適用於多重接取系統的多階檢測技術

Abstract

在本篇論文中，我們處理在多重接取系統下，某些使用者使用相同簽記(signature)時，會造成接收端無法正確得解出使用者的訊息，直接地影響系統下整體的吞吐量之問題，我們稱之為碰撞。首先，會回顧兩種多重接取系統的技術，分別為分碼多重接取系統(CDMA)以及交織多重接取系統(IDMA)，在分碼多重接取系統下使用者使用專屬的展頻碼做為簽記，而在交織多重接取系統下使用者是採用不同的交織器為簽記。我們會回顧前一屆的碩士論文中將交織多工接取系統的接收端結合廣義信道解碼聯合實體層網路編碼技術，來處裡碰撞的問題，雖然能有效的解決問題，但推論與預設環境還不夠完備，我們會在推廣到多個通道上，以及轉到頻域上傳送的情況，還有更詳細的推導。

In this thesis, we deal with the problem in the multiple access system that when many users transmit messages simultaneously, there are possibilities that some users use the same signatures. We call this condition as collision in this thesis. While the collision occurs, the system cannot successfully decode the users' messages and the performance is severely affected. We fist review two multiple access systems, Code Division Multiple Access(CDMA) and Interleave Division Multiple Access(IDMA). In a CDMA system, each user use a unique spreading code for signature. In a IDMA system, the signature is a user-specific interleaver. Multilevel Detection(MLDT) is a scheme which can recover the collision users’ messages successfully with little performance degradation. In this thesis we review the MLDT from [1] and derive the performance analysis of MLDT over the Rayleigh fading channel. Moreover, we extend the study of MLDT to the multipath fading channel and the multicarrier scenarios.