be reported is small, and independent feedback to each subband does not bring much feedback overhead, so the first feedback mode may be adopted.
  • the subbands to be reported are discontinuous in the frequency domain and irregular, so the first feedback mode can be used to feed back the PMI.
  • the preset rule is: when the subband to be reported is full band, the second feedback mode is adopted; otherwise, the first feedback mode is adopted.
  • the subbands to be reported are full bands, that is, the subbands to be reported are continuous in the frequency domain, and the number of subbands to be reported may be relatively large. At this time, the relationship between the subbands can be used to feed back the PMI by using the second feedback mode.
  • the subbands to be reported represent full bands, the subbands to be reported may be discontinuous in the frequency domain or the number is small. In this case, the first feedback mode may be used to feed back the PMI.
  • the preset rules listed above are merely examples for ease of understanding, and should not constitute any limitation to the present application.
  • the network device and the terminal device may determine the PMI feedback mode to feedback the PMI and restore the precoding matrix based on the corresponding preset rule.
  • the third indication information may be used to implicitly indicate whether the first feedback mode or the second feedback mode is used to determine the PMI.
  • the third indication information indicates that the value of K is 0, it means that it is not necessary to determine the frequency-domain base vector, and it can also be understood as determining the PMI based on the first feedback mode;
  • the value is greater than 0, it means that the frequency-domain base vector needs to be determined, which can also be understood as determining the PMI based on the second feedback mode.
  • the first feedback mode and the second feedback mode listed above are only one possible implementation manner, and should not constitute any limitation to the present application.
  • the second feedback mode may also be a feedback mode combining a combination of wideband feedback and some subband independent feedback, such as performing feedback based on only the subbands with odd numbers or only the subbands with even numbers. That is, the second feedback mode may feed back only the amplitude and phase coefficients of a part of the subbands.
  • the first feedback mode may be to perform independent feedback on the amplitude coefficients and phase coefficients of all subbands, respectively. As long as the feedback overhead of the first feedback mode is greater than the feedback overhead of the second feedback mode, the network device and the terminal device determine the feedback mode of the PMI based on the same manner, and both should fall within the protection scope of this application.
  • the second feedback mode may specifically be the feedback mode described in the method 300 above.
  • the specific process of the terminal device determining the PMI based on the feedback mode may include the terminal device determining the PMI based on the first feedback mode, or the terminal device determining the PMI based on the second feedback mode.
  • the specific process for the terminal device to determine the PMI based on the first feedback mode may refer to the feedback method of the type II codebook in the prior art. For brevity, details are not described herein again.
  • step 440 the terminal device sends a PMI. Accordingly, the network device receives the PMI.
  • step 440 is the same as the specific process of step 350 in the method 300 above. For brevity, details are not described herein again.
  • the terminal device may determine a feedback mode based on an instruction of a network device, or based on the number and / or location of subbands to be reported, and may use a feedback mode with a smaller feedback overhead to feedback PMI in some cases. For example, when the number of subbands to be reported is high or the continuity is good, the PMI is fed back through a feedback mode with a small feedback overhead, which can not only ensure high approximation accuracy, but also reduce feedback overhead. By introducing multiple feedback modes to suit different measurement situations, both feedback accuracy and feedback overhead can be taken into account, thereby achieving a balance between the two.
  • the second feedback mode provided in the present application can be well compatible with the existing feedback mode, with minor changes to the existing protocol, and is easy to implement.
  • FIG. 7 is a schematic block diagram of a communication device according to an embodiment of the present application.
  • the communication device 500 may include a transceiver unit 510 and a processing unit 520.
  • the communication device 500 may correspond to the terminal device in the foregoing method embodiment.
  • the communication device 500 may be a terminal device or a chip configured in the terminal device.
  • the communication device 500 may correspond to the terminal device in the method 300 or 400 according to the embodiment of the present application.
  • the communication device 500 may include a terminal for performing the method 300 in FIG. 3 or the method 400 in FIG. 5.
  • the unit of method performed by the device is respectively to implement a corresponding process of the method 300 in FIG. 3 or the method 400 in FIG. 5.
  • the transceiver unit 510 may be used to execute steps 320 to 350 in the method 300, and the processing unit 520 may be used to execute step 310 in the method 300.
  • the processing unit 520 is configured to determine a PMI, where the PMI includes R sets of space frequency information corresponding to R transmission layers, the R sets of space frequency information is used to determine a precoding matrix of each subband, and the R The r-th group of space-frequency information in the group of space-frequency information is used to indicate:
  • the P * L spatial domain vectors are determined by the L beam vectors in each of the P polarization directions and their wideband amplitude coefficients.
  • Each of the P * L * K coefficients is determined by A linear superposition coefficient indicating a vector operation result between one spatial domain vector in P * L spatial domain vectors and one frequency domain vector in K frequency domain vectors;
  • R is the number of transmission layers, P is the number of polarization directions, and
  • R , R, P, L, and K are all positive integers;
  • the transceiver unit 510 may be configured to send the PMI.
  • the spatial domain vector is a column vector with a dimension (P * N tx ) * 1
  • the frequency domain vector is a column vector with a dimension N sb * 1
  • a result of the vector operation includes: the spatial domain vector A product of the conjugate transpose of the frequency domain vector, or a Kronecker product of the conjugate of the frequency domain vector and the space domain vector, where N tx is an antenna port for each polarization direction N sb is the number of subbands to be reported, 1 ⁇ L ⁇ N tx , 1 ⁇ K ⁇ N sb , and N tx and N sb are positive integers.
  • the L beam vectors are taken from a subset of a predefined first vector set
  • the PMI further includes indication information of the first subset
  • the indication information of the first subset is used For indicating the position of each vector in the first subset in the first vector set.
  • the K frequency-domain vectors are taken from a second subset of a predefined second vector set
  • the PMI further includes an indication of the second subset
  • the The indication information is used to indicate a position of each vector in the second subset in the second vector set.
  • the transceiver unit 510 is further configured to receive first indication information, where the first indication information is used to indicate a value of K.
  • the transceiver unit 510 is further configured to receive second instruction information, where the second instruction information is used to indicate a value of L.
  • the transceiver unit 510 may be used to execute steps 420 and 440 in the method 400, and the processing unit 520 may be used to execute step 430 in the method 400.
  • the transceiver unit 510 may be configured to receive third indication information, where the third indication information is used to determine a feedback mode indicating a PMI based on a type II type II codebook feedback precoding matrix, and the feedback mode is the first feedback mode or A second feedback mode, the first feedback mode is a mode based on a first vector set feedback PMI, the second feedback mode is a mode based on the first vector set and a second vector set feedback PMI, the first feedback mode
  • the vector set includes multiple vectors with dimensions N tx
  • the second vector set includes multiple vectors with dimensions N sb , where N tx is the number of transmitting antenna ports in each polarization direction and N sb is to be reported N tx and N sb are positive integers;
  • the processing unit 520 may be configured to determine and send the PMI based on the feedback mode.
  • the third indication information includes indication information of a feedback mode of the PMI.
  • the third indication information is used to indicate the number and positions of the subbands to be reported.
  • the method further includes:
  • a feedback mode of the PMI is determined according to a preset rule.
  • the third indication information is carried in a radio resource control RRC message.
  • the PMI when the feedback mode is the second feedback mode, the PMI includes R group of space frequency information corresponding to R transmission layers, and the R group of space frequency information is used to determine a correspondence with each subband.
  • the precoding matrix, the rth group of space frequency information in the R group of space frequency information is used to indicate:
  • the P * L spatial domain vectors are determined by the L beam vectors in each of the P polarization directions and their wideband amplitude coefficients.
  • Each of the P * L * K coefficients is determined by A linear superposition coefficient indicating a vector operation between one spatial domain vector in P * L spatial domain vectors and one frequency domain vector in K frequency domain vectors; the L beam vectors are determined by the first vector set, so The K frequency-domain vectors are determined by the second vector set, R is the number of transmission layers, P is the number of polarization directions, and R, r, P, L, and K are all positive integers.
  • transceiver unit in the communication device 500 may correspond to the transceiver 602 in the terminal device 600 shown in FIG. 8, and the processing unit 520 in the communication device 500 may correspond to the terminal device 600 shown in FIG. 8. In the processor 601.
  • the communication device 500 may correspond to the network device in the foregoing method embodiment, for example, it may be a network device, or a chip configured in the network device.
  • the communication device 500 may correspond to the network device in the method 300 or 400 according to the embodiment of the present application.
  • the communication device 500 may include a network for performing the method 300 in FIG. 3 or the method 400 in FIG. 5.
  • the unit of method performed by the device is respectively to implement a corresponding process of the method 300 in FIG. 3 or the method 400 in FIG. 5.
  • the transceiver unit 510 may be used to execute steps 320 to 350 in the method 300, and the processing unit 520 may be used to execute step 360 in the method 300.
  • the transceiver unit 510 may be configured to receive a precoding matrix indicating PMI, where the PMI includes R groups of space frequency information corresponding to R transmission layers, and the r group of space frequency information in the R group of space frequency information is used to indicate :
  • the P * L spatial domain vectors are determined by the L beam vectors in each of the P polarization directions and their wideband amplitude coefficients.
  • Each of the P * L * K coefficients is determined by A linear superposition coefficient indicating a vector operation result between one spatial domain vector in P * L spatial domain vectors and one frequency domain vector in K frequency domain vectors;
  • R is the number of transmission layers, P is the number of polarization directions, and
  • R , R, P, L, and K are all positive integers;
  • the processing unit 520 may be configured to determine a precoding matrix of each subband based on the R group of space frequency information.
  • the spatial domain vector is a column vector with a dimension (P * N tx ) * 1
  • the frequency domain vector is a column vector with a dimension N sb * 1
  • a result of the vector operation includes: the spatial domain vector A product of the conjugate transpose of the frequency domain vector, or a Kronecker product of the conjugate of the frequency domain vector and the space domain vector, where N tx is an antenna port for each polarization direction N sb is the number of subbands to be reported, 1 ⁇ L ⁇ N tx , 1 ⁇ K ⁇ N sb , and N tx and N sb are positive integers.
  • the L beam vectors are taken from a subset of a predefined first vector set
  • the PMI further includes indication information of the first subset
  • the indication information of the first subset is used For indicating the position of each vector in the first subset in the first vector set.
  • the K frequency-domain vectors are taken from a second subset of a predefined second vector set
  • the PMI further includes an indication of the second subset
  • the The indication information is used to indicate a position of each vector in the second subset in the second vector set.
  • the transceiver unit 510 is further configured to send first indication information, where the first indication information is used to indicate a value of K.
  • the transceiver unit 510 is further configured to send second instruction information, where the second instruction information is used to indicate a value of L.
  • the spatial domain vector is a column vector with a dimension (P * N tx ) * 1
  • the frequency domain vector is a column vector with a dimension N sb * 1
  • the number of polarization directions is 1.
  • the processing unit 520 is specifically configured to traverse the values of n sb from 1 to N sb and repeatedly perform the following operations to obtain a precoding matrix corresponding to each subband:
  • v l represents the l-th beam vector among the L-beam vectors corresponding to the r-th transmission layer
  • Quantized value representing the amplitude coefficient of v l Represents the n-th sb element in the k-th frequency-domain vector of the K frequency-domain vectors corresponding to the r-th transmission layer
  • Express Conjugate A quantized value representing the magnitude of a linear superposition coefficient corresponding to the first spatial domain vector in the P * L spatial domain vectors and the kth frequency domain vector in the K frequency domain vectors, Represents a quantized value of a phase of a linear superposition coefficient corresponding to the first spatial domain vector in the P * L spatial domain vectors and the kth frequency domain vector in the K frequency domain vectors, where both l and k are positive Integer.
  • the spatial domain vector is a column vector with a dimension (P * N tx ) * 1
  • the frequency domain vector is a column vector with a dimension N sb * 1
  • the number of polarization directions is two.
  • the processing unit 520 is specifically configured to traverse the values of n sb from 1 to N sb and repeatedly perform the following operations to obtain a precoding matrix corresponding to each subband:
  • v l represents the l-th beam vector among the L-beam vectors corresponding to the r-th transmission layer
  • a quantized value representing the amplitude coefficient of v l in the first polarization direction Represents a quantized value of the amplitude coefficient of v l in the second polarization direction
  • u r, k, j represents the k th frequency domain vector of the k frequency domain vectors corresponding to the r th transmission layer n sb elements
  • Express Conjugate A quantized value representing the magnitude of a linear superposition coefficient corresponding to the lth spatial domain vector in the L spatial domain vectors in the first polarization direction and the kth frequency domain vector in the K frequency domain vectors
  • the transceiver unit 510 is used to execute steps 420 and 440 in the method 400, and the processing unit 520 may be used to execute step 410 in the method 400.
  • the processing unit 520 may be configured to generate third instruction information, where the third instruction information is used to determine a feedback mode indicating a PMI based on a type II type II codebook feedback precoding matrix, and the feedback mode is the first feedback mode or A second feedback mode, the first feedback mode is a mode based on a first vector set feedback PMI, the second feedback mode is a mode based on the first vector set and a second vector set feedback PMI, the first feedback mode
  • the vector set includes multiple vectors with dimensions N tx
  • the second vector set includes multiple vectors with dimensions N sb , where N tx is the number of transmitting antenna ports in each polarization direction and N sb is to be reported N tx and N sb are positive integers;
  • the transceiver unit 510 may be configured to send the third indication information; and may be configured to receive the PMI, where the PMI is determined based on the feedback mode.
  • the third indication information includes indication information of a feedback mode of the PMI.
  • the third indication information is used to indicate the number and positions of the subbands to be reported.
  • the method further includes:
  • a feedback mode of the PMI is determined according to a preset rule.
  • the third indication information is carried in a radio resource control RRC message.
  • the PMI when the feedback mode is the second feedback mode, the PMI includes R group of space frequency information corresponding to R transmission layers, and the R group of space frequency information is used to determine a correspondence with each subband.
  • the precoding matrix, the rth group of space frequency information in the R group of space frequency information is used to indicate:
  • the P * L spatial domain vectors are determined by the L beam vectors in each of the P polarization directions and their wideband amplitude coefficients.
  • Each of the P * L * K coefficients is determined by A linear superposition coefficient indicating a vector operation between one spatial domain vector in P * L spatial domain vectors and one frequency domain vector in K frequency domain vectors; the L beam vectors are determined by the first vector set, so The K frequency-domain vectors are determined by the second vector set, R is the number of transmission layers, P is the number of polarization directions, and R, r, P, L, and K are all positive integers.
  • transceiver unit 510 in the communication device 500 may correspond to the transceiver 720 in the network device 700 shown in FIG. 9, and the processing unit 520 in the communication device 500 may correspond to the network shown in FIG. 9.
  • the processor 710 in the device 700 may correspond to the transceiver 720 in the network device 700 shown in FIG. 9, and the processing unit 520 in the communication device 500 may correspond to the network shown in FIG. 9.
  • FIG. 8 is a schematic structural diagram of a terminal device 600 according to an embodiment of the present application.
  • the terminal device 600 includes a processor 601 and a transceiver 602.
  • the terminal device 500 further includes a memory 603.
  • the processor 601, the transceiver 602, and the memory 603 can communicate with each other through an internal connection path to transfer control and / or data signals.
  • the memory 603 is used to store a computer program
  • the processor 601 is used to store the computer program from the memory 603.
  • the computer program is called and executed to control the transceiver 602 to send and receive signals.
  • the terminal device 500 may further include an antenna 504 for sending uplink data or uplink control signaling output by the transceiver 602 through a wireless signal.
  • the processor 601 and the memory 603 may be combined into a processing device, and the processor 601 is configured to execute program codes stored in the memory 603 to implement the foregoing functions.
  • the memory 603 may also be integrated in the processor 601 or independent of the processor 601.
  • the processor 601 when the program instructions stored in the memory 603 are executed by the processor 601, the processor 601 is configured to determine a PMI, and is used to control the transceiver 602 to send the PMI.
  • the PMI includes R group space frequency information corresponding to R transmission layers, and the R group space frequency information is used to determine a precoding matrix of each subband.
  • the r-th group of space-frequency information in the R-group of space-frequency information is used to indicate:
  • P * L spatial domain vectors are determined by the L beam vectors in each of the P polarization directions and their wideband amplitude coefficients, and each of the P * L * K coefficients is used to indicate P *
  • the linear superposition coefficient of the vector operation result between one spatial domain vector in L spatial domain vectors and one frequency domain vector in K frequency domain vectors;
  • R is the number of transmission layers,
  • P is the number of polarization directions, and
  • R, r, P , L, and K are all positive integers.
  • the processor 601 when the program instructions stored in the memory 603 are executed by the processor 601, the processor 601 is used to control the transceiver 602 to receive the third instruction information; and used to determine and send the PMI based on the feedback mode.
  • the third indication information is used to determine a feedback mode indicating a PMI based on a type II codebook feedback precoding matrix, the feedback mode is a first feedback mode or a second feedback mode, and the first feedback mode is based on the first vector set feedback PMI
  • the second feedback mode is a mode based on the first vector set and the second vector set to feedback the PMI.
  • the first vector set includes a plurality of vectors with a dimension of N tx
  • the second vector set includes a plurality of vectors with a dimension of N sb
  • N tx is a number of ports of a transmitting antenna in each polarization direction
  • N sb is a report to be reported N tx and N sb are positive integers.
  • the terminal device 600 may correspond to the terminal device in the method 300 or 400 according to the embodiment of the present application.
  • the terminal device 600 may include a terminal for performing the method 300 in FIG. 3 or the method 400 in FIG. 5.
  • the unit of method performed by the device is respectively to implement a corresponding process of the method 300 in FIG. 3 or the method 400 in FIG. 5.
  • the foregoing processor 601 may be used to perform the actions implemented in the terminal device described in the foregoing method embodiment, and the transceiver 602 may be used to execute the terminal device described in the foregoing method embodiment that is sent to or received from the network device by the terminal device. action.
  • the transceiver 602 may be used to execute the terminal device described in the foregoing method embodiment that is sent to or received from the network device by the terminal device. action.
  • the above-mentioned terminal device 600 may further include a power source 605 for supplying power to various devices or circuits in the terminal device.
  • the terminal device 600 may further include one or more of an input unit 606, a display unit 607, an audio circuit 608, a camera 609, and a sensor 610, and the audio circuit It may also include a speaker 6082, a microphone 6084, and the like.
  • FIG. 9 is a schematic structural diagram of a network device 700 according to an embodiment of the present application.
  • the network device 700 includes a processor 710 and a transceiver 720.
  • the network device 700 further includes a memory 730.
  • the processor 710, the transceiver 720, and the memory 730 communicate with each other through an internal connection path, and transfer control and / or data signals.
  • the memory 730 is used to store a computer program, and the processor 710 is used to call from the memory 730.
  • the computer program is run to control the transceiver 720 to send and receive signals.
  • the processor 710 and the memory 730 may be combined into a processing device, and the processor 710 is configured to execute program codes stored in the memory 730 to implement the foregoing functions.
  • the memory 730 may also be integrated in the processor 710, or be independent of the processor 710.
  • the above network device 700 may further include an antenna 740 for sending downlink data or downlink control signaling output by the transceiver 720 through a wireless signal.
  • the processor 710 when the program instructions stored in the memory 730 are executed by the processor 710, the processor 710 is configured to control the transceiver 720 to receive a PMI, where the PMI includes R sets of space frequency information corresponding to the R transmission layers; and is used for A precoding matrix for each subband is determined based on the R-group space frequency information.
  • the r-th group of space-frequency information in the R-group of space-frequency information is used to indicate:
  • P * L spatial domain vectors are determined by the L beam vectors in each of the P polarization directions and their wideband amplitude coefficients, and each of the P * L * K coefficients is used to indicate P *
  • the linear superposition coefficient of the vector operation result between one spatial domain vector in L spatial domain vectors and one frequency domain vector in K frequency domain vectors;
  • R is the number of transmission layers,
  • P is the number of polarization directions, and
  • R, r, P , L, and K are all positive integers.
  • the processor 710 when the program instructions stored in the memory 730 are executed by the processor 710, the processor 710 is configured to generate third instruction information; and is used to control the transceiver 720 to send the third instruction information.
  • the third indication information is used to determine a feedback mode indicating a PMI based on a type II codebook feedback precoding matrix, the feedback mode is a first feedback mode or a second feedback mode, and the first feedback mode is based on the first vector set feedback PMI
  • the second feedback mode is a mode based on the first vector set and the second vector set to feedback the PMI.
  • the first vector set includes a plurality of vectors with a dimension of N tx
  • the second vector set includes a plurality of vectors with a dimension of N sb .
  • N tx is the number of transmitting antenna ports in each polarization direction
  • N sb is the number of subbands to be reported
  • N tx and N sb are positive integers.
  • the network device 700 may correspond to the network device in the method 300 or 400 according to the embodiment of the present application.
  • the network device 700 may include a network for performing the method 300 in FIG. 3 or the method 400 in FIG. 5.
  • the unit of method performed by the device is respectively used to implement the corresponding process of the method 300 in FIG. 3 or the method 400 in FIG. 5.
  • the embodiments have been described in detail, and for the sake of brevity, they are not repeated here.
  • the foregoing processor 710 may be configured to perform the actions implemented by the network device described in the foregoing method embodiment, and the transceiver 720 may be configured to perform the network device described in the foregoing method embodiment to send or receive from the terminal device to the terminal device. action.
  • the transceiver 720 may be configured to perform the network device described in the foregoing method embodiment to send or receive from the terminal device to the terminal device. action.
  • processors in the embodiment of the present application may be a central processing unit (CPU), and the processor may also be other general-purpose processors, digital signal processors (DSPs), and application-specific integrated circuits. (application specific integrated circuit (ASIC)), ready-made programmable gate array (field programmable gate array, FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc.
  • CPU central processing unit
  • DSP digital signal processor
  • ASIC application specific integrated circuit
  • FPGA field programmable gate array
  • FPGA field programmable gate array
  • the memory in the embodiments of the present application may be a volatile memory or a non-volatile memory, or may include both volatile and non-volatile memory.
  • the non-volatile memory may be read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (erasable PROM, EPROM), electrical memory Erase programmable read-only memory (EPROM, EEPROM) or flash memory.
  • the volatile memory may be a random access memory (RAM), which is used as an external cache.
  • RAM random access memory
  • SRAM static random access memory
  • DRAM dynamic random access memory
  • SDRAM synchronous dynamic random access Access memory
  • double SDRAM double data rate synchronous dynamic random access memory
  • enhanced SDRAM enhanced synchronous dynamic random access memory
  • SLDRAM synchronous connection dynamic random access Fetch memory
  • direct RAMbus RAM direct RAMbus RAM, DR RAM
  • the present application also provides a computer program product, the computer program product includes: computer program code, when the computer program code is run on a computer, the computer executes the program shown in FIG. 3 or FIG. 5 The method in the examples is shown.
  • the present application further provides a computer-readable medium, where the computer-readable medium stores program code, and when the program code is run on the computer, the computer executes the program shown in FIG. 3 or FIG. 5.
  • the computer-readable medium stores program code
  • the program code when run on the computer, the computer executes the program shown in FIG. 3 or FIG. 5.
  • the method in the examples is shown.
  • the present application further provides a system, which includes the foregoing one or more terminal devices and one or more network devices.
  • the network device in each of the foregoing device embodiments corresponds exactly to the network device or terminal device in the terminal device and method embodiments, and the corresponding module or unit performs the corresponding steps, for example, the communication unit (transceiver) performs the receiving or
  • the step of sending, other than sending and receiving, may be performed by a processing unit (processor).
  • processor For the function of the specific unit, refer to the corresponding method embodiment. Among them, there may be one or more processors.
  • a component may be, but is not limited to, a process running on a processor, a processor, an object, an executable, a thread of execution, a program, and / or a computer.
  • an application running on a computing device and a computing device can be components.
  • One or more components can reside within a process and / or thread of execution and a component may be localized on one computer and / or distributed between two or more computers.
  • these components can execute from various computer readable media having various data structures stored thereon.
  • a component may, for example, be based on a signal having one or more data packets (e.g., data from two components that interact with another component between a local system, a distributed system, and / or a network, such as the Internet that interacts with other systems through signals) Communicate via local and / or remote processes.
  • data packets e.g., data from two components that interact with another component between a local system, a distributed system, and / or a network, such as the Internet that interacts with other systems through signals
  • the disclosed systems, devices, and methods may be implemented in other ways.
  • the device embodiments described above are only schematic.
  • the division of the unit is only a logical function division.
  • multiple units or components may be combined or Can be integrated into another system, or some features can be ignored or not implemented.
  • the displayed or discussed mutual coupling or direct coupling or communication connection may be indirect coupling or communication connection through some interfaces, devices or units, which may be electrical, mechanical or other forms.
  • the units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, may be located in one place, or may be distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the objective of the solution of this embodiment.
  • each functional unit in each embodiment of the present application may be integrated into one processing unit, or each of the units may exist separately physically, or two or more units may be integrated into one unit.
  • each functional unit may be implemented in whole or in part by software, hardware, firmware, or any combination thereof.
  • software When implemented in software, it may be implemented in whole or in part in the form of a computer program product.
  • the computer program product includes one or more computer instructions (programs).
  • programs When the computer program instructions (programs) are loaded and executed on a computer, the processes or functions according to the embodiments of the present application are wholly or partially generated.
  • the computer may be a general-purpose computer, a special-purpose computer, a computer network, or other programmable devices.
