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The main goal of Cluster-based sensor networks is to decrease system delay and reduce energy consumption. LEACH is a cluster-based protocol for microsensor 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.

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The edge computing system attracts much more attention and is expected to satisfy ultra-low response time required by emerging IoT applications. Nevertheless, as there were problems on latency such as the emerging traffic requiring very sensitive delay, a new Edge Computing system architecture, namely Home Edge Computing (HEC) supporting these real-time applications has been proposed. HEC is a threelayer architecture made up of HEC servers, which are very close to users, Multi-access Edge Computing (MEC) servers and the central cloud. This paper proposes a solution to solve the problems of latency on HEC servers caused by their limited resources. The increase in the traffic rate creates a long queue on these servers, i.e., a raise in the processing time (delay) for requests. By leveraging, based on clustering and load balancing techniques, we propose a new technique called HEC-Clustering Balance. It allows us to distribute the requests hierarchically on the HEC clusters and another focus of the architecture to avoid congestion on a HEC server to reduce the latency. The results show that HEC-Clustering Balance is more efficient than baseline clustering and load balancing techniques. Thus, compared to the HEC architecture, we reduce the processing time on the HEC servers to 19% and 73% respectively on two experimental scenarios.

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Abstract-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.

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 whereInternet connection is highly disturbed or not existed. The presented solution uses transparent and automatic configuration for end user's PC or laptop. After the connection is restored, all offline activities will be synchronized to the principal Moodle platform.