الفهرس 
chapter 1Only 14 pages are availabe for public view
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Abstract
New wireless services such as HDTV, 3G, LTE, and WIMAX result in higher demand on the radio frequency spectrum. Due to the tremendous demand for the spectrum in the recent years, there will not be enough spectrum available for all wireless systems currently under development. Although, most of the spectrum is assigned to licensed services, the actual radio spectrum is underutilized. The need for a new technique that exploits this low spectrum occupancy feature has aroused. This technique is cognitive radio. It is a new technology that captures increasing attention in the wireless industry. The target of cognitive radio is to detect and access the free spectrum for opportunistic use.
Spectrum sensing in cognitive radio network is considered as one of the challenging issues facing opportunistic utilization of the frequency spectrum. Compressive sensing and collaborative compressive sensing have been proposed as effective techniques to alleviate some of the challenging issues in spectrum sensing such as the need of high speed analog to digital converter and the hidden primary user problem. This is achieved through efficient sampling by exploiting the underlying sparse structure of the measured frequency spectrum with the novel framework of compressive sensing.