1. Field of the Invention
The present invention relates to a communication device and a method used in a wireless communication system, and more particularly, to a communication device and method of handling long term evolution-wireless local area network aggregation in a wireless communication system.
2. Description of the Prior Art
Long term evolution (LTE)-wireless local area network (WLAN) aggregation can be used for increasing data rate. A user equipment (UE) is configured to transmit/receive data via both LTE and WLAN according to LTE-WLAN aggregation. However, according to the prior art, the UE transmits/receives data via only the WLAN according to an operating system (OS) of the UE, when the UE connects to both the LTE and the WLAN. In addition, an evolved Node-B (eNB) of the LTE connected by the UE releases a radio resource control (RRC) connection of the UE due to no data communication between the UE and the eNB, because the UE does not transmit any data via the LTE. Accordingly, the UE enters an idle mode. Thus, the LTE-WLAN aggregation cannot work.
In addition, the LTE-WLAN aggregation is only applied to a data radio bearer (DRB) using a radio link control (RLC) acknowledged mode (AM). An evolved packet system (EPS) bearer mapped to the DRB also has quality of service (QoS) configuration. However, the QoS configuration of the EPS bearer and the RLC AM of the DRB may not fit all applications. For example, an application is a web browsing while another application is an IP multimedia subsystem (IMS) voice call. It is proper to transmit/receive the web browsing packets using the EPS bearer, but it is improper to transmit/receive IPS voice packets of the IMS voice call using the EPS bearer, because the RLC AM introduces unnecessary latency for transmission of the IMS voice packets.
Thus, how to perform the LTE-WLAN aggregation is an important problem to be solved. In addition, the unnecessary latency for transmission of the IMS voice packets when the UE is configured with the LTE-WLAN aggregation is also an important problem to be solved.