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Localization and exchanged position information plays a big role in Vehicular Ad-Hoc Networks (VANET). Several network services and applications, such as safety messages, require location information. The data are exchanged between vehicles within their radio communication range. In real life implementation, direct communication can be interfered and blocked by obstacles on the road preventing two...
One of the main motivations of wireless communication between vehicles is to establish a mutual awareness among vehicles. Such awareness is achieved through the periodic exchange of broadcast messages with information about the current position, heading or speed of a vehicle. The probability that neighboring vehicles receive such messages successfully depends on the current radio channel and network...
Vehicle Ad Hoc Networks (VANETs), based on IEEE 802.11p, and 3G & beyond networks are characterized by their high date transmission rates and wide range communication, respectively. This paper presents an architecture that integrates between the two, making advantage of the features of each. Design guidelines pertaining to vehicle clustering and gateway management are defined. The former aims...
Recent studies on service discovery protocols in vehicular networks have shown promising results. However, very little work has been reported on how to integrate the fault tolerance feature into these mechanisms. This feature is vital for the success of the deployment of service discovery protocols in vehicular networks. Drivers on their cars should not have their requests dissatisfied or their connections...
Vehicular Ad-hoc NETworks (VANET) are emerging as a promising way to disseminate information among vehicles. As this information can range from safety to infotainment application content, and the vehicular environment has very particular characteristics, the behavior of the network must be effectively studied in order to adapt the transmission mechanisms. This work presents a model for the connectivity...
In this paper, a novel transmit power control protocol for vehicular ad-hoc networks (VANETs) is proposed that aims to improve the reliability of safety-critical broadcasts while also maximizing the transmission range. Large transmission ranges are often desirable in order to ensure that safety-critical messages reach as many vehicles as possible, particularly in highvelocity situations. However,...
Directional broadcast was proposed in VANETs in order to disseminate data to other vehicles efficiently. However, traditional directional broadcast protocols cannot provide good enough efficiency for VANETs, especially in the urban area. In this paper, we propose an efficient road-based directional broadcast protocol for VANETs in urban environment. We avoid misclassification problem that traditional...
In Vehicular Ad-hoc Network (VANET), the multi-hop routing frequently breaks off, which has a negative effect on the reliability and transmission quality of the network. The paper proposes a new routing algorithm based on the geographical position, called Multi-Priority Opportunistic Directional Routing (MPODR). The algorithm improves the existing Opportunistic Directional Forwarding Strategy from...
The increased traffic density in urban areas should be handled by a robust collision avoidance and traffic control system that is based on decentralized inter-vehicle communication. In such a special ad hoc network traditional routing protocols cannot cope with the high mobility and low link reliability, while flooding based approaches consume too many resources. Our proposed solution, Carefully Localized...
In this paper, we address the reliable alarm message dissemination in Vehicular Ad hoc NETworks (VANETs) environment. We study various techniques to disseminate emergency data, after a car crash, within a group of vehicles. We consider a trajectory-based data dissemination technique to perform broadcast flooding task optimization, and compare it with a pure flooding scheme. For the evaluation, we...
In order to achieve cooperative driving in vehicular ad hoc networks (VANET), broadcast transmission is usually used for disseminating safety-related information among vehicles. Nevertheless, broadcast over multihop wireless networks poses many challenges due to link unreliability, hidden terminal, message redundancy, and broadcast storm, etc., which greatly degrade the network performance. In this...
Researchers have suggested Vehicular Ad hoc Networks as a way to enable car to car communications and to allow for the exchange of safety and other types of information among cars. The Wireless Access in Vehicular Environments (WAVE) protocol stack is standardized by the IEEE, and it allocates spectrum for vehicular communication. In our work we prove that it does not provide sufficient spectrum for...
Vehicular ad hoc networks (VANETs), similar to other distributed systems, often require a scalable time synchronization service enabling data consistency and coordination. In this paper, we propose a new time synchronization protocol for VANETs, which provides excellent scalability, accuracy and robustness for high mobility traffic scenarios. The new protocol, Converging Time Synchronization (CTS),...
Reliable broadcasting in vehicular ad hoc networks is challenging due to its unique characteristics including intermittent connectivity and various vehicular scenarios (car traffic is possibly very dense in urban areas or very sparse on highways). In this paper, we propose a new reliable broadcast protocol which is suitable for such characteristics. To address the issue of various vehicular scenarios,...
In a self-organizing vehicular network, vehicles share and distribute information by rebroadcasting a received information packet to their neighbors. An efficient broadcast technique can offer a high reactivity without sacrificing the communication reliability. Therefore, broadcast techniques are particularly suitable for safety-related vehicular transmissions, whose goal is reaching reliably the...
Wireless vehicular communications possess significant challenges for their massive deployment in next generation vehicular networks. Some important issues that must be tackled deal with security, billing and scalability in order to provide reliable services in the case of non-safety applications. In this paper we study a service provisioning protocol intended for Vehicular-to-Infrastructure (V2I)...
One of the notoriously difficult problems in vehicular ad-hoc networks is to ensure that established paths do not break before the end of data transmission. This is a difficult problem because the network topology is changing constantly and the routing links are inherently unstable. Inspired by ticket based probing, we propose a scheme to selects a stable routing path in vehicular network environment...
Reliable delivery of emergency messages is critical for VANET safety applications. However shadowing in VANETs can cause these packets to be lost. In this paper we propose a reliable opportunistic broadcast protocol (R-OB-VAN) that overcomes this problem and maintains a high delivery ratio and low average delay. The second contribution of this work is to define a simple but realistic model of shadowing...
Safety applications developed for inter-vehicle communications (IVC) are characterized by strict reliability and delay requirements, thus relying on multi-hop broadcasting to disseminate the traffic alert messages to all surrounding vehicles. However, the conventional broadcast schemes suffer from the so-called "broadcast storm problem", a scenario in which contention and collisions happens...
Broadcast is an effective approach for safety-related information exchange to achieve cooperative driving in vehicular ad hoc network (VANET). However, it suffers from several fundamental challenges such as message redundancy, link unreliability, hidden terminal and broadcast storm, etc., which degrade the efficiency of the network greatly. To address these issues, this paper proposes a position based...
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