Ibrahima Niang

A Deterministic Key Management Scheme for Securing Cluster-Based Sensors Networks

The main goal of Cluster-based sensor networks is to decrease system delay and reduce energy consumption. LEACH is a cluster-based protocol for micro sensor networks which achieves energy-efficient, scalable routing and fair media access for sensor nodes. However, the election of a malicious or compromised sensor node as the cluster head is one the most significant breaches in cluster-based wireless sensor networks. We propose a deterministic key management scheme, called DKS-LEACH, to secure LEACH protocol against malicious attacks. Our contributions are twofold. Firstly, we design and performed a theoretical evaluation of our security model which secures the setup and study phases of LEACH protocol. Secondly, using the TOSSIM simulator, we performed an evaluation of the power consumption of DKS-LEACH. The results indicate clear advantages of our approach in preventing the election of untrustworthy cluster head as well different kind of attacks from malicious sensor nodes.

An optimized and power savings protocol for mobility energy-aware in wireless sensor networks

Mobility management in Wireless Sensor Networks (WSNs) is a complex problem that must be taken into account in all layers of the protocol stack. But this mobility becomes very challenging at the MAC level in order to do not degrade the energy efficiency between sensor nodes that are in communication. However, among medium access protocols, sampling protocols reflect better the dynamics of such scenarios. Nevertheless, the main problem, of such protocols, remains the management of collisions and idle listening between nodes. Previous approaches like B-MAC and X-MAC, based on sampling protocols present some shortcomings. Therefore, we address the mobility issue of WSNs that use as medium access sampling protocols.Firstly, we propose a mobile access solution based on the X-MAC protocol which remains a reference protocol. This protocol, called MoX-MAC, incorporates different mechanisms that enables to mitigate the energy consumption of mobile sensor nodes. Furthermore, we extend our former work (Ba et al. in Proc. of IEEE WMNC, 2011) by evaluating the lifetime of static nodes with respect to MoX-MAC protocol, as well determine the degree of depletion of static nodes due to the presence of mobile nodes.

Automatic discovery of topologies and addressing for Linear wireless sensors networks

Wireless sensor networks are a collection of sensor nodes that collaborate to sense a specific event in a given environment. When sensors monitor a structure organized linearly (e.g., pipelines, rivers, railways), they are organized in Linear WSN (LWSN, constituted by connected portions of lines), with different properties than a uniformly deployed WSN. The distributed address allocation in the ZigBee cluster-tree suffers from limitations in LWSN: the number of children is limited, as well as the maximum number of children routers, and the maximum tree depth. Stochastic address assignment, also available in ZigBee, has a high cost in exchanged messages and requires an expensive (in terms of messages and memory) routing process. This paper proposes an automatic discovery of topologies for linear wireless sensor networks combined with an efficient addressing mechanism. We show that our proposition avoids the waste of addresses while keeping the number of messages exchanged proportional to the number of nodes in the network.

Self-stabilizing k-hops clustering algorithm for wireless ad hoc networks

Most Ad Hoc networks use communications based on diffusion that are typically expensive and may cause network saturation. In order to optimize these communications, one approach is to structure networks into clusters. In this paper, we present a self-stabilizing asynchronous distributed algorithm that builds non-overlapping k-hops clusters. Our approach does not require any initialization. It is based only on information from neighboring nodes with periodic messages exchange. Starting from an arbitrary configuration, the network converges to a stable state after a finite number of steps. We prove that the stabilization is reached after at most n + 2 transitions and uses at most n * log(2n + k + 3) memory space, where n is the number of network nodes. Using the OMNeT++ simulator, we performed an evaluation of the proposed algorithm.

Fast Scalar Multiplication on Elliptic Curve Cryptography in Selected Intervals Suitable for Wireless Sensor Networks

In Wireless Sensor Networks (WSNs), providing a robust security mechanism with limited energy resources is very challenging because of sensor node’s limited resources. Symmetric-key can fulfill the requirement, but if the number of nodes is large, asymmetric-key cryptography is the best natural method because of its scalability. Asymmetric-key cryptography is power-hungry; nevertheless, Elliptic Curve Cryptosystems (ECC) are feasible and more flexible for sensor nodes. Scalar multiplication is the most widely used operation on ECC. Various methods for fast scalar multiplication are based on the binary/ternary representation of the scalar. In this paper, we present a novel technique to make fast scalar multiplication on ECC over prime field for light-weight embedded devices like sensor nodes. Our method significantly reduces the computation of scalar multiplication by an equivalent representation of points based on point order in a given interval. Since our technique can act as a support for most existing methods, after an analytical and efficiency analysis, we implement and evaluate its performance in different scenarios.

