在這篇論文中，我們在雙向放大多中繼系統中提出具有中繼點選擇機制與高頻譜效率之自動重傳要求協定。我們首先描述了一個簡單式自動重傳要求協定，其中當兩個端點接收失敗，此協定使用雙向式重傳。另外，當其中一個端點接收失敗，此協定使用單向式重傳。由於簡單式自動重傳要求協定包含單向式重傳，會造成此系統有頻譜效率損失的缺點。為了克服簡單式自動重傳要求協定的缺點，我們接著提出高頻譜效率之自動重傳要求協定，其中將簡單式重傳要求協定中的單向式重傳改變為雙向式部分重傳，即接收失敗的端點持續維持重傳而接收成功的端點將傳送新的資料。我們在雙向放大中繼系統使用高頻譜效率之自動重傳要求協定以二階通道統計形式呈現中斷機率與有效吞吐量之效能分析。藉由分析中斷機率證明高頻譜效率自動重傳要求協定可以達到全部的時間分集。為了有效地提升有效吞吐量，我們發展一種單一中繼點選擇機制。此中繼點選擇機制能夠在所有中繼點中選出一個提供最大有效吞吐量之中繼點。另外，我們也藉由有效吞吐量最佳化提供了最佳地最大重傳次數。最後，模擬結果驗證出我們提出的方法是有效的。

In this thesis, we present a spectral-efficient automatic repeat request (SEARQ) scheme with relay selection for two-way amplify-and-forward relay systems, where multiple single-antenna relays are considered but only one relay is selected to join in cooperation with two terminals. The proposed SEARQ scheme exploits two-way retransmission for failure of reception at both terminals, and adopts two-way partial retransmission for failure of reception at only one terminal in a way that the corresponding source performs retransmission and the other source continues to transmit new data. Both of the outage probability and effective throughput for the proposed SEARQ scheme are derived in closed form based on second-order channel statistics. To further improve the effective throughput performance, we develop a single-relay selection method for combination with the proposed SEARQ scheme. We also derive an optimal maximum-retransmission round for the proposed SEARQ scheme with the optimally selected relay by solving a maximization problem of the effective throughput. Simulation results are given to verify the theoretical analyses as well as to demonstrate the effectiveness of the proposed approach.

Abstract i
Contents ii
List of Figures iv
List of Tables vi
Chapter 1 Introduction 1
Chapter 2 Diversity-Multiplexing Tradeoff Analysis of AF Two-Way Relaying Channel with Hybrid ARQ over Rayleigh Fading Channels [14] 6
2.1 System Model 7
2.2 Diversity-Multiplexing Tradeoff (DMT) Analysis 9
2.2-1 DMT of Scheme I 10
2.2-2 DMT of Scheme II 14
2.3 Discussions 15
Chapter 3 A Spectral-Efficient ARQ Scheme with Relay Selection for Two-Way Amplify-and-Forward Systems 18
3.1 Motivations 19
3.2 System Model 20
3.3 A Spectral-Efficient ARQ Scheme 24
3.3-1 A Simple ARQ Scheme 24
3.3-2 Proposed Spectral-Efficient ARQ Scheme 27
3.4 Asymptotic Analysis 29
3.4-1 Outage Probability Analysis 29
3.4-2 Effective Throughput Analysis 31
3.5 Proposed Spectral-Efficient ARQ Scheme with Relay Selection 33
3.5-1 Single-Relay Selection Scheme 34
3.5-2 Optimal Maximum-Retransmission Round for the Proposed SEARQ Scheme with Relay Selection 34
Chapter 4 Simulation Results 38
Chapter 5 Conclusions 45
References 46

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