Abstract: This application provides a communication method and a communications apparatus. The method includes: generating, by a terminal device, first indication information, where the first indication information is used to indicate a precoding matrix, the precoding matrix is applied to at least one antenna panel and includes at least one precoding vector, each precoding vector includes a plurality of subvectors, each subvector corresponds to an antenna port on the antenna panel and includes two polarization vectors, and each polarization vector is generated by performing weighted combination on a plurality of basis vectors; and sending the first indication information. In embodiments of this application, accuracy of a codebook can be improved.

Abstract: Embodiments of the present invention provide a channel measurement method. The method includes: obtaining, for a to-be-measured frequency band including at least one reporting subband and at least one missing subband, channel state information of each reporting subband and channel state information of each missing subband, where the channel state information of each reporting subband is obtained based on channel estimation, and the channel state information of each missing subband is obtained according to a reference rule with reference to channel state information of a reporting subband that is indicated by the reference rule and that is in the at least one reporting subband; and sending a measurement report of the to-be-measured frequency band to a transmit end device, where the measurement report includes the channel state information of each reporting subband in the at least one reporting subband.

Abstract: A channel measurement method and a communications apparatus, the method including generating, by a terminal device, first indication information, where the first indication information indicates one or more component features of a time-varying feature, and further indicates a weighting coefficient of each component feature of the one or more component features, and the one or more component features and the weighting coefficient of each component feature represent the time-varying feature of a channel, and sending, by the terminal device, the first indication information to a network device.

Abstract: This application provides a precoding matrix indicating and determining method and a communications apparatus. The method includes: generating, by a terminal device, first indication information, and sending the first indication information to a network device, where the first indication information indicates a spatial domain vector, a frequency domain vector, and a weighting coefficient that are used to construct a precoding matrix. When a value of a rank Z is greater than 2, Z transport layers include at least one first-type transport layer, and a maximum quantity M1 of frequency domain vectors reported for the first-type transport layer satisfies: M 1 = ? p 1 × N 3 R ? , wherein p1 is a preconfigured coefficient for determining the maximum quantity of frequency domain vectors reported for the first-type transport layer, 1?p1>0, R is a preconfigured value, N3 is a length of a frequency domain vector, Z>2, and R, N3, and Z are all positive integers.

Abstract: This application describes a data transmission method, a terminal device, and a network device. The method may include determining, by a terminal device, a reporting type of channel state information (CSI), where the reporting type is used to indicate a relationship between CSI of a beam that is currently reported by the terminal device and CSI of a beam that is previously reported by the terminal device in a current reporting period. The method may also include sending, by the terminal device, CSI of N beams to a network device based on a reporting type and a codebook parameter, where the codebook parameter is used to indicate a quantity N of the currently reported beams, and N is an integer greater than or equal to 1. According to the data transmission method, the terminal device, and the network device described in the embodiments of this application, CSI reporting flexibility can be improved, thereby improving system performance.

Abstract: An apparatus and method are provided for a quantity and size of subbands in a channel state information (CSI) reporting band for flexibility and reduced complexity of terminal addressing. The method includes: determining a channel state information subband size based on a bandwidth part (BWP), determining a quantity of channel state information subbands included in a channel state information reporting band based on (i) a carrier bandwidth (CC bandwidth), (ii) the BWP bandwidth or (iii) a channel state information reference signal (CSI-RS) bandwidth and the channel state information subband size. The method further includes determining an actual quantity of resource blocks included in a starting subband and an actual quantity of resource blocks in an ending subband in the channel state information subband.

Abstract: This application provides a method for reporting a terminal device capability and a communications apparatus. The method includes: The terminal device generates first indication information and sends the first indication information to a network device. The first indication information is used to indicate one or more frequency domain parameters and one or more of the following capability parameters associated with each frequency domain parameter: a port quantity, a spatial domain parameter, a reference signal resource quantity, and a total port quantity. The frequency domain parameter is used to indicate a maximum quantity of frequency domain units that can be supported by the terminal device. The frequency domain unit is a frequency domain unit based on which the terminal device feeds back a PMI. Each capability parameter group may be used to indicate one combination of a plurality of parameters that can be supported by the terminal device.

Abstract: This application discloses a channel estimation method and apparatus, and relates to the field of communications technologies, to help reduce indication overheads. The method may include: generating and sending indication information. The indication information is used to indicate K N-dimensional spatial-domain component vectors, L M-dimensional frequency-domain component vectors, and a weight matrix, to indicate to construct an M×N-dimensional spatial-frequency matrix, or an M×N or N×M spatial-frequency matrix.

Abstract: Embodiments of this application provide a communication method and a communications apparatus. The method includes: determining a plurality of frequency domain units on which reporting of a PMI is based in reporting bandwidth. The plurality of frequency domain units include one or more first frequency domain units and third frequency domain units obtained by dividing one or more second frequency domain units. A granularity of the first frequency domain unit is less than a preconfigured first granularity, a granularity of the second frequency domain unit is a first granularity, and a granularity of the third frequency domain unit is a predetermined second granularity. The first granularity is a granularity preconfigured for reporting a CQI, a second granularity is a granularity predetermined for reporting the PMI, and the second granularity is less than the first granularity.

Abstract: Embodiments of this application disclose a channel estimation method and apparatus, and relate to the field of communications technologies, to help reduce indication overheads. The method may include: generating and sending indication information, where the indication information is used to indicate M N-dimensional precoding vectors, each precoding vector is applied to one of M frequency bands, the M N-dimensional precoding vectors form a space-frequency matrix, and the space-frequency matrix is generated by performing weighted combination on a plurality of space-frequency component matrices, where the space-frequency matrix is an M×N-dimensional space-frequency vector or an X×Y space-frequency matrix, X and Y are one and the other of M and N, M?1, N?2, and both M and N are integers.

