Modified Joint Channel Source Decoding structure for reliable image transmission

Transmission of images over unreliable channels is highly prone to errors. The existing Turbo code based Joint Channel Source Decoding (JCSD) uses weighting operation on the extrinsic information passed between the maximum a posteriori probability (MAP) decoders to minimize the transmission errors. We propose a modification to the existing structure to further enhance the visual quality by minimizing the transmission errors. In the modified structure, the weighting operation is applied on the channel soft output values instead of extrinsic information. Also, a low complexity error detection algorithm based on variance/ standard deviation and channel soft output value is proposed. Simulation results show the Peak Signal to Noise Ratio (PSNR) improvement of about 0.8-1.0 dB over existing JCSD approach for a low channel SNR value of 1dB.