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

Abstract: Embodiments of this application disclose channel state information feedback and receiving methods, a transmit-end device and a receive-end device, and relate to the field of communications technologies. The method includes: generating and sending, by a transmit-end device, codebook indication information of K transport layers, where K is an integer greater than or equal to 2; the codebook indication information includes: L pieces of beam information used by the K transport layers, and indication information used to indicate beam information associated with each of the K transport layers; L is an integer greater than or equal to 2, and a quantity of pieces of beam information associated with at least one of the K transport layers is less than L. Implementing a channel state information feedback and receiving technology provided in this application helps reduce feedback overheads of channel state information.

Abstract: This application provides a reference signal sending method, a reference signal receiving method, a network device, and a terminal device, to perform CSI (Channel State Information) measurement by using more precoding vectors (or precoding matrices), to measure more equivalent channels, thereby improving flexibility and a spatial degree of freedom of network device scheduling. The method includes: performing, by the network device, precoder cycling on a first reference signal by using at least two precoding vectors, to obtain a precoded first reference signal, where the precoded first reference signal is borne in a plurality of physical resource groups, and signals borne in any two adjacent physical resource groups correspond to different precoding vectors; and sending, by the network device, the precoded first reference signal to the terminal device by using the plurality of physical resource groups, where the first reference signal is used by the terminal device to perform CSI measurement.

Abstract: This application provides a data transmission method, so that data transmission reliability can be improved. The method includes: receiving, by the terminal device, a plurality of reference signals used for channel measurement; and sending, by the terminal device, a plurality of pieces of first indication information based on the at least one reference signal and a transmission scheme on which CSI feedback is based, where the plurality of pieces of first indication information are used to indicate x target precoding matrices, at least one of the plurality of pieces of first indication information is used to indicate one target precoding matrix, and the x target precoding matrices are determined based on the plurality of precoding matrices, where x is a quantity of target precoding matrices that need to be fed back, and x is an integer greater than 1.

Abstract: This application disclose a method for indicating and determining a precoding vector related to precoding technologies to increase an overall system performance gain. The method may include: generating indication information, and sending the indication information. The indication information is used to indicate a plurality of component vectors of a precoding vector and a combination coefficient of each component vector. The combination coefficient of the component vector includes at least one of the following types: a wideband amplitude coefficient, a narrowband amplitude coefficient, and a narrowband phase coefficient.

Abstract: This application configures a quantity and size of subbands in a channel state information (CSI) reporting band for flexibility and reduced complexity of terminal addressing by 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: The application provides manner for communicating channel state information (CSI) in a communication network. A preset length is used for equalizing lengths of CSI to be reported. The preset length is determined based on a quantity of CSI-reference signal (RS) ports. A communication device determines whether a total length of one or more indication information items to be included in the CSI is less than the preset length. If the total length of the one or more indication information items to be included in the CSI is less than the preset length, the communication device adds one or more padding bits, to obtain a CSI bit sequence including the one or more indication information items and the one or more padding bits. A total length of the CSI bit sequence is consistent with the preset length. The communication device then outputs the CSI bit sequence.

Abstract: Embodiments of the present invention provide a channel information feedback method, a channel information determining method, a receive end device, and a transmit end device. The channel information feedback method includes: generating at least one piece of description information for each of a plurality of subbands included in a wideband, where each piece of description information is used to describe a description vector of a channel matrix corresponding to the subband, the description information includes at least one of a vector parameter and a weighting parameter; and sending the at least one piece of description information. The embodiments of the present invention further provide a channel information determining method, a receive end device, and a transmit end device. A precoding effect can be improved when precoding is performed based on the description vector fed back in the technical solutions provided in the embodiments of the present invention.

Abstract: This application provides a technical solution for rank indication, and especially when a CQI number is not configured or a CQI number is 1, a network device configures a rank indication restriction parameter as that at least one of ranks whose index numbers are 0, 1, 2, and 3 is allowed to be reported by the terminal device; or even if the network device does not perform the foregoing configuration, and none of the ranks whose index numbers are 0, 1, 2, and 3 is allowed to be reported, the terminal device may select at least one rank for RI reporting, so as to resolve a problem that a system cannot work. In addition, according to embodiments of this application, bit overheads required for RI reporting may further be reduced.

