OFDMA-based IEEE802.16 implements Adaptive Modulation and Coding (AMC) which results in a different bit rate for each user depending on its position in the cell as well as the radio condition it experiences; users away from the base station experience lower throughput. We hence propose in this paper a new QoS solution that compensates the degradation in modulation by a higher number of sub-carriers so as to maintain the bit rate of streaming flows at a constant level throughout the whole coverage area. This proposal is modeled analytically in a dynamic user configuration, where users of both types, streaming and elastic, remain in the system for a finite duration. And this in multi-cell environment and for different frequency reuse schemes.
['Chadi Tarhini', 'Tijani Chahed']
AMC-Aware QoS Proposal for OFDMA-Based IEEE802.16 WiMAX Systems