A dual priority M-QAM transmission system for high quality video over mobile channels

This paper presents a dual priority transmission system for mobile channels suitable for mobile video applications. A dual priority 16-QAM is selected to transport the compressed video bitstream which is partitioned to mach the bit-error sensitivity of the transmitted symbol in terms of mapping in the constellation diagram and picture quality. The partition scheme is applied to split the ITU-T H.263-coded video bitstream and is suitable for constant bit rate transmission where the allocation of the VL-coded information amongst the two partitions is performed adoptively. Simulation results show that this strategy results in higher quality of the reconstructed video data. Investigations have been carried out for a possible extension in higher level modulation schemes such as 64 and 256 QAM and simulation results show that further improvement can be achieved. The implementation of a codec that supports the 64 and 256 QAM system is under development.