Abstract: This application provides a communication method, a communications apparatus, and a system. The method may include receiving, by a terminal device, a first group of precoded reference signals and a second group of precoded reference signals. The method may also include feeding back first indication information based on a channel state information (CSI) feedback-based transmission scheme, where the first indication information is used to determine a plurality of precoding vectors, at least one of the plurality of precoding vectors is determined by using the first group of precoded reference signals, and at least one of the plurality of precoding vectors is determined by using the second group of precoded reference signals.

Abstract: This application provides a data transmission method and apparatus, and a system.

Abstract: This application provides a data transmission method and apparatus. The method includes: receiving, by a terminal device, a first reference signal sent by a network device; measuring, by the terminal device, a downlink channel based on the first reference signal, to obtain a channel status of the downlink channel; determining, by the terminal device, a target mode from a plurality of modes based on the channel status of the downlink channel, where information that is used to feed back channel state information (CSI) and that is sent by the terminal device in different modes of the plurality of modes is different; and sending, by the terminal device, indication information to the network device, where the indication information is used to indicate the target mode. The data transmission method and apparatus in the embodiments of this application are conducive to improve flexibility of feeding back CSI.

Abstract: A precoding matrix indicating and determining method, including determining a precoding matrix indicator (PMI) having R groups of space-frequency information corresponding to R transmission layers, where the R groups of space-frequency information are used to determine a precoding matrix of each subband, and an rth group of space-frequency information in the R groups indicates P×L space domain vectors corresponding to an rth transmission layer in the R transmission layers, K frequency domain vectors corresponding to the rth transmission layer, and P×L×K coefficients corresponding to the rth transmission layer, where each of the P×L×K coefficients indicates a linear superposition coefficient of a vector operation result of a P×L space domain vectors and one of the K frequency domain vectors, R is a quantity of transmission layers, P is a quantity of polarization directions, and R, r, P, L, and K are all positive integers, and sending the PMI.

Abstract: This application provides a parameter configuration method and a communications apparatus. The method includes: receiving, by a terminal device, an indication of a first mapping relationship from a network device, where the first mapping relationship is a mapping relationship in a preconfigured first mapping relationship group, and the first mapping relationship group includes at least one mapping relationship, to indicate at least one correspondence between a reporting quantity of spatial domain vectors and a reporting quantity of frequency domain vectors; and determining, by the terminal device, the reporting quantity of spatial domain vectors and the reporting quantity of frequency domain vectors based on the first mapping relationship.

Abstract: The present disclosure relates to precoding vector indicating and determining methods and communications apparatus. In one example method, a terminal device generates first indication information, and sends the first indication information to a network device. The first indication information is used to indicate one or more frequency domain vectors and one or more weighting coefficients, where the one or more frequency domain vectors include a frequency domain vector reported for each of R frequency domain unit groups, the one or more weighting coefficients include a weighting coefficient reported for each of the R frequency domain unit groups, and a frequency domain vector and a weighting coefficient that are reported for an rth frequency domain unit group in the R frequency domain unit groups are used to construct a precoding vector corresponding to one or more frequency domain units in the rth frequency domain unit group.

Abstract: One example method for measuring a channel state information reference signal includes receiving, from a network device, a partial channel state information reference signal resource sets selected from a plurality of channel state information reference signal resource sets and indication information indicating one or more resource sets for channel measurement, which are from the partial channel state information reference signal resource sets, and performing channel measurement by using the one of the one or more resource sets for channel measurement indicated by the indication information.

Abstract: Example channel measurement methods and communications apparatus are described. One example method includes receiving a precoded reference signal by a terminal device, where the precoded reference signal is obtained by precoding a reference signal based on K angle vectors and L delay vectors. First indication information is generated and sent, where the first indication information is used to indicate P weighting coefficients corresponding to P angle-delay pairs. The P weighting coefficients are determined by using the precoded reference signal. The P angle-delay pairs and the P weighting coefficients corresponding to the P angle-delay pairs are used to determine a precoding matrix. Each angle-delay pair includes one of the K angle vectors and one of the L delay vectors. The K angle vectors and the L delay vectors are determined based on uplink channel measurement.

Abstract: A method includes generating, by a processor, first indication information based on N reference signals, where N is an integer and N?2. The first indication information indicates a plurality of component vectors for constructing a precoding matrix and a superposition coefficient of each component vector of each of M precoding vectors for constructing the precoding matrix upon which a precoding of M reference signals is based, where M is an integer and 1?M<N. The method also includes transmitting the first indication information by way of an antenna.

Abstract: A channel measurement method and a communications apparatus. The method includes: a terminal device receives precoded reference signals from a network device, where the precoded reference signals are obtained by precoding reference signals based on K angle vectors; and generates and sends first indication information, where the first indication information is used to indicate P weighting coefficients corresponding to P angle-delay pairs, the P weighting coefficients are determined based on the precoded reference signals, each of the P angle-delay pairs includes one angle vector and one delay vector corresponding to the angle vector, a delay vector corresponding to each angle vector is preconfigured, each angle vector and the delay vector corresponding to each angle vector are obtained through uplink channel measurement, and the P angle-delay pairs and the P weighting coefficients corresponding to the P angle-delay pairs are used to determine a precoding matrix.