Reliable broadcast in mobile wireless networks

This paper presents preliminary results of our research on wireless networking that supports reliable communications between nomadic hosts engaged in distributed computing and collaborative conferencing. Our network model consists of a set of low-power, radio frequency (RF) transceivers which move relative to each other across an irregular terrain subject to RF propagation impairments. The low transmitter power defines a radio coverage which limits the probability of intercept and the number of neighbors but optimizes frequency reuse. The combination of low power and propagation environment produces a network characterized by stochastic link failures. The rapidity of these failures and perturbations to the network topology defeats the use of routing policies based on maintaining routing tables or determining least cost paths. With these conditions as the background, our work addresses the need to provide reliable information exchange, mitigate bottlenecks, avoid excessive traffic, and offer scalable services without the benefit of static base station or fixed backbone support. Meeting such challenges demands a robust, flexible information transport system that delivers all required information for diverse operational scenarios. The approach emphasizes the importance of achieving guaranteed delivery across a network of limited size operating in a hostile environment rather than obtaining a high throughput per unit area, typical of commercial enterprises. The basic premise of the protocol is that host mobility and terrain prevents a priori knowledge of any host location and optimum path.