Study On Cognitive Radio System Relative Techniques Based On OFDM

In Cognitive Radio (CR) system, unlicensed users (Secondary User, SU) are allowed to access to the spectral holes for service transmission and have to yield to the licensed users (Primary User, PU) immediately at PU’s emergence. By doing these, the licensed spectrum is fully used for services which means less spectrum being wasted. Thus Cognitive Radio theory gets tremendous attention and research from the domestic and foreign research institutions and becomes the hot spot in this area.This paper focuses on the research of spectrum handoff and interference suppression. Also I build models to simulate our new scheme and get desired outputs to support our theory.Firstly, this paper introduces the background of CR’s emergence and development. Then it introduces several key techniques of CR and several scenes of application.Secondly, it makes a deep research on the development of spectrum handoff and gives a detailed analyze of spectrum handoff’s definition, scene of application and purpose. Especially, it summarizes several key techniques of spectrum handoff. Based on all of these, I put up a new spectrum handoff scheme which is so called comprehensive income scheme. This scheme brings many system performance indexes into together and then does estimation and makes choice so as to insure the whole system performance.Thirdly, it turns to the research of CR-OFDM system’s sidelobe interference and introduces several popular interference suppression techniques. Based on these, I make an improvement for normal interference cancellation carriers scheme and put up two new schemes which are so called EDC and ECC respectively. By expanding the scope of the deployment of cancellation carriers, we can get much better effect on sidelobe suppression while achieving an acceptable BER performance.Lastly, it summarizes the research results and makes a summarization and prospect for the research mentioned in this paper.