User equipment included in a wireless communication system wirelessly connects to a donor base-station to establish a macro link, wirelessly connects to a mobile relay to establish an access link, and simultaneously maintains connections with the donor base-station and the mobile relay coexisting in the same coverage area, wherein a first pre-established frequency band can be used for the access link and a second pre-established frequency band can be used for the macro link. Furthermore, the user equipment can wirelessly connect to the mobile relay to establish an access link, be assigned, from the mobile relay, a wireless resource for device-to-device communication with at least one other user equipment within the same mobile relay cell, and perform device-to-device communication with the at least one other user equipment using the assigned wireless resource.