Mohamed Aissani

Ant-DSR: Cache Maintenance Based Routing Protocol for Mobile Ad-Hoc Networks

Dynamic source routing (DSR) is a reactive routing protocol designed for mobile ad-hoc networks. It is based on two mechanisms including route discovery and route maintenance. In highly dynamic networks, the surplus use of expired routes in the cache of DSR increases the latency and the frequent diffusion of route request packets consumes bandwidth. Consequently, DSR presents handicap in terms of end- to-end delay and overhead. In this paper, we propose a new routing protocol, called Ant-DSR, which implements a distributed topology discovery mechanism through mobile agents to maintain DSR cache. Implemented and simulated on ns-2, Ant-DSR shows a better resistance in high mobility and huge load environments in comparison to DSR.

Oriented Void Avoidance Scheme for Real-Time Routing Protocols in Wireless Sensor Networks

To avoid the negative impact of void areas on real-time routing efficiency, we propose in this paper an oriented void avoidance scheme for wireless sensor networks. To select the forwarding region around a void (either clockwise or anticlockwise), the proposed scheme is guided by the target location with respect to the center of the void. Our scheme uses the right-hand rule to discover boundary nodes of the void and geometric formulas to obtain the forwarding region of a sender node located at 1-hop near the void. This node reduces its set of forwarding candidate nodes according to its already obtained forwarding region. Proposed approach is simple to implement, economic and could incorporate various other optimizations studies. Simulation showed the importance of this module and gives better performance compared to traditional schemes.

A Preventive Rerouting Scheme for Avoiding Voids in Wireless Sensor Networks

We propose in this paper an efficient void-avoidance scheme based on a novel approach to prevent data packets from meeting boundaries of voids. In our approach, the choice of the forwarding region around a discovered void is based on the locations of the sender node, of the void center and of the destination node. The first stuck node which detects a void launches a void-discovery algorithm and communicates the void center to all nodes located n-hops away from the void boundary. These nodes will launch a preventive rerouting process, by selecting the appropriate forwarding region around the void, to forward each data packet before reaching the boundary nodes. Associated to the well-known real-time routing protocol SPEED, the proposed scheme provides good performance in terms of packet delivery ratio, end-to-end delay, communication energy consumption, and control overhead.

Optimizations and Performance Study of the Dynamic Source Routing Protocol

We have conducted a performance study of the DSR protocol, in particular, for scenarios where it presents poor performance compared to that of AODV protocol. We have also carried out two optimizations on DSR, namely: generalized salvaging mechanism and cache update of the intermediate nodes with source routes discovered during the route request packets propagation. Our routing protocol, called GSM-DSR (generalized salvaging mechanism for DSR), is compared with AODV and DSR, and performance results are presented in this paper. We show, through simulations, that the salvaging optimization and the cache update do lead to an improvement of DSR performance, particularly, in large scale networks with high mobility and heavy load.

A New Approach of Announcement and Avoiding Routing Voids in Wireless Sensor Networks

Communication voids (i.e. holes) have negative impact on real-time routing protocols. To decrease both routing distance and energy consumption in large-scale sensor networks for real time applications, we propose in this paper a novel routing mechanism to make data packets avoid meeting voids in advance. After discovering boundary nodes of a void, our mechanism calculates and announces the center of the void to all nodes inside a circular area around the void. A sender node inside the announce area, at n-hops far from the boundary nodes, uses this information to obtain the appropriate forwarding region and starts countering the void in advance. For that, the sender node selects its forwarding candidate neighbors according to its already obtained forwarding region. The proposed mechanism is fairly simple to implement and saves sensor network resources.

A Comprehensive Semantic Model for Smart Object Description and Request Resolution in the Internet of Things.

