空間分集技術加入子載波功率配置在多輸入/多輸出正交分頻多工系統下之效能分析

Abstract

本研究主要在於討論在多輸入/多輸出正交分頻多工系統環境下，空間分集技術加入子載波功率配置之問題。在傳統的多輸入/多輸出空間分集下，不同的正交振幅調變符元被安置在不同的時槽上傳送，因此受到較高通道增益之符元無法分配功率至受到較低通道增益之符元上。本論文即在多輸入/多輸出正交分頻多工系統環境下，使用空間分集技術加入子載波功率配置之概念，令接收端解調時之位元或符元錯誤率進而降低。並針對加入子載波功率配置之系統，分析其計算複雜度、對通道估測誤差之容錯能力以及對於接收端回饋資訊的依賴程度。論文最後綜合比較以上分析之結果，並歸納出最適合於上、下行傳輸中使用之方法。

This thesis is mainly discussing about the issue of spatial diversity for MIMO-OFDM systems with power allocation on subcarriers. The spatial diversity techniques in traditional MIMO systems transmit the QAM symbols in different time slots, and therefore the symbols which get the higher gain can not share its power to which get the lower gain. In this thesis, different spatial diversity techniques for MIMO-OFDM systems with power allocation on subcarriers were purposed to reduce the bit error rate. Computational complexities, robustness and dependence upon feedback information of different techniques mentioned above were analyzed. Finally, we compare the results and conclude the most suitable method in upload and download situations.