Joint source-channel coding with inner irregular codes
Ragnar Thobaben, Laurent Schmalen, Peter Vary · 2008
We address the optimization of joint source-channel coding schemes for iterative source-channel decoding of first- order Markov sources. Compared to the traditional design, we propose two novelties: (1) source encoders, providing code words with a minimum Hamming distance dminges2, realized by linear block codes, and (2) irregular channel encoders which are optimized for both the source characteristics and the conditions on the channel. Inner code rates RC> 1 may be chosen in order to compensate for the additional source redundancy if required. Design examples for the AWGN channel and an overall code rate R=0.66 show that the proposed system is able to establish reliable communication within 0.3 dB of the capacity limit for an interleaver length of approximatively 200000 bits.