  • the computer instructions may be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another computer-readable storage medium, for example, the computer instructions may be from a website site, computer, server, or data center Transmission by wire (such as coaxial cable, optical fiber, digital subscriber line (DSL)) or wireless (such as infrared, wireless, microwave, etc.) to another website site, computer, server, or data center.
  • the computer-readable storage medium may be any available medium that can be accessed by a computer or a data storage device such as a server, a data center, and the like that includes one or more available medium integration.
  • the usable medium may be a magnetic medium (for example, a floppy disk, a hard disk, a magnetic tape), an optical medium (for example, a high-density digital video disc (DVD)), or a semiconductor medium (for example, a solid state disk, SSD)) and so on.
  • a magnetic medium for example, a floppy disk, a hard disk, a magnetic tape
  • an optical medium for example, a high-density digital video disc (DVD)
  • DVD high-density digital video disc
  • SSD solid state disk
  • the functions are implemented in the form of software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium.
  • the technical solution of this application is essentially a part that contributes to the existing technology or a part of the technical solution can be embodied in the form of a software product.
  • the computer software product is stored in a storage medium, including Several instructions are used to cause a computer device (which may be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the method described in the embodiments of the present application.
  • the aforementioned storage media include: U disks, mobile hard disks, read-only memories (ROMs), random access memories (RAMs), magnetic disks or compact discs and other media that can store program codes .

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Abstract

本申请提供了一种指示和确定预编码矩阵的方法以及通信装置，能够减小反馈开销。该方法包括：终端设备确定PMI，并向网络设备发送该PMI。该PMI包括与R个传输层对应的R组空频信息，该R组空频信息用于确定各子带的预编码矩阵，该R组空频信息中的第r组空频信息用于指示：与第r个传输层对应的P*L个空域向量；与第r个传输层对应的K个频域向量；以及与第r个传输层对应的P*L*K个系数。该P*L个空域向量由P个极化方向中每个极化方向上的L个波束向量及其宽带幅度系数确定，该P*L*K个系数中的每个系数用于指示P*L个空域向量中的一个空域向量与K个频域向量中的一个频域向量间的向量运算结果的线性叠加系数。

Description

指示预编码矩阵和确定预编码矩阵的方法以及通信装置
本申请要求于2018年8月10日提交中国专利局、申请号为201810910281.2、申请名称为“指示预编码矩阵和确定预编码矩阵的方法以及通信装置”的中国专利申请的优先权，其全部内容通过引用结合在本申请中。
技术领域
本申请涉及无线通信领域，并且更具体地，涉及指示预编码矩阵的方法和确定预编码矩阵的方法以及通信装置。
背景技术
在大规模多输入多输出(massive multiple-input multiple-output，Massive MIMO)技术中，可通过预编码减小多用户之间的干扰以及同一用户的多个信号流之间的干扰，有利于提高信号质量，实现空分复用，提高频谱利用率。
目前，已知一种反馈预编码矩阵的方法，终端设备可以根据接收到的参考信号进行信道测量，确定理想预编码矩阵，并通过预编码矩阵指示(precoding matrix indicator，PMI)来向网络设备反馈。为了提高反馈精度，使得网络设备获得与理想预编码矩阵较为近似的预编码矩阵，终端设备可以通过宽带反馈和子带反馈的两级反馈方式来向网络设备指示该理想预编码矩阵。具体地，终端设备可以通过宽带反馈指示被选择的波束以及各波束的宽带幅度系数的量化值，并可以通过子带反馈指示可用于各个子带的组合系数的量化值，其中组合系数例如包括子带幅度系数和子带相位系数。网络设备可以综合宽带反馈的信息和子带反馈的信息恢复出近似于理想预编码矩阵的预编码矩阵。
为了提高频谱资源的利用率，网络设备可以通过多个传输层向终端设备传输数据。然而，如果终端设备基于每个传输层进行如上所述的宽带反馈和子带反馈，可能会带来较大的反馈开销。
发明内容
本申请提供一种指示预编码矩阵的方法和确定预编码矩阵的方法以及通信装置，以减小PMI的反馈开销。
第一方面，提供了一种指示预编码矩阵的方法，该方法可以由终端设备执行，也可以由配置于终端设备中的芯片执行。
具体地，该方法包括：确定预编码矩阵指示PMI，该PMI包括与R个传输层对应的R组空频信息，该R组空频信息用于确定与各子带对应的预编码矩阵，该R组空频信息中的第r组空频信息用于指示：与R个传输层中的第r个传输层对应的P*L个空域向量；与该第r个传输层对应的K个频域向量；以及与该第r个传输层对应的P*L*K个系数；发送该PMI。
其中，该P*L个空域向量由P个极化方向中每个极化方向上的L个波束向量及其宽带幅度系数确定，P*L*K个系数中的每个系数用于指示P*L个空域向量中的一个空域向量与K个频域向量中的一个频域向量间的向量运算结果的线性叠加系数；R为传输层数，P为极化方向数，且R、r、P、L和K均为正整数。
第二方面，提供了一种确定预编码矩阵的方法，该方法可以由网络设备执行，也可以由配置于网络设备中的芯片执行。
具体地，该方法包括：接收PMI，该PMI包括与R个传输层对应的R组空频信息，该R组空频信息中的第r组空频信息用于指示：与R个传输层中的第r个传输层对应的P*L个空域向量；与第r个传输层对应的K个频域向量；以及与第r个传输层对应的P*L*K个系数；基于R组空频信息确定与各子带对应的预编码矩阵。
其中，P*L个空域向量由P个极化方向中每个极化方向上的L个波束向量及其宽带幅度系数确定，P*L*K个系数中的每个系数用于指示P*L个空域向量中的一个空域向量与K个频域向量中的一个频域向量间的向量运算结果的线性叠加系数；R为传输层数，P为极化方向数，且R、r、P、L和K均为正整数。
基于上述技术方案，终端设备可以将频域上各子带的理想预编码矩阵中的各个列向量通过空域的波束向量的线性组合来表征，并将各波束向量线性组合时使用的加权系数通过若干个频域向量的线性组合来描述。其中，每个频域向量可以用于表示各波束向量线性组合的加权系数在多个子带上的一种变化规律。从而可以通过对若干个频域向量进行不同的线性组合来描述各子带的空域向量的线性组合系数的变化规律。
由于通过多个频域向量来描述频域上不同的变化规律，充分挖掘了子带之间的关系，可利用频域的连续性，用较少的频域向量描述全部子带的变化规律，从而对反馈开销进行压缩。与现有技术中的子带独立反馈的方式相比，可以大大减小子带反馈所带来的反馈开销，同时也能够保证类型二(type II)码本的近似精度。
在本申请实施例中，为便于区分和说明，可以将上述反馈模式称为宽带反馈加子带联合反馈的反馈模式。与此相对地，可以将现有技术NR协议TS38.214的版本15(Release 15，R15)中定义的type II码本的反馈模式称为宽带反馈加子带独立反馈的反馈模式。
结合第一方面或第二方面，在某些可能的实现方式中，该空域向量是维度为(P*N tx)*1的列向量，该频域向量是维度为N sb*1的列向量，该向量运算结果包括：空域向量与频域向量的共轭转置的乘积，或，频域向量的共轭与空域向量的克罗内克尔积。其中，N tx为每个极化方向的天线端口数，N sb为待上报的子带数，1≤L≤N tx，1≤K≤N sb，且N tx和N sb均为正整数。
在另一种实现方式中，终端设备确定PMI，该PMI用于确定与N sb个子带对应的预编码矩阵，该预编码矩阵基于与R个传输层对应的R个空频矩阵获得，该PMI包括与R个空频矩阵对应的R组指示信息，R组指示信息中的第r组指示信息用于指示：与第r个传输层对应的P*L个空域列向量；与第r个传输层对应的K个频域列向量；以及用于确定第r个空频矩阵的P*L*K个加权系数，每个加权系数用于指示P*L个空域列向量的一个空域列向量与K个频域列向量中的一个频域列向量的共轭转置的乘积在第r个空频矩阵中的权重，或者，一个频域列向量的共轭与一个空域列向量的克罗内克尔积在第r个空频矩阵中的权重；发送该PMI。
相应地，网络设备接收PMI，该PMI用于确定与N sb个子带对应的预编码矩阵，该预编码矩阵基于与R个传输层对应的R个空频矩阵获得，该PMI包括与R个空频矩阵对应的R组指示信息，R组指示信息中的第r组指示信息用于指示：与第r个传输层对应的P*L个空域列向量；与第r个传输层对应的K个频域列向量；以及用于确定第r个空频矩阵的P*L*K个加权系数，每个加权系数用于指示P*L个空域列向量的一个空域列向量与K个频域列向量中的一个频域列向量的共轭转置的乘积在第r个空频矩阵中的权重，或者，一个频域列向量的共轭与一个空域列向量的克罗内克尔积在第r个空频矩阵中的权重；基于该PMI确定与N sb个子带对应的预编码矩阵。
可以理解，上述R组指示信息也就是上文中所说的R组空频信息。R个空频矩阵可以认为是R组空频信息的一种可能的表现形式。
在上述实现方式中，P*L个空域列向量可以由P个极化方向中每个极化方向上的L个波束向量和L个宽带幅度系数确定，空域列向量的维度为可以N tx*1，频域列向量的维度可以为N sb*1，N tx为每个极化方向的天线端口数，N sb为待上报的子带数，P为极化方向数，1≤L≤N tx，1≤K≤N sb，且r、k、l、R、K、L、P、N tx和N sb均为正整数。
应理解，空频矩阵仅仅是为便于理解而引入的一个概念，可以理解为是终端设备确定PMI过程中或网络设备确定预编码矩阵过程中的一个中间值，不应对本申请构成任何限定。终端设备也可以不生成该空频矩阵，直接生成PMI或确定预编码矩阵。
结合第一方面或第二方面，在某些可能的实现方式中，该空域向量是维度为(P*N tx)*1的列向量，该频域向量是维度为1*N sb的行向量，该向量运算结果包括：空域向量与频域向量的乘积，或，频域向量的转置与空域向量的克罗内克尔积。其中，N tx为每个极化方向的天线端口数，N sb为待上报的子带数，1≤L≤N tx，1≤K≤N sb，且N tx和N sb均为正整数。
结合第一方面或第二方面，在某些可能的实现方式中，该空域向量是维度为1*(P*N tx)的行向量，该频域向量是维度为1*N sb的行向量，该向量运算结果包括：空域向量的共轭转置与频域向量的乘积，或，频域向量的转置与空域向量的共轭转置的克罗内克尔积。其中，N tx为每个极化方向的天线端口数，N sb为待上报的子带数，1≤L≤N tx，1≤K≤N sb，且N tx和N sb均为正整数。
结合第一方面或第二方面，在某些可能的实现方式中，该空域向量是维度为1*(P*N tx)的行向量，该频域向量是维度为N sb*1的列向量，该向量运算结果包括：空域向量的共轭转置与频域向量的共轭转置的乘积，或，频域向量的共轭与空域向量的共轭转置的克罗内克尔积。其中，N tx为每个极化方向的天线端口数，N sb为待上报的子带数，1≤L≤N tx，1≤K≤N sb，且N tx和N sb均为正整数。
结合第一方面或第二方面，在某些可能的实现方式中，空域向量是维度为(P*N tx)*1的列向量，所述频域向量是维度为N sb*1的列向量，所述向量运算结果包括：所述空域向量与所述频域向量的共轭转置的乘积，或，所述频域向量的共轭与所述空域向量的克罗内克尔积，其中，N tx为每个极化方向的天线端口数，N sb为待上报的子带数，1≤L≤N tx，1≤K≤N sb，且N tx和N sb均为正整数。
上文列举了波束向量和频域向量分别为不同的形式时所对应的向量运算结果的具体形式。可以理解，本申请对于波束向量和频域向量的具体形式不作限定。本领域的技术人 员可以基于本申请实施例的构思，对这些波束向量和频域向量进行数学变换或等价替换，以实现与本申请相同或相似的技术效果。
结合第一方面或第二方面，在某些可能的实现方式中，上述L个波束向量取自预定义的第一向量集合中的一个子集，该PMI还包括第一子集的指示信息，该第一子集的指示信息用于指示第一子集中的各向量在第一向量集合中的位置。
该第一向量集合可以通过过采样因子扩展为多个子集，该L个波束向量可以取自其中的某一个子集，为便于区分和说明，将L个波束向量所属的子集记作第一子集。终端设备可以通过PMI来指示该第一子集中的各波束向量，以便网络设备确定该L个波束向量。
结合第一方面或第二方面，在某些可能的实现方式中，上述K个频域向量取自取自预定义的第二向量集合中的第二子集，PMI还包括第二子集的指示信息，第二子集的指示信息用于指示第二子集中的各向量在第二向量集合中的位置。
该第二向量集合也可以通过过采样因子扩展为多个子集，该K个频域向量可以取自其中的某一个子集，为便于区分和说明，将K个频域向量所属的子集记作第二子集。终端设备可以通过PMI来指示该第二子集中的各频域向量，以便网络设备确定该K个频域向量。
结合第一方面，在某些可能的实现方式中，该方法还包括：接收第一指示信息，该第一指示信息用于指示K的取值。
相应地，结合第二方面，在某些可能的实现方式中，该方法还包括：发送第一指示信息，该第一指示信息用于指示K的取值。
即，网络设备可以向终端设备指示频域向量的个数。
应理解，该频域向量的个数也可以是预先定义的，如协议定义。
结合第一方面，在某些可能的实现方式中，该方法还包括：接收第二指示信息，第二指示信息用于指示L的取值。
相应地，结合第二方面，在某些可能的实现方式中，该方法还包括：发送第二指示信息，第二指示信息用于指示L的取值。
即，网络设备可以向终端设备指示波束向量的个数。
应理解，该波束向量的个数也可以是预先定义的，如协议定义。
通过确定频域向量的个数L和波束向量的个数K，终端设备可以基于L和K从第一向量集合中确定L个波束向量，并从第二向量集合中确定K个频域向量，进而基于L个波束向量和K个频域向量确定P个极化方向上各波束向量的宽带幅度系数以及P*L*K个系数。
可选地，该空域向量是维度为(P*N tx)*1的列向量，该频域向量是维度为N sb*1的列向量。
若极化方向数为1，则根据R组空频信息确定与各子带对应的预编码矩阵，包括：在1至N sb中对n sb遍历取值，重复执行以下操作，以得到与各子带对应的预编码矩阵：
在1至R中对r遍历取值，重复执行以下操作确定第n sb个子带的预编码矩阵：基于R组空频信息中的第r组空频信息所指示的P*L个空域向量、K个频域向量以及P*L*K个系数，确定第r个传输层中的第n sb个子带的预编码向量
Figure PCTCN2019099351-appb-000001
Figure PCTCN2019099351-appb-000002
其中，v l表示与第r个传输层对应的L个波束向量中的第l个波束向量，
Figure PCTCN2019099351-appb-000003
表示v l的幅度系数的量化值，
Figure PCTCN2019099351-appb-000004
表示与第r个传输层对应的K个频域向量中的第k个频域向量中的第n sb个元素，
Figure PCTCN2019099351-appb-000005
表示
Figure PCTCN2019099351-appb-000006
的共轭，
Figure PCTCN2019099351-appb-000007
表示与P*L个空域向量中的第l个空域向量和K个频域向量中的第k个频域向量对应的线性叠加系数的幅度的量化值，
Figure PCTCN2019099351-appb-000008
表示与P*L个空域向量中的第l个空域向量和K个频域向量中的第k个频域向量对应的线性叠加系数的相位的量化值，k、l均为正整数。
基于上述操作，网络设备可以基于PMI中所指示的R组空频信息确定与各子带的预编码矩阵。
可选地，该空域向量是维度为(P*N tx)*1的列向量，该频域向量是维度为1*N sb的行向量。
若极化方向数为1，则根据R组空频信息确定与各子带对应的预编码矩阵，包括：在1至N sb中对n sb遍历取值，重复执行以下操作，以得到与各子带对应的预编码矩阵：
在1至R中对r遍历取值，重复执行以下操作确定第n sb个子带的预编码矩阵：基于R组空频信息中的第r组空频信息所指示的P*L个空域向量、K个频域向量以及P*L*K个系数，确定第r个传输层中的第n sb个子带的预编码向量
Figure PCTCN2019099351-appb-000009
Figure PCTCN2019099351-appb-000010
各参数已在上文中做了详细说明，为了简洁，这里不再赘述。
基于上述操作，网络设备可以基于PMI中所指示的R组空频信息确定与各子带的预编码矩阵。
可选地，该空域向量是维度为(P*N tx)*1的列向量，该频域向量是维度为N sb*1的列向量。
若极化方向数为2，则根据R组空频信息确定与各子带对应的预编码矩阵，包括：在1至N sb中对n sb遍历取值，重复执行以下操作，以得到与各子带对应的预编码矩阵：
Figure PCTCN2019099351-appb-000011
其中，v l表示与第r个传输层对应的L个列向量中的第l个列向量，
Figure PCTCN2019099351-appb-000012
表示第一极化方向上的v l的幅度系数的量化值，
Figure PCTCN2019099351-appb-000013
表示第二极化方向上的v l的幅度系数的量化值，u r,k,j表示与第r个传输层对应的K个列向量中的第k个列向量中的第n sb个元素，
Figure PCTCN2019099351-appb-000014
表示
Figure PCTCN2019099351-appb-000015
的共轭，
Figure PCTCN2019099351-appb-000016
表示第一极化方向上的L个空域向量中的第l个空域向量和所述K个频域向量中的第k个频域向量对应的线性叠加系数的幅度的量化值，即，第一极化方向上的v l和u r，k的向量运算结果的线性叠加系数的幅度的量化值，
Figure PCTCN2019099351-appb-000017
表示第二极化方向上的L个空域向量中的第l个空域向量和所述K个频域向量中的第k个频域向量对应的线性叠加系数的幅度的量化值，即，第二极化方向上的v l和u r,k的向量运算结果的线性叠加系数的幅度的量化值，
Figure PCTCN2019099351-appb-000018
表示第一极化方向上的第一极化方向上的L个空域向量中的第l个空域向量和所述K个频域向量中的第k个频域向量对应的线性叠加系数的相位的量化值，即，v l和u r,k的向量运算结果的相位系数的量化值，
Figure PCTCN2019099351-appb-000019
表示第二极化方向上的L 个空域向量中的第l个空域向量和所述K个频域向量中的第k个频域向量对应的线性叠加系数的相位的量化值，即，v l和u r,k的向量运算结果的线性叠加系数的相位的量化值，k、l均为正整数。
基于上述操作，网络设备可以基于PMI中所指示的R组空频信息确定与各子带的预编码矩阵。
可选地，该空域向量是维度为(P*N tx)*1的列向量，该频域向量是维度为1*N sb的行向量。
若极化方向数为2，则根据R组空频信息确定与各子带对应的预编码矩阵，包括：在1至N sb中对n sb遍历取值，重复执行以下操作，以得到与各子带对应的预编码矩阵：
Figure PCTCN2019099351-appb-000020
各参数已在上文中做了详细说明，为了简洁，这里不再赘述。
基于上述操作，网络设备可以基于PMI中所指示的R组空频信息确定与各子带的预编码矩阵。
第三方面，提供了一种指示预编码矩阵的方法，该方法可以由终端设备执行，也可以由配置于终端设备中的芯片执行。
具体地，该方法包括：接收第三指示信息，该第三指示信息用于确定基于type II码本反馈PMI的反馈模式，该反馈模式为第一反馈模式或第二反馈模式，该第一反馈模式是基于第一向量集合反馈PMI的模式，该第二反馈模式是基于第一向量集合和第二向量集合反馈PMI的模式。该第一向量集合包括多个维度为N tx的向量，第二向量集合包括多个维度为N sb的向量。其中，N tx为每个极化方向上发射天线的端口数，N sb为待上报的子带数，N tx和N sb均为正整数；基于反馈模式，确定并发送PMI。
第四方面，提供了一种指示预编码矩阵的方法，该方法可以由网络设备执行，也可以由配置于网络设备中的芯片执行。
具体地，该方法包括：生成第三指示信息，该第三指示信息用于确定基于type II码本反馈PMI的反馈模式，该反馈模式为第一反馈模式或第二反馈模式，该第一反馈模式是基于第一向量集合反馈PMI的模式，该第二反馈模式是基于第一向量集合和第二向量集合反馈PMI的模式。该第一向量集合包括多个维度为N tx的向量，第二向量集合包括多个维度为N sb的向量。其中，N tx为每个极化方向上发射天线的端口数，N sb为待上报的子带数，N tx和N sb均为正整数；发送第三指示信息；接收PMI，PMI基于反馈模式确定。
基于上述技术方案，终端设备可以基于网络设备的指示，或者，基于待上报的子带的数量和/或位置，确定反馈模式，可以在某些情况下采用反馈开销较小的反馈模式来反馈PMI。例如，在待上报的子带数较多或连续性较好的情况下，通过反馈开销较小的反馈模式来反馈PMI，既可以保证较高的近似精度，同时也可以减小反馈开销。通过引入多种反馈模式以适用于不同的测量情况，可以兼顾反馈精度和反馈开销，从而在两者间获得平衡。此外，本申请所提供的第二反馈模式，可以很好地兼容现有的反馈模式，对现有的协议改 动小，易于实现。
应理解，第二反馈模式并不仅限于本申请中所公开的宽带反馈加子带联合反馈的反馈模式。该第二反馈模式例如还可以是宽带反馈加子带部分反馈的反馈模式。第一反馈模式仍然可以是NR协议TS38.214R15中定义的type II码本的反馈模式，为便于与该第二反馈模式区分，该第一反馈模式也可以称为宽带反馈加子带全部反馈的反馈模式。
结合第三方面或第四方面，在某些可能的实现方式中，该第三指示信息包括PMI的反馈模式的指示信息。
即，由网络设备指示终端设备采用哪种反馈模式来反馈PMI。
结合第三方面或第四方面，在某些可能的实现方式中，该第三指示信息用于指示待上报的子带的数量和位置。该方法还包括：基于待上报的子带的数量和/或待上报的子带的位置，根据预设规则确定PMI的反馈模式。
即，终端设备和网络设备基于相同的预设规则确定PMI反馈模式。具体地，终端设备可以根据待上报的子带的数量和/或位置，由预设规定来确定基于哪种反馈模式反馈PMI。网络设备基于该预设规则确定了反馈模式后，可以基于该反馈模式和PMI恢复出预编码矩阵。
结合第三方面或第四方面，在某些可能的实现方式中，该第三指示信息携带在无线资源控制RRC消息中。
结合第三方面或第四方面，在某些可能的实现方式中，当反馈模式为第二反馈模式时，PMI包括与R个传输层对应的R组空频信息，R组空频信息用于确定与各子带对应的预编码矩阵，R组空频信息中的第r组空频信息用于指示：
与第r个传输层对应的P*L个空域向量；
与第r个传输层对应的K个频域向量；以及
与第r个传输层对应的P*L*K个系数。
