Cognitive radio is a technology which is being developed to bring greater efficiency, speed and reliability to users of wireless devices. The number of high powered wireless devices coming on to the market is increasing exponentially placing an unprecedented demand on the limited radio spectrum. Cognitive radio technology is seen as a potential solution to this problem as it identifies unused frequencies in a local area and switches a device to this temporarily to provide users with uninterrupted and faster mobile services.
In the following, CRS refers to Cognitive Radio Systems. One typical example of usage of CRS is in the so called “white spaces” (WS), which refers to frequency spectrum which is potentially available at a given time for further
utilisation within frequency spectrum originally planned another service (e.g. Broadcasting). Devices operating in the white spaces using cognitive radio features are called White Space Devices (WSD) [14].