Load balancing probabilistic spectrum handoff for cognitive radio networks

Spectrum mobility in cognitive radio networks aims to enhance spectrum utilization by allowing unlicensed secondary users (SUs) to access the licensed frequency bands of the primary users (PUs). It also helps to vacate the channel from the SU when the licensed PU arrives at the channel, and finds a suitable channel for the interrupted SU. In this paper, we propose a probabilistic approach to determine the target channel for the interrupted SUs. This approach is analysed based on the preemptive resume priority (PRP) M/M/1 queuing network model to evaluate and compare the latency performance and load-balancing of connection-based spectrum handoff in cognitive radio networks. The analytical formulas obtained for the extended data delivery time and the channel busy probability are used to compare the proposed approach with other spectrum handoff strategies based on the target channel sequences specified in the IEEE 802.22 wireless regional area networks (WRAN) standard (the always stay and always change). The results reveal the advantage of the probabilistic approach (based on the total arrival rate to each channel) in load balancing in terms of the variance of the channels´ busy probabilities.