Performance evaluation and system optimization of Green cognitive radio networks with a multiple-sleep mode

Cognitive radio networks (CRNs) have been emerged as a solution for realizing dynamic spectrum allocation. Green communication in CRNs will contribute to reducing emission pollution, minimizing operation cost and decreasing energy consumption. The Green CRNs would help in realizing “green spectrum management”. In this paper, we examine the key issue to show how to conserve the energy of base stations in the Green CRNs. In order to meet the demand for more sustainable green communication, we propose a multiple-sleep mode for licensed channels in CRNs. Based on a dynamic spectrum access strategy with the proposed multiple-sleep mode, we establish a continuous-time Markov chain model to capture the stochastic behavior of secondary user (SU) and primary user packets. By using the matrix geometric solution method, we obtain the steady-state probability distribution for the system model. This paper further presents analysis for performance measures in terms of the throughput of SU packets, the average latency of SU packets, the energy saving rate of the system and the channel utilization. We also provide statistical experiments with analysis and simulation to investigate the influences of the service rate of one channel and the sleep timer parameter on the system performance measures. In order to get the utmost out of the spectrum resource and meet the demands for the quality of service requirements of SUs, we construct a system cost function, and improve a Jaya algorithm employing an insect-population model to optimize the proposed energy saving strategy. We also show the optimal combination and global minimum of the system cost by numerical results.