Sami Tabbane

SEAD: A simple and efficient adaptive data dissemination protocol in vehicular ad-hoc networks

Abstract Vehicular ad-hoc network (VANET) is becoming a promising technology for improving the efficiency and the safety of intelligent transportation systems by deploying a wide variety of applications. Smart vehicles are expected to continuously exchange a huge amount of data either through safety or non-safety messages dedicated for road safety or infotainment and passenger comfort applications, respectively. One of the main challenges posed by the study of VANET is the data dissemination design by which messages have to be efficiently disseminated in a high vehicular speed, intermittent connectivity, and highly dynamic topology. In particular, broadcast mechanism should guarantee fast and reliable data delivery within a limited wireless bandwidth in order to fit the real time applications’ requirements. In this work, we propose a simple and efficient adaptive data dissemination protocol called “SEAD”. On the one hand, the originality of this work lies in its simplicity and efficiency regardless the application’s type. Simplicity is achieved through a beaconless strategy adopted to take into account the surrounding vehicles’ density. Thanks to a metric locally measured, each vehicle is able to dynamically define an appropriate probability of rebroadcast to mitigate the broadcast storm problem. Efficiency is manifested by reducing excessive retransmitted messages and hence promoting the network capacity and the transmission delay. The simulation results show that the proposed protocol offers very low packet drop ratio and network load while still maintaining a low end-to-end delay and a high packet delivery. On the other hand, SEAD protocol presents a robust data dissemination mechanism which is suitable either for safety applications or for other kinds of application. This mechanism is able to adapt the protocol performance in terms of packet delivery ratio to the application’s requirements.

Forensic investigation in Mobile Cloud environment

Cloud computing is changing the way we use mobile application by offering a powerful, scalable and on-demand computational resources to mobile users. However, this new paradigm is a challenging issue for forensic investigators since it combines two different environments. The adoption of Mobile Cloud computing solutions is increasing rapidly, so it is necessary for digital investigation applications and procedure to be adapted to this new environment. This paper provides an overview of mobile cloud forensics including challenging issues and some existing proposals in order to overcome these challenges.

Air interface dimensioning techniques for coverage and capacity-limited HSPA based networks

Dimensioning and planning air interface of the evolution of UMTS networks based on HSPA technique is interesting for mobile operators. This paper deals with coverage-limited and capacity-limited dimensioning of HSPA based Beyond 3G networks with the necessary analytical support. The models established for coverage-limited case are exploited to generate abacuses useful mainly for initial dimensioning. The capacity-limited dimensioning case is also studied through different methods based on scheduling techniques. We suggest enhancing “Fair Throughput” scheduling technique to improve coverage and capacity dimensioning performance. Finally, we assess performance of the different introduced methods for HSPA dimensioning by comparing them to basic UMTS (Release 99) dimensioning.

Energy consumption comparison for mobile video streaming encryption algorithm

Video streaming services over the Internet are being widely used in mobile networks. Currently, service providers are relying more and more on securing data transferred between the service provider, namely the video streaming server, and the end user. However, securing video content includes at least the use of video encryption algorithm requiring processing and memory capabilities, provoking more delay and energy consumption. In any other context, energy consumption may not be a very important issue, but when using a mobile device, it will certainly become one. In this paper, we are dressing a comparison between different symmetric encryption algorithms, in terms of energy consumption, while decrypting and viewing a video stream on mobile device.

ICPN: An Inter-Cloud Polymorphic Network Proposal

Inter-Cloud virtual machine (VM) migration is of great interest today to fulfill the applications’ and services’ requirements for ubiquitous resources availability anywhere and on-demand. But to migrate large volume operating systems, we will need huge network resources trough the best-effort underlying Internet. To deal with this impractical requirement, we have chosen the pre-copy migration strategy. We have proven, however, that we still need a high bandwidth for the beginning of the migration process and a low latency link for the final downtime phase. As a solution, we propose an Inter-Cloud Polymorphic Network (ICPN) design combining packet and circuit switching paradigms to meet the conflicting migrations’ network requirements. To ensure the migration transparency, we propose an admission control strategy based on the VMware vMotion downtime delay value.

