Abstract
The BCJR algorithm is an important channel decoding method. We extend it to trellis rate-distortion data
compression. Beginning from source coding principles, the derivation of the algorithm avoids channel coding or soft output ideas. The encoder does not use entropy coding;
equiprobable reproducer letters are emphasized since
these maximize entropy. The BCJR method is demonstrated by
tests of a tailbiting variant. It performs much better than the ordinary Viterbi algorithm for short and medium blocks. However, the improvement stems from tailbiting; the role of the BCJR is to achieve tailbiting in a relatively simple way. Some issues that arise with tailbiting are explored. It is shown that there is an optimal trellis state size for each block length.
compression. Beginning from source coding principles, the derivation of the algorithm avoids channel coding or soft output ideas. The encoder does not use entropy coding;
equiprobable reproducer letters are emphasized since
these maximize entropy. The BCJR method is demonstrated by
tests of a tailbiting variant. It performs much better than the ordinary Viterbi algorithm for short and medium blocks. However, the improvement stems from tailbiting; the role of the BCJR is to achieve tailbiting in a relatively simple way. Some issues that arise with tailbiting are explored. It is shown that there is an optimal trellis state size for each block length.
| Original language | English |
|---|---|
| Pages (from-to) | 3201-3207 |
| Journal | IEEE Transactions on Information Theory |
| Volume | 53 |
| Issue number | 9 |
| DOIs | |
| Publication status | Published - 2007 |
Subject classification (UKÄ)
- Electrical Engineering, Electronic Engineering, Information Engineering
Free keywords
- source codes
- rate-distortion coding
- BCJR algorithm
- data compression