Patrick Sondi

Design guidelines for quality of service support in Optimized Link State Routing-based mobile ad hoc networks

The proposals for quality of service in mobile ad hoc networks have focused on adding QoS mechanisms in best-effort routing protocols while keeping the same assumptions regarding both the network representation and the routing protocol design. Most of the solutions concentrate the algorithmic effort on QoS route computation and relax the constraint of optimizing flooding, which has, however, a great impact on resource consumption. The goal of this paper is to present guidelines that allow the design of efficient solutions accurately presented and easily comparable with each other. We first define the QoS metric as an abstraction that can be instantiated for any kind of metric, and we propose a MANET representation that integrates this abstraction into the definition of the network graph and properties. Using these concepts, while flooding optimization and QoS-aware MPR selection have usually been performed separately, we then propose a formalism that unifies MPR selection in such a way that both objectives are achieved simultaneously in a single selection. Finally, we propose a heuristic that provides an efficient solution for this problem while allowing us to control the trade-off between both objectives. Evaluations carried out on network graphs considering different spatial distributions of nodes show that our heuristic outperforms existing heuristics.

Performance Evaluation of Multimedia Applications over an OLSR-Based Mobile Ad Hoc Network Using OPNET

Mobile ad hoc network architecture allows cheap and easy deployment of network services almost anywhere and at anytime. Besides Internet access which is a best-effort service, multimedia applications are the most requested. They usually impose stringent quality of service constraints in terms of metrics including bandwidth, end-to-end delay, jitter and loss rate. In this paper, we evaluate the performance of a QoS extension of the OLSR protocol on voice communication using the OPNET simulator. The network model can represent various locations like railway stations, Campus University or traffic jam. We describe the performance end users involved in voice communication session can expect, even in presence of other traffics, like file transfer between other users in the same network.

Voice communication over mobile ad hoc networks: evaluation of a QoS extension of OLSR using OPNET

Works on voice communication over mobile ad hoc networks essentially rely on routing protocols that were originally proposed for best-effort services. However, best-effort routing is not adapted to voice communication due to real-time and quality of service constraints. In order to enable the Optimized Link State Routing (OLSR) to fulfill these constraints, we propose a QoS extension model of OLSR. This model is then evaluated using the OPNET simulator. Besides confirmation of the fact that end-to-end delay, and jitter constraints of voice applications are fulfilled, the simulation results show an improvement of the packets delivery ratio in comparison with native OLSR.

Mobile Ad Hoc Network-based Monitoring of Battlefields or Rescue Operations in Urban Scenarios

The use of satellites allows monitoring of mobile units with high precision in open environments like deserts. But when rescue operations or battles occur in urban context, humans and vehicles may go across or inside buildings, hence impeding satellite-based monitoring. In that case, a good solution for an accurate monitoring is to mount cameras on all mobile units involved in the operation. The images taken can be collected using a Mobile Ad Hoc Network (MANET) connecting all units. These data can be either sent immediately to the headquarter using long range communication or backed up on some of the mobile units for deferred processing. In this paper, we first describe an application that allows real-time and accurate images or video reconstitution of the area covered by the mobile units. The urban area, the mobile units and the application are modeled using the tools provided by the OPNET modeler. Then, we illustrate the deployment of this application on a 50-nodes MANET where the routing protocol is an extension of the Optimized Link State Routing (OLSR). Finally, we present the performance of the application evaluated by simulation on the MANET described previously.

Efficient Selection of Multipoint Relays in Wireless Ad Hoc Networks with Realistic Physical Layer

Much of the schemes for Multipoint Relay (MPR) selection in wireless ad hoc networks have been studied using the unit graph model, under the assumption that packets are always received without any error. As this model does not reflect the real scenario of transmissions, recent studies propose heuristics which enable selecting MPR under realistic assumptions. For this, they use redundancy to maximize the probability of delivery. But redundancy can increase the size of the MPR set, and therefore generating amounts of retransmissions and collisions, which can lead to degradation of the MPR protocol performance. Using reversible marking, a mechanism we presented in a previous study, we propose two heuristics which efficiently compute MPR. One of them resorts to redundancy and both compute a MPR set which size is at most log mgreater than the optimum.

