Study on QoS support in 802.11e-based multi-hop vehicular wireless ad hoc networks

Multimedia communications over vehicular ad hoc networks (VANET) will play an important role in the future intelligent transport system (ITS). QoS support for VANET therefore becomes an essential problem. In this paper, we first study the QoS performance in multi-hop VANET by using the standard IEEE 802.11e EDCA MAC and our proposed triple-constraint QoS routing protocol, Delay-Reliability-Hop (DeReHQ). In particular, we evaluate the DeReHQ protocol together with EDCA in highway and urban areas. Simulation results show that end-to-end delay performance can sometimes be achieved when both 802.11e EDCA and DeReHQ extended AODV are used. However, further studies on cross-layer optimization for QoS support in multi-hop environment are required

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

A survey on pseudonym changing strategies for Vehicular Ad-Hoc Networks

The initial phase of the deployment of Vehicular Ad-Hoc Networks (VANETs) has begun and many research challenges still need to be addressed. Location privacy continues to be in the top of these challenges. Indeed, both of academia and industry agreed to apply the pseudonym changing approach as a solution to protect the location privacy of VANETs'users. However, due to the pseudonyms linking attack, a simple changing of pseudonym shown to be inefficient to provide the required protection. For this reason, many pseudonym changing strategies have been suggested to provide an effective pseudonym changing. Unfortunately, the development of an effective pseudonym changing strategy for VANETs is still an open issue. In this paper, we present a comprehensive survey and classification of pseudonym changing strategies. We then discuss and compare them with respect to some relevant criteria. Finally, we highlight some current researches, and open issues and give some future directions

VANET Based Four Way Road Intersection Traffic Light Control Model

Traffic lights are responsible in maintaining the smooth passage of traffic in urban scenario. To enhance the efficiency of traffic control system we are utilizing the concept of Vehicular Ad-hoc Network (VANET) along with our proposed VANET Based Four Way Road Intersection Traffic Light Control Model. The proposed model facilitates more number of vehicles to cross the intersection simultaneously; reduces the vehicles waiting time at intersection. The dynamic cycle traffic control provides an adaptive mechanism to adjust the timing behavior of traffic signal in accordance to traffic demand. Traffic density estimation and traffic density analysis are the two major phases of the proposed traffic signal control. The proposed system comprises of estimation of vehicle density in different lanes approaching the intersection. The density estimation is carried out using (V2I) Vehicle to Infrastructure and (V2V) Vehicle to Vehicle communication. Further the assessment and analysis of obtained data from the estimated density part is carried out by the traffic signal controller to adjust the traffic signal cycles in accordance with the traffic requirement such that unnecessary traffic waiting time can be minimized. The proposed model and proposed Green Light Allocation algorithm is evaluated against the existing static and dynamic cycle control system using Matlab. We found that our proposed system is giving better performance by allowing more traffic volume to cross through the intersection in each cycle. Also our proposed system is reducing the waiting time of vehicles at intersection by frequently switching the Green Light among the phases of same signal cycle