On the BCJR algorithm for rate-distortion source coding

• 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.

Ämnesord

TEKNIK OCH TEKNOLOGIER  -- Elektroteknik och elektronik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Electrical Engineering, Electronic Engineering, Information Engineering (hsv//eng)

Nyckelord

source codes

rate-distortion coding

BCJR algorithm

data compression

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