Opportunistic channel-aware spectrum access for cognitive radio networks with periodic sensing

Abstract

Opportunistic spectrum access in a cognitive radio network has been a challenge due to the dynamic nature of spectrum availability and possible collisions between the primary user (PU) and the secondary user (SU). To maximize the spectrum utilization, we propose a spectrum access strategy where SU's packets are interleaved with periodic sensing to detect PU's return. We formulate the sensing/probing/access process as a maximum rate-of-return problem in the optimal stopping theory framework and show that the optimal channel access strategy is a pure threshold policy. We consider a realistic channel and system model by taking into account channel fading and sensing errors. We jointly optimize the rate threshold and the packet transmission time to maximize the average throughput of SU, while limiting interference to PU.

Outage probability of amplify-and-forward underlay cognitive relay networks with selection diversity over Nakagami-m fading channels

“…CR is one of the important technologies for wireless applications that has considered as a spectrum opportunistic technology. The main goal of CR is to exploit licensed bands without a license, where the unlicensed user (Secondary User) can use the spectrum band of the licensed user (Primary User) when the primary user is idle [1][2][3].…”

Performance analysis of amplify‐and‐forward cognitive relay networks with interference power constraints over Nakagami‐m fading channels

“…CR which was proposed in 1998 by Joseph Mitola is a promising technology to solve the spectrum shortage and to utilise the underutilised spectrum, where in CR we define two users, the first one is the primary user (PU) which have a licensed spectrum access and have the priority for transmission, and the second one is the secondary user (SU) which has unlicensed spectrum access. In the overlay strategy, the SU can acess the channel after checking that the PU does not use the channel, and if the PU suddenly has decided to transmit its own data, then the SU shall stop its transmission [2,3]. In the underlay strategy, the spectrum is accessible to the SU under an interference constraint at the PU receiver.…”