Performance Analysis of Amplify-and- Forward Relay Based Cooperative Spectrum Sensing in Fading Channels

Relay based cooperative spectrum sensing elevates the spectrum sensing problems in harsh propagation conditions if the relay nodes are positioned suitably for the dynamic spectrum access systems. This article investigates the performance of relay based spectrum sensing (energy detection based) in myriad fading environments using the area under the receiver operating characteristic curve (AUC) performance metric. AUC is a single statistical parameter, which provides better insight of detection probability compared to the receiver operating characteristic curve (ROC). The article includes the performance analysis of two-hop multi-relay amplify-and-forward (AF) relay network with channel state information (CSI) assisted relaying (variable relay gain) and blind (fixed) relay gain. A unified model is also investigated to describe the relay network for variable and fixed relay gain. Various fading and relay configurations are illustrated to show the efficacy of the energy detection based collaborative spectrum sensing in AF relay configuration using the AUC performance metric. Performance of the variable and fixed relay gain based AF relay network are analysed and compared considering different factors affecting energy sensing such as the per-hop signal-to-noise ratio (SNR), fading index, and the timebandwidth product. The results can be readily used for the design of the cognitive relay network.