Soft-decoding for self-organized map

We proposed a joint source-channel coded image-transmission scheme over an inter-symbol interference (ISI) channel. The scheme uses a self-organized-map (SOM) to encode the source data and a convolutional code to protect the quantized data. So, we can regard the ISI channel as another convolutional code. The combination of convolutional code, interleaver and ISI channel equals to a serial turbo code. In the receiver side, we decode the serial turbo code iteratively. The soft-output of the turbo decoder is utilized to get better-reconstructed images by soft decision. In our approach, when a new codebook is used or the noise power of the channels changes, we do not need to carry out the association between codevectors and transmission binary words. By performance comparison, it proves our scheme is comparable to the traditional channel-optimized vector quantization (COVQ) scheme.