Enhancing Moodle for offline learning in a degraded connectivity environment

In developing countries, higher education is an essential vehicle of the development process. Learning Management Systems (LMS) have emerged from an auxiliary role to a critical one in higher education. In short, ICT development, telecommunication infrastructures and Internet have a strong impact in the education sector especially with the advent of distance learning that is becoming more important. More and more academic institutions are moving to eLearning today and Moodle is one of the most popular LMS with several currently active sites. However, in Moodle, learners must be connected online all time they need to do eLearning activities. Moreover, the introduction of distance learning in developing countries is done with a set of constraints such as connection costs, power cuts and permanent Internet connectivity failure in some areas. This paper presents an enhanced solution for running Moodle in offline mode to improve asynchronous learning. This solution allows learners to continue eLearning activities in cases where Internet connection is highly disturbed or not existed. The presented solution uses transparent and automatic configuration for end users PC or laptop. After the connection is restored, all offline activities will be synchronized to the principal Moodle platform. This paper presents an enhanced solution for running Moodle in offline mode to improve asynchronous learning. This solution allows learners to continue eLearning activities in cases where Internet connection is highly disturbed or not existed. The presented solution uses transparent and automatic configuration for end users PC or laptop. After the connection is restored, all offline activities will be synchronized to the principal Moodle platform.

WebRTC platform proposition as a support to the educational system of universities in a limited Internet connection context

This paper proposes a collaborative system based on WebRTC technology to improve digital universities e-Learning environment. It allows teachers and students, through a web browser, to communicate via chat, audio and camera. It also supports file transfer and screen sharing for computer connected lab equipment. All these features are functional in an IP environment without need for Internet access. For its design and realization, we had to implement a WebRTC signalisation server to manage real-time applications, using the three WebRTC APIs: MediaStream for the acquisition and synchronization of audio and video, Peer Connection for communication between users browsers and RTCDataChannel for file transfer, Chat and Screen Sharing.

Using a token approach for the MAC layer of linear sensor networks: Impact of the node position on the packet delivery

Wireless sensor networks (WSNs) consist of a large number of sensor nodes which communicate via wireless links for monitoring applications. In several applications, such as the monitoring of pipelines or roads, the network topology is linear. This type of WSN is called linear sensor network (LSN). Our goal is to improve the behavior of a MAC protocol for LSNs, by using a token approach. As usual, the possession of the token grants the node permission to transmit on the medium during a given amount of time. The payload of the token is used to propagate network parameters such as delay between tokens, sleep and wakeup calendar. In this paper, we study the behavior of this MAC protocol and we evaluate the impact of the node position on the packet delivery for two types of LSNs.

Mobile learning, a solution to vocational training in Senegal

This article focuses on the issue of the use of mobile technologies, especially on online Laboratories, as a support to professional development of adults in the work situation in Senegal. More specifically, how mobile learning can be a solution to access to education for nomadic professionals working specifically in the area of computer networks? This issue is at the heart of a doctoral research underway in the context of the creation of the Senegalese Virtual University (SVU) primarily to adequately solve the problem of mass enrollment in university.

Energy optimization based on the redundancy in WSNs

Almost all WSNs (Wireless Sensor Networks) are deployed with some redundancy degree and redundancy is used only for robustness objectives. If not handled in an intelligent way, redundancy results in energy wasting because of (often unnecessary) redundant transmission and reception operations. We propose to take benefit from measurement redundancy to optimize the energy consumption and improve the end-to-end delay. We propose MR-LEACH (Measurement Redundancy aware LEACH) protocol, which is an extension to the well-known LEACH protocol to improve energy consumption in cluster-based WSNs. In addition to cluster formation according to LEACH protocol redundant nodes are grouped taking into account their redundancy and only a single node transmits data in each redundant group. This technique significantly improves the energy consumption and ensures a better end-to-end delay. Through intensive simulations, we discuss the performance of our approach and show how it outperforms the original LEACH protocol in terms of network lifetime and end-to-end delay.