Research On Cognitive Radio Technology For Multi-User Cooperative Communication

In the cognitive radio technology, secondary user accesses the spectrum by sensing the idle licensed spectrum and following the spectrum allocation policy of the system. Collaborative communication technology is a kind of technology that shares resources and cooperates with other nodes in specific ways in order to achieve a whole system's communication in a multi-user communication system. The combination of cognitive radio technology and cooperative communication technology can make full use of the advantages of both technologies?effectively improve the performance of the system and improve the spectrum utilization. Therefore, it has very important significance to study the cognitive radio technology of multi-user cooperative communication.At present, it is popular to apply intelligent algorithm into the cognitive radio technology and many good results have been achieved.However, there are still needs for intelligent algorithm to be improved due to some defects, which results in undesirable solutions.In this paper, multi-user cooperative spectrum sensing technology and multi-user cooperative relay node selection technology are studied for cognitive radio technology of multi-user cooperative communication. For the multi-user cooperative spectrum sensing technology in cognitive radio system, this paper deduces the detection probability formula theoretically,then proposes an improved adaptive genetic algorithm to solve the cooperative spectrum sensing optimization problem, which makes the convergence faster. It solves the problem of slow convergence and easy to fall into the local optimum of genetic algorithm. In multi-user cooperative relay selection of cognitive radio system, the single-user multi-relay node selection and multi-user relay node selection are studied respectively. The signal-to-noise ratio, network throughput and energy efficiency of the receiver are analyzed theoretically. The particle swarm optimization and quantum particle swarm optimization are studied and their advantages and disadvantages are analyzed. An improved quantum particle swarm optimization algorithm is proposed to solve the cooperative relay selection problem of cognitive radio.The simulation results show that the improved adaptive genetic algorithm can make the spectrum sensing problem more quickly, which saves the time and makes the system more efficient. The IQPSO algorithm can optimize the selection of relay nodes and improve the performance of the cooperative communication cognitive network better than the traditional relay selection algorithm and QPSO algorithm.