Abstract: Embodiments of the present invention provide a channel measurement method and an apparatus. The method includes: for a to-be-measured frequency band that includes at least one reporting subband and 0 or more non-reporting subbands, obtaining channel state information of each reporting subband, where the channel state information of each reporting subband is obtained based on channel estimation, and the at least one reporting subband is included in reporting subbands that are contiguous in frequency domain, or the at least one reporting subband is included in reporting subbands that are not contiguous in frequency domain; 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 one or more of the at least one reporting subband.

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: This application disclose a method for indicating and determining a precoding vector related to precoding technologies to increase an overall system performance gain. The method may include: generating indication information, and sending the indication information. The indication information is used to indicate a plurality of component vectors of a precoding vector and a combination coefficient of each component vector. The combination coefficient of the component vector includes at least one of the following types: a wideband amplitude coefficient, a narrowband amplitude coefficient, and a narrowband phase coefficient.

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: This application provides a method for configuring a channel state information reporting band, a reporting method, and a corresponding apparatus. The method includes: determining a channel state information subband size based on a bandwidth part BWP; and determining, a quantity of channel state information subbands included in a channel state information reporting band, based on a carrier bandwidth CC bandwidth or the bandwidth part BWP bandwidth or 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 included in an ending subband in the channel state information subband. Implementation of this application makes configuration of a quantity and size of subbands in a CSI reporting band more flexible, and reduces complexity of terminal addressing.

Abstract: This application provides a technical solution for rank indication, and especially when a CQI number is not configured or a CQI number is 1, a network device configures a rank indication restriction parameter as that at least one of ranks whose index numbers are 0, 1, 2, and 3 is allowed to be reported by the terminal device; or even if the network device does not perform the foregoing configuration, and none of the ranks whose index numbers are 0, 1, 2, and 3 is allowed to be reported, the terminal device may select at least one rank for RI reporting, so as to resolve a problem that a system cannot work. In addition, according to embodiments of this application, bit overheads required for RI reporting may further be reduced.

Abstract: The application provides manner for communicating channel state information (CSI) in a communication network. A preset length is used for equalizing lengths of CSI to be reported. The preset length is determined based on a quantity of CSI-reference signal (RS) ports. A communication device determines whether a total length of one or more indication information items to be included in the CSI is less than the preset length. If the total length of the one or more indication information items to be included in the CSI is less than the preset length, the communication device adds one or more padding bits, to obtain a CSI bit sequence including the one or more indication information items and the one or more padding bits. A total length of the CSI bit sequence is consistent with the preset length. The communication device then outputs the CSI bit sequence.

Abstract: The present invention belongs to the field of communications technologies, and discloses a channel state information CSI feedback method and an apparatus. The method includes: determining a codebook of at each transport layer CSI of user equipment UE, where the codebook of the CSI at each transport layer of the UE is: W=W1×W2, an element Xi in W2 is a weighting coefficient corresponding to each codeword in W1, and i is an integer greater than or equal to 1 and less than or equal to K; determining a quantity Ni of bits occupied by a quantized value of an ith element in W2, where quantized values of at least two elements in W2 occupy different quantities of bits; and feeding back the quantized value of the ith element to a network device based on Ni.

Abstract: Embodiments of the present application provide a parameter indication method and parameter determining method, a receive device, and a transmit device. The parameter indication method includes: generating indication information for each of a plurality of antenna panels, where the indication information is used to indicate an adjustment parameter of the antenna panel, and the adjustment parameter includes at least one of an amplitude adjustment parameter and a phase adjustment parameter; and sending the indication information. The embodiments of the present application further provide a parameter determining method, a receive device, and a transmit device. In the technical solutions provided in the embodiments of the present application, adjustment parameters of the plurality of antenna panels are fed back to adjust the plurality of antenna panels, so that a precoding vector constructed based on the plurality of antenna panels is more accurate.

Abstract: Embodiments can provide a precoding matrix indicating method, a precoding matrix determining method, a receive end device, and a transmit end device. In the precoding matrix indicating method, component matrices of an ideal precoding matrix and a weight of each component matrix can be determined based on at least one basic codebook. A dimension of each component matrix is the same as a dimension of the ideal precoding matrix, and a column vector of each component matrix is selected from column vectors of one of the at least one basic codebook. A precoding matrix indicator can be sent. The precoding matrix indicator can indicate the component matrices and the weight of each component matrix. With this, an ideal precoding matrix is approximately represented in a form of a weighted sum of a plurality of component matrices so that feedback overheads caused by feeding back a precoding matrix can be reduced.