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We propose a novel unified radio frame structure and medium access control (MAC) protocol for low-latency and highly reliable vehicle-to-X (V2X) communications. The radio frame structure enables short latency transmission and the unified device-to- device (D2D) communication for V2X services. The unified MAC protocol simultaneously enables the cellular-assisted and ad-hoc D2D communications to enable...
The research of vehicular networks has been studied for many years. In actual life, there are a few implementations of V2X communication system, majority of them are extremely expensive. Most importantly, detailed insight implementation procedure hasn't been provided for researches. In this paper, an efficient V2X communication system based on the IEEE 802.11p/1609.X protocol stack, also known as...
In this paper, we investigate the bottleneck traffic problems that are caused and/or amplified by path recommendation protocols in use. Distributed path recommendation protocols construct the path towards each destination in a hop-by-hop fashion. In some scenarios most of traveling vehicles, arriving the road intersection from several input road segments, are recommended to leave at the same output...
Due to the high costs of deploying and testing VANETs, simulations are required for development and evaluation of new protocols at any layer of WAVE protocol stack. Although there are powerful tools to simulate VANETs and especially the IEEE 802.11p/1609.4 DSRC/WAVE protocols, however, they are not free or not publically available. NS-2 Network Simulator is a free and widely accepted simulator used...
Many protocols and mechanisms have been proposed aiming to find an alternative path towards each targeted destination in downtown and urban areas. These protocols recommend the fastest path (i.e., least congested path) without considering the services or conditions of the recommended road segments. In this work, we propose a real-time, distributed, and context-aware path recommendation protocol. The...
Secure communication in Vehicular Ad hoc Networks (VANETs) can be achieved through a public key infrastructure (PKI). A tamper proof device (TPD) is traditionally used to statically store encryption keys in each vehicle. These keys are renewed periodically by a certificate authority (CA). In this paper, a dynamic key distribution protocol for PKI-based VANETs is proposed. A vehicle dynamically requests...
In recent years, new architectures and technologies have been proposed for Vehicular ad hoc networks (VANETs).However, the experiments to validate these proposals tend to overlook the most important and representative factors. Moreover, the scenarios simulated tend to be very simplistic (highways or Manhattan-based layouts), which could seriously affect the validity of the obtained results. In this...
To restore the performance of the system due to the failure of a BS, we propose a hybrid vehicular communication system which introduces a novel double cluster head (DCH) routing scheme. Using vehicular traces from loop Ids on the M4 motorway in the UK, the performance of the system is evaluated and compared with the single cluster head (SCH) routing scheme under different configurations. Even though,...
Cooperative vehicle safety (CVS) systems rely on vehicular ad-hoc networks operating in broadcast mode to deliver vehicle tracking and safety information to neighboring cars. This information is used to enable collision avoidance and warning systems. One of the main challenges of the eventual large scale deployment of such systems is network congestion, which could critically degrade the quality of...
In VANETs(Vehicular Ad Hoc Networks), moving from one RSU's coverage region to another will bring reauthentication in the new security domain, which can be named security handover problem. In this paper, based on mobility predictability, we propose a novel anonymous communication scheme called SCPT to address the security handover problem. It uses hash chain for vehicle's anonymous authentication...
There are many environmental factors taking effects on the communication performance of routing protocols.However, in high-density urban areas, one of the important factors is vehicle-node density. This paper proposes the vehicle- node density parameter to improve the performance of AODV routing protocol and OLSR routing protocol under two typical mobile models in VANET. The performance of routing...
The time synchronization is an important problem for wireless sensor networks. There has been many time synchronization methods proposed in the literature, such as. The purpose of them was to synchronize the whole network, which cost much time and energy. In this paper, an efficient time synchronization scheme for wireless sensor networks is proposed. According to the specific application purpose...
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...
Inter-vehicle communication is one of the most significant transmission behaviors for diverse transportation applications in the vehicular ad hoc network (VANET). The existing studies have showed that clustering is a promising solution to data communication under the mobile environment, and especially the passive clustering (PC) technique is the efficient one compared to other clustering techniques...
Improving safety on the road is one of the most challenging goals of recent investigations in VANETs (Vehicular Ad-hoc Networks). CCA (Chain Collision Avoidance) applications are a new emerging means of reducing the number of accidents on the road by providing cars with collaborative communication capabilities, thus allowing them to react against the real risk of accident which may occur in different...
The past few years have seen an increasing interest in the development of vehicular ad hoc networks resulting in many routing protocols proposals. This paper presents the results of a detailed performance evaluation of three of these protocols selected from different categories: geographic routing (i.e., GPSR), geographic opportunistic routing (i.e., GOSR), and trajectory based routing (i.e., SIFT)...
In this paper, we reveal several characteristics of a broadcast communication protocol called DSCF (Directional-Store-Carry-Forward). In recent years, realization of VANETs (Vehicular Ad-hoc Networks) has been demanded for delivering information to vehicles at a low cost. In VANETs, a vehicle may or may not find other vehicles within its radio communication range because of vehicles' mobility, which...
Vehicular ad hoc networks (VANETs) adopt the public key infrastructure (PKI) and certificate revocation lists (CRLs) to reliably secure the network. In any PKI system, the authentication of a received message is performed by checking that the certificate of the sender is not included in the current CRL, and verifying the authenticity of the certificate and signature of the sender. In this paper, we...
Mobility models represent real world scenarios for vehicular ad hoc networks (VANETs) and play a vital role in the performance evaluation of routing protocols. More research focus is now on the development of realistic mobility models for vehicular ad hoc networks. A number of mobility models have been presented and their impact on the performance on the routing protocols has been tested. In this...
In this paper, we present a performance evaluation study analyzing the behavior of a generic warning message dissemination (WMD) mechanism in a 802.11p based VANET. In our WMD method, warning-mode vehicles notify nearby vehicles in order to improve traffic safety and to control traffic congestion. Our evaluation uses 2k factorial methodology to determine the most representative factors that affect...
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