合作式編碼(collaborative coding)是針對多重存取通道(multiple access channel)編碼的技術，利用每個使用者合作式碼之間的關係，在接收端可以設計出簡單的演算法解碼出每個使用者傳輸的資訊。在沒有雜訊的固定通道之下，接收端可以保證完全正確地解碼而沒有錯誤產生；在有雜訊的固定通道之下，合作式編碼也有一些訊息保護錯誤更正的功能。如何讓每個使用者都能擁有較高的資訊傳輸速率以及系統在解碼程序中擁有較低的複雜度是沒有雜訊或是有雜訊的固定通道下合作式編碼研究的主要目標。

無線通訊是現在及未來的主要通訊技術，在無線傳輸的環境中，除了雜訊的影響之外，傳送的訊號很容易被衰褪(fading)現象嚴重破壞，造成訊號強度的不穩定以及增加接收端正確解碼的困難度。在這篇論文之中，我們介紹了一個能應用在無線衰褪通道的多重存取合作式編碼技術，它能利用合作式碼的結構和特性去估測通道的狀況，解決不同使用者在上傳過程中遭受到的時變性衰褪增益和相位偏移對解碼程序所造成的問題，還能避免因為多重存取干擾(multiple access interference)造成的效能衰減。此外，在論文中我們也提出了建構合作式碼的基本原則以及其理論背景，以達到最佳的效能以及較高的資訊傳輸速率為前提，設計出一些建構合作式碼的方法，並且做了相關的系統模擬和效能比較。

Collaborative coding means the coding techniques for multiple access channels. Collaborative coding systems with a high data rate for each user and low complexity of decoding are desired in the noiseless or noisy channels. Some $T$-user collaborative coding techniques are proposed for wireless fading channels in this thesis, and principles of code construction are also presented. Well performance and high data rate of each user are the two chief considerations of our code construction.

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