在本篇論文中，我們考慮在雙向放大轉送中繼系統(Two-Way Amplify-and-Forward Relay Systems) 存在多個單天線中繼點（Multiple Relays）且通道為非對等通道（Nonreciprocal Channels），但只有一個中繼點會被選出與兩訊號源（Two Sources）進行合作透過使用雙向中繼傳輸（Two-Way Relaying）技術來進行訊息交換；根據不同設計法則，我們提供了兩個次最佳聯合功率分配與中繼點選擇演算法。第一個方法是先透過最大化任意一中繼點與兩訊號源傳輸所產生之較小的訊雜比（Signal-to-Noise Ratio）在一個總傳輸功率（Total Transmit Power）的限制下，而獲得一最佳功率分配法（Power Allocation），根據此分配，我們可得到兩訊號源之接收訊雜比將會是相同的；因此，透過使用最佳之功率分配，我們提出一中繼點選擇法（Relay Selection）來選出可使平衡訊雜比最大的中繼點進行合作。另一方面，第二個方法則是透過最小化任意一個中繼點與兩訊號源傳輸所產生之總傳輸功率且在兩邊訊號源有著訊雜比的限制，而獲得一最佳功率分配法；接著，提出一中繼點選擇法來選出可使總傳輸功率最小的中繼點來進行合作。兩方法中的功率分配法都可經由標準的最佳化步驟而得出封閉形式的解。
　　我們可以把之前在對等通道（Reciprocal Channels）中的相關研究看成是我們提出方法之特例。電腦模擬結果也同樣顯示了我們提出的聯合功率分配與中繼點選擇法優於均勻功率分配法。

In this thesis, we present two suboptimal joint power allocation (PA) and relay selection (RS) schemes with different design objectives for two-way amplify-and-forward relay systems with nonreciprocal channels, where multiple single-antenna relays are considered and only one relay is selected for cooperation with two sources. The first approach is to maximize the smaller received signal-to-noise ratios (SNRs) at the two sources under a total transmit power constraint, where closed-form PA expressions are derived to make the received SNRs at the two sources equal for each relay, and the relay resulting in the largest balanced received SNR at the two sources is selected for cooperation. The second approach is to minimize the total transmit power under received SNR constraints at the two sources, where closed-from PA expressions are obtained based on a standard convex optimization procedure for each relay, and the relay resulting in the minimum total transmit power is selected for cooperation. It is shown that earlier works relating to these two approaches for reciprocal channels are special cases of the proposed joint PA-RS schemes. Moreover, computer simulation results show that both the proposed PA schemes without RS provide better performance than the equal PA scheme, and that using the proposed RS schemes with their own corresponding proposed PA schemes further enhances the system performance.

Abstract
List of Figures
I. Introduction
II. System Model
III. proposed Joint Suboptimal Power Allocation and Relay Selection Schemes
A. SNR Maximization Approach
B. Total Power Minimization Approach
IV. Simulation Results
V. Conclusions
References

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