This application discloses a method for sending a demodulation reference signal, a method for receiving a demodulation reference signal, and a communication apparatus. The method for sending a demodulation reference signal includes: A network device generates a first signal and sends the first signal on a first time-frequency resource, where the first signal is formed by superimposing M DMRS port signals, and delay segmentation locations corresponding to at least two of the M DMRS port signals are different. Because the first signal is formed by superposing the M DMRS port signals, that is, the network device sends a plurality of DMRS port signals on a same time-frequency resource, reference signal overheads can be reduced. The network device sends more DMRS port signals on the same time-frequency resource. In this way, the network device can send more streams without increasing pilot overheads.

This disclosure discloses an information indication method and an apparatus, to resolve a problem that indication precision of an uplink precoding matrix is low. The method includes: receiving a downlink reference signal sent by a network device on a first transmission resource; performing channel estimation based on the downlink reference signal, to obtain a downlink equivalent channel corresponding to the first transmission resource; and determining, based on the downlink equivalent channel, to-be-indicated information corresponding to a terminal device, where the to-be-indicated information indicates an uplink precoding matrix used when a first terminal device sends uplink data on the first transmission resource. The downlink equivalent channel is obtained by performing channel estimation based on the downlink reference signal.

This disclosure discloses an information indication method and an apparatus, to resolve a problem that indication precision of an uplink precoding matrix is low. The method includes: receiving a downlink reference signal sent by a network device on a first transmission resource; performing channel estimation based on the downlink reference signal, to obtain a downlink equivalent channel corresponding to the first transmission resource; and determining, based on the downlink equivalent channel, to-be-indicated information corresponding to a terminal device, where the to-be-indicated information indicates an uplink precoding matrix used when a first terminal device sends uplink data on the first transmission resource. The downlink equivalent channel is obtained by performing channel estimation based on the downlink reference signal.

A user equipment generates an HARQ-ACK codebook comprising HARQ-ACK bits for semi-persistent scheduling (SPS) physical downlink shared channels (PDSCHs) based on multiple SPS configurations, and transmits the HARQ-ACK codebook. In the HARQ-ACK codebook, with respect to an SPS configuration index and a serving cell index, an HARQ-ACK bit for an SPS PDSCH in a slot of a lower slot index precedes an HARQ-ACK bit for an SPS PDSCH in a slot of a higher slot index, and with respect to each serving cell index, an HARQ-ACK bit for an SPS PDSCH based on an SPS configuration having a lower SPS configuration index precedes an HARQ-ACK bit for an SPS PDSCH based on an SPS configuration having a higher SPS configuration index.

A user equipment generates an HARQ-ACK codebook comprising HARQ-ACK bits for semi-persistent scheduling (SPS) physical downlink shared channels (PDSCHs) based on multiple SPS configurations, and transmits the HARQ-ACK codebook. In the HARQ-ACK codebook, with respect to an SPS configuration index and a serving cell index, an HARQ-ACK bit for an SPS PDSCH in a slot of a lower slot index precedes an HARQ-ACK bit for an SPS PDSCH in a slot of a higher slot index, and with respect to each serving cell index, an HARQ-ACK bit for an SPS PDSCH based on an SPS configuration having a lower SPS configuration index precedes an HARQ-ACK bit for an SPS PDSCH based on an SPS configuration having a higher SPS configuration index.

Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a user equipment (UE) may receive a signal. The UE may measure the signal to explore one or more inactive ranks or inactive precoders. The UE may transmit, based at least in part on the measuring, a report that includes channel state information for at least one of the one or more inactive ranks or inactive precoders. Numerous other aspects are described.

The teachings herein present a method and apparatus that implement and use a factorized precoder structure that is advantageous in terms of performance and efficiency. In particular, the teachings presented herein disclose an underlying precoder structure that allows for certain codebook reuse across different transmission scenarios, including for transmission from a single Uniform Linear Array (ULA) of transmit antennas and transmission from cross-polarized subgroups of such antennas. According to this structure, an overall precoder is constructed from a conversion precoder and a tuning precoder. The conversion precoder includes antenna-subgroup precoders of size N.sub.T/2, where N.sub.T represents the number of overall antenna ports considered. Correspondingly, the tuning precoder controls the offset of beam phases between the antenna-subgroup precoders, allowing the conversion precoder to be used with cross-polarized arrays of N.sub.T/2 antenna elements and with co-polarized arrays of N.sub.T antenna elements.

The teachings herein present a method and apparatus that implement and use a factorized precoder structure that is advantageous in terms of performance and efficiency. In particular, the teachings presented herein disclose an underlying precoder structure that allows for certain codebook reuse across different transmission scenarios, including for transmission from a single Uniform Linear Array (ULA) of transmit antennas and transmission from cross-polarized subgroups of such antennas. According to this structure, an overall precoder is constructed from a conversion precoder and a tuning precoder. The conversion precoder includes antenna-subgroup precoders of size N.sub.T/2, where N.sub.T represents the number of overall antenna ports considered. Correspondingly, the tuning precoder controls the offset of beam phases between the antenna-subgroup precoders, allowing the conversion precoder to be used with cross-polarized arrays of N.sub.T/2 antenna elements and with co-polarized arrays of N.sub.T antenna elements.

The present disclosure provides a terminal device that allows constraints on user allocation to be prevented and spread codes to be allocated in a scheduler when non-adaptive HARQ is employed using a PHICH. A codeword generator generates code words by encoding data, a layer mapping unit places each CW in one or a plurality of layers, a DMRS generator generates a reference signal for each layer in which a CW is placed by using any resource among a plurality of resources defined by a mutually orthogonal plurality of OCCs, and an ACK/NACK demodulator receives a response signal indicating a retransmission request. When a response signal requesting retransmission of only a CW placed in a plurality of layers is received, the DMRS generator uses each resource having the same OCC among the plurality of resources for the reference signals generated in the corresponding layers.

The present disclosure provides a terminal device that allows constraints on user allocation to be prevented and spread codes to be allocated in a scheduler when non-adaptive HARQ is employed using a PHICH. A codeword generator generates code words by encoding data, a layer mapping unit places each CW in one or a plurality of layers, a DMRS generator generates a reference signal for each layer in which a CW is placed by using any resource among a plurality of resources defined by a mutually orthogonal plurality of OCCs, and an ACK/NACK demodulator receives a response signal indicating a retransmission request. When a response signal requesting retransmission of only a CW placed in a plurality of layers is received, the DMRS generator uses each resource having the same OCC among the plurality of resources for the reference signals generated in the corresponding layers.