Vehicular networking has significant potential to enable diverse applications associated with traffic safety, traffic efficiency and infotainment. In this survey and tutorial paper we introduce the basic characteristics of vehicular networks, provide an overview of applications and associated requirements, along with challenges and their proposed solutions. In addition, we provide an overview of the current and past major ITS programs and projects in the USA, Japan and Europe. Moreover, vehicular networking architectures and protocol suites employed in such programs and projects in USA, Japan and Europe are discussed.

Vehicular Networking: A Survey and Tutorial on Requirements, Architectures, Challenges, Standards and Solutions

Vehicular ad hoc network (VANET) is an emerging new technology integrating ad hoc network, wireless LAN (WLAN) and cellular technology to achieve intelligent inter-vehicle communications and improve road traffic safety and efficiency. VANETs are distinguished from other kinds of ad hoc networks by their hybrid network architectures, node movement characteristics, and new application scenarios. Therefore, VANETs pose many unique networking research challenges, and the design of an efficient routing protocol for VANETs is very crucial. In this article, we discuss the research challenge of routing in VANETs and survey recent routing protocols and related mobility models for VANETs.

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Routing in vehicular ad hoc networks: A survey

This paper presents a class of routing protocols called road-based using vehicular traffic (RBVT) routing, which outperforms existing routing protocols in city-based vehicular ad hoc networks (VANETs). RBVT protocols leverage real-time vehicular traffic information to create road-based paths consisting of successions of road intersections that have, with high probability, network connectivity among them. Geographical forwarding is used to transfer packets between intersections on the path, reducing the path's sensitivity to individual node movements. For dense networks with high contention, we optimize the forwarding using a distributed receiver-based election of next hops based on a multicriterion prioritization function that takes nonuniform radio propagation into account. We designed and implemented a reactive protocol RBVT-R and a proactive protocol RBVT-P and compared them with protocols representative of mobile ad hoc networks and VANETs. Simulation results in urban settings show that RBVT-R performs best in terms of average delivery rate, with up to a 40% increase compared with some existing protocols. In terms of average delay, RBVT-P performs best, with as much as an 85% decrease compared with the other protocols.

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VANET Routing on City Roads Using Real-Time Vehicular Traffic Information

Inter-vehicle communication (IVC) systems (i.e., systems not relying on roadside infrastructure) have the potential to radically improve the safety, efficiency, and comfort of everyday road travel. Their main advantage is that they bypass the need for expensive infrastructure; their major drawback is the comparatively complex networking protocols and the need for significant penetration before their applications can become effective. In this article we present several major classes of applications and the types of services they require from an underlying network. We then proceed to analyze existing networking protocols in a bottom-up fashion, from the physical to the transport layers, as well as security aspects related to IVC systems. We conclude the article by presenting several projects related to IVC as well as a review of common performance evaluation techniques for IVC systems.

/pdf/inter-vehicle-communication-systems-a-survey-4dcec4ylxn.pdf

Inter-vehicle communication systems: a survey

Checking the satisfiability of logical formulas, SMT solvers scale orders of magnitude beyond custom ad hoc solvers.

Satisfiability modulo theories: introduction and applications

Increasing need for people to be "connected"; while at the same time remain as mobile as ever poses several interesting issues in wireless networks. It is conceivable in the near-future that wireless "hotspots" experience flash crowds-like traffic arrival pattern. A common phenomena in the Internet today characterized by sudden and unpredicted increase in popularity of on-line content. In this paper, we propose SPAWN, a cooperative strategy for content delivery and sharing in future vehicular networks. We study the issues involved in using such a strategy from the standpoint of vehicular ad-hoc networks. In particular, we show that not only content server but also wireless access network load reduction is critical. We propose a "communication efficient" swarming protocol which uses a gossip mechanism that leverages the inherent broadcast nature of the wireless medium, and a piece-selection strategy that takes proximity into account in decisions to exchange pieces. We show through simulation that gossip incorporates location-awareness into peer selection, while incurring low messaging overhead, and consequently enhancing the swarming protocol performance. We develop an analytical model to characterize the performance of SPAWN.

