Yacine Ghamri-Doudane

Towards Efficient Geographic Routing in Urban Vehicular Networks

Vehicular ad hoc networks (VANETs) have received considerable attention in recent times. Multihop data delivery between vehicles is an important aspect for the support of VANET-based applications. Although data dissemination and routing have extensively been addressed, many unique characteristics of VANETs, together with the diversity in promising applications, offer newer research challenges. This paper introduces the improved greedy traffic-aware routing protocol (GyTAR), which is an intersection-based geographical routing protocol that is capable of finding robust and optimal routes within urban environments. The main principle behind GyTAR is the dynamic and in-sequence selection of intersections through which data packets are forwarded to the destinations. The intersections are chosen considering parameters such as the remaining distance to the destination and the variation in vehicular traffic. Data forwarding between intersections in GyTAR adopts an improved greedy carry-and-forward mechanism. Evaluation of the proposed routing protocol shows significant performance improvement in comparison with other existing routing approaches. With the aid of extensive simulations, we also validate the optimality and sensitivity of significant GyTAR parameters.

An Improved Vehicular Ad Hoc Routing Protocol for City Environments

The fundamental component for the success of VANET (vehicular ad hoc networks) applications is routing since it must efficiently handle rapid topology changes and a fragmented network. Current MANET (mobile ad hoc networks) routing protocols fail to fully address these specific needs especially in a city environments (nodes distribution, constrained but high mobility patterns, signal transmissions blocked by obstacles, etc.). In our current work, we propose an inter-vehicle ad-hoc routing protocol called GyTAR (improved greedy traffic aware routing protocol) suitable for city environments. GyTAR consists of two modules: (i) dynamic selection of the junctions through which a packet must pass to reach its destination, and (ii) an improved greedy strategy used to forward packets between two junctions. In this paper, we give detailed description of our approach and present its added value compared to other existing vehicular routing protocols. Simulation results show significant performance improvement in terms of packet delivery ratio, end-to-end delay, and routing overhead.

On utility models for access network selection in wireless heterogeneous networks

ldquoAlways Best Connectedrdquo (ABC) is a fundamental and challenging dimension of the fourth generation heterogeneous wireless networks. In order to enable the ABC, access network selection is obviously the key issue. In this paper, we analyze, adapt and consolidate the utility theory to define an appropriate decision mechanism in the frame of the access network selection. A thorough study of the existing proposed utility models is carried out and the limits of these methods are highlighted. Subsequently, we propose new single-criterion and multi-criteria utility forms to best capture the user satisfaction and sensitivity facing up to a bundle of access network characteristics. Mathematical proofs and numerical analysis confirm the suitability and the effectiveness of our proposed models.

Terminal-Controlled Mobility Management in Heterogeneous Wireless Networks

The coexistence of multiple access technologies deployed by different operators is fundamental for future fourth-generation mobile networks. In spite of this heterogeneity, seamless interoperator/intersystem mobility is a mandatory requirement. In this article we present a seamless mobility management approach that does not require changes to existing network infrastructure. The novelty of the proposed approach is that mobility management is fully controlled by the terminal, and network selection is user-centric, power-saving, cost-aware, and performance-aware. Total mobility management, including interface management, handover decision, and execution, is also detailed

Software defined networking-based vehicular Adhoc Network with Fog Computing

Vehicular Adhoc Networks (VANETs) have been attracted a lot of research recent years. Although VANETs are deployed in reality offering several services, the current architecture has been facing many difficulties in deployment and management because of poor connectivity, less scalability, less flexibility and less intelligence. We propose a new VANET architecture called FSDN which combines two emergent computing and network paradigm Software Defined Networking (SDN) and Fog Computing as a prospective solution. SDN-based architecture provides flexibility, scalability, programmability and global knowledge while Fog Computing offers delay-sensitive and location-awareness services which could be satisfy the demands of future VANETs scenarios. We figure out all the SDN-based VANET components as well as their functionality in the system. We also consider the system basic operations in which Fog Computing are leveraged to support surveillance services by taking into account resource manager and Fog orchestration models. The proposed architecture could resolve the main challenges in VANETs by augmenting Vehicle-to-Vehicle (V2V), Vehicle-to-Infrastructure (V2I), Vehicle-to-Base Station communications and SDN centralized control while optimizing resources utility and reducing latency by integrating Fog Computing. Two use-cases for non-safety service (data streaming) and safety service (Lane-change assistance) are also presented to illustrate the benefits of our proposed architecture.

