Abstract: The present invention relates to a wireless communication system and user equipment providing wireless communication services, and a method of transmitting and receiving data between a terminal and a base station in an evolved Universal Mobile Telecommunications System (UMTS) that has evolved from a Universal Mobile Telecommunications System (UMTS), a Long Term Evolution (LTE) system, or a LTE-A (LTE-Advanced) system and more particularly, to a method of effectively using radio resource(s) in relay node., and it may be an object of the present invention is to provide an improved method of maintaining a Quality of Service (QoS) and of managing a memory and buffer in a LTE-A system in order to effectively utilize the radio resource(s).