Lossless Turbo Source Coding with Decremental Redundancy

Recent results indicate that the same turbo principle which delivers near to optimal strategies for channel coding, can be used to obtain very efficient source coding schemes. We investigate this issue applying ten Brink’s EXIT chart analysis and show how this technique can be used to select the most efficient match of component codes and puncturing matrices to compress discrete memoryless sources. Aiming at perfect reconstruction at the decoder, i.e. lossless source coding, we present an encoding algorithm, which gradually removes the redundancy while checking the decodability of the compressed bit stream. This concept of decremental redundancy is dual to the principle of incremental redundancy that characterizes hybrid ARQ (Type II) communication protocols. Both principles can be combined when the channel is noisy.