Efficient Information Dissemination in VANETs

Abstract

IntroductionVehicular ad-hoc networks (VANETs) enable promising new possibilities to enhance traffic safety and efficiency. The vision of VANETs is that vehicles communicate spontaneously, in an ad-hoc manner over a wireless medium. Based on this inter-vehicle communication (IVC), vehicles exchange important information, e.g., about road conditions and hazardous situations. Moreover, such information can be propagated via multiple hops, thus making the dissemination of important information possible over longer distances. This is the key advantage of this kind of safety applications compared to conventional safety systems. Whereas conventional safety systems only rely on information sensed in the direct neighborhood by onboard sensors of a vehicle, active safety applications based on IVC can utilize information generated by nodes multiple hops away. Moreover, such information can be enriched on the way with information sensed by relaying cars. This greatly enhances the potential of VANET applications. The advantage is twofold:• Having information about distant hazardous situations like an accident ahead or icy road, the driver can be warned in-time, thus being able to completely avoid the dangerous situation.• Aggregating information from multiple cars enables retaining information on a higher semantic level. This way, applications like cooperative traffic jam warning and cooperative parking place detection can be realized.The enabling technology for such applications is the wireless ad-hoc communication between vehicles. Especially the dissemination of messages in a specific geographic region represents a fundamental service in VANETs to which we refer to as geographic broadcast (GeoCast). This communication paradigm is used by many applications to enhance traffic safety and efficiency but it can also serve as a basic mechanism for other routing protocols. Because of its relevance in the domain of vehicular networks, it is of key importance that the communication protocol enables efficient message dissemination. The realization of a robust and efficient broadcast mechanism is a challenging task due to the wide range of applications envisioned to build upon this communication technology, the rigorous requirements of safety applications, and the special network characteristics of vehicular networks. Therefore, the main focus of this chapter is the efficient broadcast of information for VANET applications. We want to give a broad and in-depth review of recent research in this topic and present simulation results of efficient dissemination protocols designed for such applications. This chapter is organized as follows: In Section 2 we discuss briefly different types of VANET applications, followed by an overview of different communication mechanisms Efficient Information Dissemination in VANETs 3www.intechopen.com

DPMS: A Swift Data Dissemination Protocol Based on Map Splitting

“…The first one, consists in disseminating data to all vehicles. Whereas, geocast looks for disseminating data only to vehicles in a definite geographical region, called Zone Of Relevance (ZOR) [3]. Hence, geocast is the most feasible data dissemination approach for VANET's applications.…”

“…Precision: This metric assesses to what extent the protocol is able to only inform pertinent vehicles that are actually interested in a given event e. Hence, the challenge would be to obtain higher values of geocasting which is in a snugness connection with the quality of the determination of the geocasting area 3 . The precision metric is defined as follows:…”

Vanet Ir-Cas

“…CRN) or commercial services (e.g. SA) [1,2,11,10]. To achieve efficient use of available resources, services should only be delivered to nodes when they are highly relevant to the nodes' context.…”

“…From [1,2,11,10], we deduce that the main three categories of services provided in VANET are commercial, convenience and safety services. In this work, we focus on three services that demonstrate two different VANET communication scenarios.…”

Broadcasting in Connected and Fragmented Vehicular Ad Hoc Networks

“…Since vehicles have the characteristic of high mobility, the topology of the network changes so quickly and unexpectedly, which leads to the frequent and unpredictable break down of the wireless links [5]. Another feature of VANETs is that the network topology is highly dynamic [8]. For example, in late night hours or the rural freeways, the traffic density is in a very low level; on the other hand, in huge highways or at midday hours, a very dense network can be experienced.…”