Design And Implementation Of Cognitive Radio System Based On USRP2

In this information age, the Mobile Internet has boomed because of the growing popularity of smart phone. Users' demand for access speed of mobile communication systems is growing so fast that frequency resource has nearly ran out. Frequency resource has become the bottleneck that restricts the mobile communication systems development. Traditional technologies are unable to significantly improve the frequency efficiency. Cognitive Radio is generally considered as a kind of technology which can revolutionarily improve the frequency efficiency. By sensing the electromagnetic environment, users of Cognitive Radio system choose a suitable frequency to communicate with each other that balances the service time of all the frequency. Then the frequency efficiency increases. Nowadays the researches on Cognitive Radio are popular, but they almost focus on the theory of key technologies and simulation. A Cognitive Radio real system is urgently needed to verify whether the theory is correct.This paper introduces the research status of Cognitive Radio and the architecture of Software Defined Radio. Design a complete solution of Cognitive Radio system including network structure, working process, module design and finite state machine of user. According to the solution, the Cognitive Radio system is implemented using the Software Defined Radio platform composed of USRP2 and GNU Radio. The system consists of communication module, frequency sensing, frequency allocating, frequency negotiation, link connect, IP traffic, voice traffic, link interrupt recovery and so on.This system has features as follows. First, work at the frequency between 2.3GHz and 2.7GHz. Second, sense the frequency hole correctly. Third, automatic find a suitable frequency and connect each other. Manual setting is not required. Fourth, support IP and voice traffic. Fifth, link will automatically recover when disconnect.At last the system is verified and considered to meet the needs.