Analysis of Non-Coherent Detectors for Opportunistic Spectrum Access in Broadband Wireless Networks

Abstract

The exponential growth in the number of wireless broadband service users demands an enormous increase in the available communication bandwidth, which inherently translates into an increased demand for the radio frequency spectrum. Opportunistically accessing the unused portions of the spectrum requires sensing the availability of unused bands. In this thesis, non-coherent detectors such as the energy detector and its more generalized version, the p-norm detector, which offer low-cost low-complexity spectrum sensing are considered and comprehensive techniques for performance analyses are developed. To this end, a new approximate representation for the wireless fading channels is proposed and applied to facilitate accurate, asymptotic performance analysis for the energy detector across a variety of operating conditions including fading, antenna/cooperative diversity and interference. To address the analytical difficulty involved in spectrum sensing using the p-norm detector, several accurate analytical expressions are developed and utilized to comprehensively characterize the spectrum sensing performance in generalized fading channels and in fading channels with antenna diversity. To promote tractable spectrum sensing performance analysis for arbitrary sample sizes, five accurate approximations are introduced and investigated. In another comprehensive system setup, spectrum sensing performance of the p-norm detector under the cumulative effects of path-loss, fading, and a large number of randomly deployed interfering nodes is characterized by developing a comprehensive semi-analytical technique and extended to cooperative spectrum sensing.