應用於多用戶編碼協力式通訊之高頻譜效率空時協定

Abstract

在協力式通訊系統中，給中繼站使用的額外通道所造成的頻譜效率損失，是其主要的缺點。近年來，有一種高頻譜效率的解決方案被提出來，稱作「編碼協力式通訊」。在本論文中，吾人的目標為設計基於編碼協力式通訊的空時協定，藉此達到更高的系統可靠度。吾人將提出兩種不同的協定: 空時（ST）及碼分配式（CP）編碼協力式通訊，以上兩種協定皆能達到比傳統編碼協力式通訊更好的表現，同時還能維持相同的傳輸速率以及功耗。透過成偶比對錯誤率的推導，吾人證明這兩種通訊協定皆能達到最大多樣增益。此外，針對用戶之間通道不良的情況，吾人也提出了穩健的方法及其分析。值得一提的是，雖然本論文僅對於雙用戶及四用戶的情況做介紹，吾人很容易可將之延伸到其它用戶數量。此外，協力式編碼的架構以及空時碼的選擇，也可以彈性地針對不同的需求來修改。

A major drawback of cooperative communication is the spectral efficiency loss due to additional channel needs for the relay. Recently, coded cooperation had been proposed as a spectrally efficient solution for user cooperation. In this thesis, our aim is to design space-time protocols under coded cooperation that achieve higher system reliability. We introduce two modified protocols: space-time (ST) coded cooperation and code partitioning (CP) coded cooperation. These protocols achieve remarkable gains comparing to the performance of conventional coded cooperation while maintaining the same data rate and transmit power. We conduct performance analysis in terms of pairwise error probabilities, showing that both protocols achieve extra diversity gain guaranteed by the space-time code used. Robust algorithms in case of poor inter-user link are also developed and analyzed. Although we demonstrate the case of two and four users, extension to other number of users is straightforward. Different types of code structures for cooperation and space-time coding are also flexible to choose depending on various needs.