Spectrum hole identification in multiple TV bands by adaptive threshold multi-taper spectrum estimator for cognitive radio

Cognitive radio (CR) is a wireless technology that facilitates unlicensed users to access the sensed spectrum without creating any interference to the primary user. Sensing the licensed spectrum to seek for spatiotemporal information of any possible spectrum hole is the first step needed to be performed by the CR devices. In this paper we propose an adaptive threshold technique to extract spectrum hole information from Multi-taper Spectrum Estimator (MSE) estimated spectrum. It has been found that when threshold is adapted depending on the change in noise level and presence of primary or secondary signals in a TV band, the detection performance improves compared to fixed threshold. A 400 kHz band was split into 20kHz sub bands to verify the possibility of splitting the TV bands into 200kHz bands from CR usage perspective. From analytical calculations and MATLAB simulations it has been shown that if TV band is viewed as 200 kHz sub-band channels from CR perspective; blocking probability for CR operation can be reduced. In addition it has also been shown that sensing multiple TV bands simultaneously can help CRs to find more opportunities with minor impact on system complexity.