An Efficient Handoff Scheme for Multimedia Traffic in OFDMA System

The IEEE 802.16e Broadband Wireless Access (BWA) system is developed to cater for rapidly growing requirement for multimedia wireless services. Since the heterogeneous services provided by the system are connection-oriented, Call Admission Control and required resource reservation mechanisms are needed to achieve desired quality of service (QoS). Traditional admission control algorithms are based on bandwidth or channel reservation policy, which may be incompetent in IEEE 802.16e OFDMA systems for two reasons: (i) WiMAX system supports dynamic and flexible resource allocation, and (ii) there exists a fundamental tradeoff between bandwidth resource and power resource. In this paper, we propose an efficient call admission control scheme based on maximum use of subchannels using AMC to minimize the overall transmit power in OFDMA systems. Based on power reservation, we propose two power reservation schemes for inter-cell handoff calls and intra-cell handoff calls, respectively. Correspondingly, two reservation factors are introduced, the values of which are determined by optimizing the metric of Grade of Service (GoS). Computer simulation is carried out to evaluate the performance of the proposed call admission control scheme based on power reservation.