A base station and method for use in a wireless system are provided. The method includes receiving, by a base station, one or more service data unit (SDUs) from a core network node; receiving, by the base station, a control message including respective length information of the one or more SDUs from the core network node; and processing, by the base station, the one or more SDUs, based on the length information included in the control message. The control message is transmitted after the one or more SDUs are transmitted from the core network node.