Spectrum Sensing Design Framework Based on Cross-Layer Optimization of Detection Efficiency

Cross-layer optimization of the spectrum sensing (SS) sub-system in a cognitive radio (CR) is essential for achieving the best spectrum utilization because the three SS layers - sensing radio, sensing PHY and sensing MAC - jointly determine the overall performance of the SS sub-system. In this paper we introduce a function called detection efficiency that measures how much of the idle primary user spectra is actually utilized by the CR users as a function of regulatory constraints, network specifications and the parameters of the sensing radio, MAC and PHY. By optimizing these parameters to maximize detection efficiency of the SS system, the designer can compare and select the best SS design for a given wireless network requirement. By applying this design method to evaluate several design options for the SS layers, we show that cross-layer optimization can in some cases improve the detection efficiency (and therefore spectrum utilization) from 35% to as much as 99%.