A Retransmission Control Scheme with Adjustment Factor for Hierarchical Secondary Users in CRNs

In our work, for the purpose of controlling the retransmission behavior of secondary users (SUs) in cognitive radio networks (CRNs) with hierarchical SUs, we set a feedback probability for the interrupted lower priority SUs (SU2). Whether an interrupted SU2 packet leaves the system depends on this feedback probability. This feedback probability is a system parameter associated with the amount of packets in the system. An adjustment factor is introduced to control the impact of the amount of packets on the feedback probability. By establishing a Markov chain model, we obtain some expressions of related performance metrics. Finally, by operating numerical experiments, we analyze the impact of the adjustment factor on different performance indicators of SU2.