Performance analysis of spectrum handoff under heterogeneous spectrum environment in ad hoc and centralized CR networks

Abstract

The prime objective of cognitive radio (CR) is to address the problem of spectrum scarcity and inefficient usage of spectrum, by allowing the unlicensed or cognitive users (CUs) to access the underutilized licensed spectrum of the primary users (PUs). CUs experience considerable performance degradation due to the event of random interruptions by PUs in their respective bands of operation. In this article, we develop a spectrum management scheme and evaluate the performance of the CUs under heterogeneous spectrum environment (HetSE) in both ad-hoc (opportunistic) and centralized (negotiated) CR networks. We consider a finite threshold period (Dth) for spectrum handoff delay to improve the performance of the CUs for both opportunistic situation with backup channels (OSB) and negotiated situation with backup channels (NSB). The spectrum handoff performance measuring metrics: link maintenance probability, link failure probability, probability mass function of spectrum handoff, expected number of spectrum handoff and non-completion probability of the CUs, are derived under heterogeneous spectrum environment to investigate the characteristics of the network for both opportunistic and negotiated spectrum access strategies.