Reducing congestion in obstructed highways with traffic data dissemination using adhoc vehicular networks

Vehicle-to-vehicle communications can be used effectively for intelligent transport systems (ITSs) and location-aware services. The ability to disseminate information in an ad hoc fashion allows pertinent information to propagate faster through a network. In the realm of ITS, the ability to spread warning information faster and further is of great advantage to receivers. In this paper we propose and present a message-dissemination procedure that uses vehicular wireless protocols to influence vehicular flow, reducing congestion in road networks. The computational experiments we present show how a car-following model and lane-change algorithm can be adapted to “react” to the reception of information. This model also illustrates the advantages of coupling together with vehicular flow modelling tools and network simulation tools

Performance Analysis of An Enhanced IEEE 802.11 Distributed Coordination Function Supporting Service Differentiation

As one of the fastest growing wireless access technologies, Wireless LANs (WLANs) must evolve to support adequate degrees of service differentiation. Unfortunately, current WLAN standards like IEEE 802.11 Distributed Coordination Function (DCF) lack this ability. Work is in progress to define an enhanced version capable of supporting QoS for multimedia traffic at the MAC layer. In this paper, we aim at gaining insight into two mechanisms to differentiate among traffic categories, i.e., scaling the minimum contention window size and the length of the packet payload according to the priority of each traffic flow. We propose an analysis model to compute the throughput and packet transmission delays. In additions, we derive approximations to get simpler but more meaningful relationships among different parameters. Comparisons with simulation results show that a very good accuracy of performance evaluation can be achieved by using the proposed analysis model