Adaptive Modulation in Wireless OFDMA Systems with Finite State Modeling

WiMAX is considered one of the most prominent technologies for providing a broadband wireless access (BWA) in a metropolitan area. Among several strategies, the adaptive modulation techniques has been selected for providing an efficient non line of sight (NLOS) coverage. Adaptive modulation allows the system to adapt the modulation scheme according to the channel conditions in order to enhance the system performance. This paper deals with the proposal of a state model to be used for the performance comparison of two different adaptation algorithms based on the maximization of different functional costs suitable for use in WiMAX system with an OFDMA physical structure. The algorithms' performance has been derived and compared in terms of error rate and throughput. The algorithms show a significant improvement of the system performance compared with the static case, i.e., no adaptive modulation; in particular each algorithm is suited for satisfying different QoS requirements.