An inter-FA handover scheme to improve performance of mobile WiMAX systems

Mobile WiMAX has been introduced for next generation broadband wireless access systems, and it has been designed to provide various multimedia services through highspeed wireless Internet access. However, since IEEE 802.16e standard, international standard of mobile WiMAX, defined only hard handover as mendatory, Mobile Station (MS) cannot transmit or receive packets during handover procedure. Thus real-time packets can be dropped and it may result that service providers cannot guarantee quality of service during handover procedure. Even though many researches have been done in order to reduce handover delay in mobile WiMAX, problems in inter-frequency assignment (FA) handover procedure are still not solved. In the IEEE 802.16e standard, a Base Station (BS) can request serving MS to change frequency band from current serving FA to others attached in the serving BS in order to avoid congestion in the FA that MS is connected. If an MS receives the request, an MS should perform initial entry procedure to other FA. In this paper, we propose a novel inter-FA handover algorithm in order to reduce handover latency and message overhead. From experiment results, the proposed algorithm gives better performance than conventional IEEE 802.16e standard in terms of handover latency and BS throughput.