Mohamed Shawky

Sybil Nodes Detection Based on Received Signal Strength Variations within VANET

A Vehicular Ad hoc Network is a collection of mobile hosts forming a temporary network without the aid of any established infrastructure. This flexibility in space and time induces new challenges towards the security needed to support secure communications. Indeed, VANET are subject to attacks due to their vulnerabilities; one of the most compromising attacks is the Sybil nodes attack. We present in this context a Sybil detection approach, based on received signal strength variations, allowing a node to verify the authenticity of other communicating nodes, ac- cording to their localizations. In addition, we define an estimated metric of the distinguishability degree between two nodes, allowing to determine Sybil and malicious ones within VANET. The applicability of our contributions is validated through geometrical analysis, simulations and real measurements.

Conditional Transmissions: Performance Study of a New Communication Strategy in VANET

Many solutions have been developed for routing messages in ad hoc networks. However, few of them are efficient when the network is highly dynamic. Indeed, building a routing table, discovering and maintaining a route, or localizing a node is a great challenge when the dynamic is high. This topic is currently attracting attention with vehicular ad hoc networks (VANETs), which are a special case of highly dynamic networks. VANET may allow us to enhance road safety and to develop new driver-or passenger-oriented services. In this paper, we present a novel approach for routing in highly dynamic networks, relying on condition-based communication. Instead of transporting addresses (or positions), a message is sent with some conditions used for retransmission or reception. Owing to the dynamic evaluation of the conditions, we show that this solution can efficiently support the high dynamic of vehicular networks.

IEEE 802.11 performances for inter-vehicle communication networks

The growth of wireless local area networks based on the IEEE 802.11 standard these last years represents a practical network solution offering mobility, flexibility and low cost deployment. This encourages the use of this protocol for new nomadic applications. Among such applications, wireless inter-vehicle networks could improve road security and offer new driving services. In this paper, we are interested by the performances of IEEE 802.11 protocol in networks with strong mobility like vehicle networks. Through simulations of vehicles convoys, we discuss the assessment of such protocol for large-scale vehicle-to-vehicle communications.

On the congestion control within VANET

The basic objective of congestion control is to best exploit the available network resources while preventing sustained overloads of network nodes and links. Appropriate congestion control mechanisms are essential to maintain the efficient operation of a network. Ensuring congestion control within vehicular ad hoc networks address special challenges, due to the characteristic and specificities of such environment (High dynamic and mobility of nodes, high rate of topology changes, high variability in nodes density and neighborhood, broadcast/geocast communication nature ...). In this context, we present in this paper a congestion control approach, based on the concept of dynamic priorities-based scheduling, to ensure a reliable and safe communications architecture within VANET. Messages priorities are dynamically evaluated according to their types, the network context and the neighborhood.

A cooperative congestion control approach within VANETs: formal verification and performance evaluation

The main objective of congestion control is to best exploit the available network resources while preventing sustained overloads of network nodes and links. Appropriate congestion control mechanisms are essential to provide effcient operation of a network. Ensuring congestion control within vehicular ad hoc networks faces special challenges, due to the specificities of such environment (High mobility of nodes, high rate of topology changes, high variability in nodes density and neighborhood configuration, broadcast/geocast communication nature, etc.). In this context, we present in this paper a cooperative and fully distributed congestion control approach, based on dynamic scheduling and transmission of priority-based messages, to ensure reliable and safe communication architecture within VANET. Messages priorities are dynamically evaluated according to their types, the network context, and the neighboring nodes configuration. Considering the context of high reliability and real-time response required for intervehicular communications (including emergency breaking notification for example), we propose a complete validation method of our congestion control algorithms, taking into account reliability, temporal, and operational aspects.

A cooperative and fully-distributed congestion control approach within VANETs

Appropriate congestion control mechanisms are essential to maintain the efficient operation of a network. Ensuring congestion control within vehicular ad hoc networks address special challenges, due to the characteristic and specificities of such environment (High dynamic and mobility of nodes, high rate of topology changes, high variability in nodes density and neighborhood, broadcast/geocast communication nature …). In this context, we present in this paper a cooperative and fully distributed congestion control approach, based on the concept of dynamic priorities-based scheduling and transmission, to ensure a reliable and safe communications architecture within VANET. The real applicability of our congestion control approach is validated through its formal verification and performance evaluation.

Using dynamic task level redundancy for OpenMP fault tolerance

Obtaining fault tolerant applications and systems is one of todays most important topics of research. Fault tolerance is becoming more and more essential in shared memory parallel programs and in multi/many core architectures due to the decreasing size of transistors and growing number of failures. Very few research works and techniques for fault tolerant OpenMP programs were studied. These few works are based on checkpoint and recovery, and on static thread level redundancy techniques. However, these approaches may illustrate scalability issues when the number of cores increases or when an unbalanced workload exists. To overcome these issues, we present in this paper a dynamic task level redundancy technique for fault tolerant OpenMP applications. Our method is based on dynamically applying a Triple Modular Redundancy for OpenMP tasks through a dedicated runtime and on applying a majority voting to guarantee correct results. Our flexible fault tolerant OpenMP approach has been evaluated for performance and fault coverage and it showed small overhead with good error detection and recovery rate.

Conditional transmissions, a strategy for highly dynamic vehicular ad hoc networks

Many solutions have been developed for routing messages in ad hoc networks. However, few of them are efficient when the network is highly dynamic. Indeed, when the dynamicity is high, building a routing table, discovering and maintaining a route or localizing a node is a great challenge. This topic is currently attracting attention with vehicular ad hoc networks (VANET), a special case of highly dynamic networks. VANET may allow to enhance road safety, and to develop new driver or passengers oriented services. In this paper we present a novel approach for routing in highly dynamic networks, relying on conditions-based communication. Instead of transporting addresses (or positions), a message is sent with some conditions used for retransmission or reception. Thanks to the dynamic evaluation of the conditions, we show that this solution can efficiently support the high dynamic of vehicular networks. We also analyze the performances of OLSR, Fast OLSR, AODV, and GAMER on several traffic road scenarios.

Dynamic reconfiguration for high level in-vehicle applications using IEEE-1394

In recent years, networking issues have become more and more important in the design of vehicle control systems and driver assistance functions. We present a pragmatic approach for validating real-time in-vehicle applications using IEEE-1394 bus. By validation, we mean the verification of real-time constraints that is met by the automotive applications. We describe how the IEEE-1394 standard can respond to hard real-time constraints of critical and non-critical applications. We then present a software architecture based on distributed calculators interconnected by IEEE-1394 bus and well adapted for integrating multi-sensors automotive applications.

CO-SImulation Trace Analysis (COSITA) tool for vehicle electronic architecture diagnosability analysis

In this paper we present a CO-SImulation Trace Analysis (COSITA) tool in order to analyze functional/architectural properties, in the automotive field. These properties should enhance a specific design requirement that we call functional/architectural diagnosability. The validation process is applied on a real automotive experimental embedded platform called DIAFORE based on several Electronic Control Units.