Asynchronous video coding for wireless transport

Wireless access to continuous-media services is becoming increasingly prevalent. An interactive video service is one such service, but existing compression standards are unsatisfactory for wireless packet-video services. We propose a novel strategy for video transport using a layered source coder in conjunction with a variable quality-of-service, multiple-substream abstraction for the transport. This abstraction specifically addresses the need to simultaneously obtain high spectral efficiency, good subjective quality and low perceptual delay on a wireless channel (perceptual delay is the effective end-to-end latency observed by the user). The abstraction also addresses the heterogenous transport resulting from the concatenation of a wireless access link with a broadband backbone network. We use asynchronous video reconstruction, running counter to current techniques which use strictly synchronous video processing. By doing so, we hope to achieve a perceptual delay that is much lower than the worst-case transport delay. By identifying packets to the transport with relaxed reliability and/or delay requirements, the transport can achieve high traffic capacity. Reasonable and promising simulation results are achieved, although much work remains on achieving significant video compression in this environment.