A Layer 2 Scheme of Inter-RAT Handover between UMTS and WiMAX

The future B3G or 4G mobile networks will consist of heterogeneous networks, including GSM, UMTS, WiMAX and WIFI. In order to realize a seamless vertical handover (inter-RAT handover), a variety of interworking architectures and inter-RAT handover mobility managements have been proposed. Based on the integrated coupling architecture, we propose a novel common interworking sublayer (IW sublayer) at layer 2 on RNC and UE to provide a seamless PS inter-RAT handover between UMTS and WiMAX systems. This IW sublayer scheme focuses on eliminating packet loss and reducing handover latency which are common problems for most inter-RAT handover scenarios. Compared with other context transfer schemes, the simulation results show the IW sublayer with ARQ mechanism can achieve a lossless and prompt handover procedure. In addition, this IW sublayer scheme can eliminate false fast retransmit of TCP traffics which is usually caused by packet losses or out-of-order packet arrivals.