343 research outputs found
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
CMD: A Multi-Channel Coordination Scheme for Emergency Message Dissemination in IEEE 1609.4
In the IEEE 1609.4 legacy standard for multi-channel communications in
vehicular ad hoc networks(VANETs), the control channel (CCH) is dedicated to
broadcast safety messages while the service channels (SCH's) are dedicated to
transmit infotainment service content. However, the SCH can be used as an
alternative to transmit high priority safety messages in the event that they
are invoked during the service channel interval (SCHI). This implies that there
is a need to transmit safety messages across multiple available utilized
channels to ensure that all vehicles receive the safety message. Transmission
across multiple SCH's using the legacy IEEE 1609.4 requires multiple channel
switching and therefore introduces further end-to-end delays. Given that safety
messaging is a life critical application, it is important that optimal
end-to-end delay performance is derived in multi-channel VANET scenarios to
ensure reliable safety message dissemination. To tackle this challenge, three
primary contributions are in this article: first, a channel coordinator
selection approach based on the least average separation distance (LAD) to the
vehicles that expect to tune to other SCH's and operates during the control
channel interval (CCHI) is proposed. Second, a model to determine the optimal
time intervals in which CMD operates during the CCHI is proposed. Third, a
contention back-off mechanism for safety message transmission during the SCHI
is proposed. Computer simulations and mathematical analysis show that CMD
performs better than the legacy IEEE 1609.4 and a selected state-of-the-art
multi-channel message dissemination schemes in terms of end-to-end delay and
packet reception ratio.Comment: 15 pages, 10 figures, 7 table
Adaptive Beaconing Approaches for Vehicular ad hoc Networks: A Survey
Vehicular communication requires vehicles to self-organize through the
exchange of periodic beacons. Recent analysis on beaconing indicates that the
standards for beaconing restrict the desired performance of vehicular
applications. This situation can be attributed to the quality of the available
transmission medium, persistent change in the traffic situation and the
inability of standards to cope with application requirements. To this end, this
paper is motivated by the classifications and capability evaluations of
existing adaptive beaconing approaches. To begin with, we explore the anatomy
and the performance requirements of beaconing. Then, the beaconing design is
analyzed to introduce a design-based beaconing taxonomy. A survey of the
state-of-the-art is conducted with an emphasis on the salient features of the
beaconing approaches. We also evaluate the capabilities of beaconing approaches
using several key parameters. A comparison among beaconing approaches is
presented, which is based on the architectural and implementation
characteristics. The paper concludes by discussing open challenges in the
field
Survey on Congestion Detection and Control in Connected Vehicles
The dynamic nature of vehicular ad hoc network (VANET) induced by frequent
topology changes and node mobility, imposes critical challenges for vehicular
communications. Aggravated by the high volume of information dissemination
among vehicles over limited bandwidth, the topological dynamics of VANET causes
congestion in the communication channel, which is the primary cause of problems
such as message drop, delay, and degraded quality of service. To mitigate these
problems, congestion detection, and control techniques are needed to be
incorporated in a vehicular network. Congestion control approaches can be
either open-loop or closed loop based on pre-congestion or post congestion
strategies. We present a general architecture of vehicular communication in
urban and highway environment as well as a state-of-the-art survey of recent
congestion detection and control techniques. We also identify the drawbacks of
existing approaches and classify them according to different hierarchical
schemes. Through an extensive literature review, we recommend solution
approaches and future directions for handling congestion in vehicular
communications
Time division multiple access scheduling strategies for emerging vehicular ad hoc network medium access control protocols: a survey
[EN] Vehicular ad hoc network (VANET) is an emerging and promising technology, which allows vehicles while moving on the road to communicate and share resources. These resources are aimed at improving traffic safety and providing comfort to drivers and passengers. The resources use applications that have to meet high reliability and delay constraints. However, to implement these applications, VANET relies on medium access control (MAC) protocol. Many approaches have been proposed in the literature using time division multiple access (TDMA) scheme to enhance the efficiency of MAC protocol. Nevertheless, this technique has encountered some challenges including access and merging collisions due to inefficient time slot allocation strategy and hidden terminal problem. Despite several attempts to study this class of protocol, issues such as channel access and time slot scheduling strategy have not been given much attention. In this paper, we have relatively examined the most prominent TDMA MAC protocols which were proposed in the literature from 2010 to 2018. These protocols were classified based on scheduling strategy and the technique adopted. Also, we have comparatively analyzed them based on different parameters and performance metrics used. Finally, some open issues are presented for future deployment.Tambawal, AB.; Noor, RM.; Salleh, R.; Chembe, C.; Anisi, MH.; Michael, O.; Lloret, J. (2019). Time division multiple access scheduling strategies for emerging vehicular ad hoc network medium access control protocols: a survey. Telecommunication Systems. 70(4):595-616. https://doi.org/10.1007/s11235-018-00542-8S59561670
SDDV: scalable data dissemination in vehicular ad hoc networks
