低密度同位檢查碼技術及其在數位電視廣播系統應用之研究

Abstract

錯誤更正碼的種類很多，其中有一種名為低密度同位檢查碼的錯誤更正碼在最近受到重視，因為其編碼增益直逼雪儂極限，解碼器簡單且硬體成本低。在本論文中，我們將低密度同位檢查碼的編碼與解碼方式應用於數位電視廣播系統中。傳統的數位電視廣播系統的編碼方式是由兩層編碼所組成，分別為外層編碼(里德所羅門碼)及內層編碼(迴旋碼)，而且這兩層的編碼都有各自的交錯器。為了簡化數位電視廣播系統的編碼，我們使用一個低密度同位檢查碼來取代原本的里德所羅門碼及迴旋碼，及其所對應的交錯器。我們藉著計算機模擬來比較低密度同位檢查碼與傳統的兩層編碼在數位電視廣播系統中錯誤率的表現。

This thesis proposes a new encoding and decoding method which can be applied to Digital Video Broadcasting (DVB) Systems. There are many kinds of error correction codes. Low Density Parity Check (LDPC) Code gets a lot of attention recently because its coding gain is near the Shannon limit. Moreover, the decoder is easy to implement and the hardware cost is low. Conventional Digital Video Broadcasting System uses two concatenated codes, an outer code (Reed-Solomon code) and an inner code (Convolutional code), respectively. These two codes have different interleavers. In order to simplify the coding scheme of Digital Video Broadcasting Systems, here we use a single Low Density Parity Check code to substitute for the original Reed-Solomon code and the Convolutional code, together with their interleavers. We use computer simulation to compare the bit error rate performance of the Low Density Parity Check Code and the original concatenated codes in Digital Video Broadcasting Systems.