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A Packet Dropping Mechanism in Multi-channel Cognitive Radio Networks with Classified Secondary Users

Packet dropping mechanism (PDM), which is a technology based on channel preemption, can be used in cognitive radio networks (CRNs) to achieve better system average delay. We call Secondary Users (SUs) with lower priority as SU2s in CRNs. We suppose that the system can dynamically aggregate and assign channels to the SU2 according to SU2 packet quantity in the buffer queue. Simultaneously, when an SU2 packet is interrupted, a PDM will be adopted to decrease the average delay of the system. A Markov chain is established with the purpose of analyzing the performance metrics of CRNs according to four parameters: SU2 blocking rate, SU2 throughput, SU2 average delay and channel closed ratio. In addition, numerical results are shown by contrasting the system performance of the considered PDM and conventional retransmission mechanism.