Queueing models for cognitive wireless networks with sensing time of secondary users

This paper considers queueing models for cognitive radio networks that account for the sensing time of secondary users (SUs). In cognitive radio networks, secondary users are allowed to opportunistically use idle channels originally allocated to primary users (PUs). To this end, SUs must sense the state of the channels before transmission. After sensing, if an idle channel is available, the SU can start transmission immediately; otherwise, the SU must carry out another channel sensing. In this paper, we study two retrial queueing models with an unlimited number of sensing SUs, where PUs have preemptive priority over SUs. The two models differ in whether or not an arriving PU can interrupt a SU transmission also in case there are still idle channels available. We show that both models have the same stability condition and that the model without interruptions in case of available idle channels has a slightly lower number of sensing SUs than the model with interruptions.

Automated summary

This paper explores queueing models for cognitive radio networks incorporating sensing time for SUs, focusing on two retrial queueing models with an unlimited number of sensing SUs where PUs have preemptive priority. The stability conditions are the same for both models, but the model without interruptions when idle channels are available has slightly fewer sensing SUs compared to the model with interruptions.