迴旋碼的解碼法則中，以最大概似解碼法則：腓特比演算法為較有效率的近似解碼演算法，因此廣泛地運用在許多編碼正交分頻多工系統及無線通訊系統上。雖然在802.11a的系統，仍是運用硬判決計算漢明距離的方式來實現腓特比解碼器，然而對傳輸資料的錯誤保護能力卻有限。本文主要是針對歐規數位電視地面廣播系統中多碼率的腓特比解碼器做設計與實現，其中包含QAM符碼的軟式判決、軟式判決的量化位階、通道狀態資訊、追溯深度與位元交錯編碼調變之反覆式解碼。The most efficiently decoder in convolution decode is Viterbi algorithm which is using maximum likelihood criterion, it apply in many COFDM and wireless communication system widely. Viterbi decode implementation is still using hard decision to calculate Hamming distance in 802.11a system; however its ability that error protection on transmitted data is limited. In this thesis, we discuss the design/implementation issues of Viterbi decoder for multi-rate convolutional code in DVB-T system. The issues include: soft-decision of QAM symbol, quantization levels of soft-decision, channel-state-information, traceback depth and iterative decoding for BICM in DVB-T system.
