適用於單向性與雙向性合作式通訊系統之非同調空頻碼設計: 接收端解碼研究、碼簿建立與效能分析

Abstract

本計畫旨在研究在無線合作單向性(One-way)與雙向(Two-way)性中繼網路下分散式非同調空頻碼之最佳編解碼準則、編解碼設計與效能分析。主要想探討的課題為在採用正交分頻多工調變技術的情形下，中繼站使用解碼與轉交(Decode-and-Forward, DF)模式或放大與轉交(Amplify-and-Forward, AF) 模式並於接收站使用非同調解碼方式之分散式系統模型之建立、有效編碼解碼設計、中繼站最佳增益設計以及相關之效能分析。計畫分為兩年執行，在第一年的主要的研究課題為單向性轉接模式下之非同調編解法設計與分析，包括了中繼節點採用DF與AF訊號處理方式下系統的數學模型建立、非同調空頻碼 (Space-Frequency Coding) 解碼設計、系統可提供之最大多重分集分析 (Achievable Maximum Diversity) 與其編碼設計。在第二年的主要的研究課題雙向性模式下之非同調編解法設計與分析，亦包括了DF與AF處理下系統的數學模型建立、非同調空頻碼解碼設計和系統可提供之最大多重分集分析。此兩種模式分開討論的原因主要是由於單向性模式與雙向性模式期系統細部結構上頗有差異，使得整個通訊效能分析過程迥然不同。並且個別模式下之設計與分析均有其重要性與難度。直覺上，我們可以猜測整體系統所能提供之最大多重分集正比於中繼站的數目和通道路徑數目。然而在數學上，這部份尚未被證實。我們在本計劃嘗試將其中所欠缺之數學做詳細的推導，以嚴謹的方式來驗證我們的直覺。並根據所分析的結果，進一步對系統編碼與增益作最佳化設計。

In this project, we aim to thoroughly investigate the analysis, code design criteria, and the designs of amplifying gains at the relays of distributed noncoherent space-frequency coding in wireless one-way and two-way cooperative relay networks. We consider a two-hop network, with possibly more than one source nodes, multiple relay nodes and one destination node in the wireless environment. Two different signal processing strategies are employed in the relay nodes; namely the decode-and-forward strategy and the amplify-and-forward strategy. We manage to finish the research problems in two years. In the first year, we focus on the design and analysis of distributed noncoherent space-frequency coding in one-way cooperative network. And, in the 2nd year, we switch our focus to the two-way network. Although the research problmes are similar, the detailed mathematical model and derivations are rather different between the one-way and the two-way transmission approaches. Intuitively, we can guess the maximum achievable diversity provided by the system to be proportional to the number of cooperating relays and the number of resolvable paths. But, mathematically this has not yet been justified in the literature. Our main objective of this project is to fill in the blank by rigorous mathematical analysis, and subsequently propose systematic code design procedures and amplifying gains at the relays to realize maximum achievable diversity gain and maximum transmission rate, respectively.