其中，P*L个空域向量由P个极化方向中每个极化方向上的L个波束向量及其宽带幅度系数确定，P*L*K个系数中的每个系数用于指示P*L个空域向量中的一个空域向量与K个频域向量中的一个频域向量间的向量运算的线性叠加系数；该L个波束向量取自第一向量集合，该K个频域向量取自第二向量集合。R为传输层数，P为极化方向数，且R、r、P、L和K均为正整数。
具体地，当反馈模式为第二反馈模式时，终端设备或配置于终端设备中的芯片可用于执行上述第一方面中任意一种可能的实现方式中的方法，网络设备或配置于网络设备中的芯片可用于执行上述第二方面中任意一种可能的实现方式中的方法。
第五方面，提供了一种提供了一种通信装置，包括用于执行第一方面或第三方面中任一种可能实现方式中的方法的各个模块或单元。
第六方面，提供了一种通信装置，包括处理器。该处理器与存储器耦合，可用于执行存储器中的指令，以实现上述第一方面或第三方面中任一种可能实现方式中的方法。可选地，该通信装置还包括存储器。可选地，该通信装置还包括通信接口，处理器与通信接口耦合。
在一种实现方式中，该通信装置为终端设备。当该通信装置为终端设备时，所述通信接口可以是收发器，或，输入/输出接口。
在另一种实现方式中，该通信装置为配置于终端设备中的芯片。当该通信装置为配置于终端设备中的芯片时，所述通信接口可以是输入/输出接口。
可选地，所述收发器可以为收发电路。可选地，所述输入/输出接口可以为输入/输出电路。
第七方面，提供了一种通信装置，包括用于执行第二方面或第四方面中任一种可能实现方式中的方法的各个模块或单元。
第八方面，提供了一种通信装置，包括处理器。该处理器与存储器耦合，可用于执行存储器中的指令，以实现上述第二方面或第四方面中任一种可能实现方式中的方法。可选地，该通信装置还包括存储器。可选地，该通信装置还包括通信接口，处理器与通信接口耦合。
在一种实现方式中，该通信装置为网络设备。当该通信装置为网络设备时，所述通信接口可以是收发器，或，输入/输出接口。
在另一种实现方式中，该通信装置为配置于网络设备中的芯片。当该通信装置为配置于网络设备中的芯片时，所述通信接口可以是输入/输出接口。
可选地，所述收发器可以为收发电路。可选地，所述输入/输出接口可以为输入/输出电路。
第九方面，提供了一种处理器，包括：输入电路、输出电路和处理电路。所述处理电路用于通过所述输入电路接收信号，并通过所述输出电路发射信号，使得所述处理器执行第一方面至第四方面以及第一方面至第四方面任一种可能实现方式中的方法。
在具体实现过程中，上述处理器可以为芯片，输入电路可以为输入管脚，输出电路可以为输出管脚，处理电路可以为晶体管、门电路、触发器和各种逻辑电路等。输入电路所接收的输入的信号可以是由例如但不限于接收器接收并输入的，输出电路所输出的信号可以是例如但不限于输出给发射器并由发射器发射的，且输入电路和输出电路可以是同一电路，该电路在不同的时刻分别用作输入电路和输出电路。本申请实施例对处理器及各种电路的具体实现方式不做限定。
第十方面，提供了一种处理装置，包括处理器和存储器。该处理器用于读取存储器中存储的指令，并可通过接收器接收信号，通过发射器发射信号，以执行第一方面至第四方面以及第一方面至第四方面任一种可能实现方式中的方法。
可选地，所述处理器为一个或多个，所述存储器为一个或多个。
可选地，所述存储器可以与所述处理器集成在一起，或者所述存储器与处理器分离设置。
在具体实现过程中，存储器可以为非瞬时性(non-transitory)存储器，例如只读存储器(read only memory，ROM)，其可以与处理器集成在同一块芯片上，也可以分别设置在不同的芯片上，本申请实施例对存储器的类型以及存储器与处理器的设置方式不做限定。
应理解，相关的数据交互过程例如发送指示信息可以为从处理器输出指示信息的过程，接收能力信息可以为处理器接收输入能力信息的过程。具体地，处理输出的数据可以输出给发射器，处理器接收的输入数据可以来自接收器。其中，发射器和接收器可以统称为收发器。
上述第十方面中的处理装置可以是一个芯片，该处理器可以通过硬件来实现也可以通过软件来实现，当通过硬件实现时，该处理器可以是逻辑电路、集成电路等；当通过软件来实现时，该处理器可以是一个通用处理器，通过读取存储器中存储的软件代码来实现，该存储器可以集成在处理器中，可以位于该处理器之外，独立存在。
第十一方面，提供了一种计算机程序产品，所述计算机程序产品包括：计算机程序(也可以称为代码，或指令)，当所述计算机程序被运行时，使得计算机执行上述第一方面至第四方面以及第一方面至第四方面中任一种可能实现方式中的方法。
第十二方面，提供了一种计算机可读介质，所述计算机可读介质存储有计算机程序(也可以称为代码，或指令)当其在计算机上运行时，使得计算机执行上述第一方面至第四方面以及第一方面至第四方面中任一种可能实现方式中的方法。
第十三方面，提供了一种通信系统，包括前述的网络设备和终端设备。
附图说明
图1是适用于本申请实施例提供的指示和确定预编码矩阵的方法的通信系统的示意图；
图2是本申请实施例提供的信号处理的示意图；
图3是本申请实施例提供的指示和确定预编码矩阵的方法的示意性流程图；
图4是本申请实施例提供的不同极化方向的发射天线的示意图；
图5是本申请另一实施例提供的指示预编码矩阵的方法的示意性流程图；
图6示出了待上报的子带在频域上分布的几种可能的情况；
图7是本申请实施例提供的通信装置的示意性框图；
图8是本申请实施例提供的终端设备的结构示意图；
图9是本申请实施例提供的网络设备的结构示意图。
具体实施方式
下面将结合附图，对本申请中的技术方案进行描述。
本申请实施例的技术方案可以应用于各种通信系统，例如：全球移动通信(global system for mobile communications，GSM)系统、码分多址(code division multiple access，CDMA)系统、宽带码分多址(wideband code division multiple access，WCDMA)系统、通用分组无线业务(general packet radio service，GPRS)、长期演进(long term evolution，LTE)系统、LTE频分双工(frequency division duplex，FDD)系统、LTE时分双工(time division duplex，TDD)、通用移动通信系统(universal mobile telecommunication system，UMTS)、全球互联微波接入(worldwide interoperability for microwave access，WiMAX)通信系统、未来的第五代(5th generation，5G)系统或新无线(new radio，NR)等。
为便于理解本申请实施例，首先以图1中示出的通信系统为例详细说明适用于本申请实施例的通信系统。图1示出了适用于本申请实施例的指示和确定预编码矩阵的方法的通信系统100的示意图。如图1所示，该通信系统100可以包括至少一个网络设备，例如图1所示的网络设备110；该通信系统100还可以包括至少一个终端设备，例如图1所示的终端设备120。网络设备110与终端设备120可通过无线链路通信。各通信设备，如网络 设备110或终端设备120，均可以配置多个天线。对于该通信系统100中的每一个通信设备而言，所配置的多个天线可以包括至少一个用于发送信号的发射天线和至少一个用于接收信号的接收天线。因此，该通信系统100中的各通信设备之间，如网络设备110与终端设备120之间，可通过多天线技术通信。
应理解，该通信系统中的网络设备可以是任意一种具有无线收发功能的设备。该网络设备包括但不限于：演进型节点B(evolved Node B，eNB)、无线网络控制器(radio network controller，RNC)、节点B(Node B，NB)、基站控制器(base station controller，BSC)、基站收发台(base transceiver station，BTS)、家庭基站(例如，home evolved NodeB，或home Node B，HNB)、基带单元(baseband Unit，BBU)，无线保真(Wireless Fidelity，WIFI)系统中的接入点(access point，AP)、无线中继节点、无线回传节点、传输点(transmission point，TP)或者发送接收点(transmission and reception point，TRP)等，还可以为5G，如，NR，系统中的gNB，或，传输点(TRP或TP)，5G系统中的基站的一个或一组(包括多个天线面板)天线面板，或者，还可以为构成gNB或传输点的网络节点，如基带单元(BBU)，或，分布式单元(distributed unit，DU)等。
在一些部署中，gNB可以包括集中式单元(centralized unit，CU)和DU。gNB还可以包括射频单元(radio unit，RU)。CU实现gNB的部分功能，DU实现gNB的部分功能，比如，CU实现无线资源控制(radio resource control，RRC)，分组数据汇聚层协议(packet data convergence protocol，PDCP)层的功能，DU实现无线链路控制(radio link control，RLC)、媒体接入控制(media access control，MAC)和物理(physical，PHY)层的功能。由于RRC层的信息最终会变成PHY层的信息，或者，由PHY层的信息转变而来，因而，在这种架构下，高层信令，如RRC层信令，也可以认为是由DU发送的，或者，由DU+CU发送的。可以理解的是，网络设备可以为CU节点、或DU节点、或包括CU节点和DU节点的设备。此外，CU可以划分为接入网(radio access network，RAN)中的网络设备，也可以将CU划分为核心网(core network，CN)中的网络设备，本申请对此不做限定。
还应理解，该无线通信系统中的终端设备也可以称为用户设备(user equipment，UE)、接入终端、用户单元、用户站、移动站、移动台、远方站、远程终端、移动设备、用户终端、终端、无线通信设备、用户代理或用户装置。本申请的实施例中的终端设备可以是手机(mobile phone)、平板电脑(Pad)、带无线收发功能的电脑、虚拟现实(virtual reality，VR)终端设备、增强现实(augmented reality，AR)终端设备、工业控制(industrial control)中的无线终端、无人驾驶(self driving)中的无线终端、远程医疗(remote medical)中的无线终端、智能电网(smart grid)中的无线终端、运输安全(transportation safety)中的无线终端、智慧城市(smart city)中的无线终端、智慧家庭(smart home)中的无线终端等等。本申请的实施例对应用场景不做限定。
还应理解，图1仅为便于理解而示例的简化示意图，该通信系统100中还可以包括其他网络设备或者还可以包括其他终端设备，图1中未予以画出。
为了便于理解本申请实施例，下面结合图2简单说明在信号在发送之前在物理层的处理过程。
应理解，图2中所示出的对信号的处理过程可以由网络设备执行，也可以由配置于网 络设备中的芯片执行；可以由终端设备执行，也可以由配置于终端设备中的芯片执行。本申请对此不做限定。为方便说明，下文中统称为发送设备。
如图所示，发送设备在物理信道可对来自高层的码字(code word)进行处理。其中，码字可以为经过编码(例如包括信道编码)的编码比特。码字经过加扰(scrambling)，生成加扰比特。加扰比特经过调制映射(modulation mapping)，得到调制符号。调制符号经过层映射(layer mapping)，被映射到多个层(layer)。经过层映射后的调制符号经过预编码(precoding)，得到预编码后的信号。预编码后的信号经过资源元素(resource element，RE)映射后，被映射到多个RE上。这些RE随后经过正交复用(orthogonal frequency division multiplexing，OFDM)调制后通过天线端口(antenna port)发射出去。
其中，预编码技术可以是在已知信道状态的情况下，通过在发送设备对待发射信号做预先的处理，即，借助与信道资源相匹配的预编码矩阵来对待发送信号进行处理，使得经过预编码的待发送信号与信道相适配，使得接收设备消除信道间影响的复杂度降低。因此，通过对待发送信号的预编码处理，接收信号质量(例如信号与干扰加噪声比(signal to interference plus noise ratio，SINR))得以提升。因此，采用预编码技术，可以实现发送设备与多个接收设备在相同的时频资源上传输，也就是实现了多用户多输入多输出(multiple user multiple input multiple output，MU-MIMO)。应注意，有关预编码技术的相关描述仅用于举例，并非用于限制本申请实施例的保护范围，在具体实现过程中，还可以通过其他方式进行预编码。例如，在无法获知信道矩阵的情况下，采用预先设置的预编码矩阵或者加权处理方式进行预编码等。为了简洁，其具体内容本文不再赘述。
发送设备为了获取能够与信道相适配的预编码矩阵，可以通过发送参考信号的方式来预先进行信道测量，以获取接收设备的反馈，从而确定预编码矩阵。
在一种可能的实现方式中，接收设备根据参考信号测量得到每个子带的信道矩阵H之后，可以通过对各子带的信道矩阵H或信道矩阵的协方差矩阵HH H进行奇异值分解(singular value decomposition，SVD)的方法确定每个子带的理想预编码矩阵。
以对信道矩阵H进行SVD为例，对信道矩阵H进行SVD之后可以得到：
H＝U·S·V H
其中，U、V H为酉矩阵，S为对角矩阵，其非零元素(即对角线上的元素)即为信道矩阵H的奇异值，这些奇异值通常可以按照由大到小的顺序排列。右酉矩阵V H的共轭转置V即为理想预编码矩阵。换句话说，理想预编码矩阵也就是根据信道矩阵H计算得到的预编码矩阵。
此后，接收设备可以确定分别与各子带的理想预编码矩阵较为近似的预编码矩阵，并将各个子带上近似于理想预编码矩阵的预编码矩阵通过PMI反馈给发送设备。发送设备可以根据PMI确定出近似于各个子带的理想预编码矩阵的预编码矩阵。由此，发送设备能够确定出与信道相适配的预编码矩阵来对待发送信号进行预编码处理。
因此，发送设备根据PMI确定出的预编码矩阵与理想预编码矩阵的近似度越高，也就越能够与信道状态相适配，因此也就能够提高信号的接收质量。换句话说，接收设备希望能够确定出与理想预编码矩阵最为近似的预编码矩阵指示给发送设备。
应理解，在下行传输中，该发送设备可以为网络设备或配置于网络设备中的芯片，接收设备可以为终端设备或配置于终端设备中的芯片，该参考信号可以为用于下行信道测量 的参考信号，例如，信道状态信息参考信号(channel state information reference signal，CSI-RS)。终端设备可以根据接收到的CSI-RS，进行CSI测量，并向网络设备反馈下行信道的CSI。
在上行传输中，该发送设备也可以为终端设备或配置于终端设备中的芯片，接收设备可以为网络设备或配置于网络设备中的芯片，该参考信号可以为用于上行信道测量的参考信号，例如，探测参考信号(sounding reference signal，SRS)。网络设备可以根据接收到的SRS，进行CSI测量，向终端设备指示上行信道的CSI。
其中，该CSI可以包括例如预编码矩阵指示(precoding matrix indicator，PMI)、秩指示(rank indication，RI)和信道质量指示(channel quality indicator，CQI)等。
应理解，以上列举的参考信号的类型仅为示例性说明，而不应对本申请构成任何限定，本申请也并不排除采用其他的参考信号以实现相同或相似功能的可能。
在当前技术中，终端设备反馈PMI所基于的码本可以包括类型一(type I)和类型二(type II)两类码本。其中，类型一的思想是波束选择，类型二的思想是波束线性组合。类型一的反馈开销较小，但是近似精度较低；类型二的反馈开销较大，但是近似精度较高。
为了获得近似精度较高的预编码矩阵，终端设备可以采用类型二确定预编码矩阵和反馈PMI。具体地，终端设备可以通过宽带反馈指示被选择的波束以及各波束的宽带幅度系数的量化值，并可以通过子带反馈指示可用于各个子带的组合系数的量化值，其中组合系数例如包括子带幅度系数和子带相位系数。网络设备可以综合宽带反馈的信息和子带反馈的信息恢复出近似于理想预编码矩阵的预编码矩阵。
下文示出了秩为1时两级码本形式的简单示例。
Figure PCTCN2019099351-appb-000021
其中，W表示一个传输层上一个子带待反馈的预编码矩阵，W 1由宽带反馈确定，W 2由子带反馈确定。b 0至b 3为W 1中包含的波束向量，可通过该多个波束向量的组合的索引来指示。p 0至p 7为W 1中包含的宽带幅度系数，可通过宽带幅度系数的量化值来指示。c 0至c 7为W 2中包含的子带叠加系数，可以包括子带幅度系数α 0至α 7和窄带相位系数
Figure PCTCN2019099351-appb-000022
至
Figure PCTCN2019099351-appb-000023
可分别通过窄带幅度系数α 0至α 7的量化值和窄带相位系数
Figure PCTCN2019099351-appb-000024
至
Figure PCTCN2019099351-appb-000025
的量化值来指示。
为了提高频谱资源的利用率，提高通信系统的数据传输能力，网络设备可以通过多个传输层向终端设备传输数据。然而，由上式可以看到，当传输层数增加时，例如传输层数为4，p 0至p 7以及c 0至c 7的反馈开销都将是一个传输层时的4倍。也就是说，如果终端设备基于每个传输层进行如上所述的宽带反馈和子带反馈，则随着传输层数的增加，所带来的反馈开销会成倍增加。而子带数量越多，反馈开销增加的幅度也越大。因此，希望能够提供一种方法，能够在反馈开销和近似精度之间获得平衡。
有鉴于此，本申请提供一种指示预编码矩阵的方法，基于信道在频域的相关性，灵活地选择反馈模式，在保证数据传输质量的基础上，尽可能地减少反馈开销，同时能够提高频谱资源利用率，提高通信系统的数据传输能力，提高吞吐量。
为了便于理解本申请实施例，作出以下几点说明。
第一，在本申请实施例中，“波束”可以理解为在空间某一方向上形成的信号强度的分布，“波束向量”可以用于表征“波束”。在本申请实施例中，可以通过波束赋形技术对多个波束向量进行线性叠加，使得发射波束在空间形成一定的指向性。
第二，在本申请实施例中，以子带作为频域单元的一例，详细说明了指示和确定预编码矩阵的具体方法，但这不应对本申请构成任何限定。应理解，子带仅为频域单元的一种可能的形式，该频域单元还可以为子载波、资源块(resource block，RB)等，本申请对此不作限定。此外，本申请实施例中所涉及的与子带对应的预编码矩阵，可以理解为基于子带的信道矩阵确定的预编码矩阵。在下文示出的实施例中，在未作出特别说明的情况下，“与子带对应的预编码矩阵”和“子带的预编码矩阵”所表达的含义可以是相同的。
第三，在本申请实施例中，多处涉及矩阵的变换。为便于理解，这里做统一说明。上角标*表示转置，如A *表示矩阵(或向量)A的共轭；上角标H表示共轭转置，如，A H表示矩阵(或向量)A的共轭转置。后文中为了简洁，省略对相同或相似情况的说明。
第四，在本实施例中，涉及矩阵间的克罗内克尔(Kronecker)积运算。克罗内克尔积是一个矩阵中的所有元素分别乘以另一矩阵组成的分块矩阵。例如，k*l维的矩阵A和p*q维的矩阵B的克罗内克尔积乘积得到kp*ql维的矩阵，具体如下：
Figure PCTCN2019099351-appb-000026
其中，
Figure PCTCN2019099351-appb-000027
表示克罗内克尔积运算。
第五，在下文示出的实施例中第一、第二、第三、第四以及各种数字编号仅为描述方便进行的区分，并不用来限制本申请实施例的范围。例如，区分不同的指示信息等。
第六，在下文示出的实施例中，“预先获取”可包括由网络设备信令指示或者预先定义，例如，协议定义。其中，“预先定义”可以通过在设备(例如，包括终端设备和网络设备)中预先保存相应的代码、表格或其他可用于指示相关信息的方式来实现，本申请对于其具体的实现方式不做限定。
第七，本申请实施例中涉及的“保存”，可以是指的保存在一个或者多个存储器中。所述一个或者多个存储器，可以是单独的设置，也可以是集成在编码器或者译码器，处理器、或通信装置中。所述一个或者多个存储器，也可以是一部分单独设置，一部分集成在译码器、处理器、或通信装置中。存储器的类型可以是任意形式的存储介质，本申请并不对此限定。
第八，本申请实施例中涉及的“协议”可以是指通信领域的标准协议，例如可以包括LTE协议、NR协议以及应用于未来的通信系统中的相关协议，本申请对此不做限定。
第九，“至少一个”是指一个或者多个，“多个”是指两个或两个以上。“和/或”，描述关联对象的关联关系，表示可以存在三种关系，例如，A和/或B，可以表示：单独存在A，同时存在A和B，单独存在B的情况，其中A，B可以是单数或者复数。字符“/”一般表示前后关联对象是一种“或”的关系。“以下至少一项(个)”或其类似表达，是指的这些项中的任意组合，包括单项(个)或复数项(个)的任意组合。例如，a、b和c中的至少一项(个)，可以表示：a，或，b，或，c，或，a和b，或，a和c，或，b和c，或，a、b和c，其中a，b，c可以是单个，也可以是多个。
下面将结合附图详细说明本申请实施例提供的指示和确定预编码矩阵的方法。
应理解，本申请实施例提供的方法可以应用于通过多天线技术通信的通信系统，例如，图1中所示的通信系统100。该通信系统可以包括至少一个网络设备和至少一个终端设备。网络设备和终端设备之间可通过多天线技术通信。
还应理解，下文示出的实施例并未对本申请实施例提供的方法的执行主体的具体结构特别限定，只要能够通过运行记录有本申请实施例的提供的方法的代码的程序，以根据本申请实施例提供的方法进行通信即可，例如，本申请实施例提供的方法的执行主体可以是终端设备或网络设备，或者，是终端设备或网络设备中能够调用程序并执行程序的功能模块。
以下，不失一般性，以网络设备与终端设备之间的交互为例详细说明本申请实施例提供的指示和确定预编码矩阵的方法。
图3是从设备交互的角度示出的本申请实施例提供的指示和确定预编码矩阵的方法的示意性流程图。如图3所示，该方法300可以包括步骤310至步骤360。下面详细说明方法300中的各步骤。
在步骤310中，终端设备确定PMI。
终端设备例如可以根据宽带的理想预编码矩阵和各子带的理想预编码矩阵确定PMI，通过PMI向网络设备指示各子带的理想预编码矩阵。在一种可能的实现方式中，终端设备可以根据接收到的参考信号，如CSI-RS，进行信道测量，并根据测量得到的宽带的理想预编码矩阵和各子带的理想预编码矩阵确定PMI。
可选地，在步骤310之前，该方法300还包括：步骤320，网络设备发送参考信号。相应地，终端设备接收参考信号。
网络设备可以通过多个发射天线发送参考信号。该多个发射天线可以是同一极化方向的发射天线，也可以是不同极化方向的发射天线。本申请对此不作限定。图4是不同极化方向上的发射天线的示意图。具体地，图中示出了8个发射天线，该8个发射天线对应了两个极化方向。其中，天线端口0、1、2、3是同一极化方向(例如记作第一极化方向)的天线端口，可以对应一个相同的波束向量，例如记作v 1；天线端口4、5、6、7是同一极化方向(例如记作第二极化方向)的天线端口，可以对应另一个相同的波束向量，例如记作v 2。其中，v 1和v 2可以是两个正交的离散傅里叶变换(discrete fourier transform，DFT)矢量，或者也可以是表征空间电磁波特性的数学矢量，本申请实施例对此并未特别限定。
终端设备首先可根据接收到的参考信号估计宽带和各个子带的信道矩阵，确定RI，即，建议传输的秩(rank)，也就是建议的传输层数。此后，终端设备可以根据宽带的信道矩阵确定宽带的理想预编码矩阵，并可以根据各个子带的信道矩阵确定各个子带的理想预编码矩阵。终端设备根据信道矩阵确定理想预编码矩阵的具体过程在上文中已经详细说明，为了简洁，这里不再赘述。
应理解，终端设备确定理想预编码矩阵的方法并不仅限于上文所列举，终端设备还可以根据信道状态自行确定理想预编码矩阵，例如，终端设备可以基于上下行信道的互易性确定理想预编码矩阵等，本申请对此不做限定。
还应理解，在本实施例中，RI的确定过程可以与现有技术相同，为了简洁，这里省略对其具体过程的详细说明。下文所示出的实施例主要针对PMI的确定过程进行详细说 明。
终端设备可以根据各个子带的理想预编码矩阵确定PMI。在本申请实施例中，各个子带的预编码矩阵可以由与R个传输层对应的R组空频信息确定。该R组空频信息中的每组空频信息可以包括空域信息、频域信息以及系数。具体地，第r(1≤r≤R，且r为整数)组空频信息可以用于指示：
与第r个传输层对应的P*L个空域向量；
与第r个传输层对应的K个频域向量；以及
与第r个传输层对应的P*L*K个系数。
其中，P*L个空域向量由P个极化方向中每个极化方向上的L个波束向量及其宽带幅度系数确定，P*L*K个系数中的每个系数用于指示P*L个空域向量中的一个空域向量与K个频域向量中的一个频域向量间的向量运算结果的线性叠加系数。
在一种实现方式中，该空域向量是维度为(P*N tx)*1的列向量，该频域向量是维度为N sb*1的列向量，该向量运算结果包括：空域向量与频域向量的共轭转置的乘积，或，频域向量的共轭与空域向量的克罗内克尔积。其中，N tx为每个极化方向的天线端口数，N sb为子带数，1≤L≤N tx，1≤K≤N sb，且N tx和N sb均为正整数。
