On Achievable Performance of Cognitive Radio Systems
Majed Haddad, Merouane Abdelkader Debbah, Aawatif Menouni Hayar · arXiv (Cornell University) · 2007
In this contribution1, we investigate the idea of using cognitive radio to reuse locally unused spectrum to increase the total system capacity. We consider a multiband/wideband system in which the primary and cognitive users wish to communicate to different receivers, subject to mutual interference and assume that each user knows only his channel and the unused spectrum through adequate sensing. Under this scheme, a cognitive radio will listen to the channel and, if sensed idle, will transmit during the voids. Within this setting, we provide two simple methods for sensing the idle sub-bands over the total bandwidth. We impose the constraint that users successively transmit over available bands through proper water filling. For the first time, our study has quantified the achievable gain of using cognitive radio with respect to classical radio devices and derive the total spectral efficiency as well as the maximum number of possible pairwise communications of such a cognitive radio system. We finally show that we can improve the overall system spectral efficiency by considering cognitive communications in the system. Index Terms filling. Cognitive radio, sensing, power detection, radar detection, capacity, spectral efficiency, band factor gain, water I.