對於超附載多工存取之表現研究

Abstract

過去幾年來有陸續出現許多可以提供比現有的正交分多工存取更高的頻譜使用效率的多工存取方法的研究，然而這些不同方法之間的關聯性很少被指出來，在這個碩論中我們將會提供一個統整的架構去描述這些不同的方法包括非正交多工存取(NOMA)，低密度分碼多工存取(LDS-CDMA)以及交錯器多工存取(IDMA)並且分析以及比較彼此之間的效能與複雜度。我們提供一個通用的接收端解碼方法應用於上述各個系統並且利用外信息傳遞曲線(EXIT-Chart)去分析遞迴解碼的效能，最後我們提出能量分配的方法應用於非正交多工存取並且利用電腦模擬去證實這些方法的可行性。

Several works have emerged in the past decade that can potentially provide higher spectral efficiency than that offered by existing orthogonal-channelization based air inter- faces for a xed bandwidth expansion factor. However, the connection between different schemes is seldom mentioned. In this thesis, we give a general framework to describe several popular overloaded radio access schemes such as IDMA, LDS-CDMA and NOMA to simplify later complexity and performance comparisons and analysis. A general re- ceiver structure is presented and EXIT chart based analysis of the associated iterative decoding process is provided to compare and predict the BER performance of various overloaded schemes. We give a design guideline for allocating between spreading and error-correcting coding the bandwidth expansion resource available in both AWGN and fading channels. Finally, we develop power allocation methods for 2- and 3-user NOMA systems. These approaches can be easily extended to LDS-CDMA and other overloaded systems.