We investigate a cognitive radio network in which a primary user (PU) maycooperate with a cognitive radio user (i.e., a secondary user (SU)) fortransmissions of its data packets. The PU is assumed to be a buffered nodeoperating in a time-slotted fashion where the time is partitioned intoequal-length slots. We develop two schemes which involve cooperation betweenprimary and secondary users. To satisfy certain quality of service (QoS)requirements, users share time slot duration and channel frequency bandwidth.Moreover, the SU may leverage the primary feedback message to further increaseboth its data rate and satisfy the PU QoS requirements. The proposedcooperative schemes are designed such that the SU data rate is maximized underthe constraint that the PU average queueing delay is maintained less than theaverage queueing delay in case of non-cooperative PU. In addition, the proposedschemes guarantee the stability of the PU queue and maintain the average energyemitted by the SU below a certain value. The proposed schemes also provide morerobust and potentially continuous service for SUs compared to the conventionalpractice in cognitive networks where SUs transmit in the spectrum holes andsilence sessions of the PUs. We include primary source burstiness, sensingerrors, and feedback decoding errors to the analysis of our proposedcooperative schemes. The optimization problems are solved offline and require asimple 2-dimensional grid-based search over the optimization variables.Numerical results show the beneficial gains of the cooperative schemes in termsof SU data rate and PU throughput, average PU queueing delay, and average PUenergy savings.
展开▼
