A network device sends at least one piece of DCI on a PDCCH monitoring occasion of a first PO, where all or a part of the at least one piece of DCI includes first indication information, each piece of first indication information indicates that at least one CSI-RS is available, the CSI-RS corresponds to an SSB, and the SSB corresponds to a PDCCH monitoring occasion for sending the DCI including the first indication information. The network device sends the CSI-RS indicated by the first indication information as available.