Joint Source-Channel Coding for MELP Coder
碩士 === 國立臺北科技大學 === 電機工程系所 === 94 === Source coding and channel coding are definitely different techniques in nature. The former is the method that compresses the original signals into small ones, but still maintains the perceptual quality. On the other hand, the latter adds redundancy for detecting...
| Main Authors: | , |
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| Format: | Others |
| Language: | zh-TW |
| Published: |
2006
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| Online Access: | http://ndltd.ncl.edu.tw/handle/h7dv25 |
| Summary: | 碩士 === 國立臺北科技大學 === 電機工程系所 === 94 === Source coding and channel coding are definitely different techniques in nature. The former is the method that compresses the original signals into small ones, but still maintains the perceptual quality. On the other hand, the latter adds redundancy for detecting and correcting the transmission error. In this thesis, the mixed excitation linear prediction (MELP) vocoder and the soft-output Viterbi algorithm (SOVA) are used to achieve the purpose of joint source-channel decoding (JSCD). These output statistics of MELP vocoder according to voiced or unvoiced state are regarded as the prior probability of the SOVA decoder. The proposed channel decoding scheme is called the JSCD SOVA. Both unequal error protection (UEP) and equal error protection (EEP) are also included for comparison. The experimental results show that the performance of the UEP is higher than that of the EEP in low signal-to-noise ratio (SNR) condition. In addition, using the EEP to protect transmission bits, the JSCD SOVA decoder performs better than the conventional SOVA decoder with equal prior probabilities under poor SNR environment.
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