An important challenge in the domain of vehicular ad hoc networks (VANET) is the scalability of data dissemination. Under dense traffic conditions, the large number of communicating vehicles can easily result in a congested wireless channel. In that situation, delays and packet losses increase to a level where the VANET cannot be applied for road safety applications anymore. This paper introduces scalable data dissemination in vehicular ad hoc networks (SDDV), a holistic solution to this problem. It is composed of several techniques spread across the different layers of the protocol stack. Simulation results are presented that illustrate the severity of the scalability problem when applying common state-of-the-art techniques and parameters. Starting from such a baseline solution, optimization techniques are gradually added to SDDV until the scalability problem is entirely solved. Besides the performance evaluation based on simulations, the paper ends with an evaluation of the final SDDV configuration on real hardware. Experiments including 110 nodes are performed on the iMinds w-iLab.t wireless lab. The results of these experiments confirm the results obtained in the corresponding simulations
SCALABLE MULTI-HOP DATA DISSEMINATION IN VEHICULAR AD HOC NETWORKS
Vehicular Ad hoc Networks (VANETs) aim at improving road safety and travel comfort, by providing self-organizing environments to disseminate traffic data, without requiring fixed infrastructure or centralized administration. Since traffic data is of public interest and usually benefit a group of users rather than a specific individual, it is more appropriate to rely on broadcasting for data dissemination in VANETs. However, broadcasting under dense networks suffers from high percentage of data redundancy that wastes the limited radio channel bandwidth. Moreover, packet collisions may lead to the broadcast storm problem when large number of vehicles in the same vicinity rebroadcast nearly simultaneously. The broadcast storm problem is still challenging in the context of VANET, due to the rapid changes in the network topology, which are difficult to predict and manage. Existing solutions either do not scale well under high density scenarios, or require extra communication overhead to estimate traffic density, so as to manage data dissemination accordingly. In this dissertation, we specifically aim at providing an efficient solution for the broadcast storm problem in VANETs, in order to support different types of applications. A novel approach is developed to provide scalable broadcast without extra communication overhead, by relying on traffic regime estimation using speed data. We theoretically validate the utilization of speed instead of the density to estimate traffic flow. The results of simulating our approach under different density scenarios show its efficiency in providing scalable multi-hop data dissemination for VANETs
Cognitive radio network in vehicular ad hoc network (VANET): a survey
Cognitive radio network and vehicular ad hoc network (VANET) are recent emerging concepts in wireless networking. Cognitive radio network obtains knowledge of its operational geographical environment to manage sharing of spectrum between primary and secondary users, while VANET shares emergency safety messages among vehicles to ensure safety of users on the road. Cognitive radio network is employed in VANET to ensure the efficient use of spectrum, as well as to support VANET’s deployment. Random increase and decrease of spectrum users, unpredictable nature of VANET, high mobility, varying interference, security, packet scheduling, and priority assignment are the challenges encountered in a typical cognitive VANET environment. This paper provides survey and critical analysis on different challenges of cognitive radio VANET, with discussion on the open issues, challenges, and performance metrics for different cognitive radio VANET applications
Connectivity statistics of store-and-forward inter-vehicle communication
Inter-vehicle communication (IVC) enables vehicles to exchange messages
within a limited broadcast range and thus self-organize into dynamical
vehicular ad hoc networks. For the foreseeable future, however, a direct
connectivity between equipped vehicles in one direction is rarely possible. We
therefore investigate an alternative mode in which messages are stored by relay
vehicles traveling in the opposite direction, and forwarded to vehicles in the
original direction at a later time. The wireless communication consists of two
`transversal' message hops across driving directions. Since direct connectivity
for transversal hops and a successful message transmission to vehicles in the
destination region is only a matter of time, the quality of this IVC strategy
can be described in terms of the distribution function for the total
transmission time. Assuming a Poissonian distance distribution between equipped
vehicles, we derive analytical probability distributions for message
transmission times and related propagation speeds for a deterministic and a
stochastic model of the maximum range of direct communication. By means of
integrated microscopic simulations of communication and bi-directional traffic
flows, we validated the theoretical expectation for multi-lane roadways. We
found little deviation of the analytical result for multi-lane scenarios, but
significant deviations for a single-lane. This can be explained by vehicle
platooning. We demonstrate the efficiency of the transverse hopping mechanism
for a congestion-warning application in a microscopic traffic simulation
scenario. Messages are created on an event-driven basis by equipped vehicles
entering and leaving a traffic jam. This application is operative for
penetration levels as low as 1%
Grid-Based Multichannel Access in Vehicular Networks
In vehicular networks, vehicles exchange messages with each other as well as
infrastructure to prevent accidents or enhance driver's and passenger's
experience. In this paper, we propose a grid-based multichannel access scheme
to enhance the performance of a vehicular network. To determine the feasibility
of our scheme, we obtained preliminary results using the OPNET simulation tool
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