A Downlink Mapping Algorithm for Two-Level Requests in IEEE 802.16e Systems under AMC Mode

Abstract

This paper proposes a downlink mapping algorithm for two-level requests in Orthogonal Frequency Division Multiple Access based IEEE 802.16e systems under the Adaptive Modulation and Coding (AMC) mode by which the modulation and coding scheme (MCS) of a user may be different for available subchannels. Given a set of requests each with two priorities, the proposed algorithm efficiently allocates a two-dimensional (time and frequency) burst with a suitable MCS to each user to maximize the system throughput with service differentiation. Simulation results show that the proposed algorithm outperforms the Efficient Downlink Mapping Allocation (EDMA) algorithm [5] in terms of the throughput of high priority data, but slightly sacrifice in overall throughput. The proposed algorithm can improve up to 98.8% more the average allocated ratio of urgent data than the EDMA.