Research On Resource-efficient Cooperative Spectrum Sensing

By the fast development of the wireless communication technology as well as the demand of wireless communication of people, the frequency spectrum resources have become more and more scarce like other non-renewable resources, and it has become the giant bottleneck of wireless communication development. But, by the research of many scientific workers actually indicate that the reason of the scarce of the frequency spectrum resources is the existence of "the empty frequency spectrum", and not full using of the frequency spectrum resources. The cognitive radio technology can opportunistically utilize the white space of licensed spectrum bands, and it has been considered the most effective and reliable solution of the scarce of wireless frequency spectrum resources, has already received the attention of more and more people.Using the idle licensed frequency bands must to carry on accurate and fast frequency spectrum recognition. On the one hand, that can find the blank frequency spectrum fast and use for secondary users, and raise the utilization rate of the frequency spectrum. On the other hand, once the primary users return to the licensed channels, the secondary users must be able to withdraw fast, thus do not disturb the primary users. To be a kind of fast and convenient way, the frequency spectrum sensation becomes the focal of the cognitive radio technology, and it has been at the important position in the field of cognition radio technology. Therefore, people have developed many different methods of frequency spectrum sensing. In the numerous methods, the cooperative frequency spectrum sensing was considered the reliable and efficient path to enhance the sensing performance. But, because many users simultaneously participate in this sensing process, it will increase the sensing overhead. How to fall the sensing overhead has become the hot spot topic in the cooperative sensation technology.The main content is the number of users, the number of licensed channel, cooperative sensing precision, sensing overhead and their relations between each other, and has given the computational formula of the overhead of cooperative sensing. Propose a method to reduce the sensing overhead that can choice the best number of sensing points and the sensing channels.This method can satisfy the demand of secondary users in the situation that not to disturb the primary users, and propose the concept of degree of satisfaction. The degree of satisfaction is determined by the users'number that participate in the cooperative sensing and the number of channel in the cognitive network. Through the degree of satisfaction we can determine the sensing number and the channel number's scope about cooperative sensing, simultaneously by considering the question of the sensing overhead of the cognitive radio network, therefore we can determine the optimized sensing number of users and the channels finally. So we can decrease the system's sensing overhead, and achieve the goal of highly effective cooperative sensing. Because the formula of degree of satisfaction is very complex, it must use the method of exhaust search to complete the computation part of the algorithm. Therefore, also develop some methods to reduce the load of computation. Have proven the feasibility of the optimized algorithm through the simulation, and compares the simulation result with other algorithms.