Abstract The Internet of Things is a natural continuity of the Ambient Intelligence where smart and ambient environments are built by integrating a large number of interconnected smart objects with heterogeneous capabilities abstracted as software services. The aim is to design cross-domain applications that compose and select most relevant services, which best match user requirements and closely meet the specified quality-of-service level. However, semantic description and representation of such smart devices, including their hosted services and their provided real world data, is still a challenging issue. Semantic Web technologies are seen as a promising tool for this purpose. Indeed, applying these technologies in the Internet of Things enables smart objects to efficiently share their data, exchange their services and cooperate to better satisfy both functional and non-functional user requirements. In this paper, we propose a new semantic model for smart objects description and users request resolution using ontological techniques combined with description logics. Such a model facilitates intelligent functions, including reasoning over service data and semantic interoperability enabling among devices. A case study for smart environment monitoring has been proposed to illustrate the effectiveness and usability of our approach.

An efficient real-time routing with presence of concave voids in wireless sensor networks

To bypass voids in sensor networks, most existing geographic routing protocols tend to route packets along the boundary nodes. Generally, a packet will be either forwarded along a void boundary by the right-hand rule or pushed back to find another route when it encounters the void. The two techniques consume more energy of boundary nodes, drop many packets and may incur data collisions if multiple communication sessions share the same boundary nodes. We propose in this paper an alternative and efficient void avoidance scheme. The proposed on-demand scheme consists of void discovery, void announce and packet rerouting steps. After discovering a void, a sender node inside the voids announce-area reroutes all data packets to get around the void in advance by selecting one appropriate forwarding side. The double objective of our scheme is to prevent data packets from traveling along the boundaries of voids and to avoid them the concave zones of voids. By achieving this objective we can reduce the energy consumption of boundary nodes and data collisions in these nodes. We can also reduce the packets rerouting overhead and the number of packets dropped by nodes on the boundaries of voids. Simulation showed the efficiency of our scheme.

Fault-Tolerant Prediction-Based Scheme for Target Tracking Application

Fault-Tolerance is an important function in target tracking application using wireless sensor networks. We propose in this paper, an efficient fault-tolerant approach for target tracking that prevents the loss of the target. Instead of using a single prediction mechanism, our approach uses a multi-level incremental prediction technique that adjusts the prediction precision of the target movement. The responsible node of target detection uses multiple historical information pieces to calculate multi-level predictions which have different precision levels according to the number of information pieces used. Thanks to our parametric prediction model, our approach increases the prediction success rate and decreases the target loss frequency compared to basic approaches that use simple prediction models.

Towards a New Framework for Service Composition in the Internet of Things

Internet of Things’ (IoT) services represent a great interest research topic for both academic and industrial communities due to their large application domains. New dynamic and automatic development approaches are created in order to improve their effectiveness based on service composition process. Indeed, they allow the aggregation of smart object’s services to meet complex requirements from various application areas. This paper provides an architecture that describes a framework for service composition in IoT. Moreover, it proposes a rule-based reasoner where several facts and rules (knowledge base) are inferred to satisfy user queries. This approach is designed and implemented using SysML and Prolog platform respectively. The use-cases scenario and extensive tests show clearly the interest, feasibility, and suitability of the rule-based system for service composition in the IoT.

Multi-agent System Based Service Composition in the Internet of Things

The Internet of Things’ (IoT) services offer an asset to improve IoT applications and their effectiveness in order to provide smartness to our environment. Academic and industrial actors are engaged to develop the IoT service composition paradigm. Indeed, it enables the aggregation of IoT services to satisfy complex supplies from several application domains. It can also be used to develop original IoT applications in an efficient, flexible and dynamic way. This paper proposes an approach for IoT service composition using a multi-agent system where several agents are engaged to satisfy the user’s request. Simple reflex agents represent services, links, and requests. However, goal-based agent stands for the reasoner of the proposed MAS. The SysML language and the Netlogo platform are used respectively to design and implement the proposed approach. The test scenarios show obviously the importance, practicability, and suitability of the multi-agent systems for the IoT application based on service composition.