Soumaya Cherkaoui

IEEE 802.11p modeling in NS-2

In an effort to develop a simulation framework for evaluating the performance of wireless access technologies for vehicular networks, the authors have studied the internal structure of the simulator, NS-2, as well as the draft wireless technology IEEE 802.11p. This intended framework aims at replicating, as far as possible, the access technology characteristics in the simulator and with the help of realistic scenarios intends to give an objective view of the performance of applications destined for intelligent transport systems. The framework is first designed to meet the requirements set for vehicle to infrastructure communications, with a view of later extending it to vehicle to vehicle communications for vehicular ad hoc networks.

Intelligent QoS management for multimedia services support in wireless mobile ad hoc networks

In this paper, we propose a new intelligent cross-layer QoS support for wireless mobile ad hoc networks. The solution, named FuzzyQoS, exploits fuzzy logic for improving traffic regulation and the control of congestion to support both real-time multimedia (audio/video) services and non-real-time traffic services. FuzzyQoS includes three contributions: (1) a fuzzy logic approach for best-effort traffic regulation (FuzzyQoS-1), (2) a new fuzzy Petri nets technique (FuzzyQoS-2) for modeling and analyzing the QoS decision making for traffic regulation control, and (3) a fuzzy logic approach for threshold buffer management (FuzzyQoS-3). In FuzzyQoS-1, the feedback delay information received from the network is used to perform a fuzzy regulation for best-effort traffic. Using fuzzy logic, FuzzyQoS-3 uses fuzzy thresholds to adapt to the dynamic conditions. The evaluation of FuzzyQoS performances was studied under different mobility, channel, and traffic conditions. The results of simulations confirm that a cross layer design using fuzzy logic at different levels can achieve low and stable end-to-end delay, and high throughput under different network conditions. These results will benefit delay- and jitter-sensitive real-time services.

Deterministic access for DSRC/802.11p vehicular safety communication

In this work, we present the design of an efficient Deterministic medium Access (DA) for Dedicated Short-Range Communication (DSRC) vehicular safety communication over IEEE 802.11p, called Vehicular DA (VDA). VDA supports two types of safety services (emergency and routine safety messages) with different priorities and strict requirements on delay, especially for emergency safety messages. VDA processes both types of safety messages to maintain a balance between two conflicting requirements: reducing chances of packets collisions and lowering the transmission delay. To avoid long delays and high packets collisions, VDA allows vehicles to access the wireless medium at selected times with a lower contention than would otherwise be possible within two-hop neighborhood by the classical 802.11p EDCA or DCF schemes. Particularly, our scheme provides an efficient adaptive adjustment of the Contention Free Period (CFP) duration to establish a priority between emergency and routine messages. Simulations show that the proposed scheme clearly outperforms the classical DCF scheme used by 802.11p in high-offered load conditions while bounding the transmission delay of safety messages.

Queuing model for EVs charging at public supply stations

As electric vehicles become more popular, public charging stations for such vehicles will become common. Since the load introduced by such stations on the grid is high, the smart grid will need to balance the load among charging stations in an area while minimizing the waiting time for users to have their vehicles charged. In this paper, we present an approach for balancing the load among charging stations in an area while minimizing the charging time of electric vehicles. We propose a model where vehicles communicate beforehand with the grid to convey information about their charging status, and develop a mathematical model of handling requests for charging vehicles at public charging station based on queuing theory. Finally, we propose an algorithm for directing vehicles to charging stations in a way to minimize their waiting time to charge completion. The simulation results show the effectiveness of the proposed approach when considering both real electric vehicle and charging station characteristics and constraints.

Implementing online feature interaction detection in SIP environment: early results

The article proposes a solution for detecting feature interactions (FI) at runtime in SIP-based IP telephony architectures. The solution takes into account the special context of SIP that permits end user programmability, which means the possibility for end users to design their own tailored services and personalize them as much as they like. Programmability implies that services are roomed and run in the end user devices. This renders more frequent the so called multi-component FI situations, where conflicting services reside in different network components. This type of FI is the more complicated one. The presented solution is handled by FIMA, a feature interaction management agent that is introduced as a central network manager. We focus on the implementation requirements of an online detection method. The proposed solution deals with multi-component FI situations as well as another FI situation type, called single-component.

