Abstract
Two-way relaying, exploiting relays to realize information exchange between two source nodes over a shared wireless channel, has received much attention in recent years due to its high efficiency of channel utilization. Considering a two-way relay system with multiple relays, how to design the relays’ weighting factors and allocate the power of the two source nodes and the relays to enhance the network capacity has become a critical issue. In this thesis, we propose a joint weighting design and power allocation (WD-PA) algorithm in a two-way amplify-and-forward relay system to minimize the sum of mean-square-errors (sum-MSE) of the received signals at the two source nodes. The algorithm alternates between two parts: obtaining relays’ optimal weighting factors for a specific PA, which is derived as a closed-form solution, and searching a PA that could minimize the sum-MSE via a gradient-descent algorithm. In addition, for a required number of relays, we also propose a simple but efficient multi-relay selection scheme to obtain an appropriate relay set which is more possible to attain the smallest sum-MSE. Computer simulation results show that the proposed WD-PA algorithm has better sum-MSE and sum bit-error-rate (sum-BER) performance than that of the equal power allocation scheme. The results also demonstrate that using the proposed relay selection scheme, the sum-MSE of a two-way relay system is further reduced as compared to that with a random relay selection method, especially in high signal-to-noise ratio regions.