在另一种实现方式中，该空域向量是维度为(P*N tx)*1的列向量，该频域向量是维度为1*N sb的行向量，该向量运算结果包括：空域向量与频域向量的乘积，或，频域向量的转置与空域向量的克罗内克尔积。
在又一种实现方式中，该空域向量是维度为1*(P*N tx)的行向量，该频域向量是维度为1*N sb的行向量，该向量运算结果包括：空域向量的共轭转置与频域向量的乘积，或，频域向量的转置与空域向量的共轭转置的克罗内克尔积。
在再一种实现方式中，该空域向量是维度为1*(P*N tx)的行向量，该频域向量是维度为N sb*1的列向量，该向量运算结果包括：空域向量的共轭转置与频域向量的共轭转置的乘积，或，频域向量的共轭与空域向量的共轭转置的克罗内克尔积。
上文列举了波束向量和频域向量分别为不同的形式时所对应的向量运算结果的具体形式。可以理解，本申请对于波束向量和频域向量的具体形式不作限定。本领域的技术人员可以基于本申请实施例的构思，对这些波束向量和频域向量进行数学变换或等价替换，以实现与本申请相同或相似的技术效果。
下文中为方便说明，假设该空域向量是维度为(P*N tx)*1的列向量，该频域向量是维度为N sb*1的列向量。本领域的技术人员在下文示出的具体实现方式的基础上，通过数学变换或等价替换也可以确定相应的PMI，并可基于PMI确定各子带的预编码矩阵。
在一种实现方式中，该R组空频信息可用于确定R个空频矩阵。具体地，第r个传输层的空频矩阵可以由第r个传输层的空频信息确定。其中，第r个传输层的空域信息可以由第r个传输层上被选择的空域的波束向量(例如，L个，L≥1且为整数)以及这L个波束向量在各个极化方向上的宽带幅度系数确定，第r个传输层的频域信息可以由第r个传输层上被选择的频域基向量(即上文所述的频域向量，例如，K个，K≥1且为整数)确定；第r个传输层的空频矩阵可以由第r个传输层、P个极化方向上的L个波束向量及其宽带幅度系数和K个频域基向量确定的P*L*K个分量矩阵线性叠加得到，第r个传输层的系数可以由各分量矩阵的线性叠加系数确定。其中，频域上各子带的理想预编码矩阵中 的各个列向量可以通过空域的波束向量的线性组合来表征，而各波束向量线性组合时使用的加权系数可以通过上述K个频域基向量的线性组合来描述。每一个频域基向量可用于表示加权系数在频域的多个子带上的一种变化规律。
需要说明的是，在本实施例中，为方便区分和说明，将取自第二向量集合的频域向量称为频域基向量。此外，下文还涉及到频域列向量的描述，频域列向量可以是直接从第二向量集合中确定的频域基向量，也可以是频域基向量与幅度系数的乘积。因此，在本实施例中，频域基向量和频域列向量的维度可以是相同的。并且，在未作出特别说明的情况下，“频域基向量”和“频域向量”所表达的含义相同。后文中为了简洁，省略对相同或相似情况的说明。
在本申请实施例中，L和K决定了PMI的开销大小。L和K的取值均可以由网络设备预先配置并指示给终端设备；也可以是预先定义，如协议定义；也可以由网络设备配置其中的一个值，协议定义另一个值；还可以是由终端设备确定后上报给网络设备；还可以是网络设备预先配置多个候选值给终端设备，终端设备从网络设备该多个候选值中选择一个并上报网络设备。本申请对此不做限定。
当K由网络设备配置时，可选地，该方法300还包括：步骤330，网络设备发送第一指示信息，该第一指示信息用于指示K的取值。相应地，终端设备接收该第一指示信息。
当L由网络设备配置时，可选地，该方法300还包括：步骤340，网络设备发送第二指示信息，该第二指示信息用于指示L的取值。相应地，终端设备接收该第一指示信息。
网络设备可以通过同一信令或不同的信令向终端设备指示K和L的取值。即，第一指示信息和第二指示信息可以承载在同一信令中，也可以承载不同的信令中，本申请对此不做限定。
可选地，该第一指示信息携带在无线资源控制(radio resource control，RRC)消息中。
可选地，该第二指示信息携带在RRC消息中。
应理解，网络设备将第一指示信息和第二指示信息携带在RRC消息中配置给终端设备仅为一种可能的实现方式，而不应对本申请构成任何限定。当K和L由网络设备配置时，网络设备也可将第一指示信息和/或第二指示信息携带在其他信令中，例如，MAC CE或DCI等，本申请对此不做限定。此外，第一指示信息和第二指示信息可以携带在同一信令中，也可以携带在不同的信令中，本申请对此不作限定。
为便于理解和说明本申请实施例，下文中假设发射天线的极化方向数为P，每个极化方向的发射天线的端口数为N tx，接收天线的端口数为N rx，传输层数为R，N tx＞1，N rx≥1，R≥1，P≥1，且R、P、N tx、N rx均为整数。
在本实施例中，空频矩阵例如可以是维度为(P*N tx)*N sb的矩阵。该矩阵中的每一个列向量可对应于一个子带。R个空频矩阵中每个空频矩阵的第n sb(1≤n sb≤N sb，且n sb为整数)个列向量抽取出来，便可以得到R个维度为N tx*1的列向量。将该R个维度为(P*N tx)*1的列向量按照传输层从1至R的顺序从左到右依次排列，可以得到维度为(P*N tx)*R的矩阵，该矩阵即为与第n sb个子带对应的预编码矩阵。
该空频矩阵例如也可以是维度为(P*N tx*N sb)*1的列向量。该列向量中包括与多个子带对应的多组元素。例如，第1个元素至第P*N tx个元素对应于第一个子带，第P*N tx+1个元素至第2P*N tx个元素可以对应于第二个子带，以此类推，最后的P*N tx个元素可对应 于第N sb个子带。将R个空频矩阵中每个空频矩阵中与第n sb个子带对应的P*N tx个元素抽取出来，也可以得到R个维度为(P*N tx)*1的列向量。将该R个维度为(P*N tx)*1的列向量按照传输层从1至R的顺序从左到右依次排列，也可以得到为维度为(P*N tx)*R的矩阵，该矩阵即为与第n sb个子带对应的预编码矩阵。
需要说明的是，上文中所描述的空频矩阵是终端设备在确定PMI过程中的一个中间值，终端设备可以基于各子带的信道矩阵确定各个传输层对应的空域信息、频域信息以及加权系数，而并不一定会生成上述空频矩阵。
下文中仅为便于理解，以维度为(P*N tx)*N sb的矩阵作为空频矩阵的一例对终端设备确定PMI的过程做详细说明，但这不应对本申请构成任何限定。例如，终端设备可以仅确定用于生成上述空频矩阵的各个列向量。终端设备在获得了各传输层对应的空域信息和频域信息之后，便可以生成可用于确定各个子带的预编码矩阵的PMI。此外，维度为(P*N tx*N sb)*1的列向量可以是(P*N tx)*N sb的矩阵变换得到，确定该维度为(P*N tx*N sb)*1的列向量的具体过程与确定维度为(P*N tx)*N sb的矩阵的具体过程是相似的，本领域的技术人员在确定维度为(P*N tx)*N sb的矩阵的过程中，经过简单的数学变换或替换，便可以得到维度为(P*N tx*N sb)*1的列向量。
为便于理解和说明本实施例，下面将结合具体的实现方式详细说明终端设备确定PMI的具体过程。应理解，下文中列举了两种终端设备确定PMI的实现方式，包括实现方式一和实现方式二，但这不应对本申请构成任何限定。本申请对于终端设备确定PMI的具体实现方式不做限定。
实现方式一、
步骤i)
终端设备根据各个子带的信道矩阵，确定宽带的理想预编码矩阵。
具体地，终端设备可以根据各个子带的信道矩阵，确定各个子带的信道的协方差矩阵，然后将各个子带对应的协方差矩阵相加后做SVD得到宽带的理想预编码矩阵。
例如，各个子带的信道矩阵H的维度为(P*N tx)*N rx。其中P表示极化方向数，P≥1，且为整数。基于各个子带的信道矩阵确定各个子带的信道矩阵的协方差矩阵HH H的维度为(P*N tx)*(P*N tx)。将各子带的信道矩阵的协方差矩阵相加后做SVD可以得到宽带的理想预编码矩阵，其维度可以为(P*N tx)*R。对于每个传输层来说，该宽带的理想预编码矩阵在一个传输层可对应一个维度为(P*N tx)*1的列向量。以下为方便说明，将该维度为(P*N tx)*1的列向量记作宽带的理想预编码向量。
此后，终端设备可以基于每个传输层确定所对应的空频矩阵。为方便说明，以下步骤(包括步骤ii至步骤v)基于第r(1≤r≤R，且r为整数)个传输层详细说明终端设备确定空频矩阵的具体过程。终端设备可以将r在1至R中遍历取值，通过重复执行以下步骤ii至步骤iv，得到用于指示与R个传输层对应的R个空频矩阵的R组指示信息。换句话说，PMI可以包括与R个传输层对应的R组指示信息，每组指示信息可用于指示一个空频矩阵。
步骤ii)
终端设备将第r个传输层上的宽带的理想预编码向量投影到空域，以获得第r个传输层上的P*L个空域列向量。
该R个传输层中任意两个传输层上的L个波束向量可以彼此相同，也可以互不相同，本申请对此不做限定。
此外，P个极化方向中任意两个极化方向上的L个波束向量可以彼此相同，也可以互不相同，本申请对此不做限定。
若该R个传输层中任意两个传输层上的L个波束向量彼此相同，且P个极化方向中任意两个极化方向上的L个波束向量可以彼此相同，则终端设备可以先确定该L个波束向量，然后再分别确定各传输层上该L个波束向量在P个极化方向上的宽带幅度系数。例如，该L个波束向量可以记作v 0，v 1，……，v L-1，P＝2，第r个传输层的第一个极化方向上L个波束向量的宽带幅度系数可以记作a 0，a 1，……，a L-1，第r个传输层上的第二个极化方向上L个波束向量的宽带幅度系数可以记作a L，a L+1，……，a 2L-1。则可以得到第r个传输层上的P个极化方向上L个波束向量与所对应的宽带幅度系数之积如下：a 0v 0，a 1v 1，……，a L-1v L-1，a Lv 0，a L+1v 1，……，a 2L-1v L-1。为方便区分和说明，本实施例中将一个波束向量与对应的宽带幅度系数的乘积称为一个中间向量，可以理解，一个中间向量可以由一个波束向量及其对应的宽带幅度系数确定，一个中间向量可用于确定一个空域列向量。中间向量的维度可以是N tx*1，由此确定的一个空域列向量的维度可以是(P*N tx)*1。
若该R个传输层中各传输层上的L个波束向量互不相同，终端设备可以分别确定各个传输层的P个极化方向上的L个波束向量以及对应的宽带幅度系数。相似地，若该P个极化方向中各极化方向上的L个波束向量互不相同，终端设备可以分别确定各个极化方向上的L个波束向量以及对应的宽带幅度系数。终端设备确定每个传输层、每个极化方向上的L个波束向量的方式可以是相同的。
下文中为方便说明，假设该R个传输层中任意两个传输层上的L个波束向量彼此相同，且P个极化方向上任意两个极化方向上的L个波束向量彼此相同。则终端设备可以基于某一个传输层、某一个极化方向确定L个波束向量，然后确定第r个传输层的P个极化方向上L个波束向量的宽带幅度系数。
其中，用于确定L个波束向量的传输层可以为R个传输层中的任意一个传输层，例如，可以为第一个传输层，也可以为第R个传输层。用于确定L个波束向量的传输层可以是预先指定的某一传输层，如协议定义，也可以是网络设备指示的某一个传输层。下文为方便说明，以第r个传输层为例来说明终端设备确定L个波束向量以及L个波束向量的宽带幅度系数的具体过程。
用于确定L个波束向量的极化方向可以为P个极化方向中的任意一个极化方向，例如，可以为第一个极化方向，也可以为第P个极化方向。用于确定L个波束向量的极化方向可以是预先指定的某一极化方向，如协议定义，也可以是网络设备指示的某一个极化方向。下文中，为方便说明，以第r个传输层、第p个极化方向为例来说明终端设备确定L个波束向量的具体过程，并以第r个传输层为例来说明终端设备确定L个波束向量在P个极化方向上的宽带幅度系数的具体过程。
首先，终端设备可以将第r个传输层上的宽带的理想预编码向量投影到空域，以获得空域上的L个波束向量以及L个波束向量的宽带幅度系数。
具体地，终端设备可以根据第一向量集合和第r个传输层上的宽带的理想预编码向量确定空域上的L个波束向量以及L个波束向量的宽带幅度系数。
其中，该第一向量集合可以包括多个维度为N tx*1的列向量，且每个列向量均为二维(2dimension，2D)-DFT向量或者过采样2D-DFT向量。其中，2D可以表示两个不同的方向，如，水平方向和垂直方向。
在一种可能的设计中，该第一向量集合可以包括N tx个列向量，该N tx个列向量中的任意两个列向量相互正交。终端设备可以从该N tx个列向量中选择L个列向量作为空域上被选择的L个波束向量。
具体地，终端设备可以将宽带的理想预编码向量中某一个(例如，第p个)极化方向上的理想预编码向量与第一向量集合中的各个列向量做内积，以获得多个值。可以理解，该多个值均为复数。终端设备可以进一步从该多个值中确定模较大的L个值，该L个值中的任意一个值的模大于其余N tx-L个值中的任意一个值的模。该第一向量集合中用于生成该L个值的L个列向量可以作为空域上的L个波束向量。
在另一种可能的设计中，该第一向量集合可以包括O 1*O 2*N tx个列向量，其中O 1、O 2是过采样因子，O 1≥1，O 2≥1，O 1、O 2不同时为1，且均为整数。该第一基向量可以包括O 1*O 2个子集，每个子集包括N tx个列向量，且每个子集内的任意两个列向量相互正交。终端设备可以从该O 1*O 2个子集中选择一个子集，被选择的子集中包括被选择的L个波束向量。
由于每个极化方向上的宽带的理想预编码向量的维度也为N tx*1。终端设备可以将某一个(例如，第p个)极化方向上的宽带的理想预编码向量与第一向量集合中O 1*O 2个子集中的N tx个列向量求内积，可得到O 1*O 2组值，每组值包括N tx个值。终端设备可以从每组值中确定出模较大的L个值，并可进一步对该O 1*O 2组值中的L个值做比较，以选择出一组值。被选择的这一组值中的L个值的模大于其余的O 1*O 2-1组值中任意一组的L个值的模。该第一向量集合中用于生成这组值的L个列向量即为空域上被选择的L个波束向量。可以理解，该L个波束向量属于上述O 1*O 2个子集中的一个子集，例如可以记作第一子集。
由于配置了P个极化方向的发射天线，终端设备可以将p在1至P中遍历取值，重复执行下述操作，以得到P个极化方向中每个极化方向上的L个宽带幅度系数：将P个极化方向中的第p个极化方向上的宽带的理想预编码向量与上文中所确定的L个波束向量做内积所得到的值的模可以作为第p个极化方向上的L个列向量的宽带幅度系数。通过重复执行上述操作，终端设备可以得到P个极化方向中每个极化方向上的L个宽带幅度系数，即，P*L个宽带幅度系数。
终端设备可以进一步确定P*L个中间向量。首先，终端设备可以将p在[1，P]中遍历取值，依次得到P个极化方向中每个极化方向上的L个中间向量。其中，第p个极化方向上的L个中间向量可以通过将l在1至L中遍历取值，重复执行下述操作获得：将L个波束向量中的第l个波束向量与第p个极化方向上的L个宽带幅度系数中的第l个宽带幅度系数相乘，得到第p个极化方向上的第l个中间向量。通过重复执行上述操作，终端设备可以得到第p个极化方向上的L个中间向量。
此后，终端设备可以根据该P*L个中间向量确定P*L个空域列向量。如前所述，每个中间向量的维度为N tx*1，每个极化方向上的L个中间向量构成的矩阵的维度可以为N tx*L，P个极化方向上的P*L个中间向量构造的矩阵的维度可以为(P*N tx)*(P*L)。为方便 说明，下文中可以将由P个极化方向上的P*L个中间向量构造的矩阵记作空间矩阵W 1，该空间矩阵W 1中的每个列向量称为一个空域列向量。
例如，假设P＝2，第一个极化方向上的L个中间向量为a 0v 0，a 1v 1，……，a L-1v L-1，第二个极化方向上的L个空域列向量为a Lv 0，a L+1v 1，……，a 2L-1v L-1。则基于该P个极化方向上的中间向量可以构造得到空间矩阵W 1如下：
Figure PCTCN2019099351-appb-000028
其中，a 0至a 2L-1表示宽带幅度系数，v 0至v L-1表示波束向量。也就是说，该空间矩阵中第(p-1)*L+1列至第p*L列、第p行至第p*N tx行的元素可以为第p个极化方向上的L个中间向量确定，也就可以由L个波束向量与第p个极化方向的L个宽带幅度系数相乘得到。
该空间矩阵可以是第r个传输层的空域信息一种表现形式。
应理解，上文的过程仅为便于理解而示出，终端设备在确定该P*L个空域列向量的过程中，并不一定会生成上述空间矩阵。终端设备可以直接根据L个波束向量和不同极化方向上对应的宽带幅度系数确定不同极化方向的中间向量。例如，终端设备可以根据第p个极化方向的宽带幅度系数和L个波束向量确定L个中间向量，并可以根据空域列向量的维度确定空域列向量，该空域列向量中除了第p行至第p*N tx行的元素为上述L个中间向量中的元素，其他行的元素均可以为零。基于上述过程，终端设备便可以根据P个极化方向上的宽带幅度系数以及L个波束向量确定出P*L个空域列向量。
还应理解，上文中将某一极化方向上的宽带的理想预编码向量与第一向量集合中的各列向量求内积确定L个波束向量，并将该L个波束向量作为P个极化方向的波束向量的方法仅为一种可能的实现方式。终端设备也可以将P个极化方向中每个极化方向上的宽带的理想预编码向量分别与第一向量集合中的各列向量求内积确定与P个极化方向分别对应的P*L个波束向量。本申请对此不做限定。
步骤iii)
终端设备将第r个传输层上的各子带的理想预编码向量通过P*L个空域列向量的线性组合来表征时，确定各空域列向量的加权系数。
具体地，终端设备可以基于现有技术中的方法，根据每个子带的信道矩阵确定所对应的理想预编码矩阵，其维度可以为(P*N tx)*R。对于每个传输层来说，各子带的理想预编码矩阵在一个传输层可对应一个维度为(P*N tx)*1的列向量。以下为方便说明，将该维度为(P*N tx)*1的列向量记作子带的理想预编码向量。
此后，终端设备可以基于一个子带的理想预编码向量与上文步骤ii得到的P*L个空域列向量做内积，得到P*L个值。该P*L个值除以步骤ii中确定的P*L个宽带幅度系数所得到的值为与这个子带对应的加权系数。该加权系数可以理解为：这个子带的理想预编码向量通过P*L个空域列向量的线性组合表征时各空域列向量的加权系数。
若将与每个子带对应的P*L个加权系数作为一个列向量，则可以得到与N sb个子带对应的N sb个列向量。按照N sb个子带的顺序将N sb个列向量从左向右依次排列，可以得到一个维度为(P*L)*N sb的矩阵。该矩阵的每个列与一个子带对应，每个列中的元素用于表示相对应的子带在通过P*L个空域列向量的线性组合表征时各空域列向量的加权系数。
步骤iv)
终端设备确定第r个传输层上的K个频域基向量。
需要说明的是，R个传输层中任意两个传输层上的K个频域基向量可以彼此相同，也可以互不相同，本申请对此不作限定。若R个传输层上任意两个传输层上的K个频域基向量彼此相同，则该R个传输层上的频域基向量可以为K个，终端设备可以基于某一个传输层确定K个频域基向量；若R个传输层中各传输层上的K个频域基向量彼此各不相同，则该R个传输层上的频域基向量可以为R*K个，终端设备可以基于R个传输层中的每个传输层确定K个频域基向量。
下文中为方便说明，假设该R个传输层中任意两个传输层上的K个频域基向量彼此相同，则终端设备可以基于某一个传输层确定K个频域基向量。用于确定K个频域基向量的传输层可以为R个传输层中的任意一个传输层，例如，可以为第一个传输层，也可以为第R个传输层。用于确定K个频域基向量的传输层可以是预先指定的某一传输层，如协议定义，也可以是网络设备指示的某一个传输层。下文为方便说明，以第r个传输层为例来说明终端设备确定K个频域基向量的具体过程。
终端设备可以将第r个传输层上各子带的叠加系数在第二向量集合上投影，以获得K个频域基向量。
其中，第二向量集合可以包括多个维度为N sb*1的列向量，且每个列向量均为离散傅里叶变换(discrete fourier transform，DFT)向量或者过采样DFT向量或离散傅里叶向量的截断或过采样DFT向量的截断。
这里所说的“截断”可以理解为从DFT向量或过采样DFT向量中截取出来的部分元素构成的向量。举例而言，假设DFT向量为16维列向量，可以从中截取出前10个元素构成一个10维的列向量，该10维的列向量可视为上述16维的DFT向量的截断。在本实施例中，截断的维度可以为N sb*1。
在本实施例中，第二向量集合中的每一个列向量可以理解为频域上的一种变化规律。本实施例希望能够通过将步骤iii中确定的各个子带的理想预编码向量通过L个波束向量表征时该L个波束向量的加权系数通过第二向量集合中的若干个(例如K个)频域基向量的线性组合来表征。因此，步骤iv中要确定的K个频域基向量也就是上文所述的若干个频域基向量。
在一种可能的设计中，该第二向量集合可以包括N sb个列向量，该N sb个列向量中的任意两个列向量相互正交。终端设备可以从该N sb个列向量中选择K个列向量作为频域上被选择的K个基向量，即，K个频域基向量。
终端设备可以将该N sb个列向量组合成一个维度为N sb*N sb的矩阵，例如记作F。此后，终端设备可以将步骤iii中得到的维度为(P*L)*N sb的矩阵分别与矩阵F相乘，得到维度为(P*L)*N sb的矩阵。对该矩阵中的N sb个列分别求模，可得到N sb个值。从该N sb个值中选出模较大的K个值，该K个值中的任意一个值的模大于其余N sb-K个值中的任意一个值的模。该第二向量集合中用于生成该K个值的K个列可以是频域上被选择的K个基向量。
在另一种可能的设计中，该第二向量集合可以包括O 3*N sb个列向量，其中O 3是过采样因子，O 3≥1，且为整数。该第二向量集合可以包括O 3个子集，每个子集包括N sb个列 向量，且每个子集内的任意两个列向量相互正交。终端设备可以从该O 3个子集中选择一个子集，被选择的子集中包括被选择的K个频域基向量。
终端设备将每个子集中的N sb个列向量组合成一个维度为N sb*N sb的矩阵，例如记作F i(1≤i≤O 3，且i为整数)，可以得到O 3个维度为N sb*N sb的矩阵。终端设备可以将步骤iii中得到的维度为(P*L)*N sb的矩阵依次与矩阵F 1至F O3相乘，得到维度为(P*L)*N sb的O 3个矩阵。将各矩阵中的每个列分别求模，可得到O 3组值，每组值包括N sb个值。终端设备可以从每组值中选出模较大的K个值，并可进一步对O 3组值中的K个值做比较，以选择出一组值。被选择的这组值中的K个值的模大于其余的O 3-1组值中任意一组的K个值的模。该第二向量集合中用于生成该K个值的列向量可以是频域上被选择的K个频域基向量。可以理解，该K个频域基向量属于上述O 3个子集中的一个子集，例如可以记作第二子集。
步骤v)
终端设备确定P*L*K个加权系数。
终端设备在步骤iv中确定的K个频域基向量可以构成维度为N sb*K的矩阵。
终端设备可以将在步骤iii中确定的维度为(P*L)*N sb的矩阵，以及上述维度为N sb*K的矩阵，确定得到维度为(P*L)*K的矩阵，例如，可以将上述步骤iii中确定的维度为(P*L)*N sb的矩阵与维度为N sb*K的矩阵相乘，得到维度为(P*L)*K的矩阵。该矩阵可以称为系数矩阵。该系数矩阵中的每个元素为一个加权系数，每个加权系数可以包括幅度系数和相位系数。可以理解，该系数矩阵中的P*L行对应于空域列向量的P*L个列，该系数矩阵的K个列对应于频域基向量的K个列。即，该P*L行的系数为P*L个空域列向量的加权系数，该K列的系数为K个频域基向量的加权系数。
步骤vi)
终端设备确定PMI。
终端设备可以根据在步骤ii中确定的第r个传输层上的P*L个空域列向量、步骤iv中确定的第r个传输层上的K个频域基向量以及步骤v中确定的P*L*K个加权系数，确定与R个传输层对应的R个空频矩阵。
如前所述，该空频矩阵可以是维度为(P*N tx)*N sb的矩阵，也可以是维度为(P*N tx*N sb)*1的列向量。例如，当该空频矩阵是维度为(P*N tx)*N sb的矩阵时，该空频矩阵可以表示为：
Figure PCTCN2019099351-appb-000029
其中，W 1由维度为(P*N tx)*1的P*L个空域列向量确定；H由P*L*K个加权系数确定；V 2由维度为N sb*1的K个频域基向量确定。
或者，W 1由维度为(P*N tx)*1的P*L个空域列向量确定，V 2由维度为N sb*1的K个频域基向量和幅度系数确定，H由P*L*K个相位系数确定，或，由P*L*K个相位系数和幅度系数确定。当V 2由频域基向量和幅度系数确定时，该幅度系数可以是从步骤v中确定的加权系数中分离出来的幅度系数。具体地，K个频域基向量可以对应于该系数矩阵中的K个列，第k个列中可以分配一个幅度系数给第k个频域基向量，然后将原系数矩阵中的第k个列中的幅度系数分别除以分配给第k个频域基向量的幅度系数后得到的值作为该系数矩阵中的幅度系数。该幅度系数可以保留，此时H由幅度系数和相位系数确定，该幅度系数也可以全部置为1，此时H由相位系数确定。
因此，W 1可以是维度为(P*N tx)*L的矩阵，H可以是维度为(P*L)*K的系数矩阵， V 2可以是维度为N sb*K的矩阵。
终端设备可以基于上文所确定的空频矩阵确定PMI，也可以基于步骤ii中确定的第r个传输层上的P*L个空域列向量、步骤iv中确定的第r个传输层上的K个频域基向量以及步骤v中确定的P*L*K个加权系数确定PMI。本申请对此不做限定。
具体地，该PMI可以包括与R个传输层对应的R组指示信息。该R组指示信息中的第r组指示信息可用于指示：
与第r个传输层对应的P*L个空域列向量；
与第r个传输层对应的K个频域列向量；和
用于确定该第r个空频矩阵的P*L*K个加权系数。
其中，P*L个空域列向量由步骤ii中描述的由第一向量集合中的L个波束向量和P个极化方向中每个极化方向上的L个宽带幅度系数确定。即，空域列向量中的非零元素可以是由L个波束向量与各极化方向的L个宽带幅度系数的乘积确定。每个空域列向量的维度可以为(P*N tx)*1。
