A method and apparatus are disclosed for assisting data transmission in a wireless communication system. In one embodiment, the method includes the UE establishing at least three logical channels which includes at least a first logical channel, a second logical channel, and a third logical channel. The method further includes the UE being configured with periodic uplink resource by a base station, wherein the periodic uplink resource is shared by the first logical channel and the second logical channel, but is not shared by the third logical channel. The method also includes the UE performing a first transmission via the periodic uplink resource, wherein the first transmission includes data associated with the first logical channel and/or data associated with the second logical channel.