Channel and complexity scalable image transmission

We present a source-channel coding system which is well suited for transmission over channels with varying channel states as common in mobile environments or broadcast scenarios. The system consists of a progressive source coder, a high-memory convolutional code (CC) with puncturing for unequal error protection (UEP) and a sequential decoding unit referred to as far end error decoder (FEED). In contrast to the conventional design goal of channel coding systems to minimize the bit error probability the presented system aims on maximizing the contiguously error-free part of the source message. Additionally, FEED allows one to localize the first error in the decoded message and only the virtually error free part is delivered to the source decoder. For image transmission gains up to 1.2 dB in average PSNR can be obtained compared to the best known system with the same channel decoder complexity. Finally, FEED allows a trade-off between receiver complexity and quality