Research On Relay Selection And Resource Allocation In Wireless Cooperative Network

The rapid development of wireless communication causes increasingly high business demands for people, such as high transmission rate, bandwidth, and quality of service and so on. Moreover, with the popularity of the concept of green communication, how to make more effective use of system resources and reduce waste of it has become an important reference standard in communication system design. As a key technology for future wireless communication, cooperative communication is a good solution to the above problems, because it can effectively combat the adverse effects of channel fading, improve communication reliability and reduce system resources, which has a great broad application prospect. However, for the wide use of cooperative communication, there are key technical issues like relay selection and power distribution which must be resolved first. Existing researches on these strategies are mostly about centralized control methods, which not only results in a large signaling overhead but also is not applicable especially in networks where channels are time-varying and the number of users is large. However, distributed strategy only needs exchange of part of information among the users and relay nodes, which can greatly save system resources. Therefore, based on improvement of energy efficiency and the fairness among users, this paper elaborates the basic technology background in cooperative communication and studies the distributed node selection strategy and power allocation in the wireless cooperative network.Firstly, this paper proposes a global optimization scheme of distributed relay selection and power allocation in the single-source multi-relay communication networks where initial energy and maximal transmission power of all nodes are constrained. More importantly, this scheme gives full consideration of the node energy state and the channel state. Through the further analysis of network outage probability, it is verified that our scheme can fully guarantee the transmission reliability of network system. Then the simulation is carried out under the varying scenario condition where exist the different number of relay nodes and the different maximum transmission power of each node respectively, showing the performance of energy efficiency and transmission reliability of our proposed scheme is more excellent than direct transmission mechanism and the cooperative scheme only considering the channel state information.Secondly, in view of selfishness of nodes and distributed power allocation in multi-user cooperative networks, this paper studies the scheme of relay node selection and power allocation based on Stackelberg Game, bringing the joint optimization of network resources allocation among all nodes. In addition, the scheme fully involves the channel conditions to achieve a dynamic initial power cost price of the relay nodes. Simulation results show that this scheme can punish the users owning good channel conditions as well as compensate users owning bad ones, thus improving the fairness among all users. After that, taking consideration that the user information of node in actual networks nodes is private and in order to enhance the scalability of large-scale network using game algorithm, Perfect Bayesian Equilibrium is applied, which effectively reduces the game algorithm complexity. Finally, the summary work of the full paper is done.