A method of supporting direct communication between wireless devices, the method comprising: receiving, by a first wireless device and from a base station, configuration information associated with direct data transmission between wireless devices, wherein the configuration information comprises information of a resource selection mode for direct data transmission, and wherein the information of a resource selection mode indicates a resource pool from which the first wireless device selects a resource for direct data transmission to a second wireless device; characterized by identifying, based on a discovery procedure, target identities of a plurality of target wireless devices including the second wireless device; mapping a target identity of the second wireless device, among the plurality of target wireless devices, to a first group identity, and mapping a target identity of a third wireless device, among the plurality of target wireless devices, to a second group identity; generating a radio resource control, RRC, message to be transmitted to the base station, wherein the RRC message comprises information of the target identity of the second wireless device and information of the target identity of the third wireless device; transmitting the RRC message to the base station; generating a buffer status report to be transmitted to the base station, wherein the buffer status report comprises a first field that indicates mapping information between the first group identity and the target identity of the second wireless device and a second field that indicates mapping information between the second group identity and the target identity of the third wireless device; and transmitting the buffer status report to the base station. receiving, by a first wireless device and from a base station, configuration information associated with direct data transmission between wireless devices, wherein the configuration information comprises information of a resource selection mode for direct data transmission, and wherein the information of a resource selection mode indicates a resource pool from which the first wireless device selects a resource for direct data transmission to a second wireless device; characterized by identifying, based on a discovery procedure, target identities of a plurality of target wireless devices including the second wireless device; mapping a target identity of the second wireless device, among the plurality of target wireless devices, to a first group identity, and mapping a target identity of a third wireless device, among the plurality of target wireless devices, to a second group identity; generating a radio resource control, RRC, message to be transmitted to the base station, wherein the RRC message comprises information of the target identity of the second wireless device and information of the target identity of the third wireless device; transmitting the RRC message to the base station; generating a buffer status report to be transmitted to the base station, wherein the buffer status report comprises a first field that indicates mapping information between the first group identity and the target identity of the second wireless device and a second field that indicates mapping information between the second group identity and the target identity of the third wireless device; and transmitting the buffer status report to the base station.