Mixed positioning system guaranteeing the continuity of indoor/outdoor tracking

Global Positioning System (GPS) or Global Navigation Satellite System (GNSS) are not always the best positioning systems, particularly in indoor environments. This explains the emergence of other indoor positioning systems, such as Wireless Fidelity (Wi-Fi). This latter is based on the trilateration technique to determine the position of an object through reference points. To optimize the outdoor as indoor localization, the system integrates three different systems GPS, Wi-Fi and the Simultaneous Localization And Mapping (SLAM), using a coefficient of confidence that can qualify the accuracy and the quality of the positioning data. The idea comes from relay race sport where each player passes the baton to the nearest player of the same team. In our case, it is the transition from the outside positioning system to the inside one. The solution enables to switch from a system to another without producing a sudden “jumping” and creates a “unified environment” between the three systems.

Optimized dimensioning methods for HSPA based Beyond 3G mobile networks

Planning and dimensioning air interface of the evolution of UMTS networks based on HSPA techniques is crucial for mobile operators. The objective of this paper is to present simple and accurate planning models and methodologies integrating advanced aspects for the new standardized RF evolved HSPA Beyond 3G techniques. We suggest and compare three dimensioning methods for HSPA based UMTS networks using different scheduling techniques. Analytical detailed modelling support is given for the introduced methods. We also extend “Fair Throughput” scheduling technique to enhance dimensioning performance. The last one is evaluated and it is shown to improve cell size and capacity by outperforming other suggested methods based on classical scheduling techniques.

Joint mode selection and power allocation for better traffic offloading in D2D communications

Device-to-Device (D2D) technology underlying the cellular network is an attractive solution for future generation network to increase cellular traffic offloading. When two devices are close enough, D2D communication allows a direct communication between them without the mediation of the cellular base station. However, since D2D communication shares the same uplink cellular network radio resource, D2D communication mode selection remains challenging to limit the mutual interference between D2D and cellular links. In this paper, a new D2D mode selection scheme based on a new criterion is proposed aiming at maximizing the cellular traffic offload while respecting the quality of service of cellular users. More precisely, we introduce a noise rise parameter which takes into account the cellular link distance, the D2D link distance, and user’s required throughput. The D2D links are admitted under the constraint of a certain noise rise threshold. To further enhance the achieved throughput of D2D users while respecting the overall interference level in the network, a new power control algorithm is also proposed. Simulation results show that our proposed mode selection scheme provides a tradeoff between traffic offloading and the overall radio capacity in the network. They also prove that the D2D communication mode is more attractive at the cell edge and when D2D users are close enough to each other. In addition, we show the effectiveness of our proposed power control scheme as compared to both static and Rate-Adaptive Water Filling power allocation schemes.

A secure data storage based on revocation game-theoretic approaches in cloud computing environments

Cloud computing is an innovative model that is gaining attention and wide popularity among IT professionals and users. It provides a new mode of use of IT resources by offering everything as a service (storage, servers, network, etc.) and provisioning resources on-demand. In cloud computing environments, users outsource their data to distributed data centers in the cloud and entrust cloud providers with its storage and processing. However, data outsourcing and multi-tenants introduce new security issues that have to be addressed. In fact, being stored externally, data are no longer under the control of their owners. The storage and processing mechanisms may not be fully trustworthy and thus data confidentiality and privacy may be at risk. Therefore, in this paper, we will deal with securing stored data in shared cloud computing environment. First, we will present an overview of the main security issues addressed in the literature. Then we will focus on providing a game-theoretic model to secure the stored data from malicious users. To that purpose, we have proposed a sequential revocation game where cloud users have to choose the best strategy from a set of three strategies in order to revoke and eliminate the malicious user while minimizing their costs. At the end, we will discuss the different outcomes of this game using the subgame perfect Nash equilibrium concept.

Network Coding scheme behavior in a Vehicle-to-Vehicle safety message dissemination

Message dissemination is considered as a challenging task in Vehicular Ad-hoc network (VANET). In particular, safety messages, such as, road accident warning, traffic congestion warning, etc., are the most critical messages type that need to be efficiently transmitted in a wireless and mobile network where the topology changes dynamically. Many protocols have been proposed for the sake of disseminating information with a high data reachability and a low end-to-end delay in a limited bandwidth. In this work, we focus on a new trend of dissemination protocols based on the “Network Coding” (NC) scheme. Precisely, we intent to study the NC gain toward safety message dissemination and deduce its suitability in accordance to such application requirements. To this end, three NC-based protocols are proposed for the aim at thoroughly studying the impact of such technique on the safety message dissemination performance. The gain of NC scheme is studied under different traffic densities (from low to high dense network). The simulation results show that NC could be an efficient solution to overcome the intermittent connectivity in sparse network mainly for comfort applications but not suitable for safety message dissemination, especially in high dense network, since it may introduce a high transmission delay.