Multi-directional Warning Message Dissemination Protocol Based on Motion Vector Clustering for VANETs

Problem. Most broadcast suppression protocols in vehicular ad hoc networks (VANET) mainly focus on one-dimensional message dissemination model for both highway and urban scenarios. Due to the non-line-of-sight (NLOS) problem occuring frequently in urban scenario, protocols mostly rely on either infrastructure or the vehicle that is passing through the intersection to forward the message in multiple directions manner. However, these one-dimensional message dissemination models fail to take into account realistic road topologies and traffic distribution. As a result, they tend to miss some possible dissemination directions. Method. Vehicles travelling on the same road share similar motion pattern due to the constraint of road topology. Each motion pattern represents a road topology as well as a potential dissemination direction. By identifying motion pattern of one-hop neighbors, the proposed motion vector protocol (MVP) enables a vehicle not only to identify potential dissemination directions without the support from infrastructure or a road map but also to make suppression decisions without any additional information from periodic beacons. Results. The total number of transmissions for simple flooding (each node broadcasts once) compared with MVP ranges respectively as follows: 90.2-269.7 and 40.6-72.3. Also, the number of saved rebroadcasts for simple flooding compared with MVP ranges respectively as follows: 0%-0% and 57%-73%. In the case of reachability, the simple flooding compared with MVP ranges 100%-100% and 100%-100% respectively. Finally, the average latency of the entire dissemination for simple flooding and MVP ranges 0.01446-0.01286s and 0.1127-0.1565s respectively. Conclusions. The experimental results show that MVP achieves high reachability, while still significantly reducing rebroadcast redundancy. One distinctive feature of MVP is that it is capable of operating on complex road topology such as a roundabout, curve road, branch road, etc., with multi-directional traffic in it

Comments and corrections to ’dominating sets and neighbor elimination-based broadcasting algorithms in wireless networks

Abstract—Our paper [1] generated a lot of interest among researchers in ad hoc networks. A number of researchers questioned, through their articles, or directly to the first author, the correctness of the described procedure, and the correctness of the claim that the procedure does not need any communication exchange between nodes, in addition to “hello ” messages needed to learn information about neighboring nodes. This correspondence completes the article by providing the actual dominating set definitions used in the procedure (from which zero communication overhead follows easily), the correct procedure (the published one has few misprints at key places), and the proof that the new definitions and procedure indeed define connected dominating sets. Index Terms—Broadcasting, ad hoc networks, dominating sets.

Minimum Energy Broadcast in Duty Cycled Wireless Sensor Networks

We study the problem of finding a minimum energy broadcast tree in duty cycled wireless sensor networks. In such networks, every node has a wakeup schedule and is awake and ready to receive packets or transmit in certain time slots during the schedule and asleep during the rest of the schedule. We assume that a forwarding node needs to stay awake to forward a packet to the next hop neighbor until the neighbor is awake. The minimum energy broadcast tree minimizes the number of additional time units that nodes have to stay awake in order to accomplish broadcast. We show that finding the minimum energy broadcast tree is NP-hard. We give two algorithms for finding energy-efficient broadcast trees in such networks. We performed extensive simulations to study the performance of these algorithms and compare them with previously proposed algorithms. Our results show that our algorithms exhibit the best performance in terms of average number of additional time units a node needs to be awake, as well as in terms of the smallest number of highly loaded nodes, while being competitive with previous algorithms in terms of the total number of transmissions and delay

Dynamic wireless mobile framework for distributed collaborative real-time information generation and control systems

Intelligent Transportation Systems (ITS) have only recently discovered the exciting possibilities in the nomadic and ubiquitous computing space to build a new generation of information systems by allowing the vehicle to act both as a carrier and consumer of wireless (and thus omnipresent) information. Wide deployment of such ITS systems may eventually allow for more dynamic and efficient transportation systems, which can contribute in several ways towards greater economic growth whilst respecting environmental sustainability. A great number of researchers have dedicated considerable time and resources to tackling traffic related issues by utilising the new wireless capabilities enabled by ITS; such initiatives cover a wide range of applications such as safety, knowledge sharing and infotainment. Indicative of the extent of such efforts is the plethora of research projects initiated by many national and multi-national organisations such as the EU Framework Programme for Research and Technological Development. To achieve their goals, proposed solutions from such organisations depend on the development and deployment of intelligent wireless mobile communication systems, where data dissemination issues make the prospect of efficient and effective communication a challenging proposition. Presently, Car-to-Car and Car-to-Infrastructure communications are two distinct avenues that make possible efficient and reliable delivery of messages via direct radio links in traffic areas. In all cases, high quality of communication performance is desirable for a communication system composed mostly of roaming participants; such a system needs to be dynamic, flexible and infrastructure-less. Consequently, Mobile Ad hoc Network (MANET)-based networks are a natural fit to ITS