Multi-Objective Optimization of a QoS-Aware Channel Allocation in Cognitive Radio Networks using NSGA-II Algorithm

In this paper the QoS-aware channel allocation problem formulated as an optimization problem with two conflicting objectives; spectrum utilization and fairness among secondary users (SUs) subject to channel availabilities constraints. Any possible channel allocation which could be a solution of the optimization problem, encoded as a binary chromosome. By having coded available spectrum opportunities instead of all channel-user combinations, the search space is significantly reduced. Designing the QoS-aware channel assignment scheme is based on NSGA-II Algorithm to find the optimum allocation of these two objectives jointly and finally the set of Pareto optimal solutions achieved by proposed algorithm in discrete space of feasible solutions. Simulation results demonstrate the trade-off between spectrum utilization and fairness and the Pareto optimum points. Binary Integer Programming (BIP) confirms the results of the proposed evolutionary scheme in small-scale instances while our scheme outperforms BIP method significantly in computational for large-scale ones.