錯誤更正碼是一種在資料傳遞前後做編解碼的技術，此技術可以保護資料不受外界干擾而損毀。在通訊傳輸或是硬體儲存上，都已經有廣泛的應用。近年來，區塊渦輪碼已被推薦應用在多個領域，像是IEEE 802.16e、衛星通訊系統、光纖傳輸系統以及記憶體儲存裝置等等。區塊渦輪碼的核心構造是其軟式輸入軟式輸出的解碼器。對於低錯誤品質的應用上，因為高複雜度和計算時間長的問題，要做出一個很有效率的解碼器是很難的。在這篇論文中，我們提出了一個可被應用於區塊渦輪碼上，使用距離理論的Chase軟式輸入軟式輸出解碼器。在整體的設計上，本篇論文提出了三個概念去提升整體的解碼效率，並且兼顧了面積成本上面的考量。我們應用了一個門檻排序演算法去找出四個最小的輸入訊號，一個以滾桶式移位器為基礎的尋錯電路去找出錯誤位置方程式的根，以及一個片段線性方程式去簡化淨輸出值的運算。這個解碼器的吞吐量有700Mbps，並且在面積上只佔了30K左右的邏輯閘數量。作為一個區塊渦輪碼的組成要素，我們提出的解碼器在錯誤率跟訊雜比的表現上有很好的貢獻。與現今提出過的區塊渦輪碼相比，在低訊雜比的應用中我們有0.4-0.9 dB的增益表現。文中的三個概念亦可看做獨立的設計，在降低複雜度以及提升解碼效率上面皆提出了改善的方式。

Recently, Block turbo codes have been suggested to many applications, such as IEEE 802.16e, satellite communication systems, optical fiber transmission systems and memory storages. The core of the block turbo code is the soft-input-soft-output (SISO) decoder. For high error performance applications, due to its high complexity and long decoding latency, it is hard to design an efficient SISO decoder. In this thesis, we proposed a SISO Chase decoder for a distance-based (64, 51, 6)2 block turbo code. The proposed decoder uses a threshold-sorting algorithm for finding 4-least-reliable inputs, a barrel-shifter-based error locator to finding roots of error locator polynomial,
and a piece-wise-linear function to simplify the calculations of the extrinsic values. The throughput of the decoder is about 700 Mbps, with lower than 30K gate counts. As a component code of block turbo codes, the proposed SISO decoder has good contributions in bit-error-rate (BER) over signal-noise ratio (SNR). Compare to existing block turbo decoders, the error performance has gain 0.4-0.9 dB in low SNR applications. In addition, the three concepts in this thesis can be designed individually. These designs give good solutions both in reducing complexity and increasing decoding speed.

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