In this study, the authors have analysed the performance of selection relaying at each hop in a decode-and-forward (DF)-based multi-hop cognitive radio (CR) system deploying cooperative spectrum sensing. The decisions on spectrum availability are taken by a number of sensing CRs (SCRs) at the first level and are sent to a fusion centre (FC) over pre-existing clusters of relaying CRs (RCRs). The RCRs are being used in a secondary role for relaying the spectrum decision besides sensing their own area primary user. The decision of each SCR is relayed to FC one-by-one via number of RCR clusters by selecting a maximum signal-to-noise ratio link at each cluster independently. The selected RCR forwards the decision to the next level using DF protocol. The closed-form expressions for probability of missed detection and false alarm are derived at the FC. An optimal combining rule is devised at the FC. A comparative graphical analysis of power saving in case of multi-hop transmission to that of single-hop transmission is also presented. The number of hops for the considered system is optimised based on a trade-off relation between error rate and transmission delay.
['Dhanesh Goel', 'Vemuri Sai Krishna', 'Manav R. Bhatnagar']
Selection relaying in decode-and-forward multi-hop cognitive radio systems using energy detection