Research On Spectrum Sensing Technology In Cognitive Radio

In recent year, as the rapidly development of the wireless conmunication applications, thelackage of spectrum rescources become a unavoidable problem. The future of communicationface a challenge like never before. However, the spectrum recources are not really scares, thewireless spectrum usually distributed by government in a fixed manner. This already fixedspectrum management methods have caused problems. For example, some spectrum havebeen atributed was not used, while others was using too much frequently. The DynamicSpectrum Access (DSA)technology in cognitive radio eases the problems. The DSA sensesthe spectrum environment in time domain, frequency domain, space domain, code domainand find the unused spectrum and accessed to use in order to improve the spectrum efficiency.In the paper, The basical theory of cognitive radio is introduced, Then the definition ofcognitive radio, the network of congtive radio, the physical structure of cognitive raido frontend is explaned. Andthe key technology of cognitive radio, the spectrum sensing technologyand the model of cognitive network are disscussed, In this paper we discussed three detectionmethods based on transmitters, they are Matched filter method, The energy detection and thecyclostationary detection.At last in this paper the cyclostationary detection about OFDM singals is concentrated, thetrandional OFDM signals used IDFT to implement modulation, however the DHT and DCTalso can do the same things. In this paper the DHT-OFDM signals used cyclostationarydectetion, thecyclostationary signatures are setted in the subbcarriers, in the received end dothe signal classification.