The Design And Implementation Of Cognitive Radio And The Research Of Silent Period

With the penetration of wireless communication technology, spectrum resourceshave been employed more widely. The scarceness of spectrum hampers the sustainingdevelopment of wireless communication. By sensing the spectrum environment andadjusting the transmission parameters in real time, cognitive radio can use the licensedspectrum in an opportunistic way, which will solve the problem of lacking wirelessspectrum and makes itself a hot topic in wireless communication in recent years.Based on the basic theory of cognitive radio, firstly, a manage-center basedcognitive radio communication system which is composed of a spectrum environmentsimulator, several cognitive nodes and an administrator is proposed in this paper. Thedesign of the system’s working circumstance, the functional capability of each entity,and the information transmitted between nodes as well as its frame format areintroduced in detail. Then the system is implemented on hardware-basedDSP+FPGA.Secondly a distributed system is proposed and its working process is wellintroduced and is proved to be useable by software-simulation. At last, this paperfocuses on the quiet period in cognitive radio system and introduced a primary userdetection method without silent period assisted by communication bit error rate. Theimprovement of original system by using the detection method above is also introduced.