/pdf/co-operative-downloading-in-vehicular-ad-hoc-wireless-3820kp8wp7.pdf

Co-operative downloading in vehicular ad-hoc wireless networks

Smart antennas present a radical way to improve the capacity of wireless networks. The advantages of such antennas can be leveraged by the MAC and higher layers. In this paper, we present SPACE-MAC, a MAC protocol which enables "spatial reuse" of the medium by multiple transmit/receive pairs which are in the same collision domain. SPACE-MAC prevents interference between such pairs by selectively nulling the signals from potentially interfering transmissions. This is achieved in a totally distributed fashion utilizing channel state information (CSI) at both transmitter and receiver to adjust antennas weights for each packet transmission. SPACE-MAC can operate effectively in cluttered (e.g., indoor) environments. SPACE-MAC achieves spatial reuse without requiring a separate channel for exchanging channel state information. This allows considerably better channel utilization. We investigate performance improvements of SPACE-MAC with respect to IEEE 802.11 DCF MAC using omnidirectional antennas.

http://nrlweb.cs.ucla.edu/publication/download/367/getPDF.pdf

SPACE-MAC: enabling spatial reuse using MIMO channel-aware MAC

Future vehicular networks are expected to deploy short-range communication technology for inter-vehicle communication In addition to vehicle-to-vehicle communication, users will be interested in accessing the multimedia-rich Internet from within the vehicular network This motivates a compelling application of Co-operative Networking in the Vehicular Ad-Hoc network where the Ad Hoc network extends and complements the Internet The broadcast nature of the wireless medium drives us to explore different design paradigms from the ones used in typical wired settingsA new paradigm in content delivery on the Internet using peer-peer swarming protocols is emerging [1,2] We propose SPAWN, a simple cooperative strategy for content delivery in future vehicular networks We study the issues involved in using such a strategy from the standpoint of Vehicular Ad-Hoc networks Several enhancements to a popular swarming protocol (BitTorrent) are discussed including a gossip mechanism that leverages the inherent broadcast nature of the wireless medium, and a piece-selection strategy that uses proximity to exchange pieces quicker Preliminary results show that SPAWN increases the perceived performance of the network, resulting in faster downloads for popular files

/pdf/spawn-a-swarming-protocol-for-vehicular-ad-hoc-wireless-45s1jptuyf.pdf

SPAWN: a swarming protocol for vehicular ad-hoc wireless networks

AdTorrent is an integrated system for search, ranking and content delivery in car networks. AdTorrent builds on the notion of Digital Billboards, a scalable “push” model architecture for ad content delivery. We present a detailed analysis of the performance impact of key design parameters such as scope of the query flooding on the query hit ratio. Our mobility model for the urban, vehicular scenario can be used in conjunction with the analytical model for estimating query hit ratio by a system designer to determine the scope of the query flooding as a function of the available storage per vehicle for their application.

/pdf/adtorrent-delivering-location-cognizant-advertisements-to-1kfy8uhzsu.pdf

AdTorrent: Delivering Location Cognizant Advertisements to Car Networks

Advertisements, are the most important source of revenue for some of the biggest Internet-based companies. With vehicular networks poised to become part of the Internet in the near future, this new “edge” of the Internet represents a new frontier that companies will be striving to reach. In this paper we investigate the feasibility of targeted dissemination of ad content in a car network. We present Digital Billboards, a scalable “push” model architecture for ad content delivery. We then propose, AdTorrent, an integrated system for search, ranking and content delivery in this architecture. We evaluate our design using a realistic vehicular mobility model which captures mobility characteristics such as temporal and spatial dependencies and geographic restrictions.

/pdf/adtorrent-digital-billboards-for-vehicular-networks-10c1nqo9g5.pdf

Alok Nandan

Papers

Co-operative downloading in vehicular ad-hoc wireless networks

SPACE-MAC: enabling spatial reuse using MIMO channel-aware MAC

SPAWN: a swarming protocol for vehicular ad-hoc wireless networks

AdTorrent: Delivering Location Cognizant Advertisements to Car Networks

AdTorrent: Digital Billboards for Vehicular Networks