Two-way Collaborative Communication System Power Resource Allocation And Relay Selection Algorithm

With the rapid development of mobile multimedia applications, higher speed, reliability and quality-of-service (QoS) are required. How to overcome multi-path effects, the use of multiple input multiple output (MIMO) technology advantages to become the starting point of the cooperative communication. It forms a virtual MIMO system by mutually sharing the antennas among numbers of adjacent single-antenna users or nodes in cooperative region, in order to achieve the spatial diversity. The cooperative scheme provides a novel idea for the realization of the MIMO technology, and it also has already become a research hotspot of the new generation of wireless communications technology.In this paper, we focus on the two-way multiple access broadcast (MABC) and the improved time division broadcast (TDBC) amplify-and-forward (AF) half-duplex (HD) relaying system, studying the power allocation problem based on the maximum average rate when the relaying system power was limited, and proposing two relay select schemes. The main works of this paper is listed as follows:Firstly, an overview of the propagation characteristics of radio signal, the cooperative diversity gain, the architecture of cooperative relaying network, the cooperative schemes, the advantages and disadvantages of cooperative communication, is provided.Secondly, the one-way AF-HD relaying system requires four time slots to complete the exchange of information, which reducing the spectral efficiency. In order to improve this deficiency, two different types of relay models in two-way AF-HD relaying system are studied, which are the MABC model and the improved TDBC relay model, and the former model consists of two time slots, the latter contains three gaps and there is a direct link signal. In order to avoid the complexity of solving higher order equation, we proposed suboptimal power allocation scheme for two systems based on the average transmission rate of single node. And the expression of rate is derived. Both the link performance and the level of node power are analyzed by MATLAB simulation, respectively. The results indicate that the position of relay node and direct link are obviously changing the transmission rate. Finally, the problem about how to choose the optimal relay node within the cooperative regions is analyzed. In real networks, a large number of relay nodes exist in the cooperative regions, and each relay node is likely to become the auxiliary node. However, the two source nodes can not use all relay nodes in the cooperative regions to aid in transmission, because the system power resources are always limited. Then, for the two-way MABC-AF-HD relaying system, the relay selection schemes based on the average transmission rate and average equivalent channel gain are provided. By analysis of the simulation, the superiority of the relay selecting schemes based on the average equivalent channel gain has been obtained.