Chain-Branch-Leaf: A clustering scheme for vehicular networks using only V2V communications

Abstract The development of vehicular networks leads to a plethora of new applications that are already becoming essential to the drivers and to cooperative vehicles. One important condition to the continuity of these new services is the existence of an ubiquitous network access, which cannot be completely guaranteed. In this context, developing reliable ad hoc vehicle-to-vehicle communications is a good alternative that also becomes mandatory. This work proposes a clustering scheme that combines the information on road configuration, vehicle mobility and link quality in order to build a structure similar to a vehicular network infrastructure, while relying only on the vehicles. This clustering scheme can be integrated into any reactive, proactive, or geographic ad hoc routing protocol in order to optimize the flooding of messages and simplify routing operations. The evaluations realized through simulation show that the proposed clustering scheme allows creating and maintaining a stable backbone during a significant time. Moreover, the simulation results show that the proposed clustering scheme reduces significantly the impact of broadcast traffic flooding in comparison with well-established techniques such as multipoint relaying, to mention few.

Toward a Honeypot Solution for Proactive Security in Vehicular Ad Hoc Networks

Vehicular Ad Hoc Network (VANET) is an application of the general concept of Mobile Ad hoc Network (MANET) in the transportation domain. Playing a key-role in Intelligent Transportation Systems (ITS), VANETs are vulnerable to threats that may jeopardize the in-vehicle security, thus subsequently causing accidents. Moreover, on looking at the connected car paradigm that enables interaction between both in-vehicle services as well as devices, and services with outside ones, VANETs will have to inherit security risks of conventional information technologies (IT) systems. This makes it necessary to resort to approaches providing supports and services that are capable to tackle the resulting wide range of security risks. Many works have been dedicated to VANETs security. Mostly the focus has been on data security, relying on cryptographic centric tools in order to ensure privacy, anonymity, and data security. Contrary to this, we propose an approach that aims to proactively address issues beyond data security that could hinder VANETs to become a reality if not properly faced. Although inspired by honeypots used in wired networks, it differs because of the need for tools and methods that should be sufficiently efficient and flexible to ensure context-awareness of security measures.

Generating Test Scenarios Based on Real-World Traces for ERTMS Telecommunication Subsystem Evaluation

The European Rail Traffic Management System (ERTMS) allows increasing the utilization of the track by using a wireless mobile technology, the GSM-R, for dynamic signaling and control of the trains. However, the GSM-R will become the bottleneck regarding the performance of the ERTMS due to the increase of both the trains’ traffic, and the resources needed by all the applications that contribute to safety in rail transportation and to satisfaction of the users. In this context, it is necessary to develop the tools that will allow evaluating the impact on the GSM-R of the scenarios that could occur, but that are costly or difficult to test on real tracks. In this paper, we propose an approach that consists in using real-world traces of trains moving on ERTMS lines to build specific scenarios for evaluating the ERTMS telecommunication subsystem. In this way, we are able to guarantee that these evaluations are very realistic due to the fact that the train moves following the functional specification of ERTMS. Moreover, our approach is particularly interesting for the future of ERTMS since the same scenarios can be used to evaluate other prospective wireless mobile technologies that could replace the GSM-R, such as LTE.

Using Real-World Car Traffic Dataset in Vehicular Ad Hoc Network Performance Evaluation

Vehicular ad hoc networking is an emerging paradigm which is gaining much interest with the development of new topics such as the connected vehicle, the autonomous vehicle, and also new high-speed mobile communication technologies such as 802.11p and LTE-D. This paper presents a brief review of different mobility models used for evaluating performance of routing protocols and applications designed for vehicular ad hoc networks. Particularly, it describes how accurate mobility traces can be built from a real-world car traffic dataset that embeds the main characteristics affecting vehicle-to-vehicle communications. An effective use of the proposed mobility models is illustrated in various road traffic conditions involving communicating vehicles equipped with 802.11p. This study shows that such dataset actually contains additional information that cannot completely be obtained with other analytical or simulated mobility models, while impacting the results of performance evaluation in vehicular ad hoc networks. Keywords—MOCoPo dataset; mobility models; vehicular ad hoc networks; simulation; performance evaluation

Performance evaluation of AODV, DSR, GRP and OLSR for VANET with real-world trajectories

Vehicular communications can be achieved through the infrastructure (Vehicle-to-infrastructure network, V2I), as well as directly through vehicle-to-vehicle communication (V2V) via ad hoc networks. In V2V communications, the routing protocols are designed in order to optimize the dissemination of messages. This paper presents an evaluation of routing protocols such as the Optimized Link State Routing (OLSR), Ad hoc On-demand Distance Vector (AODV), Dynamic Source Routing (DSR), and Geographic Routing Protocol (GRP), while considering both vehicular safety application requirements and mobility models based on real-world traces of vehicular traffic. The results show that, though proactive routing protocols perform better in this context, the four routing protocols fail to fulfill the safety application requirements on the delay metric even for a reasonable number of vehicles.