An Analysis of Emergency Message Delivery Scheme in Inter-Vehicular Networking

Inter-vehicle networking has been proved to be an efficient and enabling system for the enhancement of road safety. With the help of inter-vehicle networking, a driver can be notified with a warning message for a traffic jam or collision in a real-time mode, and thus, take a positive action promptly to avoid entering jam areas or multiple-vehicle collisions. In this paper, we study the performance of an emergency message delivery scheme in an inter-vehicle network. When a critical safety-related event occurs in a vehicle, such as a sudden brake or the emerging of a road hazard, an emergency message is automatically generated and broadcast to the neighboring vehicles within a safety area through an onehop or multiple-hops delivery. If the message is received by all the vehicles with the safety area before the deadline, the safety is guaranteed. However, the emergency message delivery scheme encounters significant challenges to meet the high requirements on both latency and reliability. At first, the topology of an inter-vehicle networking is normally unknown and time varying. Moreover, wireless coverage and channel fading under diverse road situations seriously impact the connectivity among the vehicles within the safety area. In this paper, we build up a simplified model to study the relation between the size of safety area and the message delivery distance per hop and the number of hops. Through theoretical analysis and computer simulations, the statistical characteristics of the size of safety area (Ds) as a function of the message delivery distance per hop (R), the number of hops (N), and the vehicle arrival rate (γ) will be carefully investigated. The obtained research results can be used to estimate the required number of hops and possible latency to deliver emergency messages within a designed safety area.