Recent advances in mobile video communications

Mobile channels cannot provide guaranteed quality of service parameters. We illustrate this problem with a ray tracing simulation of an indoor DECT channel. Unreliable transmission poses severe problems for the transmission of motion video, using compression schemes such as described in the ITU-T H.263 international standard due to temporal error propagation. We discuss compatible extensions of H.263 that utilize a feedback channel for robust transmission. In conjunction with FEC and ARQ, an intelligent source coder control can provide excellent robustness at bit error rates worse than 10/sup -2/.