Research On Wireless Cooperative Relay Selection Algorithm Based On Outage Probability

With the rapid development of modern wireless communication technology, it has made people's life easy and plentiful. To better satisfy people's higher requirements, wireless communication technology needs to be further developed, so that the future wireless communication system could achieve faster transfer rate, bigger system capacity and higher spectrum efficiency. While the fading effect existing in the wireless channel res tricts its development, which challenges the anti fading performance of wireless communication system. Cooperative communication uses the cooperation of each node in the system to transfer information and share channel space, so as to form a virtual MIMO system, which can effectively overcome the fading effect and improve performance of wireless communication system. Relay node selection algorithm is one of the most popular research topics in cooperative communication. Based on the existing algorithms, this paper further researches the relay node selection algorithm that can effectively improve the cooperative performance and accordingly reduce computational complexity and overhead of the system.First of all, in this paper, the related knowledge of cooperat ive communication is introduced, including the principle of cooperative communication, main application scenarios, basic model, main technology, forwarding protocols and forwarding methods, their performances are analyzed and compared. Moreover, this paper introduces the existing relay node selection algorithm, power allocation algorithm in cooperative communication and related algorithms' deficiencies, then brings up the main points of this paper.Secondly, in view of the shortcomings of existing relay node selection algorithms, this paper proposes a multi optimization goals and efficient relay node selection algorithm. In order to reduce the system overhead, the algorithm of relay node selection uses statistical channel state information between nodes to select relay node. The specific steps of this algorithm are as follows. When determine the source node has the need of cooperation according to the decision theorem proposed in this paper, this algorithm defines equivalent channel gain of the relay nodes to select pre-selection of relay nodes, which improve the efficiency of relay node selection. To minimize the single relay average outage probability for the target, calculate the number of cooperative relay nodes. With the joint optimization goal of the outage probability and network lifetime, solving the joint optimization function and priority scheduling of pre-selected relay nodes to determine the cooperative relay node set. Finally, the simulation and analysis of this algorithm are carried out. The simulation results show that this proposed algorithm can effectively improve the performance of cooperative system and reduce the complexity.Then, in order to further optimize the performance of the cooperative system, this paper puts forward a single relay node selection algorithm based on relay node equivalent channel gain and solves stationary point of optimization function to realize power allocation to minimize the outage probability. Moreover, a multi-relay node selection algorithm based on power allocation is proposed. This algorithm uses Lagrange multiplier method and dichotomy method to realize power allocation, and the relay node selection is realized by the relay node contribution factor ranking method. The simulation results show that the relay node selection algorithm based on power allocation can reduce outage probability more effectively. Compared with the traditional algorithm and other sub-optimal algorithm, the algorithm proposed in this paper can achieve better performance and reduce computatio n.Finally, the content of this paper is summarized and evaluated, and the future research direction is put forward.