Wahabou Abdou

Priority levels based multi-hop broadcasting method for vehicular ad hoc networks

This paper deals with broadcasting problem in vehicular ad hoc networks (VANETs). This communication mode is commonly used for sending safety messages and traffic information. However, designing an efficient broadcasting protocol is hard to achieve since it has to take into account some parameters related to the network environment, for example, the network density, in order to avoid causing radio interferences. In this paper, we propose a novel Autonomic Dissemination Method (ADM) which delivers messages in accordance with given priority and density levels. The proposed approach is based on two steps: an offline optimization process and an adaptation to the network characteristics. The first step uses a genetic algorithm to find solutions that fit the network context. The second one relies on the Autonomic Computing paradigm. ADM allows each vehicle to dynamically adapt its broadcasting strategy not only with respect to the network density, but also in accordance to the priority level of the message to send. The experimental results show that ADM effectively uses the radio resources even when there are globally many messages to send simultaneously. Moreover, ADM allows to increase the message delivery ratio and to reduce the latency and radio interferences.

ViSiDiA: A Java Framework for Designing, Simulating, and Visualizing Distributed Algorithms

Simulation tools are useful for detailed analysis of distributed systems that are increasingly present in our daily lives. ViSiDiA (Visualization and Simulation of Distributed Algorithms) is a platform that aims both to facilitate teaching distributed algorithms and to contribute to the research activities. This paper presents design features and examples of how to implement new ViSiDiAs algorithms. These implementations can be done using the Java language or by using the ViSiDiAs GUI (just drawing the relabelling rules that correspond to considered algorithm). We also present a more complex problem for which ViSiDiA served as a simulation and analysis tool.

Broadcasting Information in Variably Dense Environment Using Connectionless Data Exchange (CoLDE)

Our main goal is to develop a new solution to use multi-tier broadcast in order to deliver messages to all the devices in certain areas, whether they are connected to different networks, or not connected to any network. We use beacons (management frames) in the IEEE 802.11 protocol to send data from the access point to the clients without an association, and we use the probe request/response to exchange small amounts of data without being connected to the same network and without threatening the security of any of them.

Adaptive-Segmentation and Flexible-Delay Based Broadcasting Protocol for VANETs

A Vehicular Ad hoc Network (VANET) is an interconnection of vehicles that communicate through wireless technologies. It offers to road users a wide variety of applications which can be classified into four main categories: safety, road traffic, comfort and infotainment. This paper deals with safety applications. Their main goal is to detect critical road conditions (e.g. accidents, black ice, etc.) and/or send notifications to other vehicles in the network. An effective dissemination of such a message relies on multi-hop retransmissions. Thus an explicit or implicit cooperation between vehicles is needed in order to relay the message over a wide area. The main challenge is to avoid the broadcast storm problem. This paper proposes an efficient segment-delay based method that divides the road into several segments depending on the network density and utilises a waiting time update technique to expedite the dissemination process with respect to network performance.

An autonomic message dissemination protocol for Vehicular Ad hoc Networks: a density and priority levels aware approach

AbstractThe broadcasting communication mode is widely used in Vehicular Ad hoc Networks. It is used for sending emergency messages, road-traffic information or to help routing protocols to determine routes. This communication mode is known to be hard to achieve efficiently since it depends on the network density. Indeed, broadcasting methods may cause network congestion if they are not well designed. This paper introduces a novel Autonomic Dissemination Method (ADM) which delivers messages in accordance with given message classes and network density levels. The proposed approach is based on two steps: an offline optimization process and an online adaptation to the network characteristics. ADM allows each node to dynamically adapt its broadcasting strategy not only with respect to the network density, but also according to the class of the message to send: emergency (high-priority), road-traffic (medium-priority) or either comfort message (low-priority). The ultimate goal of ADM is to make effective use of radio resources when there are many messages to send simultaneously. This approach increases the efficiency of the broadcast process in terms of message delivery ratio, latency and interferences reduction. The autonomic computing paradigm improves the robustness of protocols.

A novel multi-hop broadcasting method for VANETs based on autonomic computing paradigm

Broadcasting is widely used in Vehicular Ad hoc Networks (VANETs) but it is hard to achieve efficiently since it depends on the network density, i.e. may cause network congestion if the protocols are not well designed. This paper introduces a novel Autonomic Dissemination Method (ADM) which delivers messages in accordance with given priority and density levels. The proposed approach is based on two steps: an offline optimization process and an online adaptation to the network characteristics. The aim is to make effective use of radio resources when there are many messages to send simultaneously. ADM allows each node to dynamically adapt its broadcasting strategy not only with respect to the network density, but also according to the priority level of the message to send. This leads to increasing the efficiency of the broadcasting process in terms of message delivery ratio, latency and interference reduction.

Behaviour Study of an Evolutionary Design for Permutation Problems

This paper studies an evolutionary representation/crossover combination for permutation problems, which are met in many application fields. Many efficient methods exist to solve these various variants. Increasing performances of computers also permitted to tackle more complex instances. But real-life applications make new conjunctions of constraints appear every day. Then, searching new complementary ways to tackle efficiently these numerous constraints is still necessary. This paper focuses on such an approach. It deals with evolutionary algorithms, which have been already often used to solve permutation problems. It studies the behaviour of an evolutionary design, based on a Lehmer code representation coupled with a simple n-point crossover. The goal is not to propose a new problem-tailored method which provides good performances for solving a given variant of problem or for a given class of benchmarks. The paper uses various measures to study the transmission of properties from parents to children, and the behaviour in terms of exploitation and exploration. The paper gives a review on related works, illustrates the issues which remain quite ill-understood for this representation and also gives experimental results by comparison with the permutation encoding more classically used in the literature.

NICE-MRP: A near-optimal radio-interference aware multi-path routing protocol for MANETs

Nowadays, with the miniaturization of communication devices, dense and highly mobile ad-hoc networks are very common. Besides, more and more devices have several radio interfaces. In such an environment, multi-path routing should be considered. Yet, only few multi-path ad-hoc routing protocols take into account the radio-interferences which might arise between two geographically close routes. Moreover, they generally only forbid the addition of interfering paths rather than looking for a different, more optimized, solution. This paper presents NICE-MRP, a novel multi-path routing protocol for mobile ad-hoc networks giving efficient solutions with respect to physical radio-interferences between paths. This protocol discovers and stores several combinations of non-interfering multi-path routes. The best multi-path route is used to transmit data, whereas alternative multi-path routes are kept to dynamically react to route breakages due to mobility and node failures. Compared to other well-known protocols, NICE-MRP presents good qualities in terms of latency, overhead and packet losses. Besides, these results end to be rather independent from the degree of mobility.