Coded Hierarchical Modulation for Wireless Progressive Image Transmission

A robust coded scheme for progressive multimedia transmission is proposed for additive white Gaussian noise, flat Rayleigh fading channels, and frequency-selective channels using different unequal error protection methods in combination. Hierarchical modulation is coupled with a packetization/combining strategy and an efficient channel encoder consisting of a cyclic redundancy check outer coder concatenated with an inner rate-compatible punctured convolutional coder. Distortion-optimal hierarchical parameters are jointly chosen with the set of channel coding parameters on a packet-switched wireless network with fixed length packets. A lower bound for the performance improvement of the proposed system is derived and shown to give significant gains at lower packet sizes and higher transmission rates. The proposed system is also shown to outperform several existing schemes for realistic wireless channels.