5,730 research outputs found
Hybrid-Vehcloud: An Obstacle Shadowing Approach for VANETs in Urban Environment
Routing of messages in Vehicular Ad-hoc Networks (VANETs) is challenging due
to obstacle shadowing regions with high vehicle densities, which leads to
frequent disconnection problems and blocks radio wave propagation between
vehicles. Previous researchers used multi-hop, vehicular cloud or roadside
infrastructures to solve the routing issue among the vehicles, but they suffer
from significant packet delays and frequent packet losses arising from obstacle
shadowing. We proposed a vehicular cloud based hybrid technique called
Hybrid-Vehcloud to disseminate messages in obstacle shadowing regions, and
multi-hop technique to disseminate messages in non-obstacle shadowing regions.
The novelty of our approach lies in the fact that our proposed technique
dynamically adapts between obstacle shadowing and non-obstacle shadowing
regions. Simulation based performance analysis of Hybrid-Vehcloud showed
improved performance over Cloud-assisted Message Downlink Dissemination Scheme
(CMDS), Cross-Layer Broadcast Protocol (CLBP) and Cloud-VANET schemes at high
vehicle densities
Hybrid-Vehfog: A Robust Approach for Reliable Dissemination of Critical Messages in Connected Vehicles
Vehicular Ad-hoc Networks (VANET) enable efficient communication between
vehicles with the aim of improving road safety. However, the growing number of
vehicles in dense regions and obstacle shadowing regions like Manhattan and
other downtown areas leads to frequent disconnection problems resulting in
disrupted radio wave propagation between vehicles. To address this issue and to
transmit critical messages between vehicles and drones deployed from service
vehicles to overcome road incidents and obstacles, we proposed a hybrid
technique based on fog computing called Hybrid-Vehfog to disseminate messages
in obstacle shadowing regions, and multi-hop technique to disseminate messages
in non-obstacle shadowing regions. Our proposed algorithm dynamically adapts to
changes in an environment and benefits in efficiency with robust drone
deployment capability as needed. Performance of Hybrid-Vehfog is carried out in
Network Simulator (NS-2) and Simulation of Urban Mobility (SUMO) simulators.
The results showed that Hybrid-Vehfog outperformed Cloud-assisted Message
Downlink Dissemination Scheme (CMDS), Cross-Layer Broadcast Protocol (CLBP),
PEer-to-Peer protocol for Allocated REsource (PrEPARE), Fog-Named Data
Networking (NDN) with mobility, and flooding schemes at all vehicle densities
and simulation times
A Taxonomy for Congestion Control Algorithms in Vehicular Ad Hoc Networks
One of the main criteria in Vehicular Ad hoc Networks (VANETs) that has
attracted the researchers' consideration is congestion control. Accordingly,
many algorithms have been proposed to alleviate the congestion problem,
although it is hard to find an appropriate algorithm for applications and
safety messages among them. Safety messages encompass beacons and event-driven
messages. Delay and reliability are essential requirements for event-driven
messages. In crowded networks where beacon messages are broadcasted at a high
number of frequencies by many vehicles, the Control Channel (CCH), which used
for beacons sending, will be easily congested. On the other hand, to guarantee
the reliability and timely delivery of event-driven messages, having a
congestion free control channel is a necessity. Thus, consideration of this
study is given to find a solution for the congestion problem in VANETs by
taking a comprehensive look at the existent congestion control algorithms. In
addition, the taxonomy for congestion control algorithms in VANETs is presented
based on three classes, namely, proactive, reactive and hybrid. Finally, we
have found the criteria in which fulfill prerequisite of a good congestion
control algorithm
Assisting V2V failure recovery using Device-to-Device Communications
This paper aims to propose a new solution for failure recovery (dead-ends) in
Vehicle to Vehicle (V2V) communications through LTE-assisted Device-to-Device
communications (D2D). Based on the enhanced networking capabilities offered by
Intelligent Transportation Systems (ITS) architecture, our solution can
efficiently assist V2V communications in failure recovery situations. We also
derive an analytical model to evaluate generic V2V routing recovery failures.
Moreover, the proposed hybrid model is simulated and compared to the generic
model under different constrains of worst and best cases of D2D discovery and
communication. According to our comparison and simulation results, the hybrid
model decreases the delay for alarm message propagation to the destination
(typically the Traffic Control Center TCC) through the Road Side Unit (RSU)Comment: 3 page
Relieving the Wireless Infrastructure: When Opportunistic Networks Meet Guaranteed Delays
Major wireless operators are nowadays facing network capacity issues in
striving to meet the growing demands of mobile users. At the same time,
3G-enabled devices increasingly benefit from ad hoc radio connectivity (e.g.,
Wi-Fi). In this context of hybrid connectivity, we propose Push-and-track, a
content dissemination framework that harnesses ad hoc communication
opportunities to minimize the load on the wireless infrastructure while
guaranteeing tight delivery delays. It achieves this through a control loop
that collects user-sent acknowledgements to determine if new copies need to be
reinjected into the network through the 3G interface. Push-and-Track includes
multiple strategies to determine how many copies of the content should be
injected, when, and to whom. The short delay-tolerance of common content, such
as news or road traffic updates, make them suitable for such a system. Based on
a realistic large-scale vehicular dataset from the city of Bologna composed of
more than 10,000 vehicles, we demonstrate that Push-and-Track consistently
meets its delivery objectives while reducing the use of the 3G network by over
90%.Comment: Accepted at IEEE WoWMoM 2011 conferenc
Stable Infrastructure-based Routing for Intelligent Transportation Systems
Intelligent Transportation Systems (ITSs) have been instrumental
in reshaping transportation towards safer roads, seamless
logistics, and digital business-oriented services under the umbrella of
smart city platforms. Undoubtedly, ITS applications will demand
stable routing protocols that not only focus on Inter-Vehicle Communications
but also on providing a fast, reliable and secure interface to
the infrastructure. In this paper, we propose a novel stable infrastructure-
based routing protocol for urban VANETs. It enables vehicles
proactively to maintain fresh routes towards Road-Side Units
(RSUs) while reactively discovering routes to nearby vehicles. It
builds routes from highly stable connected intersections using a selection
policy which uses a new intersection stability metric. Simulation
experiments performed with accurate mobility and propagation
models have confirmed the efficiency of the new protocol and its
adaptability to continuously changing network status in the urban
environment
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