Improving spectrum handoff utilization for prioritized cognitive radio users by exploiting channel bonding with starvation mitigation

In this study, priority based non-preemptive M/G/1 queueing model of spectrum handoff scheme is proposed in Wireless Cognitive Radio Networks. Channel bonding mechanism with starvation mitigation is employed in order to improve spectrum handoff utilization for secondary users. Since spectrum handoff offers an opportunity to secondary users for continuing their communication, it is of critical significance to determine action of primary users. In the queueing model, prioritized data traffic with aging solution to starvation is exploited to meet requirements of the secondary users. In aging mechanism; when the packet of the low priority secondary user waits in the queue more than three frame times, priority of that packet is increased. Packets of secondary users are categorized into three different priority classes, i.e., urgent, real time, and non-real time where non-real time data packets have the lowest priority while urgent data packets have the highest priority. Channel bonding mechanism is described as combining two subsequent time slots if the size of the packet is bigger than one time slot. Idle time slots for channel bonding are determined using both proactive and reactive decision based spectrum handoff schemes. Before starting spectrum handoff process with proactive scheme, first of two subsequent time slot is sensed using reactive scheme. Riverbed Modeler simulation software is utilized to simulate channel bonding and aging mechanisms. Analytical results are shown to be matched with the simulation results obtained under different load and arrival rates. This study has also exposed that the throughput of secondary users could be increased significantly by employing aging solution to starvation, and channel bonding mechanisms.