K个频域列向量可以由步骤iv中描述的频域的K个频域基向量确定，P*L*K个加权系数可以由步骤v中描述的加权系数确定。即，频域列向量可以是由第二向量集合确定得到的K个频域基向量。或者，K个频域列向量可以步骤iv中描述的频域的K个频域基向量和步骤v中描述的加权系数中的幅度系数确定，P*L*K个加权系数可以由步骤v中描述的加权系数的相位系数确定。即，频域列向量也可以是由该K个频域基向量与各频域基向量的幅度系数的乘积确定的K个列向量。每个频域列向量的维度可以为N sb*1。
具体地，该K个频域列向量可以是上文中描述的由第二向量集合中选择的K个频域基向量，此时，该P*L*K个加权系数可以包括该K个波束向量的幅度系数和相位系数。该K个频域列向量也可以是K个频域基向量与K个幅度系数的乘积而构成的频域列向量，此时，该P*L*K个加权系数可以仅包括该K个频域基向量的相位系数。每个加权系数可以用于指示P*L个空域列向量中的一个空域列向量与K个频域列向量中的一个频域列向量的共轭转置的乘积在第r个空频矩阵中的权重，或者，个频域列向量的共轭与一个空域列向量的克罗内克尔积在第r个空频矩阵中的权重。
假设第l个空域列向量记作v l，第k个频域列向量记作u k，与第l个空域列向量、第k个频域列向量对应的加权系数记作g l,k，则加权系数g l,k可以表示
Figure PCTCN2019099351-appb-000030
在第r个空频矩阵中的权重，或者，也可以表示
Figure PCTCN2019099351-appb-000031
在第r个空频矩阵中的权重。
如前所述，任意两个传输层的L个波束向量有可能是彼此相同的，也可能是互不相同的；任意两个传输层的K个频域基向量有可能是彼此相同的，也可能是互不相同的。
当任意两个传输层的L个波束向量彼此相同，且任意两个传输层的K个频域基向量彼此相同时，该L个波束向量和K个频域基向量可以不用在每组指示信息中重复指示。
则，该PMI具体可以包括：
L个波束向量的索引；
R组宽带幅度系数的指示信息；
K个频域基向量的索引；
R组加权系数的指示信息。
其中，R组宽带幅度系数中的每组宽带幅度系数包括P*L个系数，R组加权系数中的 每组加权系数包括P*L*K个系数。
当任意两个传输层的L个波束向量互不相同，且任意两个传输层的K个频域基向量互不相同时，该L个波束向量和K个频域基向量也可以在每组指示信息中分别指示。
则，该PMI可以包括R组指示信息，该R组指示信息中的第r组指示信息具体可包括：
与第r个传输层对应的L个波束向量的索引；
与第r个传输层对应的P*L个宽带幅度系数的指示信息；
与第r个传输层对应的K个频域基向量的索引；
P*L*K个加权系数的指示信息。
应理解，上文列举的PMI包含的具体内容仅为示例，不应对本申请构成任何限定。例如，任意两个传输层的L个波束向量可以彼此相同，任意两个传输层的K个频域基向量可以彼此不同，此情况下，该PMI可以包括：L个波束向量的索引，以及与R个传输层一一对应的K个频域基向量的索引。本申请对此不做限定。
如前所述，第一向量集合可以通过过采样因子扩展为O 1*O 2*N tx个列向量，空域上被选择的L个波束向量可以是取自该O 1*O 2*N tx个列向量中的一个子集，即上文所述的第一子集。因此，该PMI还可以包括用于指示该第一子集的指示信息，以指示该第一子集中的各个列向量在第一向量集合中的位置。
例如，第一向量集合可以包括O 1*O 2个组，每个组为一个子集。该L个波束向量可以取自上述O 1*O 2个组中的某一个组。上述第一子集的指示信息例如可以是L个波束向量所在的组在O 1*O 2个组中的索引。
与此相似地，第二向量集合也可以通过过采样因子扩展为O 3*N sb个列向量，频域上被选择的K个频域基向量可以是取自该O 3*N sb个列向量中的一个子集，即上文所述的第二子集。因此，该PMI还可以包括用于指示该第二子集的指示信息，以指示该第二子集中的各列向量在第二向量集合中的位置。
例如，该第二向量集合可以包括O 3个组，每个组为一个子集。该K个波束向量可以取自上述O 3个组中的某一个组。上述第二子集的指示信息例如可以使K个波束向量所在的组在O 3个组中的索引。
可选地，与第r个传输层对应的P*L个宽带幅度系数可以通过归一化方式来指示。
具体地，终端设备可以首先确定该P*L个宽带幅度系数中的最大值。以该最大值为基准，求出剩余的P*L-1个宽带幅度系数相对于该最大值的比值。该P*L个宽带幅度系数的指示信息可以包括该最大值的量化值的索引以及剩余的P*L-1个宽带幅度系数相对于该最大值的比值的量化值的索引。
应理解，通过归一化方式来指示P*L个宽带幅度系数仅为一种可能的实现方式，而不应对本申请构成任何限定。例如，终端设备也可以指示该P*L个宽带幅度系数的量化值的索引，或者，通过差分的方式指示该P*L个宽带幅度系数。本申请对于终端设备指示P*L个宽带幅度系数的具体方法不做限定。
可选地，上述P*L*K个加权系数可以通过矩阵的形式表现，例如，可以是维度为(P*L)*K的矩阵。为方便区分和说明，可以将P*L*K个加权系数构成的矩阵称为系数矩阵。该系数矩阵中的P*L个行可以对应于空域的P*L个列向量，该系数矩阵中的K个列可以对 应于频域的K个列向量。
可选地，与第r个传输层对应的P*L*K个加权系数可以通过归一化方式来指示。
在一种实现方式中，终端设备可以从该P*L*K个加权系数中确定幅度最大的加权系数(例如记作最大系数)，并指示该最大系数在系数矩阵中的位置(例如，该最大系数在该系数矩阵中的行的序号和列的序号)。然后，终端设备可以进一步指示该系数矩阵中每一行中幅度最大的加权系数(例如记作行内最大系数)相对于上述最大系数的相对值，以及每一行的其他加权系数相对于同一行的行内最大系数的相对值；或者，终端设备也可以进一步指示该系数矩阵中每一列中幅度最大的加权系数(例如记作列内最大系数)相对于上述最大系数的相对值，以及每一列的其他加权系数相对于同一列的列内最大系数的相对值。
在另一种实现方式中，终端设备可以从该P*L*K个加权系数中确定幅度最大的加权系数(即上述最大系数)，并指示该最大系数在系数矩阵中的位置(例如，该最大系数在该系数矩阵中的行的序号和列的序号)。然后，终端设备可以进一步指示该系数矩阵中其他加权系数相对于该最大系数的相对值。
应理解，通过归一化方式来指示P*L*K个加权系数仅为一种可能的实现方式，而不应对本申请构成任何限定。例如，终端设备也可以直接指示该P*L*K个加权系数的量化值的索引，或者，通过差分的方式指示该P*L*K个加权系数。本申请对于终端设备指示P*L*K个加权系数的具体方法不作限定。
该P*L*K个加权系数中的每个加权系数可以包括幅度系数和相位系数。各幅度系数的反馈开销可以是相同的，终端设备例如可以使用t 0(t 0≥1，且t 0为整数)个比特反馈幅度系数。各相位系数的反馈开销也可以是相同的，终端设备例如可以使用b 0(b 0≥1，且b 0为整数)个比特反馈幅度系数。
为了减小PMI的反馈开销，终端设备也可以对不同的幅度系数分配不同的反馈开销，和/或，对不同的相位系数分配不同的反馈开销。例如，终端设备可以将宽带幅度系数较大的空域列向量所对应的系数矩阵中的行采用较多的比特来量化，例如，采用t 1(t 1＞t 0，且t 1为整数)个比特反馈幅度系数，和/或，采用b 1(b 1＞b 0，且b 1为整数)个比特反馈相位系数；也可以将宽带幅度系数较小的空域列向量所对应的系数矩阵中的行采用较少的比特来量化，例如，采用t 2(0＜t 2＜t 0，且t 2为整数)个比特反馈幅度系数，和/或，采用b 2(0＜b 2＜b 0，且b 2为整数)个比特反馈相位系数。
应理解，当终端设备对系数矩阵中的某些行采用较多的比特来量化时，可以采用较多的比特来量化幅度系数，或相位系数，或幅度系数和相位系数；当终端设备对系数矩阵中的某些列采用较少的比特来量化时，可以采用较少的比特来量化幅度系数，或相位系数，或幅度系数和相位系数，本申请对此不作限定。
举例而言，可以从P*L个空域列向量中确定宽带幅度系数较大的M个列，该M个列对应于系数矩阵中的M个行的量化比特数可以大于剩余的P*L-M行的量化比特数。其中，M≥1，且为整数。M的值可以是网络设备指示的，也可以是预先定义的，如协议定义，还可以是终端设备确定并反馈给网络设备的，本申请对此不做限定。
可选地，L个波束向量中至少两个波束向量对应的频域基向量的个数不同。
对于每个极化方向来说，L个波束向量可以对应于系数矩阵中的L个行，K个频域基 向量可以对应于系数矩阵中的K个列。L个波束向量中的第l个波束向量对应于系数矩阵中的第l个行，该第l个行中的k个系数与K个频域基向量对应。与不同的波束向量对应的频域基向量的个数可以不同。如第l个波束向量对应的频域基向量为K个，与第l+1个波束向量对应的频域基向量可以为K’(1≤K’＜K)个。
由于L个波束向量的宽带幅度系数不同，对于宽带幅度系数较大的波束向量，其在频域对应的频域基向量的个数可以多一些；对于宽带幅度系数较小的波束向量，其在频域对应的频域基向量的个数可以少一些。由于宽带幅度系数较大的波束向量在线性组合中所占的权重较大，对近似精度的影响也较大。因此，可以对宽带幅度系数较大的波束向量在频域分配更多的频域基向量，以通过更多的频域基向量的线性组合来描述这些波束向量在线性组合时使用的加权系数，从而有利于提高PMI的近似精度。
如前所述，由于系数矩阵的维度(P*L)*K，若要使空域的L个波束向量投影到频域的波束向量的个数不同，可以通过控制L个空域的波束向量对应于系数矩阵中的行向量中的非零元素的个数来实现。
举例而言，可以从P*L个空域列向量中确定宽带幅度系数较大的M个列，该M个列对应于系数矩阵中的M个行，该M个行中的元素可以均为非零元素，而剩余的P*L-M行中，每一行可以包括一个或多个零元素。系数矩阵中的某一个元素为零，则表示该零元素在该系数矩阵中的列的序号(例如，第m个列)可以对应于K个频域列向量中的列序号，也就是该K个频域列向量中的第m个列向量未使用，从而可以达到控制频域基向量的个数的效果。
可选地，R个传输层中至少两个传输层的波束向量的个数不同。
例如，可以将第一个传输层的波束向量的个数配置为L，其他传输层的波束向量的个数配置为L’，1≤L’＜L，且L’为整数。
可选地，R个传输层中至少两个传输层的频域列向量的个数不同。
例如，可以将第一个传输层的频域列向量的个数配置为K，其他传输层的频域列向量的个数配置为K’，1≤K’＜K，且K’为整数。
可选地，R个传输层中至少两个传输层的波束向量的个数不同，且R个传输层中至少两个传输层的频域列向量的个数不同。
例如，将第一个传输层的波束向量的个数配置为L，频域列向量的个数配置为K，其他传输层的波束向量的个数配置为L’，频域列向量的个数配置为K’，1≤L’＜L，1≤K’＜K，且L’、K为整数。
应理解，以上列举的PMI的多种可能的量化方式，但不应对本申请构成任何限定。本申请对于各个传输层的空域列向量、频域列向量以及加权系数的具体的量化方式不做限定。
实现方式二、
步骤i)
终端设备根据各个子带的信道矩阵，确定各子带的理想预编码矩阵。
具体地，终端设备可以基于现有技术中的方法，根据每个子带的信道矩阵确定所对应的理想预编码矩阵，其维度可以为(P*N tx)*R。对于每个传输层来说，各子带的理想预编码矩阵在一个传输层可对应一个维度为(P*N tx)*1的列向量。以下为方便说明，将该 维度为(P*N tx)*1的列向量记作子带的理想预编码向量。
步骤ii)
终端设备确定与第r个传输层对应的P*L个波束向量、K个频域基向量以及P*L*K个加权系数。
如前所述，R个传输层中任意两个传输层的L个波束向量可能彼此相同，各传输层的L个波束向量也可能是互不相同的。若该R个传输层中任意两个传输层上的L个波束向量彼此相同，终端设备可以基于某一个传输层确定L个波束向量；若该R个传输层中任意两个传输层上的L个波束向量彼此不同，终端设备可以分别基于每个传输层确定相应的L个波束向量。应理解，终端设备基于一个传输层确定L个波束向量的具体过程可以是相同的。
P个极化方向中任意两个极化方向的L个波束向量可能彼此相同，各极化方向上的L个波束向量也可能互不相同。若该P个极化方向中任意两个极化方向上的L个波束向量彼此相同，终端设备可以基于某一个极化方向确定L个波束向量；若该P个极化方向中各极化方向上的L个波束向量互不相同，终端设备可以基于每个极化方向确定L个波束向量。
在本实施例中，假设P个极化方向中任意两个极化方向上的L个波束向量彼此相同，因此第r个传输层对应的波束向量的个数P*L中的P＝1，即，与第r个传输层对应的波束向量的个数为L。
应理解，当P个极化方向中任意两个极化方向上的L个波束向量彼此相同时，终端设备可以基于某一个极化方向确定L个波束向量。终端设备具体基于哪一个极化方向确定L个波束向量可以是预先定义的，如协议定义，也可以是网络设备指示的，本申请对此不作限定。
R个传输层中任意两个传输层的K个频域基向量可能彼此相同，各传输层的K个波束向量也可能互不相同。若该R个传输层中任意两个传输层上的K个频域基向量彼此相同，终端设备可以基于某一个传输层确定K个频域基向量；若该R个传输层中任意两个传输层上K个频域基向量彼此不同，终端设备可以分别基于每个传输层确定相应的K个频域基向量。应理解，终端设备基于每个传输层确定K个频域基向量的具体过程可以是相同的。
应理解，当R个传输层中任意两个传输层的L个波束向量彼此相同、任意两个传输层的K个频域基向量彼此相同时，终端设备可以基于某一个传输层确定L个波束向量和K个频域基向量时。终端设备具体基于哪一个传输层确定L个波束向量和K个频域基向量可以是预先定义的，如协议定义，也可以是网络设备指示的，本申请对此不作限定。
为方便说明，下面以终端设备基于第r个传输层确定L个波束向量和K个频域基向量为例来说明其具体过程。可以理解，若R个传输层中任意两个传输层上的L个波束向量彼此不同，或R个传输层中任意两个传输层上的K个频域基向量彼此不同，终端设备可以基于相同的方式来确定与每个传输层分别对应的L个波束向量或K个频域基向量。
具体地，终端设备可以将步骤i中确定的第r个传输层上各个子带的理想预编码向量按照子带从1至N sb的顺序从左到右依次排列，得到维度为(P*N tx)*N sb的矩阵，例如记作W。该矩阵W即为上文所述的空频矩阵的一例。该空频矩阵可以是与P个极化方向对应的P个分量矩阵。例如，该矩阵W中第p个极化方向上的分量矩阵可以记作W p，则 W p的维度为N tx*N sb。其中，p为1至P中的任意整数值。
终端设备将某一极化方向上的分量矩阵在空域和频域投影，以确定空域被选择的L个波束向量和频域被选择的K个基向量。其中，该分量矩阵可以是第一个极化方向的分量矩阵，也可以是第P个极化方向的分量矩阵，本申请对此不作限定。使用哪个极化方向的分量矩阵可以由网络设备指示终端设备，也可以预先定义，如协议定义，本申请对此不作限定。
下文中为方便说明，假设终端设备将第p个极化方向上的分量矩阵在第一向量集合构成的矩阵和第二向量集合构成的矩阵投影来确定L个波束向量和K个基向量。
假设第一向量集合包括维度为N tx*1的N tx个列向量，将该N tx个列向量按照从左至右的顺序依次排布可得到维度为N tx*N tx的矩阵，例如记作B s；假设第二基向量和包括维度为N sb*1的N sb个列向量，将该N sb个列向量按照从左至右的顺序依次排布可得到维度为N sb*N sb的矩阵，例如记作B f。
终端设备将第p个极化方向上的分量矩阵W p在B s和B f上投影，可以通过将W p左乘B s的共轭转置，并右乘B f实现，即，
Figure PCTCN2019099351-appb-000032
投影后得到的矩阵例如记作Y p，则
Figure PCTCN2019099351-appb-000033
该矩阵Y p的维度可以为N tx*N sb。可以理解，该矩阵是与第p个极化方向对应的矩阵。
从该矩阵Y p中确定出最强的L个行和最强的K个列。例如，终端设备可以对矩阵Y p中的N tx个行分别求模，选出模较大的L个行；并可以对矩阵Y p中的N sb个列分别求模，选出模较大的K个列。根据模较大的L个行的序号，从第一向量集合中确定该被选择的L个列向量，该L个列向量所在列的序号即为上述L个行的序号，该L个列向量可以是被选择的L个波束向量。根据模较大的K个列的序号，从第二向量集合中确定被选择的K个列向量，该K个列向量所在列的序号即为上述K个列的序号，该K个列向量也就可以是被选择的K个频域基向量。
终端设备可以将从第一向量集合中选出的L个列抽取出来按照从左到右的顺序排列可得到维度为N tx*L的矩阵，例如记作U 1,p，U 1,p中的L个列可以是L个波束向量。由于假设P个极化方向上的任意两个极化方向上的L个波束向量彼此相同，则可以由L个波束向量构造得到维度为(P*N tx)*L的矩阵U 1。例如，假设P＝2，则U 1的结构例如可以为
Figure PCTCN2019099351-appb-000034
其中，U 1,1＝U 1,2，均为由L个波束向量构成的维度为N tx*L的矩阵。
终端设备可以将从第二向量集合中选出的K个列抽取出来按照从左到右的顺序排列可得到维度为N sb*K的矩阵，例如记作U 2，U 2中的K个列可以是K个频域基向量。
将p在1至P中遍历取值，重复以下操作，可以得到P个极化方向中每个极化方向上的L*K个系数，即，P*L*K个系数：将矩阵U 1,p的共轭转置和矩阵U 2在第p个极化方向上的空频矩阵W p上投影，例如，将W p左乘
Figure PCTCN2019099351-appb-000035
右乘U 2，可以得到L*K个系数。该L*K个系数即为第p个极化方向上的系数。
通过重复上述操作，可以得到P个极化方向上的P*L*K个系数，该P*L*K个系数可以构成维度为(P*L)*K的矩阵，例如记作X。
由此可以得到空频矩阵
Figure PCTCN2019099351-appb-000036
其中，U 1由L个波束向量确定，U 2由K个频域基向量确定，X由P*L*K个加权系数确定。因此，U 1可以是维度为(P*N tx)*L的矩阵，X可以是维度为(P*L)*K的系数矩阵，U 2可以是维度为N sb*K的矩阵。
可以理解，该空频矩阵与实现方式一中的空频矩阵
Figure PCTCN2019099351-appb-000037
可以是等价的，或者说，是可以互相转换的。
在该空频矩阵中，系数矩阵X中的每个系数包括幅度系数和相位系数。根据该幅度系数可以进一步确定L个波束向量在每个极化方向上的宽带幅度系数，或者，可以进一步确定L个波束向量在每个极化方向上的宽带幅度系数和K个频域基向量在每个极化方向上的幅度系数。
在一种实现方式中，终端设备可以将上述维度为(P*L)*K的矩阵中P*L个行的每行中模最大的系数提取出来，得到P*L个系数。终端设备可以将该P*L个系数中的幅度系数作为L个波束向量在P个极化方向上的宽带幅度系数。由此可以得到P*L个中间向量，每个中间向量的维度为N tx*1。该P*L个中间向量可以构造得出维度为(P*N tx)*(P*L)的矩阵，该矩阵中第(p-1)*L+1列至第p*L列、第p行至第p*N tx行的元素可以为第p个极化方向上的L个中间向量确定，也就可以由L个波束向量分别与第p个极化方向的L个宽带幅度系数相乘得到，该矩阵也就是空频矩阵中的W 1。
然后，终端设备可以求各行中各系数的相对值。其中，第l行中各系数的相对值可以通过第l行中各系数的模与从第l行取出的宽带幅度系数的模的比值表示。各系数的相对值即为加权系数，各加权系数所构成的维度为(P*L)*K的矩阵即为系数矩阵，也就是空频矩阵中的系数矩阵H。K个频域基向量即为K个频域列向量，即，U 2＝V 2。
在另一种实现方式中，终端设备可以将上述维度为(P*L)*K的矩阵中P*L个行的每行中模最大的系数提取出来，得到P*L个系数。该P*L个系数中的幅度系数可以作为L个波束向量在P个极化方向上的宽带幅度系数，由此可以得到P*L个空域列向量，也就可以得到空频矩阵中的W 1。
终端设备可进一步将K个列的每列中模最大的系数提取出来，得到K个系数。该K个系数的幅度系数可以作为K个频域基向量的幅度系数，由此可以得到K个频域列向量，也就是空频矩阵中的V 2。
此后，终端设备可以确定空频矩阵中的系数矩阵H。该系数矩阵H的维度为(P*L)*K，系数矩阵H中的元素h i，j可以是上述(P*L)*K的矩阵中的元素除以第i行的最大模和第j列的最大模得到，也可以直接基于原矩阵X中的相位系数确定。
步骤iii)
终端设备确定PMI。
终端设备可以基于上文所确定的空频矩阵确定PMI，也可以基于步骤ii中确定的与第r个传输层对应的P*L个空域列向量、K个频域列向量和(P*L)*K加权系数，确定PMI。本申请对此不做限定。
该PMI中的具体内容在上文实现方式一的步骤vi)中已经做了详细说明，为了简洁，这里不再赘述。
应理解，上文中结合实现方式一和实现方式二列举了终端设备确定PMI的两种可能的实现方式，但这不应对本申请构成任何限定，本申请对于确定PMI的具体实现方式不做限定。
在步骤350中，终端设备发送PMI。相应地，网络设备接收PMI。
具体地，该PMI可以携带在CSI中。终端设备可以通过例如物理上行控制信道(physical  uplink control channel，PUCCH)或物理上行共享信道(physical uplink shared channel，PUSCH)，将CSI发送给网络设备，以便于网络设备基于该CSI中的PMI恢复出预编码矩阵。
在步骤360中，网络设备根据PMI，确定与各个子带对应的预编码矩阵。
网络设备在接收到上述PMI之后，可以根据与R个传输层对应的R个空频信息，确定与各个子带对应的预编码矩阵，也可以根据该R个空频信息确定空频矩阵，然后确定与各子带对应的预编码矩阵。
下面详细说明网络设备确定各个子带的预编码矩阵的具体过程。
可选地，空域向量是维度为(P*N tx)*1的列向量，频域向量是维度为N sb*1的列向量，极化方向数为1，步骤360具体包括：
在1至N sb中对n sb遍历取值，重复执行以下操作，以得到各子带的预编码矩阵：
在1至R中对r遍历取值，重复执行以下操作确定第n sb个子带的预编码矩阵：基于R组空频信息中的第r组空频信息所指示的P*L个空域向量、K个频域向量以及P*L*K个系数，确定第r个传输层中的第n sb个子带的预编码向量
Figure PCTCN2019099351-appb-000038
Figure PCTCN2019099351-appb-000039
其中，
Figure PCTCN2019099351-appb-000040
可以对应于第n sb个子带，可用于确定第n sb个子带在第r个传输层上的预编码向量。v l表示与第r个传输层对应的L个波束向量中的第l个波束向量，
Figure PCTCN2019099351-appb-000041
表示v l的幅度系数的量化值，
Figure PCTCN2019099351-appb-000042
表示与第r个传输层对应的K个频域向量中的第k个频域向量中的第n sb个元素，
Figure PCTCN2019099351-appb-000043
表示
Figure PCTCN2019099351-appb-000044
的共轭，
Figure PCTCN2019099351-appb-000045
表示与P*L个空域向量中的第l个空域向量和K个频域向量中的第k个频域向量对应的线性叠加系数的幅度的量化值，
Figure PCTCN2019099351-appb-000046
表示与P*L个空域向量中的第l个空域向量和K个频域向量中的第k个频域向量对应的线性叠加系数的相位的量化值。
即，分别确定R个传输层数与第n sb个子带对应的预编码向量，从而确定与第n sb个子带对应的预编码矩阵，从而确定N sb个子带的预编码矩阵。
可选地，空域向量是维度为(P*N tx)*1的列向量，频域向量是维度为N sb*1的列向量，极化方向数为2，步骤360具体包括：
在1至N sb中对n sb遍历取值，重复执行以下操作，以得到与各子带对应的预编码矩阵：
在1至R中对r遍历取值，重复执行以下操作确定第n sb个子带的预编码矩阵：基于R组空频信息中的第r组空频信息所指示的P*L个空域向量、K个频域向量以及P*L*K个系数，确定第r个传输层中的第n sb个子带的预编码向量
Figure PCTCN2019099351-appb-000047
Figure PCTCN2019099351-appb-000048
其中，
Figure PCTCN2019099351-appb-000049
可以对应于第n sb个子带，可用于确定第n sb个子带在第r个传输层上的预编码向量。v l表示与第r个传输层对应的L个列向量中的第l个列向量，
Figure PCTCN2019099351-appb-000050
表示第一极化方向上的v l的幅度系数的量化值。
Figure PCTCN2019099351-appb-000051
表示第二极化方向上的v l的幅度系数的量化值。u r,k,j表示与第r个传输层对应的K个列向量中的第k个列向量中的第n sb个元素，
Figure PCTCN2019099351-appb-000052
表 示
Figure PCTCN2019099351-appb-000053
的共轭。
Figure PCTCN2019099351-appb-000054
表示第一极化方向上的L个空域向量中的第l个空域向量和所述K个频域向量中的第k个频域向量对应的线性叠加系数的幅度的量化值，即，第一极化方向上的v l和u r,k的向量运算结果的线性叠加系数的幅度的量化值。
Figure PCTCN2019099351-appb-000055
表示第二极化方向上的L个空域向量中的第l个空域向量和所述K个频域向量中的第k个频域向量对应的线性叠加系数的幅度的量化值，即，第二极化方向上的v l和u r,k的向量运算结果的线性叠加系数的幅度的量化值。
Figure PCTCN2019099351-appb-000056
