DVB-T2之錯誤更正碼之實現及效率改善

Implementation and Efficiency Improvement of DVB-T2 Error-Correcting Code

黃舜傑(Shun-Jie Huang)

指導教授 ： 尤信程

國立臺北科技大學/電資學院/資訊工程系研究所/碩士(2012年)

摘要

歐洲電信標準組織(ETSI)所制定的第二代歐規數位電視地面廣播標準(DVB-T2)已在多個國家推行使用。DVB-T2系統使用了外編碼BCH碼和內編碼LDPC碼讓訊號有更好的保護機制，本論文在既有的DVB-T2軟體接收端模組上利用和積(Sum-Product)演算法實現LDPC碼的軟式錯誤更正，並使用無須估測訊雜比、量化與查表法快速完成耗時的運算。對於在調變時進行過穿刺(puncturing)處理的LDPC碼，則使用節點合併的方法產生新的檢查矩陣來加速解碼。另外我們提出一個方法觀察Log-likelihood ratio(LLR)在多次迭代(Iteration)解碼中的變化，由觀察的數值判斷LDPC碼字是否能完全錯誤更正，進而提早放棄因訊雜比過小而無法解回的LDPC碼字來減少不必要的迭代所造成的時間浪費。

關鍵字

DVB-T2 ； punctrued LDPC code ； 和積演算法

並列摘要

The European standard for digital video broadcasting over terrestrial (DVB-T) has been implemented in several countries. DVB-T2 system uses BCH code and LDPC codes for the signal to have a better protection. We use the Sum-Product algorithm to achieve the Soft-decision decoding of LDPC codes in the original software module. We use no need to estimate the signal to noise ratio, quantization, and look-up table method to quickly complete the time-consuming operation. In order to accelerate the puncturing LDPC decoding, we use check-node merging method to generate a new parity check matrix. Finally, we invented by observing the change of Log-likelihood ratio in the number of iterations in the decoding, and thus early to give up due to signal to noise ratio is too small and unable to correct LDPC codeword to reduce waste time caused by the unnecessary iterations.

並列關鍵字

DVB-T2 ； punctrued LDPC code ； Sum-Product algorithm

參考文獻

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[2] ETSI, Implementation guidelines for a second generation digital terrestrial television broadcasting system (DVB-T2), DVB Document A133, Feb. 2009.

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