Combined diversity and improved energy detection in cooperative spectrum sensing with faded reporting channels

Abstract

In this paper we evaluate the performance of cooperative spectrum sensing (CSS) where each cognitive radio (CR) employs an improved energy detector (IED) with multiple antennas and uses selection combining (SC) for detecting the primary user (PU) in noisy and faded sensing (S) channels. We derive an expression for the probability of false alarm and expressions for probability of missed detection in non-faded (AWGN) and Rayleigh faded sensing environments in terms of cumulative distribution function (CDF). Each CR transmits its decision about PU via noisy and faded reporting (R) channel to fusion center (FC). In this paper we assume that S-channels are noisy and Rayleigh faded while several cases of fading are considered for R-channels such as: (i) Hoyt (or Nakagami-q), (ii) Rayleigh, (iii) Rician (or Nakagami-n), and (iv) Weibull. A Binary Symmetric channel (BSC) with a fixed error probability (r) in the R-channel is also considered. The impact of fading in R-channel, S-channel and several network parameters such as IED parameter, normalized detection threshold, number of CRs, and number of antennas on missed detection and total error probability is assessed. The effects of Hoyt, Rician, and Weibull fading parameters on overall performance of IED-CSS are also highlighted.

Keywords

• Cooperative spectrum sensing
• Improved energy detector
• Fading channels
• Hard decision fusion rules
• Total error probability