Adaptive Spectrum Sensing in Cognitive Radio Employing Multitaper Method and Higher-Order STBC Techniques

Abstract

The effects of the non-parametric multitaper method (MTM) and symmetrical higher-order space-time block-code (STBC) with full diversity techniques on the performance of spectrum sensing (SS) in cognitive radio (CR) systems are studied. The overall wireless link performance can be improved by using the STBC techniques to combat the multipath fading effects in wireless channels. The MTM is integrated with the STBC for spectrum estimation (SE), which will be termed multitaper spectrum estimation (MTSE)-STBC, and the given analysis of which is developed using the quadrature form approximation. Also, classical SE algorithms commonly focus on a fixed performance assessment method based on predefined false alarms or detection probabilities. Licensed users need to be protected against interference that opportunistic users might cause. An appropriate thresholding policy that varies concerning the designated values of false alarm and detection rates can achieve such protection. Utilization factors are instrumental in providing further protection for licensed users or occupied spectrum holes, and they need to be determined in advance and adopted in the detection policy. If utilization factors are not desirable, then a fine selection of appropriate threshold values will need to be decided as they have a major impact on the overall error probability performance. Using analytical and simulation methods, the assessment results revealed improved performance of the MTSE-STBC compared to other classical methods such as the Periodogram especially in the aspects of efficient transmission and less error probability. The proposed adaptive thresholding technique also proved useful in coping with different SE settings.