表示第一极化方向上的第一极化方向上的L个空域向量中的第l个空域向量和所述K个频域向量中的第k个频域向量对应的线性叠加系数的相位的量化值，即，v l和u r,k的向量运算结果的相位系数的量化值。
Figure PCTCN2019099351-appb-000057
表示第二极化方向上的L个空域向量中的第l个空域向量和所述K个频域向量中的第k个频域向量对应的线性叠加系数的相位的量化值，即，v l和u r,k的向量运算结果的线性叠加系数的相位的量化值。
即，分别确定R个传输层数与第n sb个子带对应的预编码向量，从而确定与第n sb个子带对应的预编码矩阵，从而确定N sb个子带的预编码矩阵。
可以理解的是，上文列举的公式是基于空域向量和频域向量均为列向量的情况而定义的，若空域向量为列向量，频域向量为行向量，则：
当极化方向数为1时，
Figure PCTCN2019099351-appb-000058
当极化方向数为2时，
Figure PCTCN2019099351-appb-000059
各参数在上文中已经做了详细说明，为了简洁，这里不再赘述。
可选地，在步骤360中，网络设备也可以基于PMI确定R个空频矩阵，并进一步根据该R个空频矩阵确定与N sb个子带对应的预编码矩阵。
网络设备可以根据PMI恢复得到与R个传输层对应的R个空频矩阵。如前所述，空频矩阵可以是维度为(P*N tx)*N sb的矩阵，也可以是维度为(P*N tx*N sb)*1的列向量。网络设备可以分别基于不同的形式恢复R个空频矩阵。此后，网络设备也可以基于上文所列举的公式恢复出第r个传输层与第n sb个子带对应的列向量
Figure PCTCN2019099351-appb-000060
该列向量
Figure PCTCN2019099351-appb-000061
可对应于维度为(P*N tx)*N sb的矩阵的第n sb个列向量，也可以对应于维度为(P*N tx*N sb)*1的列向量中的第(P*Ntx)*(n sb-1)+1个至第(P*Ntx)*n sb个元素组成的列向量。由R个传输层上的第n sb个列向量可以确定第n sb个子带的预编码矩阵。
应理解，当空域向量和频域向量分别为行向量，或者，空域向量为行向量、频域向量为列向量时，可以基于上述公式进行数学变换得到
Figure PCTCN2019099351-appb-000062
的表达式。
需要说明的是，当空域向量和频域向量均为列向量时，上述第一向量集合和第二向量集合均可以为列向量集合，但应理解，第一向量集合和第二向量集合并不仅限于上述实施例中所列举的形式。例如，该第二向量集合中的各向量也可以经过数学变换，如取其中的各向量的共轭后构成新的第二向量集合，此时网络设备仍可沿用上述公式3或公式4来确定预编码矩阵。
当空域向量为列向量，频域向量为行向量时，上述第一向量集合可以为列向量集合，第二向量集合可以为行向量集合。例如，该第二向量集合中的各行向量可以是上文中实施例所列举的第二向量集合中的各列向量经过数学变换得到，如取各向量的转置，或者共轭 转置，构成新的第二向量集合。本申请对此不作限定。当对第二向量集合中的各列向量转置得到新的第二向量集合时，网络设备可以沿用上述公式1或公式2来确定预编码矩阵；当对第二向量集合中的各列向量取共轭转置得到新的第二向量集合时，网络设备可以沿用上述公式3或公式4来确定预编码矩阵。
若空频矩阵为维度为(P*N tx*N sb)*1的列向量，则该空频矩阵可以是由上述P*L*K个分量矩阵线性叠加得到，该分量矩阵可以是由K个频域列向量中的一个频域列向量的共轭向量与P*L个空域列向量中的一个空域列向量的克罗内克尔积得到。此情况下，网络设备仍然可以基于上文所述的公式恢复出第r个传输层的空频矩阵中的与第n sb个子带对应的列向量
Figure PCTCN2019099351-appb-000063
可以理解，该列向量
Figure PCTCN2019099351-appb-000064
可以是从维度为(P*N tx*N sb)*1的列向量中的第(n sb-1)*(P*N tx)+1至第n sb*(P*N tx)个元素组成的列向量。
此后，网络设备根据与R个传输层对应的R个空频矩阵，确定与第N sb个子带对应的预编码矩阵。
基于上文列举的方法，网络设备可以得到与R个传输层对应的R个空频矩阵。每个空频矩阵包括了与N sb个子带对应的一个列向量。网络设备可以将每个空频矩阵中与第n sb个子带对应的列向量抽取出来，得到R个与第n sb个子带对应的列向量，每个列向量的维度可以是(P*N tx)*1。该R个列向量组合后可得到维度为(P*N tx)*R的矩阵，该矩阵即与第n sb个子带对应的预编码矩阵。
如前所述，空频矩阵可以为维度为(P*N tx)*N sb的矩阵，也可以为维度为(P*N tx*N sb)*1的列向量。网络设备可以基于不同的形式确定各传输层上与各子带对应的列向量，进而确定与各子带对应的预编码矩阵。
若空频矩阵为维度为(P*N tx)*N sb的矩阵，则该矩阵中的N sb个列向量与N sb个子带一一对应。网络设备可以将R个空频矩阵中每个空频矩阵的第n sb列抽取出来，得到R个维度为(P*N tx)*1的列向量，将该R个列向量按照传输层由1至R的顺序从左到右依次排列，并进行归一化处理后，可以得到维度为(P*N tx)*R的矩阵，该矩阵也就是与第n sb个子带对应的预编码矩阵。其中，归一化处理可以通过对R个列向量中每个列向量的各元素乘以每列的归一化系数，以使得各元素的功率之和等于1，并可通过对R个列向量乘以整体的归一化系数，以使得各列向量的功率之和等于1。本申请对于归一化处理的具体方法不做限定。
若空频矩阵为(P*N tx*N sb)*1的列向量，则该列向量中的每P*N tx个连续的元素对应了一个子带。网络设备可以按照该N tx*N sb个元素的排布顺序，将每P*N tx个连续的元素作为一列，可以抽取出N sb个列，将该N sb个列按照传输层由1至R的顺序从左到右依次排列，可以得到维度为(P*N tx)*N sb的矩阵，该矩阵中的N sb个列向量与N sb个子带一一对应。此后，网络设备可以按照上文所描述的方法恢复出与第n sb个子带对应的预编码矩阵。
将n sb在1至N sb中遍历取值，重复执行以上操作，网络设备便可以恢复出与N sb个子带对应的预编码矩阵。
应理解，上文列举的网络设备恢复出预编码矩阵的方法仅为一种可能的实现方式，而不应对本申请构成任何限定。例如，空频矩阵作为恢复预编码矩阵的一个中间值，有可能并未生成。本申请对于网络设备基于PMI恢复出预编码矩阵的具体实现方式不做限定。
基于上述方法，终端设备可以将频域上各子带的理想预编码矩阵中的各个列向量通过空域的波束向量的线性组合来表征，并将各波束向量线性组合时使用的加权系数通过若干 个频域基向量的线性组合来描述。其中，每个频域基向量可以用于表示多个子带上的一种变化规律。因此，可以通过对若干个频域基向量进行不同的线性组合来描述各子带的空域列向量的组合系数的变化规律。由于通过多个频域基向量来描述频域上不同的变化规律，充分挖掘了子带之间的关系，可利用频域的连续性，用较少的频域基向量描述全部子带的变化规律，从而对反馈开销进行压缩。与现有技术中的子带独立反馈的方式相比，可以大大减小子带反馈所带来的反馈开销，同时也能够保证type II码本的近似精度。
应理解，上文中仅为便于理解，以列向量作为波束向量和频域基向量的形式为例详细说明本申请实施例，但这不应对本申请构成任何限定，本申请并不排除波束向量和频域基向量为行向量的可能。本领域的技术人员基于相同的构思，经过数学变换或等价替换，仍然可以通过上述反馈方式来反馈PMI和确定预编码矩阵。
在这种情况下，上述第一向量集合可以包括以下至少一项：维度为N tx的2D-DFT向量、维度为N tx的2D-DFT向量的转置、维度为N tx的2D-DFT向量的共轭、维度为N tx的2D-DFT向量的共轭转置、维度为N tx的过采样2D-DFT向量、维度为N tx的过采样2D-DFT向量的转置、维度为N tx的过采样2D-DFT向量的共轭以及维度为N tx的过采样2D-DFT向量的共轭转置。该第一向量还可以包括2D-DFT向量的截断、2D-DFT向量的转置的截断、2D-DFT向量的共轭的截断、2D-DFT向量的共轭转置的截断、过采样2D-DFT向量的截断、过采样2D-DFT向量的转置的截断、维度为N tx的过采样2D-DFT向量的共轭的截断以及过采样2D-DFT向量的共轭转置的截断，且截断的维度可以为N tx。
上述第二向量集合可以包括以下至少一项：维度为N sb的DFT向量、维度为N sb的DFT向量的转置、维度为N sb的DFT向量的共轭、维度为N sb的DFT向量的共轭转置、维度为N sb的过采样DFT向量、维度为N sb的过采样DFT向量的转置、维度为N sb的过采样DFT向量的共轭以及维度为N sb的过采样DFT向量的共轭转置。第二向量集合还可以包括DFT向量的截断、DFT向量的转置的截断、DFT向量的共轭的截断、DFT向量的共轭转置的截断、过采样DFT向量的截断、过采样DFT向量的转置的截断、过采样DFT向量的共轭的截断以及过采样DFT向量的共轭转置的截断中的至少一项，且截断的维度可以为N sb。
因此，第一向量集合可以提供多个维度为N tx的波束向量，第二向量集合可以提供多个维度为N sb的频域基向量。
需要说明的是，上文提供的指示预编码矩阵的方法特别适用于子带数量多且子带连续的情况，该方法可以充分利用子带之间的相关性，对反馈开销进行压缩，减小了多个子带独立反馈带来的巨大开销。然而，在某些情况下，子带数量并不是很多，或者子带之间并不连续，若沿用现有的宽带反馈和子带反馈结合的方式来反馈PMI，可能并不会带来很大的反馈开销。并且在子带不连续的情况下，通过子带独立反馈的方式可以保证较高的近似精度。因此，本申请另提供一种指示预编码矩阵的方法，能够结合不同的场景，采用反馈模式反馈PMI，既能够保证近似精度，又节省了反馈开销。
下面结合图5详细说明本申请另一实施例提供的预编码矩阵的方法。
图5是从设备交互的角度示出的本申请另一实施例提供的指示预编码矩阵的示意性流程图。如图5所示，该方法400可以包括步骤410至步骤440。下面详细说明方法400中的各步骤。
在步骤410中，网络设备生成第三指示信息，该第三指示信息用于确定基于type II码本反馈PMI的反馈模式。
在本实施例中，基于type II码本反馈PMI的反馈模式可以包括至少两种，终端设备基于第三指示信息确定的反馈模式可以为第一反馈模式或第二反馈模式。其中，第一反馈模式为基于第一向量集合反馈PMI的模式，第二反馈模式为基于第一向量集合和第二向量集合反馈PMI的模式。
其中，上述第一向量集合可以包括以下至少一项：维度为N tx的2D-DFT向量、维度为N tx的2D-DFT向量的转置、维度为N tx的2D-DFT向量的共轭、维度为N tx的2D-DFT向量的共轭转置、维度为N tx的过采样2D-DFT向量、维度为N tx的过采样2D-DFT向量的转置、维度为N tx的过采样2D-DFT向量的共轭以及维度为N tx的过采样2D-DFT向量的共轭转置。该第一向量还可以包括2D-DFT向量的截断、2D-DFT向量的转置的截断、2D-DFT向量的共轭的截断、2D-DFT向量的共轭转置的截断、过采样2D-DFT向量的截断、过采样2D-DFT向量的转置的截断、维度为N tx的过采样2D-DFT向量的共轭的截断以及过采样2D-DFT向量的共轭转置的截断，且截断的维度可以为N tx。
上述第二向量集合可以包括以下至少一项：维度为N sb的DFT向量、维度为N sb的DFT向量的转置、维度为N sb的DFT向量的共轭、维度为N sb的DFT向量的共轭转置、维度为N sb的过采样DFT向量、维度为N sb的过采样DFT向量的转置、维度为N sb的过采样DFT向量的共轭以及维度为N sb的过采样DFT向量的共轭转置。第二向量集合还可以包括DFT向量的截断、DFT向量的转置的截断、DFT向量的共轭的截断、DFT向量的共轭转置的截断、过采样DFT向量的截断、过采样DFT向量的转置的截断、过采样DFT向量的共轭的截断以及过采样DFT向量的共轭转置的截断中的至少一项，且截断的维度可以为N sb。
在本实施例中，第一向量集合可以提供多个空域的波束向量，第二向量集合可以提供多个频域基向量。作为一种可能的实现方式，该第一反馈模式例如可以是NR协议TS38.214版本15(Release 15，R15)中定义的type II码本的反馈模式，具体可以是宽带反馈和子带独立反馈结合的反馈模式。该第二反馈模式例如可以是上文中结合方法300描述的反馈模式，相比于第一反馈模式而言，该第二反馈模式可以理解为宽带反馈和子带联合反馈结合的反馈模式。基于上文中的描述可以看到，第二反馈模式基于频域的连续性，利用子带之间的关系，将多个子带联合反馈，相比于第一反馈模式来说，大大减小了反馈开销。
在本实施例中，该第三指示信息可以用于指示以下任意一项信息：
a)PMI的反馈模式；或
b)待上报的子带的数量和位置；或
c)频域列向量的个数K。
当该第三指示信息用于指示a)时，即网络设备通过该第三指示信息直接指示PMI的反馈模式。
当该第三指示信息用于指示b)时，该第三指示信息可以复用现有的信令。在信道测量过程中，网络设备可以通过参数配置信息向终端设备指示待上报的子带的数量以及在频带中的位置。待上报的子带的数量和/或位置可用于确定PMI的反馈模式。当该第三指示信息用于指示c)时，该第三指示信息可以与上文所描述的第一指示信息为同一信息。频 域列向量的个数可以等于频域基向量的个数。若频域基向量的个数K为0可用于隐式地指示采用第一反馈模式，频域列向量的个数K大于0可用于隐式地指示采用第二反馈模式。
在步骤420中，网络设备发送该第三指示信息。相应地，终端设备接收该第三指示信息。
作为示例而非限定，该第三指示信息可以携带在RRC消息、MAC CE或者DCI中。终端设备可以根据该第三指示信息，确定PMI的反馈模式。
在步骤430中，终端设备基于第三指示信息，确定反馈模式，并基于反馈模式确定PMI。
可选地，步骤430具体包括：
步骤4301，终端设备可以基于第三指示信息，确定反馈模式；
步骤4302，终端设备基于反馈模式确定PMI。
下面详细说明步骤4301。
若终端接收到的第三指示信息为上文所描述的a)，终端设备便可以根据该第三指示信息所指示的反馈模式确定PMI。
若终端设备接收到的第三指示信息为上文所描述的b)，终端设备可以根据该第三指示信息所指示的子带的数量和/或位置，基于预设规则确定PMI的反馈模式。在这种情况下，网络设备也可以基于相同的预设规则确定PMI的反馈模式，以便基于所确定的反馈模式，根据终端设备后续反馈的PMI恢复出预编码矩阵。
在一种实现方式中，待上报的子带例如可以通过位图来指示。例如，子带数为10，可采用10个比特与该10个子带一一对应。待上报的子带所对应的比特位可以置“1”，不上报的子带所对应的比特位可以置“0”；或者，待上报的子带所对应的比特位可以置“0”，不上报的子带所对应的比特位可以置“1”。本申请对此不作限定。
应理解，通过位图来指示待上报的子带仅为一种可能的实现方式，不应对本申请构成任何限定，本申请对于网络设备指示待上报的子带的具体方式不作限定。例如，网络设备也可以直接向终端设备指示待上报的子带的编号等。
可选地，该预设规则是：待上报的子带数小于预设的第一阈值时，采用第一反馈模式；待上报的子带数大于或等于该第一阈值时，采用第二反馈模式。
即，当待上报的子带数较少时，子带独立反馈带来的反馈开销较小，可以采用第一反馈模式；当待上报的子带数较多时，子带独立反馈带来的反馈开销较大，可以采用第二反馈模式。
其中，该第一阈值可以是网络设备预先配置给终端设备的，也可以是预先定义的，如协议定义，还可以是终端设备确定并上报给网络设备的，本申请对此不作限定。
可选地，该预设规则是：待上报的子带数大于或等于预定义的门限时，采用第二反馈模式；待上报的子带数小于预定义的门限时，采用第一反馈模式。
由于待上报的子带数较多时，通过子带独立反馈可能会带来较大的反馈开销，因此可以采用第二反馈模式来减小反馈开销。
例如，该预定义的门限可以是协议定义的，可以是固定不变的，也可以随子带的总数变化，协议可以定义不同的子带数所对应的门限值。如，子带数为10，门限值为5。即，总共10个子带，待上报的子带数大于或等于5时；采用第二反馈模式，待上报的子带数 小于5时，采用第一反馈模式；又如，子带数为20，门限值为10。即，总共20个子带，待上报的子带数大于或等于10时，采用第二反馈模式；待上报的子带数小于10时，采用第一反馈模式。
可选地，该预设规则是：待上报的子带不连续时，采用第一反馈模式；待上报的子带连续时，采用第二反馈模式。
即，当待上报的子带在频域上不连续时，通过第二反馈模式反馈的PMI恢复出来的预编码矩阵的近似精度可能低于第一反馈模式，因此可以优先采用第一反馈模式；当待上报的子带在频域上连续时，通过第二反馈模式反馈的PMI恢复出来的预编码矩阵的近似精度可能与第一反馈模式基本相同，因此，可以采用反馈开销较小的第二反馈模式。
当待上报的子带用位图来指示，且用“1”指示待上报的子带，用“0”指示不上报的子带时，若位图中多个连续的比特位为“1”，且任意两个连续的“1”之间不存在“0”，则认为待上报的子带连续。若位图中相邻的两个“1”中间存在“0”，则认为待上报的子带不连续。
可选地，该预设规则是：待上报的子带不连续，但在频域上呈规律排布时，采用第二反馈模式；待上报的子带不连续，且在频域上排布无规律时，采用第一反馈模式。
例如，若待上报的子带不连续，但在频域上规律排布，如，相邻的两个待上报的子带中间间隔有一个或更多个子带；又如，待上报的子带的编号均为奇数或均为偶数。在这种情况下，可以采用第二反馈模式。否则，可以采用第一反馈模式。
其中，待上报的子带是否连续可以通过以下方式来判断。
可选地，该预设规则是：待上报的子带数量大于或等于第一阈值，且待上报的子带连续时，采用第二反馈模式；否则采用第一反馈模式。
即，当待上报的子带数较多且在频域上连续时，可以优先采用反馈开销较小的第二反馈模式。当待上报的子带数较少时，由于子带独立反馈带来的反馈开销也并不大，因此可以采用第一反馈模式。当待上报的子带数在频域上不连续时，通过第二反馈模式反馈的PMI恢复出来的预编码矩阵的近似精度可能低于第一反馈模式，因此可以采用第一反馈模式。
图6示出了待上报的子带在频域上分布的几种可能的情况。如图所示，每个方格可代表一个子带，其中带阴影的子带表示待上报的子带。在情况1中，多个待上报的子带在频域上连续分布，且待上报的子带数量较多，因此，可以采用上述第二反馈模式反馈PMI。在情况2中，待上报的子带数量很少，对每个子带独立反馈并不会带来太大的反馈开销，因此可以采用第一反馈模式。在情况3中，待上报的子带在频域上不连续，并且无规律，因此可以采用第一反馈模式反馈PMI。
应理解，这里仅为便于理解，以图6示出的几种情况为例，说明了在此预设规则下确定反馈模式的方法，但这不应对本申请构成任何限定。当预设规则不同时，基于相同的情况确定的反馈模式也可能略有不同。
可选地，该预设规则是：待上报的子带为全带时，采用第二反馈模式；否则采用第一反馈模式。
当待上报的子带为全带时，也就是待上报的子带在频域上连续，并且待上报的子带的数量可能比较多。此时，可以利用子带之间的关系，采用第二反馈模式反馈PMI。当待上报的子带表示全带时，则待上报的子带可能在频域上不连续，或者数量较少，此时可以采 用第一反馈模式反馈PMI。
应理解，上文中列举的预设规则仅为便于理解而示例，不应对本申请构成任何限定。当协议默认采用上述某一项预设规则确定PMI的反馈模式时，网络设备和终端设备可以基于相应的预设规则确定PMI的反馈模式来反馈PMI和恢复预编码矩阵。
当该第三指示信息用于指示c)时，该第三指示信息可以用于隐式地指示采用第一反馈模式还是二反馈模式来确定PMI。具体地，当该第三指示信息指示K的值为0时，则表示不需要确定频域基向量，也就可以理解为基于第一反馈模式来确定PMI；当该第三指示信息指示K的值大于0时，则表示需要确定频域基向量，也就可以理解为基于第二反馈模式来确定PMI。应理解，上文中列举的第一反馈模式和第二反馈模式仅为一种可能的实现方式，而不应对本申请构成任何限定。例如，第二反馈模式还可以是宽带反馈和部分子带独立反馈结合的反馈模式，如，仅基于序号为奇数的子带或仅基于序号为偶数的子带做反馈。也就是说，第二反馈模式可以仅反馈部分子带的幅度系数和相位系数。与此相对地，第一反馈模式可以是对全部子带的幅度系数和相位系数分别做独立反馈。只要第一反馈模式的反馈开销大于第二反馈模式的反馈开销，网络设备和终端设备基于相同的方式确定PMI的反馈模式，均应落入本申请的保护范围内。
还应理解，当第三指示信息为c)时，该第二反馈模式具体可以是上文方法300中所描述的反馈模式。
步骤4302中，终端设备基于反馈模式确定PMI的具体过程可以包括终端设备基于第一反馈模式确定PMI，或者终端设备基于第二反馈模式确定PMI。
其中，终端设备基于第一反馈模式确定PMI的具体过程可以参考现有技术中type II码本的反馈方式，为了简洁，这里不再赘述。
终端设备基于第二反馈模式确定PMI的具体过程可以参考上文中对方法300的具体说明，为了简洁，这里不再赘述。
在步骤440中，终端设备发送PMI。相应地，网络设备接收PMI。
应理解，步骤440的具体过程与上文方法300中的步骤350的具体过程相同，为了简洁，这里不再赘述。
基于上述方法，终端设备可以基于网络设备的指示，或者，基于待上报的子带的数量和/或位置，确定反馈模式，可以在某些情况下采用反馈开销较小的反馈模式来反馈PMI。例如，在待上报的子带数较多或连续性较好的情况下，通过反馈开销较小的反馈模式来反馈PMI，既可以保证较高的近似精度，同时也可以减小反馈开销。通过引入多种反馈模式以适用于不同的测量情况，可以兼顾反馈精度和反馈开销，从而在两者间获得平衡。此外，本申请所提供的第二反馈模式，可以很好地兼容现有的反馈模式，对现有的协议改动小，易于实现。
以上，结合图2至图6详细说明了本申请实施例提供的指示和确定预编码矩阵的方法。以下，结合图7至图9详细说明本申请实施例提供的通信装置。
图7是本申请实施例提供的通信装置的示意性框图。如图7所示，该通信装置500可以包括收发单元510和处理单元520。
在一种可能的设计中，该通信装置500可对应于上文方法实施例中的终端设备，例如，可以为终端设备，或者配置于终端设备中的芯片。
具体地，该通信装置500可对应于根据本申请实施例的方法300或400中的终端设备，该通信装置500可以包括用于执行图3中的方法300或图5中的方法400中的终端设备执行的方法的单元。并且，该通信装置500中的各单元和上述其他操作和/或功能分别为了实现图3中的方法300或图5中的方法400的相应流程。
其中，当该通信装置500用于执行图3中的方法300时，收发单元510可用于执行方法300中的步骤320至步骤350，处理单元520可用于执行方法300中的步骤310。
具体地，该处理单元520用于确定PMI，所述PMI包括与R个传输层对应的R组空频信息，所述R组空频信息用于确定各子带的预编码矩阵，所述R组空频信息中的第r组空频信息用于指示：
与第r个传输层对应的P*L个空域向量；
与所述第r个传输层对应的K个频域向量；以及
与所述第r个传输层对应的P*L*K个系数；
其中，所述P*L个空域向量由P个极化方向中每个极化方向上的L个波束向量及其宽带幅度系数确定，所述P*L*K个系数中的每个系数用于指示P*L个空域向量中的一个空域向量与K个频域向量中的一个频域向量间的向量运算结果的线性叠加系数；R为传输层数，P为极化方向数，且R、r、P、L和K均为正整数；
该收发单元510可用于发送所述PMI。
可选地，所述空域向量是维度为(P*N tx)*1的列向量，所述频域向量是维度为N sb*1的列向量，所述向量运算结果包括：所述空域向量与所述频域向量的共轭转置的乘积，或，所述频域向量的共轭与所述空域向量的克罗内克尔积，其中，N tx为每个极化方向的天线端口数，N sb为待上报的子带数，1≤L≤N tx，1≤K≤N sb，且N tx和N sb均为正整数。
可选地，所述L个波束向量取自预定义的第一向量集合中的一个子集，所述PMI还包括所述第一子集的指示信息，所述第一子集的指示信息用于指示所述第一子集中的各向量在所述第一向量集合中的位置。
可选地，所述K个频域向量取自取自预定义的第二向量集合中的第二子集，所述PMI还包括所述第二子集的指示，所述第二子集的指示信息用于指示所述第二子集中的各向量在所述第二向量集合中的位置。
可选地，所述收发单元510还用于接收第一指示信息，所述第一指示信息用于指示K的取值。
可选地，所述收发单元510还用于接收第二指示信息，所述第二指示信息用于指示L的取值。
当该通信装置500用于执行图5中的方法400时，收发单元510可用于执行方法400中的步骤420和步骤440，处理单元520可用于执行方法400中的步骤430。
具体地，收发单元510可用于接收第三指示信息，所述第三指示信息用于确定基于类型二type II码本反馈预编码矩阵指示PMI的反馈模式，所述反馈模式为第一反馈模式或第二反馈模式，所述第一反馈模式是基于第一向量集合反馈PMI的模式，所述第二反馈模式是基于所述第一向量集合和第二向量集合反馈PMI的模式，所述第一向量集合包括多个维度为N tx的向量，所述第二向量集合包括多个维度为N sb的向量，其中，N tx为每个极化方向上发射天线的端口数，N sb为待上报的子带数，N tx和N sb均为正整数；
处理单元520可用于基于所述反馈模式，确定并发送所述PMI。
可选地，所述第三指示信息包括所述PMI的反馈模式的指示信息。
可选地，所述第三指示信息用于指示所述待上报的子带的数量和位置；以及
所述方法还包括：
基于待上报的子带的数量和/或所述待上报的子带的位置，根据预设规则确定所述PMI的反馈模式。
可选地，所述第三指示信息携带在无线资源控制RRC消息中。
