探討SOVA在渦輪碼遞迴式解碼上的效能

Investigating the Performance of Turbo Decoding with SOVA

翁柏正(Po-Cheng Weng)

指導教授 ： 劉玉蓀

中原大學/工學院/電機工程研究所/碩士(2002年)

https://doi.org/10.6840/cycu200200349

摘要

摘要

本論文主要探討SOVA(Soft Output Viterbi Algorithm)在渦輪碼遞迴式解碼上的效能，並提出改善解碼效果的方法。SOVA解碼演算法則是引用傳統的VA(Viterbi Algorithm)演算法，經過兩個修正後，可以提供事先項(a priori information)來適用於遞迴式解碼，而這種演算法則相較於MAP(Maximum A Posteriori Algorithm)大幅降低了計算複雜度，但是相對的解碼效果也遜色許多。本文中資料先經由渦輪碼編碼，然後採用BPSK(Binary Phase-Shift Keying)調變，通道的干擾僅考慮熱雜訊，來模擬SOVA應用在渦輪碼上的解碼效果。最後針對於SOVA解碼效果的不佳，我們得知原因出在於事先項的可靠度不夠，因此提出四個方法來調整事先項，用以增加信任度，進而達到提升SOVA的解碼效果。

關鍵字

軟式解碼 ； 渦輪碼

並列摘要

Abstract

In this thesis, the main ideas are investigating the performance of turbo codes applying SOVA (Soft Output Viterbi Algorithm) in wireless communication systems. Comparing with MAP (Maximum A Posteriori Algorithm), the advantage of SOVA is providing a low complexity decoder. We propose four methods to improve the performance of SOVA decoding. The simulation results verify that these methods improve the performance of original SOVA.

並列關鍵字

SOVA ； turbo codes

參考文獻

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