BEP walls for cooperative Bayesian detection with reporting channel errors

The focus of this paper is on performance limitations for cooperative spectrum sensing in cognitive radios caused by reporting channel errors. In this paper, hard decision (HD) based cooperative sensing (CS) is considered. Each secondary user (SU) detecting a primary user (PU) sends a one-bit local decision to a fusion center (FC). The reporting channel errors may cause bit errors which may be non-identically distributed. The reporting channels are modeled as binary symmetric channels with certain bit error probability (BEP). The limiting performances of the Chair-Varshney and K-out-of-N fusion rules at the FC are analyzed in the presence of reporting channel errors and later numerical results are presented. Earlier works in the literature have shown the existence of a BEP wall in the presence of reporting channel errors for CS under the constraints on the probabilities of missed detection and false alarm. In this paper, the BEP wall phenomenon for HD based CS is studied in a Bayesian formulation such that there is a constraint on the average probability of error.