單載波分頻多工系統中的疊代決策回饋混合式等化演算法

Iterative Decision-Feedback Hybrid Equalization in SC-FDM

馬笠瑜(Li-Yu Ma)

指導教授 ： 鐘嘉德

共同指導教授 ： 陳維昌(Wei-Chang Chen)

國立臺灣大學/電機資訊學院/電信工程學研究所/碩士(2022年)

https://doi.org/10.6342/NTU202200152

摘要

單載波分頻多工(SC-FDM)是當代無線通訊上行傳輸廣泛使用的技術。為了改善符元決策的性能表現，有著決策回饋的疊代等化演算法是需要被考慮的。在本篇論文中提出一種適用於單載波分頻多工系統的疊代決策回饋混合式等化演算法(IDFHE)，此演算法結合了修正式線性最小均方誤差(MLM)和約束最小平方(CLS)兩種非疊代等化演算法。不同於以往的決策回饋等化技術，本文所提出的IDFHE演算法在疊代過程中根據不同等化器的特性使用了不同的等化器設計準則，藉此改善符元決策性能。在性能表現的部分，本文討論了在隨機分段頻散通道上的位元錯誤機率(bit error probability, BEP)以及計算複雜度，結果顯示本文提出的演算法相比以往的決策回饋等化(DFE)演算法可以達到更好的位元錯誤機率並且維持相似的計算複雜度。此外，經由分析訊號對干擾加雜訊比(signal-to-interference-plus-noise ratio, SINR)、訊號雜訊比(signal-to-noise power ratio, SNR)推導出的位元錯誤機率也被展示為IDFHE性能結果的精確分析和分析下界。隨著Rician K值增加，模擬結果愈來愈接近分析下界，代表干擾消除的效果隨著K值增加而愈來愈好。

關鍵字

單載波分頻多工 ； 非疊代等化 ； 約束最小平方 ； 決策回饋等化 ； 分段頻散通道

並列摘要

Single-carrier frequency division multiplexing (SC-FDM) is a well-known technique used for the uplink transmission of wireless communication networks. In SC-FDM, non-iterative equalization methods may suffer from intersymbol interference (ISI). To improve the performance of symbol decision, the iterative equalization with decision-feedback is necessary. In this thesis, an algorithm named iterative decision-feedback hybrid equalization (IDFHE) is proposed for SC-FDM system. In IDFHE, modified linear minimum mean square error (MLM) equalization is utilized in the first few iterations and constrained least-square (CLS) equalization is utilized in the last iteration. Different from the previous decision-feedback equalization (DFE) techniques where the criteria for filter design in all iterations are the same, the proposed IDFHE provides an iterative equalization algorithm combined with different filter design criteria in different iterations according to the characteristics of non-iterative algorithms. The performance characteristics including the bit error probability (BEP) over random block dispersive channels and the computational complexity are discussed in this thesis. It is shown that the proposed IDFHE achieves better BEP performance with comparable computational complexity in comparison with the previous DFE algorithm. Also, the analytical BEP results derived from the effective signal-to-interference-plus-noise power ratio (SINR) and post-excision perfect effective SNRs are depicted as the exact analysis for the first iteration and the lower bounds for the other iterations respectively in the proposed IDFHE. It is observed that as the Rician K factor increases, the simulation results approach to the analytical lower bounds, which indicates that the ISI cancellation becomes more precise.

並列關鍵字

Single-carrier frequency division multiplexing ； non-iterative equalization ； constrained least-square ； decision-feedback equalization ； block dispersive channel

參考文獻

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