Prioritized Proactive Scheme for Spectrum Handoff Decision in Cognitive Radio Networks

Cognitive Radio Networks have been designed to increase spectrum utilization by utilizing temporarily unused spectrum bands in the primary user´s licensed spectrum by secondary (unlicensed) users. In general, when a primary user appears in a band occupied by a secondary user, the secondary user will temporarily cease its transmission and change the operating channel. Unfortunately, successive spectrum handoffs can degrade quality of service (QoS) of the interrupted users. Spectrum handoff mechanism should help cognitive radio users to guarantee QoS. In particular, it should facilitate the channel clearing whilst searching for target vacant channel(s) for completing interrupted secondary users´ transmission when the licensed primary user appears at the engaged licensed band. In this paper, a prioritized proactive spectrum handoff decision scheme is proposed to evaluate the total service time for the implemented model. The proposed scheme is modeled using a preemptive resume priority (PRP) M/M/1 queue. It gives a high priority to interrupted users to resume their transmission before any other uninterrupted secondary users. The implemented scheme outperforms the existing spectrum handoff decision schemes in terms of total service time.