Genetic algorithm-based energy efficient multicast scheduling for WiMAX relay networks

IEEE 802.16e (also known as Mobile WiMAX) is the international standard for wireless metropolitan area networks. To enhance the network throughput and extend the coverage of base station, IEEE then defined the 802.16j standard. Clearly, one of the popular applications for WiMAX is the multicast service. On the other hand, the design of power saving technologies is important since mobile stations are often powered by batteries. Hence we want to study the maximum energy-efficient multicast scheduling (MEMS) problem for an IEEE 802.16j network with transparent mode. Specifically, the base station should determine how to schedule the multicast data in a multicast superframe such that the multicast energy efficiency of the network is maximal. To the best of our knowledge, this problem has never been seriously addressed before. In this paper, we first formally model the MEMS problem, which is NP-complete. To solve this problem in real-time, we then propose a genetic algorithm, named GAMS, to quickly obtain the suboptimal multicast scheduling. The use of genetic algorithm is justified by the fact that the base station can control when to terminate the iterative process of evolution at any time needed. Simulation results show that GAMS is promising in terms of execution time and multicast energy efficiency.