可选地，当所述反馈模式为所述第二反馈模式时，所述PMI包括与R个传输层对应的R组空频信息，所述R组空频信息用于确定与各子带对应的预编码矩阵，所述R组空频信息中的第r组空频信息用于指示：
与第r个传输层对应的P*L个空域向量；
与所述第r个传输层对应的K个频域向量；以及
与所述第r个传输层对应的P*L*K个系数；
其中，所述P*L个空域向量由P个极化方向中每个极化方向上的L个波束向量及其宽带幅度系数确定，所述P*L*K个系数中的每个系数用于指示P*L个空域向量中的一个空域向量与K个频域向量中的一个频域向量间的向量运算的线性叠加系数；所述L个波束向量由所述第一向量集合确定，所述K个频域向量由所述第二向量集合确定，R为传输层数，P为极化方向数，且R、r、P、L和K均为正整数。
应理解，各单元执行上述相应步骤的具体过程在上述方法实施例中已经详细说明，为了简洁，在此不再赘述。
应理解，该通信装置500中的收发单元可对应于图8中示出的终端设备600中的收发器602，该通信装置500中的处理单元520可对应于图8中示出的终端设备600中的处理器601。
在另一种可能的设计中，该通信装置500可对应于上文方法实施例中的网络设备，例如，可以为网络设备，或者配置于网络设备中的芯片。
具体地，该通信装置500可对应于根据本申请实施例的方法300或400中的网络设备，该通信装置500可以包括用于执行图3中的方法300或图5中的方法400中的网络设备执行的方法的单元。并且，该通信装置500中的各单元和上述其他操作和/或功能分别为了实现图3中的方法300或图5中的方法400的相应流程。
其中，当该通信装置500用于执行图3中的方法300时，收发单元510可用于执行方法300中的步骤320至步骤350，处理单元520可用于执行方法300中的步骤360。
具体地，收发单元510可用于接收预编码矩阵指示PMI，所述PMI包括与R个传输层对应的R组空频信息，所述R组空频信息中的第r组空频信息用于指示：
与第r个传输层对应的P*L个空域向量；
与所述第r个传输层对应的K个频域向量；以及
与所述第r个传输层对应的P*L*K个系数；
其中，所述P*L个空域向量由P个极化方向中每个极化方向上的L个波束向量及其宽带幅度系数确定，所述P*L*K个系数中的每个系数用于指示P*L个空域向量中的一个空域向量与K个频域向量中的一个频域向量间的向量运算结果的线性叠加系数；R为传输 层数，P为极化方向数，且R、r、P、L和K均为正整数；
处理单元520可用于基于所述R组空频信息确定各子带的预编码矩阵。
可选地，所述空域向量是维度为(P*N tx)*1的列向量，所述频域向量是维度为N sb*1的列向量，所述向量运算结果包括：所述空域向量与所述频域向量的共轭转置的乘积，或，所述频域向量的共轭与所述空域向量的克罗内克尔积，其中，N tx为每个极化方向的天线端口数，N sb为待上报的子带数，1≤L≤N tx，1≤K≤N sb，且N tx和N sb均为正整数。
可选地，所述L个波束向量取自预定义的第一向量集合中的一个子集，所述PMI还包括所述第一子集的指示信息，所述第一子集的指示信息用于指示所述第一子集中的各向量在所述第一向量集合中的位置。
可选地，所述K个频域向量取自取自预定义的第二向量集合中的第二子集，所述PMI还包括所述第二子集的指示，所述第二子集的指示信息用于指示所述第二子集中的各向量在所述第二向量集合中的位置。
可选地，所述收发单元510还用于发送第一指示信息，所述第一指示信息用于指示K的取值。
可选地，所述收发单元510还用于发送第二指示信息，所述第二指示信息用于指示L的取值。
可选地，所述空域向量是维度为(P*N tx)*1的列向量，所述频域向量是维度为N sb*1的列向量，所述极化方向数为1。所述处理单元520具体用于在1至N sb中对n sb遍历取值，重复执行以下操作，以得到与各子带对应的预编码矩阵：
在1至R中对r遍历取值，重复执行以下操作确定第n sb个子带的预编码矩阵：基于所述R组空频信息中的第r组空频信息所指示的P*L个空域向量、所述K个频域向量以及所述P*L*K个系数，确定所述第r个传输层中的第n sb个子带的预编码向量
Figure PCTCN2019099351-appb-000065
Figure PCTCN2019099351-appb-000066
其中，v l表示与所述第r个传输层对应的L个波束向量中的第l个波束向量，
Figure PCTCN2019099351-appb-000067
表示v l的幅度系数的量化值，
Figure PCTCN2019099351-appb-000068
表示与所述第r个传输层对应的K个频域向量中的第k个频域向量中的第n sb个元素，
Figure PCTCN2019099351-appb-000069
表示
Figure PCTCN2019099351-appb-000070
的共轭，
Figure PCTCN2019099351-appb-000071
表示与所述P*L个空域向量中的第l个空域向量和所述K个频域向量中的第k个频域向量对应的线性叠加系数的幅度的量化值，
Figure PCTCN2019099351-appb-000072
表示与所述P*L个空域向量中的第l个空域向量和所述K个频域向量中的第k个频域向量对应的线性叠加系数的相位的量化值，l、k均为正整数。
可选地，所述空域向量是维度为(P*N tx)*1的列向量，所述频域向量是维度为N sb*1的列向量，所述极化方向数为2。所述处理单元520具体用于在1至N sb中对n sb遍历取值，重复执行以下操作，以得到与各子带对应的预编码矩阵：
在1至R中对r遍历取值，重复执行以下操作确定第n sb个子带的预编码矩阵：基于所述R组空频信息中的第r组空频信息所指示的P*L个空域向量、所述K个频域向量以及所述P*L*K个系数，确定所述第r个传输层中的第n sb个子带的预编码向量
Figure PCTCN2019099351-appb-000073
Figure PCTCN2019099351-appb-000074
其中，v l表示与所述第r个传输层对应的L个波束向量中的第l个波束向量，
Figure PCTCN2019099351-appb-000075
表示第一极化方向上的v l的幅度系数的量化值，
Figure PCTCN2019099351-appb-000076
表示第二极化方向上的v l的幅度系数的量化值，u r,k,j表示与所述第r个传输层对应的K个频域向量中的第k个频域向量中的第n sb个元素，
Figure PCTCN2019099351-appb-000077
表示
Figure PCTCN2019099351-appb-000078
的共轭，
Figure PCTCN2019099351-appb-000079
表示所述第一极化方向上的L个空域向量中的第l个空域向量和所述K个频域向量中的第k个频域向量对应的线性叠加系数的幅度的量化值，
Figure PCTCN2019099351-appb-000080
表示所述第二极化方向上的L个空域向量中的第l个空域向量和所述K个频域向量中的第k个频域向量对应的线性叠加系数的幅度的量化值，
Figure PCTCN2019099351-appb-000081
表示所述第一极化方向上的L个空域向量中的第l个空域向量和所述K个频域向量中的第k个频域向量对应的线性叠加系数的相位的量化值，
Figure PCTCN2019099351-appb-000082
表示所述第二极化方向上的L个空域向量中的第l个空域向量和所述K个频域向量中的第k个频域向量对应的线性叠加系数的相位的量化值，l、k均为正整数。
当该通信装置500用于执行图5中的方法400时，收发单元510用于执行方法400中的步骤420和步骤440，处理单元520可用于执行方法400中的步骤410。
具体地，处理单元520可用于生成第三指示信息，所述第三指示信息用于确定基于类型二type II码本反馈预编码矩阵指示PMI的反馈模式，所述反馈模式为第一反馈模式或第二反馈模式，所述第一反馈模式是基于第一向量集合反馈PMI的模式，所述第二反馈模式是基于所述第一向量集合和第二向量集合反馈PMI的模式，所述第一向量集合包括多个维度为N tx的向量，所述第二向量集合包括多个维度为N sb的向量，其中，N tx为每个极化方向上发射天线的端口数，N sb为待上报的子带数，N tx和N sb均为正整数；
收发单元510可用于发送所述第三指示信息；并可用于接收所述PMI，所述PMI基于所述反馈模式确定。
可选地，所述第三指示信息包括所述PMI的反馈模式的指示信息。
可选地，所述第三指示信息用于指示所述待上报的子带的数量和位置；以及
所述方法还包括：
基于待上报的子带的数量和/或所述待上报的子带的位置，根据预设规则确定所述PMI的反馈模式。
可选地，所述第三指示信息携带在无线资源控制RRC消息中。
可选地，当所述反馈模式为所述第二反馈模式时，所述PMI包括与R个传输层对应的R组空频信息，所述R组空频信息用于确定与各子带对应的预编码矩阵，所述R组空频信息中的第r组空频信息用于指示：
与第r个传输层对应的P*L个空域向量；
与所述第r个传输层对应的K个频域向量；以及
与所述第r个传输层对应的P*L*K个系数；
其中，所述P*L个空域向量由P个极化方向中每个极化方向上的L个波束向量及其宽带幅度系数确定，所述P*L*K个系数中的每个系数用于指示P*L个空域向量中的一个 空域向量与K个频域向量中的一个频域向量间的向量运算的线性叠加系数；所述L个波束向量由所述第一向量集合确定，所述K个频域向量由所述第二向量集合确定，R为传输层数，P为极化方向数，且R、r、P、L和K均为正整数。
应理解，各单元执行上述相应步骤的具体过程在上述方法实施例中已经详细说明，为了简洁，在此不再赘述。
还应理解，该通信装置500中的收发单元510可对应于图9中示出的网络设备700中的收发器720，该通信装置500中的处理单元520可对应于图9中示出的网络设备700中的处理器710。
图8是本申请实施例提供的终端设备600的结构示意图。如图所示，该终端设备600包括处理器601和收发器602。可选地，该终端设备500还包括存储器603。其中，处理器601、收发器602和存储器603之间可以通过内部连接通路互相通信，传递控制和/或数据信号，该存储器603用于存储计算机程序，该处理器601用于从该存储器603中调用并运行该计算机程序，以控制该收发器602收发信号。可选地，终端设备500还可以包括天线504，用于将收发器602输出的上行数据或上行控制信令通过无线信号发送出去。
上述处理器601和存储器603可以合成一个处理装置，处理器601用于执行存储器603中存储的程序代码来实现上述功能。具体实现时，该存储器603也可以集成在处理器601中，或者独立于处理器601。
可选地，当存储器603中存储的程序指令被处理器601执行时，该处理器601用于确定PMI，并用于控制收发器602发送PMI。
其中，该PMI包括与R个传输层对应的R组空频信息，该R组空频信息用于确定各子带的预编码矩阵。该R组空频信息中的第r组空频信息用于指示：
与第r个传输层对应的P*L个空域向量；
与第r个传输层对应的K个频域向量；以及
与第r个传输层对应的P*L*K个系数。
其中，P*L个空域向量由P个极化方向中每个极化方向上的L个波束向量及其宽带幅度系数确定，P*L*K个系数中的每个系数用于指示P*L个空域向量中的一个空域向量与K个频域向量中的一个频域向量间的向量运算结果的线性叠加系数；R为传输层数，P为极化方向数，且R、r、P、L和K均为正整数。
可选地，当存储器603中存储的程序指令被处理器601执行时，该处理器601用于控制收发器602接收第三指示信息；并用于基于反馈模式确定并发送PMI。该第三指示信息用于确定基于type II码本反馈预编码矩阵指示PMI的反馈模式，该反馈模式为第一反馈模式或第二反馈模式，该第一反馈模式是基于第一向量集合反馈PMI的模式，该第二反馈模式是基于第一向量集合和第二向量集合反馈PMI的模式。其中，第一向量集合包括多个维度为N tx的向量，第二向量集合包括多个维度为N sb的向量，N tx为每个极化方向上发射天线的端口数，N sb为待上报的子带数，N tx和N sb均为正整数。
具体地，该终端设备600可对应于根据本申请实施例的方法300或400中的终端设备，该终端设备600可以包括用于执行图3中的方法300或图5中的方法400中的终端设备执行的方法的单元。并且，该终端设备600中的各单元和上述其他操作和/或功能分别为了实现图3中的方法300或图5中的方法400的相应流程。
上述处理器601可以用于执行前面方法实施例中描述的由终端设备内部实现的动作，而收发器602可以用于执行前面方法实施例中描述的终端设备向网络设备发送或从网络设备接收的动作。具体请见前面方法实施例中的描述，此处不再赘述。
可选地，上述终端设备600还可以包括电源605，用于给终端设备中的各种器件或电路提供电源。
除此之外，为了使得终端设备的功能更加完善，该终端设备600还可以包括输入单元606、显示单元607、音频电路608、摄像头609和传感器610等中的一个或多个，所述音频电路还可以包括扬声器6082、麦克风6084等。
图9是本申请实施例提供的网络设备700的结构示意图。如图所示，该网络设备700包括处理器710和收发器720。可选地，该网络设备700还包括存储器730。其中，处理器710、收发器720和存储器730之间通过内部连接通路互相通信，传递控制和/或数据信号，该存储器730用于存储计算机程序，该处理器710用于从该存储器730中调用并运行该计算机程序，以控制该收发器720收发信号。
上述处理器710和存储器730可以合成一个处理装置，处理器710用于执行存储器730中存储的程序代码来实现上述功能。具体实现时，该存储器730也可以集成在处理器710中，或者独立于处理器710。
上述网络设备700还可以包括天线740，用于将收发器720输出的下行数据或下行控制信令通过无线信号发送出去。
可选地，当存储器730中存储的程序指令被处理器710执行时，该处理器710用于控制收发器720接收PMI，该PMI包括与R个传输层对应的R组空频信息；并用于基于该R组空频信息确定各子带的预编码矩阵。该R组空频信息中的第r组空频信息用于指示：
与第r个传输层对应的P*L个空域向量；
与第r个传输层对应的K个频域向量；以及
与第r个传输层对应的P*L*K个系数。
其中，P*L个空域向量由P个极化方向中每个极化方向上的L个波束向量及其宽带幅度系数确定，P*L*K个系数中的每个系数用于指示P*L个空域向量中的一个空域向量与K个频域向量中的一个频域向量间的向量运算结果的线性叠加系数；R为传输层数，P为极化方向数，且R、r、P、L和K均为正整数。
可选地，当存储器730中存储的程序指令被处理器710执行时，该处理器710用于生成第三指示信息；并用于控制收发器720发送该第三指示信息。该第三指示信息用于确定基于type II码本反馈预编码矩阵指示PMI的反馈模式，该反馈模式为第一反馈模式或第二反馈模式，该第一反馈模式是基于第一向量集合反馈PMI的模式，该第二反馈模式是基于第一向量集合和第二向量集合反馈PMI的模式。其中，第一向量集合包括多个维度为N tx的向量，第二向量集合包括多个维度为N sb的向量。N tx为每个极化方向上发射天线的端口数，N sb为待上报的子带数，N tx和N sb均为正整数。
具体地，该网络设备700可对应于根据本申请实施例的方法300或400中的网络设备，该网络设备700可以包括用于执行图3中的方法300或图5中的方法400中的网络设备执行的方法的单元。并且，该网络设备700中的各单元和上述其他操作和/或功能分别为了实现图3中的方法300或图5中的方法400的相应流程，各单元执行上述相应步骤的具体 过程在上述方法实施例中已经详细说明，为了简洁，在此不再赘述。
上述处理器710可以用于执行前面方法实施例中描述的由网络设备内部实现的动作，而收发器720可以用于执行前面方法实施例中描述的网络设备向终端设备发送或从终端设备接收的动作。具体请见前面方法实施例中的描述，此处不再赘述。
应理解，本申请实施例中的处理器可以为中央处理单元(central processing unit，CPU)，该处理器还可以是其他通用处理器、数字信号处理器(digital signal processor，DSP)、专用集成电路(application specific integrated circuit，ASIC)、现成可编程门阵列(field programmable gate array，FPGA)或者其他可编程逻辑器件、分立门或者晶体管逻辑器件、分立硬件组件等。
还应理解，本申请实施例中的存储器可以是易失性存储器或非易失性存储器，或可包括易失性和非易失性存储器两者。其中，非易失性存储器可以是只读存储器(read-only memory，ROM)、可编程只读存储器(programmable ROM，PROM)、可擦除可编程只读存储器(erasable PROM，EPROM)、电可擦除可编程只读存储器(electrically EPROM，EEPROM)或闪存。易失性存储器可以是随机存取存储器(random access memory，RAM)，其用作外部高速缓存。通过示例性但不是限制性说明，许多形式的随机存取存储器(random access memory，RAM)可用，例如静态随机存取存储器(static RAM，SRAM)、动态随机存取存储器(DRAM)、同步动态随机存取存储器(synchronous DRAM，SDRAM)、双倍数据速率同步动态随机存取存储器(double data rate SDRAM，DDR SDRAM)、增强型同步动态随机存取存储器(enhanced SDRAM，ESDRAM)、同步连接动态随机存取存储器(synchlink DRAM，SLDRAM)和直接内存总线随机存取存储器(direct rambus RAM，DR RAM)。
根据本申请实施例提供的方法，本申请还提供一种计算机程序产品，该计算机程序产品包括：计算机程序代码，当该计算机程序代码在计算机上运行时，使得该计算机执行图3或图5所示实施例中的方法。
根据本申请实施例提供的方法，本申请还提供一种计算机可读介质，该计算机可读介质存储有程序代码，当该程序代码在计算机上运行时，使得该计算机执行图3或图5所示实施例中的方法。
根据本申请实施例提供的方法，本申请还提供一种系统，其包括前述的一个或多个终端设备以及一个或多个网络设备。
上述各个装置实施例中网络设备与终端设备和方法实施例中的网络设备或终端设备完全对应，由相应的模块或单元执行相应的步骤，例如通信单元(收发器)执行方法实施例中接收或发送的步骤，除发送、接收外的其它步骤可以由处理单元(处理器)执行。具体单元的功能可以参考相应的方法实施例。其中，处理器可以为一个或多个。
在本说明书中使用的术语“部件”、“模块”、“系统”等用于表示计算机相关的实体、硬件、固件、硬件和软件的组合、软件、或执行中的软件。例如，部件可以是但不限于，在处理器上运行的进程、处理器、对象、可执行文件、执行线程、程序和/或计算机。通过图示，在计算设备上运行的应用和计算设备都可以是部件。一个或多个部件可驻留在进程和/或执行线程中，部件可位于一个计算机上和/或分布在两个或更多个计算机之间。此外，这些部件可从在上面存储有各种数据结构的各种计算机可读介质执行。部件可例如 根据具有一个或多个数据分组(例如来自与本地系统、分布式系统和/或网络间的另一部件交互的二个部件的数据，例如通过信号与其它系统交互的互联网)的信号通过本地和/或远程进程来通信。
本领域普通技术人员可以意识到，结合本文中所公开的实施例描述的各示例的单元及算法步骤，能够以电子硬件、或者计算机软件和电子硬件的结合来实现。这些功能究竟以硬件还是软件方式来执行，取决于技术方案的特定应用和设计约束条件。专业技术人员可以对每个特定的应用来使用不同方法来实现所描述的功能，但是这种实现不应认为超出本申请的范围。
所属领域的技术人员可以清楚地了解到，为描述的方便和简洁，上述描述的系统、装置和单元的具体工作过程，可以参考前述方法实施例中的对应过程，在此不再赘述。
在本申请所提供的几个实施例中，应该理解到，所揭露的系统、装置和方法，可以通过其它的方式实现。例如，以上所描述的装置实施例仅仅是示意性的，例如，所述单元的划分，仅仅为一种逻辑功能划分，实际实现时可以有另外的划分方式，例如多个单元或组件可以结合或者可以集成到另一个系统，或一些特征可以忽略，或不执行。另一点，所显示或讨论的相互之间的耦合或直接耦合或通信连接可以是通过一些接口，装置或单元的间接耦合或通信连接，可以是电性，机械或其它的形式。
所述作为分离部件说明的单元可以是或者也可以不是物理上分开的，作为单元显示的部件可以是或者也可以不是物理单元，即可以位于一个地方，或者也可以分布到多个网络单元上。可以根据实际的需要选择其中的部分或者全部单元来实现本实施例方案的目的。
另外，在本申请各个实施例中的各功能单元可以集成在一个处理单元中，也可以是各个单元单独物理存在，也可以两个或两个以上单元集成在一个单元中。
在上述实施例中，各功能单元的功能可以全部或部分地通过软件、硬件、固件或者其任意组合来实现。当使用软件实现时，可以全部或部分地以计算机程序产品的形式实现。所述计算机程序产品包括一个或多个计算机指令(程序)。在计算机上加载和执行所述计算机程序指令(程序)时，全部或部分地产生按照本申请实施例所述的流程或功能。所述计算机可以是通用计算机、专用计算机、计算机网络、或者其他可编程装置。所述计算机指令可以存储在计算机可读存储介质中，或者从一个计算机可读存储介质向另一个计算机可读存储介质传输，例如，所述计算机指令可以从一个网站站点、计算机、服务器或数据中心通过有线(例如同轴电缆、光纤、数字用户线(digital subscriber line，DSL))或无线(例如红外、无线、微波等)方式向另一个网站站点、计算机、服务器或数据中心进行传输。所述计算机可读存储介质可以是计算机能够存取的任何可用介质或者是包含一个或多个可用介质集成的服务器、数据中心等数据存储设备。所述可用介质可以是磁性介质，(例如，软盘、硬盘、磁带)、光介质(例如，高密度数字视频光盘(digital video disc，DVD))、或者半导体介质(例如固态硬盘(solid state disk，SSD))等。
所述功能如果以软件功能单元的形式实现并作为独立的产品销售或使用时，可以存储在一个计算机可读取存储介质中。基于这样的理解，本申请的技术方案本质上或者说对现有技术做出贡献的部分或者该技术方案的部分可以以软件产品的形式体现出来，该计算机软件产品存储在一个存储介质中，包括若干指令用以使得一台计算机设备(可以是个人计算机，服务器，或者网络设备等)执行本申请各个实施例所述方法的全部或部分步骤。而 前述的存储介质包括：U盘、移动硬盘、只读存储器(read-only memory，ROM)、随机存取存储器(random access memory，RAM)、磁碟或者光盘等各种可以存储程序代码的介质。
以上所述，仅为本申请的具体实施方式，但本申请的保护范围并不局限于此，任何熟悉本技术领域的技术人员在本申请揭露的技术范围内，可轻易想到变化或替换，都应涵盖在本申请的保护范围之内。因此，本申请的保护范围应以所述权利要求的保护范围为准。

Claims (56)

  1. 一种指示预编码矩阵的方法，其特征在于，包括；
    确定预编码矩阵指示PMI，所述PMI包括与R个传输层对应的R组空频信息，所述R组空频信息用于确定各子带的预编码矩阵，所述R组空频信息中的第r组空频信息用于指示：
    与所述R个传输层中的第r个传输层对应的P*L个空域向量；
    与所述第r个传输层对应的K个频域向量；以及
    与所述第r个传输层对应的P*L*K个系数；
    其中，所述P*L个空域向量由P个极化方向中每个极化方向上的L个波束向量及其宽带幅度系数确定，所述P*L*K个系数中的每个系数用于指示所述P*L个空域向量中的一个空域向量与所述K个频域向量中的一个频域向量间的向量运算结果的线性叠加系数；R为传输层数，P为极化方向数，且R、r、P、L和K均为正整数；
    发送所述PMI。
  2. 如权利要求1所述的方法，其特征在于，所述空域向量是维度为(P*N tx)*1的列向量，所述频域向量是维度为N sb*1的列向量，所述向量运算结果包括：所述空域向量与所述频域向量的共轭转置的乘积，或，所述频域向量的共轭与所述空域向量的克罗内克尔积，其中，N tx为每个极化方向的天线端口数，N sb为待上报的子带数，1≤L≤N tx，1≤K≤N sb，且N tx和N sb均为正整数。
  3. 如权利要求1或2所述的方法，其特征在于，所述L个波束向量取自预定义的第一向量集合中的一个子集，所述PMI还包括所述第一子集的指示信息，所述第一子集的指示信息用于指示所述第一子集中的各向量在所述第一向量集合中的位置。
  4. 如权利要求1至3中任一项所述的方法，其特征在于，所述K个频域向量取自预定义的第二向量集合中的第二子集，所述PMI还包括所述第二子集的指示信息，所述第二子集的指示信息用于指示所述第二子集中的各向量在所述第二向量集合中的位置。
  5. 如权利要求1至4中任一项所述的方法，其特征在于，所述方法还包括：
    接收第一指示信息，所述第一指示信息用于指示K的取值。
  6. 如权利要求1至5中任一项所述的方法，其特征在于，所述方法还包括：
    接收第二指示信息，所述第二指示信息用于指示L的取值。
  7. 一种确定预编码矩阵的方法，其特征在于，包括：
    接收预编码矩阵指示PMI，所述PMI包括与R个传输层对应的R组空频信息，所述R组空频信息中的第r组空频信息用于指示：
    与所述R个传输层中的第r个传输层对应的P*L个空域向量；
    与所述第r个传输层对应的K个频域向量；以及
    与所述第r个传输层对应的P*L*K个系数；
