Mobility Aware Event Dissemination in VANET

Many future VANET applications will be event-driven and will require events of different kinds to be delivered to vehicles en route in time. In this work, we propose a publish-subscribe based communication framework for a service provider (SP) that utilizes its roadside units (RSUs) to deliver relevant events to moving vehicles. Vehicles subscribe to a SP for specific types of events; the events are also reported to the SP. The SP delivers the events to the subscribed vehicles within the validity periods of both the subscriptions and the events through RSUs placed along the route of the vehicles. The problem is referred as the Minimum Cost Event Placement Problem [10] that schedules the placement of events in RSUs for different time intervals so that the events are delivered to the subscribed vehicles while incurring minimum cost of utilization of the RSUs. In this paper, we give a ln n approximation algorithm for the problem, where n is the number of subscriptions. We then propose a centralized online algorithm to solve the problem. A lower bound on the cost of utilization of the RSUs for a given set of subscriptions and events is presented next. Detailed simulation results in realistic city traffic scenarios are presented to show the performance of the algorithms.