Research On Multiple Relay Selection Schemes In Cooperative Networks

Wireless communication has become the high-tech pillar industries of countries all over the world. The distributed virtual multi-antenna system is used in cooperative diversity technology to achieve spatial diversity, which is composed by the source node and one or more neighbor nodes. The performance of outage probability is improved by the collaboration among nodes. The collaboration has become one of the most important technologies in the current and future wireless communication, by which the node selection problem has been widespread concerned. This dissertation focuses on selection problem of the relay nodes in cooperative communications, taking the signal to noise ratio (SNR) and energy efficiency of relay nodes as the main optimized objectives, to research the multi-relay selection algorithm. Main contents are as follows:1. Generalizing the ideology of single-relay selection algorithm to the multi-relay selection scene of single-input-single-output (SISO). Under the premise of known all the channel state information in the two time slots, we propose an optimal relay sorting algorithm, and provide a sorting algorithm based multi-relay selection algorithm, to select the relay nodes which have the optimal SNR for cooperation.2. In the scene of single-input-multi-output (SIMO), under the premise of known channel state information, taking the SNR and energy efficiency (SNR/Total Power) as the optimal objectives, we propose a relay selection algorithm based on candidate solution set:the algorithm selects a optimal candidate relay set for every user to ensure the fairness of node selection. The simulation results demonstrate the feasibility of the algorithm.3. We propose a multi-relay selection algorithm based on genetic algorithm. Transforming the relay collaboration problem into a0-1programming problem, the algorithm is continuous learning to select the optimal relay set for collaboration through genetic algorithms. The simulation results show that:the genetic algorithm based multi-relay selection algorithm can achieve higher SNR and energy efficiency (SNR/Total Power), and get the optimal solution.