An Infrastructure-Free Traffic Information System for Vehicular Networks

Vehicular networks are the major ingredients of the envisioned Intelligent Transportation Systems (ITS) concept. An important component of ITS which is currently attracting wider research focus is road traffic information processing. This has widespread applications in the context of vehicular networks. The existing centralized approaches for traffic estimation are characterized by longer response times. They are also subject to higher processing requirements and possess high deployment costs. In this paper, we propose a completely distributed and infrastructure-free mechanism for road density estimation. The proposed solution is adaptive and scalable and targets city traffic environments. The approach is based on the distributed exchange and maintenance of traffic information between vehicles traversing the routes. The performance analysis of the proposed mechanism shows the accuracy of the algorithm for different traffic densities. It also gives insights into the promptness of information delivery in the mechanism based on delay analysis at road intersections. This promptness is a necessary condition to various applications requiring reliable decision making based on road traffic awareness.

A survey on fault tolerance in small and large scale wireless sensor networks

Fault tolerance is one of the most important wireless sensor networks requirements. It ensures that the network continues to function correctly even when some components fail. In fact, fault tolerance is a need in this type of networks due to sensor node characteristics, radio communications and hostile environments in which these networks are deployed. In this survey, we give an overview of WSN mechanisms that provide or improve the fault tolerance property of wireless sensor networks. However, the different solutions presented in this survey are not only intended to mechanisms dedicated to fault tolerance, but they also include all the mechanisms allowing the prevention of fault occurrence such as energy aware routing and data aggregation and compression. Besides the classification of fault tolerance mechanisms according to the tasks they target (data management, flow management), we also propose a new classification based on the network size, since the performance of the majority mechanisms depends on the size in terms of geographical area and number of nodes. Thus, a well performing protocol conceived for small networks may be inadequate for large networks and vice versa.

Designing scalable on-demand policy-based resource allocation in IP networks

Today, the policy-based management approach is recognized as an efficient solution to simplify the complex task of managing and controlling networks. To this end, the IETF has introduced a reference framework to build PBM systems. However, this framework only addresses the provisioning of relatively long validity period services based on pre-defined service level agreements. Furthermore, very little work addresses the scalability properties of the instantiation of this framework in a real network. This work aims to extend the IETF PBM framework in order to support dynamic provisioning of short term services (end system signaling) as well as an instantiation scheme that is scalable (distributed provisioning of edge routers). This instantiation scheme is based on the distribution of the provisioning process while keeping centralized only the parts that involve critical resources, that is, the bandwidth brokerage. The performance properties of the proposed scheme are then demonstrated throughout both extensive experimentation and a short analytical study. The results of this work are intended to be used as a guideline to help network operators to design scalable PBM system in order to offer to their customers services with QoS assurance in an on-demand basis.

A Cooperative Low Power Mac Protocol for Wireless Sensor Networks

Over the last decade cooperative communication in wireless sensor networks (WSN) received much attention. A lot of works have been done to propose a MAC layer that supports cooperative communication. However the impact of the association of a cooperative communication technique with a low power listening scheme was not studied in the literature. In this paper we propose CL-MAC, a Cooperative Low power mac protocol for WSNs. CL-MAC implements jointly Low Power Listening and cooperative communication. More precisely, we propose two variants of this protocol: a proactive version CL-MAC(P) and a reactive version CL-MAC(R). In order to evaluate the performances of the two proposed CL-MAC variants, we compare its to those of X-MAC. Simulation results proved that our protocol is able to enhance the use of the channel and to reach promising energy preservation especially in dense networks.

Joint routing and location-based service in VANETs

Geographic routing protocols use location information when they need to route packets. In the meantime, location information are maintained by location-based services provided by network nodes in a distributed manner. Routing and location services are very related but are used separately. Therefore, the overhead of the location-based service is not considered when we evaluate the geographic routing overhead. Our aim is to combine routing protocols with location-based services in order to reduce communication establishment latency and routing overhead. Our main contribution is to reduce the location overhead. Thus, we propose two combinations: (1) a geographic routing protocol with GLS called Hybrid Routing and Grid Location Service (HRGLS) and (2) a geographic routing protocol with HLS denoted Hybrid Routing and Hierarchical Location Service (HRHLS), where instead of launching an exact position request, we send the packet to the old destination position and when the packet is approaching the former position, we request the exact one. The complexity of the location query cost in both proposed schemes is O(logN), while it is O(N) in the case of HLS and GLS. Simulation results also confirm the complexity analysis and show promising results in terms of latency, packet delivery ratio and control message overhead.