Transmission precoding matrix indication method and device

A communications method, comprising:

• receiving downlink control information from a network device, wherein the downlink control information comprises an indicator field which is used to indicate an index of an uplink transmission precoding matrix, wherein a bit quantity of the indicator field is related to a quantity of precoding matrices comprised in a codebook subset, and
• receiving, from the network device, a configuration message that is used to indicate the codebook subset which the indexed uplink transmission precoding matrix belongs to.

A communications apparatus, comprising a processor, wherein the processor is configured to execute instructions stored in a memory to cause the apparatus to

• send downlink control information to a terminal device, wherein the downlink control information comprises an indicator field which is used to indicate an index of an uplink transmission precoding matrix, wherein a bit quantity of the indicator field is related to a quantity of precoding matrices comprised in a codebook subset;
• and
• send, to the terminal device, a configuration message that is used to indicate the codebook subset which the indexed uplink transmission precoding matrix belongs to.

A communications apparatus, comprising a processor, wherein the processor is configured to execute instructions stored in a memory to cause the apparatus to

• receive downlink control information from a network device, wherein the downlink control information comprises an indicator field which is used to indicate an index of an uplink transmission precoding matrix, wherein a bit quantity of the indicator field is related to a quantity of precoding matrices comprised in a codebook subset;
• and
• receive, from the network device, a configuration message that is used to indicate the codebook subset which the indexed uplink transmission precoding matrix belongs to.