合作式網路下以空頻區塊碼及正交分頻多工之接收端對抗多重頻率位移

Abstract

在合作式通訊下，我們提出一個新的空頻結合技巧用於Alamouti編碼的正交分頻多工系統。由於合作式天線是分散式的，可能存在多重頻率位移效應，然而以傳統的空頻解碼技術是不適用的。為了有效率的消除符間干擾(ISI)及載波間干擾(ICI)，我們提出的方法最佳的結合兩個分別同步的訊號。基於低計算量複雜度考量，通常使用疊代式干擾消除對抗多重存取干擾而非直接消除，經由模擬結果表示，我們提出的方式搭配疊代式干擾消除技術可以得到良好的位元錯誤率效能，而且對於多重頻率位移有更好的容忍度。

In this thesis, a new space-frequency combination technique is proposed for Alamouti coded Orthogonal Frequency Division Multiplexing (OFDM) in the context of cooperative communications. Since cooperative antennas are distributed, there may exist multiple carrier frequency offsets (CFOs) and traditional space-frequency decoding may not apply. The proposed method optimally combines the two sets of separately synchronized signal in order to eliminate inter-symbol interference (ISI) and inter-carrier interference (ICI) effectively. Iterative interference cancellation instead of exact cancellation is usually used to combat multiple access interference (MAI) for lower computational complexity. Through simulation results, it is observed that the proposed method with iterative ICI cancellation achieve good bits error rate (BER) performance and a better tolerance of multiple CFOs.