Using utility and microutility to manage resources in vehicle ad hoc networks

Abstract

We describe an approach to propagating streams of information in Vehicle Ad-Hoc Networks (VANETs) based on sources of information predicting where the information will be useful—information is pushed “based on statistical pull” rather than actual requests for information. In this paper we describe how sources can model the potential usefulness of their information using utility functions that describe where and at what data rates the information will be useful. These utility functions can converted to more compact “microutilities” that travel with the individual data packets. The microutilities allow the information forwarding protocols to operate distributedly and independently on individual data packets, while achieving good overall coordination and delivery for the entire data stream. We describe the algorithms used to convert utility functions to microutilities, and how the microutilites can be used to make simple in-transit propagation decisions that reflect the intention of the original utility function from which they are derived. Our algorithms insure that both proactive planning and any reactive dropping of information in-transit are done consistent with the needs of the applications—for example, for vehicle safety applications the position and velocity of vehicles will be propagated frequently at short distances, while parking garage applications can advertise their current availability less frequently at longer distances. In this way data streams from both high priority (safety) and lower priority (traffic and commercial) applications can be propagated in the same network. We show experimental results that demonstrate the advantage of such a utility–microutilty approach in serving the needs of diverse intelligent transportation system applications. end{abstract}