Applicability of position-based routing for VANET in highways and urban environment Ant´ onio Fonseca a,* , Teresa Vaz˜ ao a a INESC-ID/Instituto Superior T´ ecnico - Av. Prof. Dr. Anibal Cavaco Silva, 2744-016 Porto Salvo, Portugal Abstract In the last years many routing protocols proposals have been made considering the particular VANET characteristics. From the many proposals that came up, the protocols based on the vehicles positions were found to be the most adequate to VANETs due to their resilience to handling the nodes position variation. In this study we will survey the existing position-based routing protocols. Unlike other studies we will emphasise on their applicability to different environments. We start by characterising the vehicular network environment, namely the urban and the highway environments. Afterwards, topology-based protocols are compared to position-based protocols and to the latter are identified the different used strategies and their performances are qualitatively evaluated relatively to different metrics. The different position-based routing proposals are described including a pseudo-code specification, and a comparison is made based on different perspectives. To conclude, the main constrains to urban and highway environments are characterised and the adaptability of each protocol to each of the environments is evaluated. Keywords: Vehicular ad-hoc networks, position-based routing, urban, highway, survey 1. Introduction Recent advances in wireless technologies and embedded sys- tems extended the use of communications to new domains. Taking advantages of such technological advances, vehicle and equipment manufacturers have recognised the opportunity of enhancing the surface transportation by using the communica- tion capabilities of the Vehicular Ad-hoc Networks (VANET) to offer an Intelligent Transportation System (ITS) to the drivers. The major goal of this system is to improve the drivers safety by informing them about dangers and situations that they cannot see. It will also be used to support other services such as broad- cast of weather or traffic conditions or infotainment to make a trip more pleasant to the passengers [1] [2]. In [3] the most relevant applications have been surveyed and the major techni- cal challenges identified showing that major modifications are needed in all the layers of the Open Systems Interconnection (OSI) reference model. To support such variety of services, ITS will provide communication amongst vehicles, between vehi- cles and the roadway infrastructure and from latter to vehicles and wireless devices that are carried by drivers, pedestrians and cyclists. Due to the well-defined mobility pattern of the nodes and characteristics of the surrounding environment, most of the so- lutions that have been proposed for Mobile Ad-hoc Networks (MANET) are not suitable for VANET [4][5]. In [6] it is shown that the different type of applications, the resources and the en- vironment make VANET a unique area of wireless communi- cation. * Corresponding author tel. +351 917924148 fax +351 214233268 Email addresses: afonseca@tagus.inesc-id.pt (Ant´ onio Fonseca), teresa.vazao@ist.utl.pt (Teresa Vaz˜ ao) Thus, a significant effort is being put to design solutions for this new type of environment by the industry, standardisation bodies and the research community, as surveyed in [7]. A significant number of research projects have been made funding by national agencies or international entities, which are targeted to the development of new technologies, applications, services and to the promotion of energy efficiency and road safety. A few examples of these projects can be represented by the Network on Wheels (NoW) [8], Fleetnet [9] and CarTALK 2000 [10] projects that are being developed by car manufac- turers in consortium with other entities. Also, important au- tomobile manufacturers have joined their efforts and created a non-profit organisation, the Car2Car Communication Consor- tium (C2CCC) [11], which aims at increasing road safety and trafficefficiency through the use of VANET communications. Some more recent projects were CVIS [12] that aim to define the core technologies for the infrastructure, SAFEPOT [13], to increase road safety and COOPERS [14] that uses the road op- erators view of the road [15]. eCoMove is an ongoing project that aims to use vehicle cooperation for a more eco-friendly driving [16]. A major result of these efforts, promoted by the COMeSafety initiative [17], is the coordination and consolidation of the sci- entific results that lead to the definition of a common reference architecture with a direct commitment of standardisation bod- ies, such as European Telecommunications Standards Institute (ETSI) TC ITS and the International Organization for Standards (ISO) TC204 WG16 (ITS Communications). This Communi- cation Access for Land Mobile (CALM) architecture described in [18] and briefly surveyd in [19] was been adopted in Europe since then. Another important contribution was made by the Institute of Electrical and Electronics Engineers (IEEE) with the stan- Preprint submitted to Network and Computer Applications December 26, 2011