Strategic spectrum occupancy for secondary users in cognitive radio networks with retrials

Abstract

This article investigates joining strategies and admission control policy for secondary users (SUs) with retrial behavior in a cognitive radio (CR) system where a single primary user (PU) coexists with multiple SUs. Under a certain reward‐cost structure, SUs opportunistically access the PU band when it is not occupied by the PU. If the band is available upon arrival, an SU decides with a probability either to use the band immediately or to balk the system. If the band is occupied, the SU must decide whether to enter the system as a retrial customer or to leave the system. Once the PU requests for service, the service of SU being served, if any, will be interrupted, and the interrupted SU leaves the band and retries for service after a random amount of time. In this article, we study the equilibrium behavior of non‐cooperative SUs who want to maximize their benefit in a selfish, distributed manner with delay‐sensitive utility function. The socially optimal strategies of SUs are also derived. To utilize the PU band more efficiently and rationally, an admission control policy is proposed to regulate SUs who enter the system in order to eliminate the gap between the individually and socially optimal strategies.

Optimal Pricing Strategies in Cognitive Radio Networks With Heterogeneous Secondary Users and Retrials

“…By comparing the revenue-optimal and socially pricing strategies under the discrete and continuous distributions of the delay-sensitive parameter, it is found the revenue-optimal price is not less than the socially optimal one. Furthermore, we carefully check the conclusion that the profit-maximizing joining probability coincides with the socially optimal one drawn in Wang et al [17] for the homogeneous SUs, and find that this conclusion no longer holds when the delay-sensitivity of SUs is heterogeneous; that is, the profit-maximizing joining probability is not greater than the socially optimal one in the case with heterogeneous SUs.…”

“…Upon the arrival of a PU demand, if the band is occupied by an SU demand, this SU demand will be squeezed out by the PU. Assume SUs have perfect detecting of PUs after joining the system and when being transmitted through the PU band, which is common in literature, such as [10]- [17], and we will try to relax this assumption in the future research. Furthermore, the service times have general distribution functions G(x) with the Laplace-Stieltjes transform g * (s) = ∞ 0 e −sy dG(x) and the finite first two moments β 1 , β 2 for PUs, and F(x) with the Laplace-Stieltjes transform f * (s) = ∞ 0 e −sx dF(x) and the finite first two moments µ 1 , µ 2 for SUs.…”

“…But this assumption is not reasonable since the interrupted SU is designated a priority without any pay. Thus, with or without perfect sensing, Wang et al [17], [18] relaxed such an assumption and they assumed the interrupted SU enters a retrial orbit to compete with other SUs fairly. In these two papers, under the assumption that SUs are homogeneous and the transmission times for the PU and SUs follow Exponential distributions, a pricing strategy maximizing the social welfare was proposed.…”

“…In these two papers, under the assumption that SUs are homogeneous and the transmission times for the PU and SUs follow Exponential distributions, a pricing strategy maximizing the social welfare was proposed. When analyzing under perfect sensing [17], it is concluded by numerical examples that the profit-maximizing joining probability is in consistence with the socially optimal one. However, considering that each arriving SU carries a distinct job, their sensitivity to delay may differ.…”

“…In our model, the interrupted SUs join a retrial orbit and retry independently for later service, in contrast to the assumptions in previous studies that they are lost or waiting in front of the server. In addition, relaxing the restriction identified in [17] that only one PU is licensed to access the band and consequently no PU ever waits in queue, we allow for multiple PUs that are transmitted by the FCFS discipline.…”