Remote user equipment, further referred to as remote UE , wherein the remote UE comprises: a processor, configured to trigger a buffer status report BSR; and a communications interface, configured to send , to relay user equipment, further referred to as relay UE , the BSR triggered by the processor, wherein the BSR is used to provide a base station with a size of available to-be-transmitted data in a buffer of the remote UE ; characterized by the processor being further configured to: before the communications interface sends the BSR to the relay UE , obtain a control signaling resource pool and a data resource pool that are configured by the base station for the remote UE , wherein the control signaling resource pool and the data resource are used by the remote UE to transmit resource request information; and select a first resource from the control signaling resource pool, and select a second resource from the data resource pool; and the communications interface is specifically configured to: send sidelink control information SCI to the relay UE by using the first resource; and send, to the relay UE by using the second resource, a Media Access Control protocol data unit MAC PDU that comprises the BSR, wherein the SCI comprises indication information used to indicate location information of the second resource; wherein the MAC PDU comprises a Media Access Control header MAC header and a first Media Access Control control element MAC CE, the MAC header comprises a first Media Access Control subheader MAC subheader, and the first MAC CE comprises the BSR; and the first MAC subheader comprises a logical channel ID LCID, and the LCID is used to indicate that the first MAC CE is a BSR MAC CE and indicate a format of the BSR MAC CE. a processor, configured to trigger a buffer status report BSR; and a communications interface, configured to send , to relay user equipment, further referred to as relay UE , the BSR triggered by the processor, wherein the BSR is used to provide a base station with a size of available to-be-transmitted data in a buffer of the remote UE ; characterized by the processor being further configured to: before the communications interface sends the BSR to the relay UE , obtain a control signaling resource pool and a data resource pool that are configured by the base station for the remote UE , wherein the control signaling resource pool and the data resource are used by the remote UE to transmit resource request information; and select a first resource from the control signaling resource pool, and select a second resource from the data resource pool; and the communications interface is specifically configured to: send sidelink control information SCI to the relay UE by using the first resource; and send, to the relay UE by using the second resource, a Media Access Control protocol data unit MAC PDU that comprises the BSR, wherein the SCI comprises indication information used to indicate location information of the second resource; wherein the MAC PDU comprises a Media Access Control header MAC header and a first Media Access Control control element MAC CE, the MAC header comprises a first Media Access Control subheader MAC subheader, and the first MAC CE comprises the BSR; and the first MAC subheader comprises a logical channel ID LCID, and the LCID is used to indicate that the first MAC CE is a BSR MAC CE and indicate a format of the BSR MAC CE. <EOS>