Abstract: This application discloses a channel state information feedback method and a communication apparatus. The method includes: determining channel state information based on a first codebook, and sending the channel state information. The first codebook is determined based on a channel represented by one or more spatial-frequency domain column vectors, and the one or more spatial-frequency domain column vectors indicate the channel in joint spatial-frequency domain. In this solution, the first codebook may be determined based on the channel represented by the one or more spatial-frequency domain column vectors. Because the one or more spatial-frequency domain column vectors may represent the channel in joint spatial-frequency domain, that is, the first codebook represents the channel based on joint spatial-frequency domain, a joint spatial-frequency domain feature may be fully used, to explore a sparse feature of the channel, thereby improving system performance.

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 indicates 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: Example channel measurement methods and a communication apparatus are described. One example method include receiving a precoded reference signal and indication information by a terminal device, where the indication information is used to indicate a relative delay between a first delay and a second delay, and the first delay and the second delay are determined through uplink channel measurement. The terminal device performs channel measurement based on the precoded reference signal and the indication information.

Abstract: This application provides a channel state information (CSI) feedback method including: a terminal device selects B complex coefficients from K complex coefficients according to a preset priority rule, and provides feedback, where K is a quantity of complex coefficients that the terminal device is allowed to feed back, and the preset priority rule is related to at least one of the following: an index value of each complex coefficient in the K complex coefficients, an index value of a reference signal port corresponding to each complex coefficient in the K complex coefficients in S reference signal ports, or an index value of each complex coefficient in the K complex coefficients in a plurality of complex coefficients that are allowed to be selected for a corresponding reference signal port, where S is a quantity of reference signal ports that the terminal device is allowed to select.

Abstract: This application relates to the field of communication technologies, and discloses a communication method and apparatus. The method includes: A terminal device works on a plurality of downlink carriers, and the plurality of downlink carriers include a first downlink carrier and a second downlink carrier. The terminal device obtains first channel information, where the first channel information includes second channel information, and the first downlink carrier and the second downlink carrier share the second channel information; and sends the first channel information to an access network device. In this manner, the first downlink carrier and the second downlink carrier support sharing of a part or all of channel 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 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.

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 indicates 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 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.

Abstract: A method for indicating channel state information CSI measurement and a communication apparatus. A network device indicates, to a terminal device by using first indication information, one or more frequency domain units in a downlink reference signal resource that are used by the terminal device to obtain CSI. The terminal device determines, based on the first indication information, which frequency domain units in the downlink reference signal resource are used to obtain the CSI, and perform measurement in the frequency domain unit to obtain the CSI. The network device flexibly configures CSI measurement based on a system status, to control obtaining of the CSI. This helps the terminal device obtain the CSI more pertinently based on the indication in different cases.

Abstract: One example method includes receiving one or more precoded reference signals, where the one or more precoded reference signals are obtained by precoding one or more reference signals based on K angle vectors. First indication information can then be generated, where the first indication information is used to indicate at least one delay vector and P weighting coefficients corresponding to P angle-delay pairs, the at least one delay vector and the P weighting coefficients are determined based on the one or more precoded reference signals, each of the P angle-delay pair includes one of the K angle vectors and one of the at least one delay vector, and the P angle-delay pairs and the P weighting coefficients are used to determine a precoding matrix, where P and K are positive integers, and where P?1, K?1. The first indication information can then be sent.

Abstract: Example channel measurement methods and a communication apparatus are described. One example method include receiving a precoded reference signal and indication information by a terminal device, where the indication information is used to indicate a relative delay between a first delay and a second delay, and the first delay and the second delay are determined through uplink channel measurement. The terminal device performs channel measurement based on the precoded reference signal and the indication information.

Abstract: The present disclosure relates to beamforming methods and devices. In one example method, an access network device calculates an uplink channel frequency response, calculates a model parameter in a channel frequency response mathematical model based on the uplink channel frequency response and each uplink subcarrier frequency, where the model parameter has reciprocity on uplink and downlink subcarrier frequencies, constructs a downlink channel frequency response based on the model parameter, the channel frequency response mathematical model, and each downlink subcarrier frequency, calculates a beamforming weight for each downlink subcarrier frequency based on the downlink channel frequency response, and performs downlink beamforming on an antenna array based on the beamforming weight for each downlink subcarrier frequency, where the antenna array is a dual-polarized antenna array or a single-polarized antenna array.

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: One example method includes receiving one or more precoded reference signals, where the one or more precoded reference signals are obtained by precoding one or more reference signals based on K angle vectors. First indication information can then be generated, where the first indication information is used to indicate at least one delay vector and P weighting coefficients corresponding to P angle-delay pairs, the at least one delay vector and the P weighting coefficients are determined based on the one or more precoded reference signals, each of the P angle-delay pair includes one of the K angle vectors and one of the at least one delay vector, and the P angle-delay pairs and the P weighting coefficients are used to determine a precoding matrix, where P and K are positive integers, and where P?1, K?1. The first indication information can then be sent.

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.

Abstract: This application provides a method for configuring channel state information CSI reporting and a communication apparatus. The method includes: A terminal device receives configuration information for CSI reporting, where the configuration information for the CSI reporting is associated with configuration information of a first reference signal and configuration information of a second reference signal, the second reference signal is used for measuring an uplink channel, and the first reference signal is used for measuring a downlink channel. The terminal device performs channel measurement based on the first reference signal and the second reference signal to generate a CSI, and feeds back CSI. By using uplink and downlink channel reciprocity, the terminal device may not need to feed back information with reciprocity, for example, an angle and a delay, so that feedback overheads of the terminal device are reduced.

Abstract: A method and an apparatus for determining a broadcast beam weighted value are provided. The method includes: obtaining an angle path loss spectrum of a target cell at a current moment, where the angle path loss spectrum includes signal path loss values of a target base station in the target cell in a plurality of directions; determining a beam angle power spectrum based on the angle path loss spectrum, where the beam angle power spectrum includes signal transmit powers of the target base station in the plurality of directions, and in the beam angle power spectrum, a signal transmit power in a direction with a relatively large signal path loss value in the angle path loss spectrum is relatively large; determining a broadcast beam weighted value based on the beam angle power spectrum; and forming a target broadcast beam based on the broadcast beam weighted value.

Abstract: The present disclosure relates to beamforming methods and devices. In one example method, an access network device calculates an uplink channel frequency response, calculates a model parameter in a channel frequency response mathematical model based on the uplink channel frequency response and each uplink subcarrier frequency, where the model parameter has reciprocity on uplink and downlink subcarrier frequencies, constructs a downlink channel frequency response based on the model parameter, the channel frequency response mathematical model, and each downlink subcarrier frequency, calculates a beamforming weight for each downlink subcarrier frequency based on the downlink channel frequency response, and performs downlink beamforming on an antenna array based on the beamforming weight for each downlink subcarrier frequency, where the antenna array is a dual-polarized antenna array or a single-polarized antenna array.

Abstract: Embodiments of this application disclose a method and an apparatus for determining a broadcast beam weighted value. The method includes: obtaining an angle path loss spectrum of a target cell at a current moment, where the angle path loss spectrum includes signal path loss values of a target base station in the target cell in a plurality of directions; determining a beam angle power spectrum based on the angle path loss spectrum, where the beam angle power spectrum includes signal transmit powers of the target base station in the plurality of directions, and in the beam angle power spectrum, a signal transmit power in a direction with a relatively large signal path loss value in the angle path loss spectrum is relatively large; determining a broadcast beam weighted value based on the beam angle power spectrum; and forming a target broadcast beam based on the broadcast beam weighted value.