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.