sending, by a terminal device, first indication information, wherein the first indication information indicates that the terminal device supports receiving a synchronization broadcast block (SS/PBCH block) in a slot with an extended cyclic prefix;

receiving, by the terminal device, a slot format index, wherein the slot format index indicates a row in a slot format table, the row in the slot format table indicates symbol attributes respectively corresponding to at least 12 symbols, the symbol attribute comprises a location of an uplink symbol U, a downlink symbol D, or a flexible symbol F; and

determining, by the terminal device, a slot format of the extended cyclic prefix based on the slot format index, wherein the slot format of the extended cyclic prefix comprises a downlink symbol D, and at least one uplink symbol U or at least one flexible symbol F.