    其中，所述P*L个空域向量由P个极化方向中每个极化方向上的L个波束向量及其宽带幅度系数确定，所述P*L*K个系数中的每个系数用于指示所述P*L个空域向量中的一个空域向量与所述K个频域向量中的一个频域向量间的向量运算结果的线性叠加系数； R为传输层数，P为极化方向数，且R、r、P、L和K均为正整数；
    基于所述R组空频信息确定各子带的预编码矩阵。
  8. 如权利要求7所述的方法，其特征在于，所述空域向量是维度为(P*N tx)*1的列向量，所述频域向量是维度为N sb*1的列向量，所述向量运算结果包括：所述空域向量与所述频域向量的共轭转置的乘积，或，所述频域向量的共轭与所述空域向量的克罗内克尔积，其中，N tx为每个极化方向的天线端口数，N sb为待上报的子带数，1≤L≤N tx，1≤K≤N sb，且N tx和N sb均为正整数。
  9. 如权利要求7或8所述的方法，其特征在于，所述L个波束向量取自预定义的第一向量集合中的一个子集，所述PMI还包括所述第一子集的指示信息，所述第一子集的指示信息用于指示所述第一子集中的各向量在所述第一向量集合中的位置。
  10. 如权利要求7至9中任一项所述的方法，其特征在于，所述K个频域向量取自预定义的第二向量集合中的第二子集，所述PMI还包括所述第二子集的指示信息，所述第二子集的指示信息用于指示所述第二子集中的各向量在所述第二向量集合中的位置。
  11. 如权利要求7至10中任一项所述的方法，其特征在于，所述方法还包括：
    发送第一指示信息，所述第一指示信息用于指示K的取值。
  12. 如权利要求7至11中任一项所述的方法，其特征在于，所述方法还包括：
    发送第二指示信息，所述第二指示信息用于指示L的取值。
  13. 如权利要求7至12中任一项所述的方法，其特征在于，所述空域向量是维度为(P*N tx)*1的列向量，所述频域向量是维度为N sb*1的列向量，所述极化方向数为1，以及
    所述根据所述R组空频信息确定与各子带对应的预编码矩阵，包括：
    在1至N sb中对n sb遍历取值，重复执行以下操作，以得到各子带的预编码矩阵：
    在1至R中对r遍历取值，重复执行以下操作确定第n sb个子带的预编码矩阵：基于所述R组空频信息中的第r组空频信息所指示的P*L个空域向量、所述K个频域向量以及所述P*L*K个系数，确定所述第r个传输层中的第n sb个子带的预编码向量
    Figure PCTCN2019099351-appb-100001
    Figure PCTCN2019099351-appb-100002
    其中，v l表示与所述第r个传输层对应的L个波束向量中的第l个波束向量，
    Figure PCTCN2019099351-appb-100003
    表示v l的幅度系数的量化值，
    Figure PCTCN2019099351-appb-100004
    表示与所述第r个传输层对应的K个频域向量中的第k个频域向量中的第n sb个元素，
    Figure PCTCN2019099351-appb-100005
    表示
    Figure PCTCN2019099351-appb-100006
    的共轭，
    Figure PCTCN2019099351-appb-100007
    表示与所述P*L个空域向量中的第l个空域向量和所述K个频域向量中的第k个频域向量对应的线性叠加系数的幅度的量化值，
    Figure PCTCN2019099351-appb-100008
    表示与所述P*L个空域向量中的第l个空域向量和所述K个频域向量中的第k个频域向量对应的线性叠加系数的相位的量化值，l、k均为正整数。
  14. 如权利要求7至12中任一项所述的方法，其特征在于，所述空域向量是维度为(P*N tx)*1的列向量，所述频域向量是维度为N sb*1的列向量，所述极化方向数为2，以及
    所述根据所述R组空频信息确定与各子带对应的预编码矩阵，包括：
    在1至N sb中对n sb遍历取值，重复执行以下操作，以得到与各子带对应的预编码矩阵：
    在1至R中对r遍历取值，重复执行以下操作确定第n sb个子带的预编码矩阵：基于 所述R组空频信息中的第r组空频信息所指示的P*L个空域向量、所述K个频域向量以及所述P*L*K个系数，确定所述第r个传输层中的第n sb个子带的预编码向量
    Figure PCTCN2019099351-appb-100009
    Figure PCTCN2019099351-appb-100010
    其中，v l表示与所述第r个传输层对应的L个波束向量中的第l个波束向量，
    Figure PCTCN2019099351-appb-100011
    表示第一极化方向上的v l的幅度系数的量化值，
    Figure PCTCN2019099351-appb-100012
    表示第二极化方向上的v l的幅度系数的量化值，u r,k,j表示与所述第r个传输层对应的K个频域向量中的第k个频域向量中的第n sb个元素，
    Figure PCTCN2019099351-appb-100013
    表示
    Figure PCTCN2019099351-appb-100014
    的共轭，
    Figure PCTCN2019099351-appb-100015
    表示所述第一极化方向上的L个空域向量中的第l个空域向量和所述K个频域向量中的第k个频域向量对应的线性叠加系数的幅度的量化值，
    Figure PCTCN2019099351-appb-100016
    表示所述第二极化方向上的L个空域向量中的第l个空域向量和所述K个频域向量中的第k个频域向量对应的线性叠加系数的幅度的量化值，
    Figure PCTCN2019099351-appb-100017
    表示所述第一极化方向上的L个空域向量中的第l个空域向量和所述K个频域向量中的第k个频域向量对应的线性叠加系数的相位的量化值，
    Figure PCTCN2019099351-appb-100018
    表示所述第二极化方向上的L个空域向量中的第l个空域向量和所述K个频域向量中的第k个频域向量对应的线性叠加系数的相位的量化值，l、k均为正整数。
  15. 一种指示预编码矩阵的方法，其特征在于，包括：
    接收第三指示信息，所述第三指示信息用于确定基于类型二type II码本反馈预编码矩阵指示PMI的反馈模式，所述反馈模式为第一反馈模式或第二反馈模式，所述第一反馈模式是基于第一向量集合反馈PMI的模式，所述第二反馈模式是基于所述第一向量集合和第二向量集合反馈PMI的模式，所述第一向量集合包括多个维度为N tx的向量，所述第二向量集合包括多个维度为N sb的向量，其中，N tx为每个极化方向上发射天线的端口数，N sb为待上报的子带数，N tx和N sb均为正整数；
    基于所述反馈模式，确定并发送所述PMI。
  16. 如权利要求15所述的方法，其特征在于，所述第三指示信息包括所述PMI的反馈模式的指示信息。
  17. 如权利要求15所述的方法，其特征在于，所述第三指示信息用于指示所述待上报的子带的数量和位置；以及
    所述方法还包括：
    基于所述待上报的子带的数量和/或所述待上报的子带的位置，根据预设规则确定所述PMI的反馈模式。
  18. 如权利要求15至17中任一项所述的方法，其特征在于，所述第三指示信息携带在无线资源控制RRC消息中。
  19. 如权利要求15至18中任一项所述的方法，其特征在于，当所述反馈模式为所述第二反馈模式时，所述PMI包括与R个传输层对应的R组空频信息，所述R组空频信息用于确定与各子带对应的预编码矩阵，所述R组空频信息中的第r组空频信息用于指示：
    与第r个传输层对应的P*L个空域向量；
    与所述第r个传输层对应的K个频域向量；以及
    与所述第r个传输层对应的P*L*K个系数；
    其中，所述P*L个空域向量由P个极化方向中每个极化方向上的L个波束向量及其宽带幅度系数确定，所述P*L*K个系数中的每个系数用于指示P*L个空域向量中的一个空域向量与K个频域向量中的一个频域向量间的向量运算的线性叠加系数；所述L个波束向量由所述第一向量集合确定，所述K个频域向量由所述第二向量集合确定，R为传输层数，P为极化方向数，且R、r、P、L和K均为正整数。
  20. 一种指示预编码矩阵的方法，其特征在于，包括：
    生成第三指示信息，所述第三指示信息用于确定基于类型二type II码本反馈预编码矩阵指示PMI的反馈模式，所述反馈模式为第一反馈模式或第二反馈模式，所述第一反馈模式是基于第一向量集合反馈PMI的模式，所述第二反馈模式是基于所述第一向量集合和第二向量集合反馈PMI的模式，所述第一向量集合包括多个维度为N tx的向量，所述第二向量集合包括多个维度为N sb的向量，其中，N tx为每个极化方向上发射天线的端口数，N sb为待上报的子带数，N tx和N sb均为正整数；
    发送所述第三指示信息；
    接收所述PMI，所述PMI基于所述反馈模式确定。
  21. 如权利要求20所述的方法，其特征在于，所述第三指示信息包括所述PMI的反馈模式的指示信息。
  22. 如权利要求20所述的方法，其特征在于，所述第三指示信息用于指示所述待上报的子带的数量和位置；以及
    所述方法还包括：
    基于所述待上报的子带的数量和/或所述待上报的子带的位置，根据预设规则确定所述PMI的反馈模式。
  23. 如权利要求20至22中任一项所述的方法，其特征在于，所述第三指示信息携带在无线资源控制RRC消息中。
  24. 如权利要求20至23中任一项所述的方法，其特征在于，当所述反馈模式为所述第二反馈模式时，所述PMI包括与R个传输层对应的R组空频信息，所述R组空频信息用于确定与各子带对应的预编码矩阵，所述R组空频信息中的第r组空频信息用于指示：
    与第r个传输层对应的P*L个空域向量；
    与所述第r个传输层对应的K个频域向量；以及
    与所述第r个传输层对应的P*L*K个系数；
    其中，所述P*L个空域向量由P个极化方向中每个极化方向上的L个波束向量及其宽带幅度系数确定，所述P*L*K个系数中的每个系数用于指示P*L个空域向量中的一个空域向量与K个频域向量中的一个频域向量间的向量运算的线性叠加系数；所述L个波束向量由所述第一向量集合确定，所述K个频域向量由所述第二向量集合确定，R为传输层数，P为极化方向数，且R、r、P、L和K均为正整数。
  25. 一种通信装置，其特征在于，包括：
    处理单元，用于确定预编码矩阵指示PMI，所述PMI包括与R个传输层对应的R组空频信息，所述R组空频信息用于确定各子带的预编码矩阵，所述R组空频信息中的第r组空频信息用于指示：
    与所述R个传输层中的第r个传输层对应的P*L个空域向量；
    与所述第r个传输层对应的K个频域向量；以及
    与所述第r个传输层对应的P*L*K个系数；
    其中，所述P*L个空域向量由P个极化方向中每个极化方向上的L个波束向量及其宽带幅度系数确定，所述P*L*K个系数中的每个系数用于指示所述P*L个空域向量中的一个空域向量与所述K个频域向量中的一个频域向量间的向量运算结果的线性叠加系数；R为传输层数，P为极化方向数，且R、r、P、L和K均为正整数；
    收发单元，用于发送所述PMI。
  26. 如权利要求25所述的通信装置，其特征在于，所述空域向量是维度为(P*N tx)*1的列向量，所述频域向量是维度为N sb*1的列向量，所述向量运算结果包括：所述空域向量与所述频域向量的共轭转置的乘积，或，所述频域向量的共轭与所述空域向量的克罗内克尔积，其中，N tx为每个极化方向的天线端口数，N sb为待上报的子带数，1≤L≤N tx，1≤K≤N sb，且N tx和N sb均为正整数。
  27. 如权利要求25或26所述的通信装置，其特征在于，所述L个波束向量取自预定义的第一向量集合中的一个子集，所述PMI还包括所述第一子集的指示信息，所述第一子集的指示信息用于指示所述第一子集中的各向量在所述第一向量集合中的位置。
  28. 如权利要求25至27中任一项所述的通信装置，其特征在于，所述K个频域向量取自预定义的第二向量集合中的第二子集，所述PMI还包括所述第二子集的指示信息，所述第二子集的指示信息用于指示所述第二子集中的各向量在所述第二向量集合中的位置。
  29. 如权利要求25至28中任一项所述的通信装置，其特征在于，所述收发单元还用于接收第一指示信息，所述第一指示信息用于指示K的取值。
  30. 如权利要求25至29中任一项所述的通信装置，其特征在于，所述收发单元还用于接收第二指示信息，所述第二指示信息用于指示L的取值。
  31. 一种通信装置，其特征在于，包括：
    收发单元，用于接收预编码矩阵指示PMI，所述PMI包括与R个传输层对应的R组空频信息，所述R组空频信息中的第r组空频信息用于指示：
    与所述R个传输层中的第r个传输层对应的P*L个空域向量；
    与所述第r个传输层对应的K个频域向量；以及
    与所述第r个传输层对应的P*L*K个系数；
    其中，所述P*L个空域向量由P个极化方向中每个极化方向上的L个波束向量及其宽带幅度系数确定，所述P*L*K个系数中的每个系数用于指示所述P*L个空域向量中的一个空域向量与所述K个频域向量中的一个频域向量间的向量运算结果的线性叠加系数；R为传输层数，P为极化方向数，且R、r、P、L和K均为正整数；
    处理单元，用于基于所述R组空频信息确定各子带的预编码矩阵。
  32. 如权利要求31所述的通信装置，其特征在于，所述空域向量是维度为(P*N tx)*1的列向量，所述频域向量是维度为N sb*1的列向量，所述向量运算结果包括：所述空域向量与所述频域向量的共轭转置的乘积，或，所述频域向量的共轭与所述空域向量的克罗内克尔积，其中，N tx为每个极化方向的天线端口数，N sb为待上报的子带数，1≤L≤N tx， 1≤K≤N sb，且N tx和N sb均为正整数。
  33. 如权利要求31或32所述的通信装置，其特征在于，所述L个波束向量取自预定义的第一向量集合中的一个子集，所述PMI还包括所述第一子集的指示信息，所述第一子集的指示信息用于指示所述第一子集中的各向量在所述第一向量集合中的位置。
  34. 如权利要求31至33中任一项所述的通信装置，其特征在于，所述K个频域向量取自预定义的第二向量集合中的第二子集，所述PMI还包括所述第二子集的指示信息，所述第二子集的指示信息用于指示所述第二子集中的各向量在所述第二向量集合中的位置。
  35. 如权利要求31至34中任一项所述的通信装置，其特征在于，所述收发单元还用于发送第一指示信息，所述第一指示信息用于指示K的取值。
  36. 如权利要求31至35中任一项所述的通信装置，其特征在于，所述收发单元还用于发送第二指示信息，所述第二指示信息用于指示L的取值。
  37. 如权利要求31至36中任一项所述的通信装置，其特征在于，所述空域向量是维度为(P*N tx)*1的列向量，所述频域向量是维度为N sb*1的列向量，所述极化方向数为1，以及
    所述根据所述R组空频信息确定与各子带对应的预编码矩阵，包括：
    在1至N sb中对n sb遍历取值，重复执行以下操作，以得到各子带的预编码矩阵：
    在1至R中对r遍历取值，重复执行以下操作确定第n sb个子带的预编码矩阵：基于所述R组空频信息中的第r组空频信息所指示的P*L个空域向量、所述K个频域向量以及所述P*L*K个系数，确定所述第r个传输层中的第n sb个子带的预编码向量
    Figure PCTCN2019099351-appb-100019
    Figure PCTCN2019099351-appb-100020
    其中，v l表示与所述第r个传输层对应的L个波束向量中的第l个波束向量，
    Figure PCTCN2019099351-appb-100021
    表示v l的幅度系数的量化值，
    Figure PCTCN2019099351-appb-100022
    表示与所述第r个传输层对应的K个频域向量中的第k个频域向量中的第n sb个元素，
    Figure PCTCN2019099351-appb-100023
    表示
    Figure PCTCN2019099351-appb-100024
    的共轭，
    Figure PCTCN2019099351-appb-100025
    表示与所述P*L个空域向量中的第l个空域向量和所述K个频域向量中的第k个频域向量对应的线性叠加系数的幅度的量化值，
    Figure PCTCN2019099351-appb-100026
    表示与所述P*L个空域向量中的第l个空域向量和所述K个频域向量中的第k个频域向量对应的线性叠加系数的相位的量化值，l、k均为正整数。
  38. 如权利要求31至36中任一项所述的通信装置，其特征在于，所述空域向量是维度为(P*N tx)*1的列向量，所述频域向量是维度为N sb*1的列向量，所述极化方向数为2，以及
    所述根据所述R组空频信息确定与各子带对应的预编码矩阵，包括：
    在1至N sb中对n sb遍历取值，重复执行以下操作，以得到与各子带对应的预编码矩阵：
    在1至R中对r遍历取值，重复执行以下操作确定第n sb个子带的预编码矩阵：基于所述R组空频信息中的第r组空频信息所指示的P*L个空域向量、所述K个频域向量以及所述P*L*K个系数，确定所述第r个传输层中的第n sb个子带的预编码向量
    Figure PCTCN2019099351-appb-100027
    Figure PCTCN2019099351-appb-100028
    其中，v l表示与所述第r个传输层对应的L个波束向量中的第l个波束向量，
    Figure PCTCN2019099351-appb-100029
    表示第一极化方向上的v l的幅度系数的量化值，
    Figure PCTCN2019099351-appb-100030
    表示第二极化方向上的v l的幅度系数的量化值，u r,k,j表示与所述第r个传输层对应的K个频域向量中的第k个频域向量中的第n sb个元素，
    Figure PCTCN2019099351-appb-100031
    表示
    Figure PCTCN2019099351-appb-100032
    的共轭，
    Figure PCTCN2019099351-appb-100033
    表示所述第一极化方向上的L个空域向量中的第l个空域向量和所述K个频域向量中的第k个频域向量对应的线性叠加系数的幅度的量化值，
    Figure PCTCN2019099351-appb-100034
    表示所述第二极化方向上的L个空域向量中的第l个空域向量和所述K个频域向量中的第k个频域向量对应的线性叠加系数的幅度的量化值，
    Figure PCTCN2019099351-appb-100035
    表示所述第一极化方向上的L个空域向量中的第l个空域向量和所述K个频域向量中的第k个频域向量对应的线性叠加系数的相位的量化值，
    Figure PCTCN2019099351-appb-100036
    表示所述第二极化方向上的L个空域向量中的第l个空域向量和所述K个频域向量中的第k个频域向量对应的线性叠加系数的相位的量化值，l、k均为正整数。
  39. 一种通信装置，其特征在于，包括：
    收发单元，用于接收第三指示信息，所述第三指示信息用于确定基于类型二type II码本反馈预编码矩阵指示PMI的反馈模式，所述反馈模式为第一反馈模式或第二反馈模式，所述第一反馈模式是基于第一向量集合反馈PMI的模式，所述第二反馈模式是基于所述第一向量集合和第二向量集合反馈PMI的模式，所述第一向量集合包括多个维度为N tx的向量，所述第二向量集合包括多个维度为N sb的向量，其中，N tx为每个极化方向上发射天线的端口数，N sb为待上报的子带数，N tx和N sb均为正整数；
    处理单元，用于基于所述反馈模式，确定所述PMI；
    所述收发单元还用于发送所述PMI。
  40. 如权利要求39所述的通信装置，其特征在于，所述第三指示信息包括所述PMI的反馈模式的指示信息。
  41. 如权利要求39所述的通信装置，其特征在于，所述第三指示信息用于指示所述待上报的子带的数量和位置；以及
    所述处理器还用于基于所述待上报的子带的数量和/或所述待上报的子带的位置，根据预设规则确定所述PMI的反馈模式。
  42. 如权利要求39至41中任一项所述的通信装置，其特征在于，所述第三指示信息携带在无线资源控制RRC消息中。
  43. 如权利要求39至42中任一项所述的通信装置，其特征在于，当所述反馈模式为所述第二反馈模式时，所述PMI包括与R个传输层对应的R组空频信息，所述R组空频信息用于确定与各子带对应的预编码矩阵，所述R组空频信息中的第r组空频信息用于指示：
    与第r个传输层对应的P*L个空域向量；
    与所述第r个传输层对应的K个频域向量；以及
    与所述第r个传输层对应的P*L*K个系数；
    其中，所述P*L个空域向量由P个极化方向中每个极化方向上的L个波束向量及其宽带幅度系数确定，所述P*L*K个系数中的每个系数用于指示P*L个空域向量中的一个空域向量与K个频域向量中的一个频域向量间的向量运算的线性叠加系数；所述L个波束向量由所述第一向量集合确定，所述K个频域向量由所述第二向量集合确定，R为传输层数，P为极化方向数，且R、r、P、L和K均为正整数。
  44. 一种通信装置，其特征在于，包括：
    处理单元，用于生成第三指示信息，所述第三指示信息用于确定基于类型二type II码本反馈预编码矩阵指示PMI的反馈模式，所述反馈模式为第一反馈模式或第二反馈模式，所述第一反馈模式是基于第一向量集合反馈PMI的模式，所述第二反馈模式是基于所述第一向量集合和第二向量集合反馈PMI的模式，所述第一向量集合包括多个维度为N tx的向量，所述第二向量集合包括多个维度为N sb的向量，其中，N tx为每个极化方向上发射天线的端口数，N sb为待上报的子带数，N tx和N sb均为正整数；
    收发单元，用于发送所述第三指示信息；并用于接收所述PMI，所述PMI基于所述反馈模式确定。
  45. 如权利要求44所述的通信装置，其特征在于，所述第三指示信息包括所述PMI的反馈模式的指示信息。
  46. 如权利要求44所述的通信装置，其特征在于，所述第三指示信息用于指示所述待上报的子带的数量和位置；以及
    所述处理单元还用于基于所述待上报的子带的数量和/或所述待上报的子带的位置，根据预设规则确定所述PMI的反馈模式。
  47. 如权利要求44至46中任一项所述的通信装置，所述第三指示信息携带在无线资源控制RRC消息中。
  48. 如权利要求44至47中任一项所述的通信装置，其特征在于，当所述反馈模式为所述第二反馈模式时，所述PMI包括与R个传输层对应的R组空频信息，所述R组空频信息用于确定与各子带对应的预编码矩阵，所述R组空频信息中的第r组空频信息用于指示：
    与第r个传输层对应的P*L个空域向量；
    与所述第r个传输层对应的K个频域向量；以及
    与所述第r个传输层对应的P*L*K个系数；
    其中，所述P*L个空域向量由P个极化方向中每个极化方向上的L个波束向量及其宽带幅度系数确定，所述P*L*K个系数中的每个系数用于指示P*L个空域向量中的一个空域向量与K个频域向量中的一个频域向量间的向量运算的线性叠加系数；所述L个波束向量由所述第一向量集合确定，所述K个频域向量由所述第二向量集合确定，R为传输层数，P为极化方向数，且R、r、P、L和K均为正整数。
  49. 一种通信装置，其特征在于，包括：
    处理器，用于执行如权利要求1至6中任一项所述方法中的确定步骤；
    收发器，用于执行如权利要求1至6中任一项所述方法中的发送和/或接收的步骤。
  50. 一种通信装置，其特征在于，包括：
    处理器，用于执行如权利要求7至14中任一项所述方法中的确定步骤；
    收发器，用于执行如权利要求7至14中任一项所述方法中的发送和/或接收的步骤。
  51. 一种通信装置，其特征在于，包括：
    处理器，用于执行如权利要求15至19中任一项所述方法中的确定步骤；
    收发器，用于执行如权利要求15至19中任一项所述方法中的发送和/或接收的步骤。
  52. 一种通信装置，其特征在于，包括：
    处理器，用于执行如权利要求20至24中任一项所述方法中的生成和/或确定的步骤；
    收发器，用于执行如权利要求20至24中任一项所述方法中的发送和/或接收的步骤。
  53. 一种处理装置，其特征在于，包括处理器，所述处理器用于执行存储器中存储的计算机程序，以使得所述装置实现如权利要求1至24中任一项所述的方法。
  54. 一种处理装置，其特征在于，包括：
    存储器，用于存储计算机程序；
    处理器，用于从所述存储器调用并运行所述计算机程序，以使得所述装置实现如权利要求1至24中任一项所述的方法。
  55. 一种计算机可读介质，其特征在于，包括计算机程序，当所述计算机程序在计算机上运行时，使得所述计算机执行如权利要求1至24中任一项所述的方法。
  56. 一种计算机程序产品，所述计算机程序产品包括计算机程序，当所述计算机程序在计算机上运行时，使得计算机执行如权利要求1至24中任一项所述的方法。
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