Multi-Class "Channel+Beam" Handoff in Cognitive Radio Networks with Multi-Beam Smart Antennas

In this paper, we propose the concept of "channel+ beam" hando2642 (CBH) in cognitive radio networks (CRNs) with multi-beam smart antennas (MBSAs). We address the multi-class spectrum hando2642 issue, based on the user priority, by using the mixed Preemptive/Non-Preemptive M/G/1 queueing model with discretion rule. The discretion rule sets the threshold for the preemption of the low-priority secondary users (SUs) based on the remaining service time. Since each beam of the MBSA can use a di2642erent CRN channel, we design a delay-constrained CBH scheme in which the packets in the interrupted beam can be detoured through neighboring beams. The probability of beam hando2642 is determined based on their channel capacity and bu2642er fullness of the queue associated with the neighboring beams. By using the CBH model with discretion rule, a low priority SU can escape from multiple interruptions during the completion of its service. Our simulation results show that the mixed queueing model with discretion rule reduces the queueing delay (i.e., hando2642 delay) of the high priority SUs, and the packet detouring scheme gives fair spectrum access opportunities to the low priority SUs.