Research On Cooperative Sensing In Cognitive Radio

Wireless spectrum is precious and non-renewable. With the development of mobile communication theory and application technology, mobile communication business is on a stage of accelerating development,3G and4G communication service is constantly enriching human’s life. But the shortage of wireless spectrum resources is increasingly serious. But related studies suggest that, much of the wireless spectrum resources are not be fully utilized, severe waste is existed in spectrum usage. So it is a very important question of how to make full use of the existing spectrum resource and improve the spectral efficiency.Cognitive radio is a kind of frontier technology aiming to solve the problem of spectrum resources shortage. It finds out spectrum holes in the authorized channels through spectrum sensing of second users, distribute and use these idle spectrum reasonably, so as to increase the wireless spectrum efficiency greatly. Green communication is suggested to solve the problem of wireless communication energy consumption and improve the efficiency of resource use in wireless communication system. Combined these two theories, it is very meaningful to detect spectrum hole effectively in a cognitive radio system, and improve the system resource utilization rate, so as to reduce the resource cost and improve the system performance.This paper mainly study and analyze cooperative spectrum sensing algorithm in the cognitive radio, and put forward a algorithms of collaboration sensing based on the policy database and another algorithm of user selection in cooperative sensing. Firstly, the algorithm of cooperative sensing based on policy database establishes two database of spectrum sensing algorithm and data fusion algorithm. Divide channel protection level for the channels in the system, and choose available algorithms of spectrum sensing and data fusion from the databases, so as to improve the sensing probability of each channel and reduce the interference for the communication of main users from second users, improve the system performance.Secondly, this paper proposes a algorithm of user selection in cooperative sensing. It analyzes the characteristics of multiple users sense multiple channels and multiple users sense single channel. In the situation of multiple users sensing multiple channels, because of the second users’number limiting, it will lead to a low sensing perception if allocating the second users to each channel equally. So set channel switching to the second users in this system, which means a second user need to detect several channels. This will get the balance of system cost and sensing perception based on acceptable time cost and energy cost. In another situation of the multiple users detect single channel, it only need to consider the relationship between the energy cost and the spectrum sensing accuracy, because no channel switching is existed. Research shows that, with the number of second users increasing in the cooperative sensing, the system utility function presents a peak, and the peak represents the best number of cooperative sensing users. The results show that, cognitive radio system can determine a best second users’ number of cooperative sensing to acquire the balance of system resources cost and sensing accuracy, and accord’with the main thought of green communication.