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In [1] we show how vehicles can opportunistically exploit infrastructure through open access points (APs) to efficiently communicate with other vehicles. We also highlight the importance of the use of a correct mobility model, since the advantages that may derive from the use of an infrastructure may not be appreciated because of a lack of accuracy. We continue our study based on realistic vehicular...
We propose a novel group signature based security framework for vehicular communications. Compared to the traditional digital signature scheme, the new scheme achieves authenticity, data integrity, anonymity, and accountability at the same time. Furthermore, we describe a scalable role-based access control approach for vehicular networks. Finally, we present a probabilistic signature verification...
Simulation of network protocol behavior in Vehicular Ad Hoc Network (VANET) scenarios is the predominant basis for evaluating the applicability of particular protocols developed in the Mobile Ad Hoc Network (MANET) domain. As the selection of a mobility model influences the outcome of simulations to a great deal, the use of a representative model is necessary for producing meaningful evaluation results...
Secure communication of time critical information in V2V networks is expected to be achieved via a robust infrastructure that provides security related services at all times. This paper explores the dependence of performance of secure V2V communications on the mechanisms used by the security infrastructure. We propose and analyze a performance metric termed the confidence on security infrastructure...
Through a field implementation of vehicular ad hoc networks (VANET), we report the observation of a monotonic dependence of maximum relative velocity between two vehicles and their separation, for typical suburban driving. We introduce a hierarchical phenomenological model of driving behavior to describe this observation. As an example, we illustrate how we use this model to predict the expected Doppler...
We consider the problem of adjusting transmission power for vehicle-to-vehicle broadcast safety communication in vehicular ad hoc networks. Given a target communication range designated by a vehicle safety application, the power control algorithm is designed to select a transmission power no greater than necessary for the targeted range. The power control algorithm results in higher communication...
Content sharing using cooperative peer-to-peer model has become increasingly more popular in a vehicular ad hoc network (VANET). The small transmission window from a vehicle to an access point (AP), high mobility of vehicles, and intermittent and short-lived connectivity to an AP provide incentives for vehicles to cooperate with one another to obtain information from the Internet. These characteristics...
In this paper we propose a relay-based solution to extend the service range of roadside APs. When a vehicle moves towards the AP, its signal quality to the AP may be poor. At this time, it uses a relay vehicle ahead of it which has good signal quality, to relay the data. When the vehicle is moving away from the AP, it uses a relay node behind it to set up a backward relay path to keep the connection...
This paper addresses the problem of real-time video transmission in vehicular networks. We show that the video quality of real-time services is greatly decreased when there is network congestion in different traffic situations. We propose a solution that applies frame skipping and transcoding together with frame rate reduction techniques over IEEE 802.11 based vehicular networks. Our approach improves...
In performance studies of vehicular ad hoc networks, the underlying mobility model plays a major role. In this paper, we investigate the influence of three mobility models on the performance of ad hoc network routing protocols (AODV and GPSR). As a benchmark, we use the popular random waypoint mobility model. Our second model is based on a vehicular traffic simulator that we proposed in earlier work...
IEEE- and ASTM-adopted dedicated short range communications (DSRC) standard towards 802.lip is a key enabling technology for the next generation of vehicular safety communication. Broadcasting of safety messages is one of the fundamental services in DSRC. In this paper, requirements and channel design of vehicular ad hoc networks for safety applications are addressed. Performance of vehicle-to-vehicle...
This paper proposes an ITS system that uses not only integrated cellular and ad hoc relaying technologies, but also users' mobility profiles. It focuses on a subsystem where cellular bandwidth is used mostly for control signals, and an ad hoc distribution network (ADN) is used for file downloading and video streaming. The paper formulates an optimization problem with the objective being to maximize...
Recently, vehicular networks have begun to attract much attention in industry as well as academia. In particular, IEEE 802.11-based solutions for vehicular networks are also investigated by IEEE 802.11p. As the original IEEE 802.11 standard is designed only for little mobility, the IEEE 802.11p working group should address important issues such as frequent disconnection and handoff. We first introduce...
Building a wireless sensor network in a car has important benefits in terms of cost reduction, having an open architecture, and fuel efficiency. One option for implementing such an intra-car wireless network is to use RFID technology. In this paper, we report the results of extensive experiments carried out at Carnegie Mellon University in collaboration with General Motors for understanding the capabilities...
In this paper, we propose a hybrid wireless data access algorithm in mobile hotspots, which enables ubiquitous Internet access in vehicular networks. We first introduce a novel architecture with proxy cache (PC) for strongly consistent wireless data access and investigate the trade-off relationship between a PC-based poll-each-read (P-PER) algorithm and a PC-based callback (P-CB) algorithm. We then...
Unmanned aerial vehicle (UAV)-aided wireless ad- hoc networks have become an important component of today's battleground. This paper considers the dynamic spectrum management problem in a single-theater UAV-aided ad-hoc wireless network. We propose spectrum management and rate allocation algorithms in a multi-rate, multi-channel UAV-aided ad hoc wireless network that uses link adaptation. We also...
The paper proposes a MAC layer protocol called QoMOR (QoS-aware MAC protocol using optimal retransmission) that is designed to provide QoS in a decentralized network with multiple sensor (source) nodes that do not have the capability to receive acknowledgements from the sink node. A minimum data delivery probability between the sensor and sink nodes is achieved by allowing each source node to transmit...
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