Research On Resource Allocation And Relay Selection For Cooperative Cognitive Radio Network

With the rise of intelligent terminals, especially smart phones, news messages, e-commerce, social network and other network wireless applications have been widely used. People's access to information is becoming more and more convenient, and Demand for information is growing. People put forward higher requirements for the transmission rate and quality of service of wireless communication system. At the same time, limited and scarce radio spectrum resources make improving spectral efficiency an increasingly urgent task. Cognitive radio(CR) spectrum as an effective means to improve spectrum utilization since birth has been widely concerned and researched, in which cognitive users multiplex authorized spectrum in various ways under the premise of not affecting the quality of authorized communication, thereby increasing the chance of cognitive users to communicate and improving the spectrum utilization. Furthermore Multiple-input multiple-output(MIMO) technology and cooperative communications technology can improve system capacity, spectral efficiency, increase the coverage range of the system, but also become effective means to improve the spectrum efficiency. Cognitive radio, combined MIMO technology and cooperative communication technology can further increase system capacity and improve the spectrum efficiency. In this paper, the main work is as follows:At first, MIMO technology and cooperative communication technology are introduced into cognitive radio network and resource allocation problem in Cooperative cognitive radio network(CCRN) is studied. A transmission mechanism based on the joint allocation of time, frequency and space domain resources is proposed for the cooperative cognitive radio network(CCRN). The proposed scheme employs multi-antenna cognitive user as a relay. Via adaptive time-slot and bandwidth allocation, bottleneck in the two-hop transmission can be eliminated. End-to-end transmission of primary user is improved, while the cognitive user which assists primary transmission gets the opportunity to communicate, which achieves a "win-win".Next, a relay selection algorithm taking fairness into account is given for the situation in which multiple cooperative cognitive users are included. On one hand, the relay selection employs proportional fair to achieve inter-cognitive-user fairness. On the other hand,proper reward is determined by adjusting the incentive factor of the selected cognitive relay. The proposed algorithm could improve the data rate of both primary and cognitive systems, and afford fair reward to the cognitive users. At last, energy efficiency of cognitive relay in cooperative cognitive radio network is studied. Cognitive relay's energy consumption of relaying primary data, is incorporated into scheduling weight calculation. At the expense of certain data rate and scheduling fairness cognitive relay's energy consumption is reduced, thereby to increase energy efficiency. Adjusting the value of the energy efficiency factor dynamically, you can make a reasonable trade-off when cognitive relay is selected between the data rate of primary system, cognitive relay selection equity and energy efficiency.