具計算效率且節省記憶體的第三代行動通訊渦輪碼解碼器

Abstract

目前的無線通訊系統中，資料量的傳輸需求愈來愈大，而在傳輸通道的非理想效應影響下經常使得傳輸資料出現錯誤。為了有效降低錯誤率，第三代行動通訊(3GPP，3GPP2…等)系統均採用了目前更正能力最強的渦輪碼。渦輪碼的硬體實現中最大的難題在於解碼時需要大量的記憶體及大量的運算。一般渦輪碼解碼器中所採用的節省記憶體架構(sliding window)雖可解決記憶體的問題，但同時也會導致更多的運算量。在節省記憶體及運算量的考量下，本論文的目的是以另一種節省記憶體的架構(halfway)實現一個和原始架構比起來可節省記憶體且不增加任何運算量的渦輪碼解碼器。在解碼上，我們採用Max-Log-MAP algorithm使得運算複雜度降低。在硬體上，我們使用了只包含一個Max-Log-MAP解碼器的硬體架構。

Turbo codes have become one of the necessary specifications for the state-of-the-art communication systems. The difficulties in implementing turbo decoder are the vast computational complexities and the request for a lot of memories. The most public method for decreasing the need of memories is sliding window method. But using sliding window method will increase the computational complexities. This thesis is purposed to propose a calculation efficient and memory saving turbo decoder. We use another memory saving algorithm – halfway algorithm, in our turbo decoder. This successfully decreases the computational complexities and the need of memory capacity. Besides, we adopt Max-Log-MAP algorithm in our design in order to simplify the hardware.