Primary User QoS and Activity Concerned Resource Allocation Algorithm in OFDM Based Cognitive Radio System

Efficient and reliable resource allocation algorithm is one of the key problems for the realization of cognitive radio networks. Due to the rapidly changing characteristics of cognitive environment, water-filling algorithm is difficult to meet this environment because of the interaction with primary users. In this paper, we propose a primary user Quality of service (QoS) and activity concerned resource allocation algorithm in OFDM based cognitive radio system with a risk-return model which reflects availability of subcarriers or primary user activity and date transmission outage probability constraint to guarantee primary users’ QoS. Taking maximization of the expected sum rate of cognitive system as the objective function, we solve this optimization problem by a Lagrangian dual method under the introduced primary user outage probability constraint. Finally, the performance comparison of water-filling algorithm and our algorithm is given. The simulation results show that the proposed algorithm can obtain more transmission capacity and effectively guarantee primary users’ QoS.