Perceptually-based robust image transmission over wireless channels

A robust image transmission system incorporating perceptually-based coding and error protection is proposed for wireless channels. The perceptually-based image coder consists of a wavelet transformation, uniform quantization, and variable-length entropy encoding. The coded data is placed in a spatially scalable stream divided into segments of varying perceptual importance and tolerance to transmission errors. A novel unequal error protection system is designed using turbo codes for the wireless channel, neural networks to predict decoder error and calculate erasures, and outer turbo-code concatenation of Reed-Solomon codes at different rates. A model of error tolerance is developed to minimize the added redundancy required to meet the desired throughput performance and visual quality level. The proposed system provides excellent reliability allowing the transmission of high visual quality images at a small additional redundancy and low signal-to-noise ratio (4.5 dB).