Goldsmith, Andrea Stanford University
An ad-hoc wireless network is a collection of possibly mobile wireless nodes that self-configure to form a network without the aid of any established infrastructure. The lack of infrastructure is extremely compelling for applications where a communications infrastructure is too expensive to deploy, cannot be deployed quickly, or is simply not feasible. Such applications range from multi-hop wireless broadband Internet access to sensor networks to building or highway automation to voice, image, and video communication for emergency response, a life-saving capability urgently needed by our society. The nature of ad-hoc wireless networks makes support of delay-critical applications such as voice and video quite challenging. In this project the investigators study a new framework for ad-hoc wireless network design to support such delay- critical applications. The framework includes dynamic allocation of network resources to support media requirements, protocols that are robust to variations and uncertainties in the network, and adaptive media compression techniques that preserve end-to-end network connectivity even when network conditions are poor. The results of the project are expected to have a significant impact on the development of future wireless networks and the enabling of critical applications. The framework being developed to support delay-critical applications in ad-hoc wireless networks is based on cross-layer design across the network protocol stack. The design incorporates adaptation across multiple protocol layers, including the application, transport, network, and link layers. Within this framework, the investigators develop a suite of new techniques to balance network congestion and distortion of real-time media streams by jointly optimizing error-resilient source coding, packet scheduling, stream-based routing, link capacity assignment, and adaptive link layer techniques. The optimization is carried out dynamically by all nodes, based on link state communication, to continuously adapt to changing link and trac conditions. The research project systematically investigates these new ideas and ultimately demonstrates them in a small testbed.