RSU cloud and its resource management in support of enhanced vehicular applications

We propose Roadside Unit (RSU) Clouds as a novel way to offer non-safety application with QoS for VANETs. The architecture of RSU Clouds is delineated, and consists of traditional RSUs and specialized micro-datacenters and virtual machines (VMs) using Software Defined Networking (SDN). SDN offers the flexibility to migrate or replicate virtual services and reconfigure the data forwarding rules dynamically. However, frequent changes to service hosts and data flows not only result in degradation of services, but are also costly for service providers. In this paper, we use Mininet to analyze and formally quantify the reconfiguration overhead. Our unique RSU Cloud Resource Management (CRM) model jointly minimizes reconfiguration overhead, cost of service deployment and infrastructure routing delay. To the best of our knowledge, we are the first to utilize this approach. We compare the performance of purist approach to our Integer Linear Programming (ILP) model and our innovative heuristic for the CRM technique and discuss the results. We will show the benefits of a holistic approach in Cloud Resource Management with SDN.

Decision-Making Assistance in Engineering-Change Management Process

Effective engineering-change management (ECM) is a real challenge in mechanical engineering industry and manufacturing companies. Computer-aided design systems are usually connected to other systems such as ERP or product data management, but currently this integration does not provide effective means to manage engineering change (EC). While communication between multidisciplinary teams working on a project is known to have a significantly positive impact on the ECM, the communication between disciplines is generally performed solely through message exchange. Experts could feel the need to meet to agree on the requested changes, which in turn translates into longer design and manufacturing processes. There is a need for a system that assists human experts in making decisions about ECs. Such a system will considerably reduce the processing time following a change-request procedure. This paper proposes a collaborative tool named EchoMag, which assists designers and experts during the change-management process. The proposed system ensures the coherence of data between the various disciplines involved in the change process. EchoMag also assists experts in making decisions by proposing alternative solutions when change requests are not agreed upon. Software agents were used to implement EchoMag for which a prototype was developed. Results of the implementation are discussed.

Advanced mobility models for ad hoc network simulations

It is well known that mobility modeling plays an important role when assessing the performance of MANET protocols during a simulation test. This paper presents a tool to generate realistic mobility traces for MANET simulations. A new mobility model called AMADEOS was developed as an extension for the CANUMobisim framework. To model mobility for simulation environments, a new mobility model was created that takes into account obstacles. AMADEOS makes it easy and fast to automatically generate realistic mobility. It allows to edit spatial environments with polygonal obstacles to he used within simulations. It also allows to visualize an animation of the generated mobility traces. A new propagation model based on ray tracing was also implemented as part of AMADEOS.

Detecting faulty and malicious vehicles using rule-based communications data mining

The reliability of most safety applications that are based on vehicular communications, depends in turn on the reliability of data received by each vehicle from its neighbors. Routine messages exchanged in Vehicular Ad hoc Networks (VANETs) include crucial information for safety applications such as direction, position, etc. A vehicle failure and/or a malicious vehicle transmitting false information may affect the data collection scheme and cause a disturbance for safety applications. In such a scenario, (1) the faulty/malicious vehicle should be detected rapidly and (2) routine messages exchange should be updated in consequence. To be able to detect the faulty/malicious vehicle, we developed a mechanism that collects, at a single vehicle, data regarding each neighbour transmission, and extracts the temporal correlation rules between vehicles implicated in transmissions in the neighbourhood. With the mechanism, called VANETs Association Rules Mining (VARM), a mining process will take place during a-priori constant historical period. The associations rules formulated during the mining process will be used to detect a faulty or malicious vehicle, i.e., a vehicle which is not correlated with vehicles in the neighbourhood following these rules. To react after this kind of anomaly detection, an 1:N technique is used as a protection for reestablishing the accuracy of the data collection process between vehicles communicating in the neighbourhood. Simulation results demonstrate the efficiency of the VARM scheme.

Mobility management for highly mobile users and vehicular networks in heterogeneous environments

With the recent developments in wireless networks, different radio access technologies are used in different places depending on capacity in terms of throughput, cell size, scalability etc. In this context, mobile users, and in particular highly mobile users and vehicular networks, will see an increasing number and variety of wireless access points enabling Internet connectivity. Such a heterogeneous networking environment needs, however, an efficient mobility management scheme offering the best connection continuously. In this paper, a mobility management architecture focusing on efficient network selection and timely handling of vertical and horizontal hand-overs is proposed. The solution is based on Mobile IP where hand-over decisions are taken based upon calculations of a metric combining delay and delay jitter. For efficiency reasons, the frequency of binding updates is dynamically controlled, depending on speed and variations in the metric. The dynamic frequency of binding updates helps the timely discovery of congested access points and cell edges so as to allow efficient hand-overs that minimize packet drops and hand-over delays. Results show that the overall signaling cost is decreased and changes in networking conditions are detected earlier compared to standard Mobile IP.