在此篇論文中，我們以壓縮前送(Compress-and-Forward, CF)的概念為基礎之下提出了一個新的架構，此方法利用最大期望(Expectation Maximization, EM)演算法來使整體效能收斂至局部最佳解。
根據最大期望演算法的特性，當我們給定不同的初始值時，整體效能會收斂至不同的局部最佳解。在我們所提出的方法之中，目的地端會將所得到之較佳的偵測結果給回傳至中繼端，作為下一次運算的初始值，藉由所回傳之較佳的判斷值，在中繼端不斷的疊代求解出新的局部最佳解，接著再將中繼端所偵測得到之解傳送到目的地端，進而求解出最終欲得到的訊號。此方法中，我們還可以在中繼端利用最大期望演算法來估測通道，因此我們將所提出的方法稱為分散式偵測與估測。從模擬圖中我們可以明顯的看出，所提出的架構可使整體效能在疊代的過程中逐步改善，最終收斂到局部最佳解。

In this thesis, a new scheme based on the concept of compress-and-forward (CF) technique has been proposed. And expectation maximization (EM) algorithm is utilized to attain the aim of converging to a local optimum solution. According to the characteristic of EM algorithm, destination node would feed back a better decision to the relay node to be the next initial value. After the iteration, relay node would obtain a better detection result which would converge to a local optimum performance. At last the destination node would receive the optimum detection result from each relay and make a final decision. In the new structure, channel estimation can also be made at the relay node by EM algorithm, which is the reason why it is called joint distributed detection and estimation. Simulation shows that the proposed scheme would acquire an iteration gain at both the relay and destination node.

Chapter 1 Introduction......................................................1
1.1 EM Algorithm..................................................................5
Chapter 2 Problem Statement and System.................8
Chapter 3 Derivation of Relay Decision Rules and Destination Rules.............................................................12
3.1 Joint Detection and Estimation at the Relay Nodes..................................................................................12
3.2 Joint Detection and Estimation at the Destination Node....................................................................................17
3.2.1 Initial Step..............................................................17
3.2.2 With Memory for Past Local Decisions............21
Chapter 4 Simulation.....................................................28
Chapter 5 Conclusion....................................................35
Abbreviation........................................................................36
References.........................................................................37

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