Wassef Louati

Distributed Hash table-based routing and data management in wireless sensor networks: a survey

Recent advances in Wireless Sensor Networks (WSN) have led to a great breakthrough in sensors design and features. These technological novelties have brought additional challenges to WSN. Sensornets are seeking for new approaches for efficient data routing and management. The last few years have witnessed the emergence of several approaches that build Distributed Hash Tables (DHTs) over WSN. DHTs are initially conceived for efficient data lookup in large-scale wired networks. The main objective of this combination is to manage location-independent data and nodes identification. DHT mapping over WSN brings however new challenges. This paper presents an analytical survey on applying DHT techniques in WSNs. It describes existing DHT-based routing and data management protocols and includes a detailed classification of them.

Energy-aware Virtual Ring Routing in Wireless Sensor Networks

Virtual Ring Routing (VRR) is an ad-hoc routing protocol that avoids flooding the network. It uses location independent identifiers for packet routing. However, VRR does not take into consideration the amount of energy in nodes, leading to the failure of several nodes in the network. To resolve this problem, we have adopted a hierarchical Distributed Hash Table in the VRR architecture. In the resulting architecture, the energy powerful sensors are responsible for most message traffic. Weak sensors are then utilized less frequently than powerful sensors. The experimental results show that Coral-based VRR consumes less energy than VRR and extends the network lifetime.

SPSD: A Scalable P2P-based Service Discovery Architecture

A peer-to-peer (P2P)-based service discovery architecture for large-scale networks is presented. Services and queries are described using XML with descriptions mapped to numeric keys that preserve expressiveness. The architecture relies on a trie-based data structure built on top of a distributed hash table (DHT) to perform key-based routing of descriptions in service resolvers. Performance analysis and evaluation results collected from an emulation of the system show that the architecture is scalable, efficient and capable of load balancing for both service distribution and query resolution.

CLEVER: Cluster-based Energy-aware Virtual Ring Routing in randomly deployed wireless sensor networks

Energy-aware routing is an important remedy to face the quick failure of energy-constrained nodes in Wireless Sensor Networks. Network clustering with electing energy-powerful nodes as cluster heads is a perfect solution. However, such clustering requires ideal nodes placement to afford best performances. Manual nodes placement is not always possible, the sensors can be randomly deployed. In such networks, the cluster heads cannot always communicate directly. In this paper, we present a novel clustering strategy for randomly deployed heterogeneous sensors, in which a cluster is defined as a set of energy-powerful nodes placed at the range of each other. The proposed protocol, called CLEVER (Cluster-based Energy-aware Virtual Ring Routing), uses virtual identity-based routing for intra and inter-cluster communications. The experimental results show that CLEVER increases drastically the network lifetime and optimizes efficiently sensors energy.

The optimal transmitting power in randomly deployed heterogeneous Wireless Sensor Networks for predetermined average node degree

Radio communications are the most important sources of energy consumption in Wireless Sensor Networks (WSN). Optimizing the sensors transmitting power with keeping the required nodes average degree preserves significantly the sensors energy. In this paper, we analyze the optimal transmitting power needed by each sensor to reach a given average node degree in heterogeneous WSN. The problem that we aim solving in this paper is the following: given a set of heterogeneous sensors having various capabilities: weak nodes and strong nodes that are scattered randomly in a field according to a Poisson Point Process with densities λ1 and λ2 respectively. What is the optimal transmitting power needed by each sensor to ensure k-average degree? We investigate also a related problem: What has the most important effect on weak nodes transmitting power: The quantity of the strong nodes or their quality in terms of energy supply? Our analytical study has been validated with Monte-Carlo simulations.

Consistent and efficient bootstrapping ring-based protocol in randomly deployed wireless sensor networks

Ring-based protocols in Wireless Sensor Networks are facing a major challenge on their bootstrapping phase since at the end of this step, all the nodes should be placed into one global consistent ring. Existing bootstrapping ring-based protocols form initially multiple consistent rings and propose solutions to heal these rings into a global consistent one. Our proposed solution avoids the formation of separated rings and forms directly one global consistent ring by orchestrating the nodes joining process and avoiding concurrent joining. Simulation results show that our approach ensures network stabilization in a short time and without consuming a lot of energy.

Personal Overlay Networks Management Using a P2P-based Publish/Subscribe Naming System

The personal network (PN) concept extends the personal area network (PAN) by including remote personal nodes, such as nodes at home or in the office. This extension is achieved through dynamic tunnels established between the remote PN entities. Scalability presents a major challenge for tunnel management in PNs due to their dynamic nature and the increasing number of simultaneously supported PNs. To reduce the PN management complexity, this paper proposes to use a peer-to-peer-based publish/subscribe naming (PPNS) system. The PPNS system enables an automated provisioning of the location information in the tunnel endpoints. A centralised management approach is proposed for the on-demand PN establishment and a distributed management approach is proposed for the always-on PN establishment.

A P2P-Based Middleware for Wide-Area Service Discovery

Several service discovery protocols are deployed in local-area networks allowing users to be informed about the services in their vicinities. However, these local-area discovery protocols are incapable of exposing the services to remote users. This paper proposes a P2P-based naming system to ensure wide-area service discovery for communications between devices and services often remotely located. The naming system enables the transparency of the discovery protocols by defining a unified naming scheme for services in wide-area environments. The naming system has a scalable P2P architecture and integrates a notification service which informs subscribers about the services and their mobility. As an application use case, this work extends UPnP, a local-area and plug-and-play service discovery protocol, to a wide-area service discovery system using the proposed P2P-based middleware.

Energy-Aware Distributed Hash Table-Based Bootstrapping Protocol for Randomly Deployed Heterogeneous Wireless Sensor Networks

Distributed Hash Table (DHT)-based protocols having the structure of a ring, are promotive solutions to randomly deployed location unaware Wireless Sensor Networks (WSN). These protocols are able to ensure routing and data management efficiently and independently from any location information. However, their bootstrapping phase is challenging since each node should be well positioned into a global virtual ring at the same time. Simultaneous nodes joining leads to multiple inconsistencies. Moreover, existing DHT-based bootstrapping protocols do not take into account nodes heterogeneity whereas most of WSN are nowadays heterogeneous. In this paper, we propose an energy-aware bootstrapping protocol that not only organizes directly the nodes into a global consistent virtual ring but also allows it to build an energy efficient backbone for routing and data management. Simulation results show that our bootstrapping protocol improves drastically the DHT-based routing protocol performance and extends the network lifetime.

Towards a semantic-driven and scalable publish/subscribe framework

Heterogeneous networks, including personal, home and collaborative enterprise networks are aimed at interconnecting diverse communities of users. In the case of large communities of mobile, distributed and collaborating users sharing their multimedia content, scalable and semantic approaches are needed to facilitate the efficient publication and discovery of data. In this work, we propose an approach aimed at efficiently providing the required functionalities for dynamically managing the resources and the multimedia content of interconnected home networks, as well as providing the required community sharing capabilities. Our solution consists in combining the benefits of both ontologies and peer-to-peer approaches, by taking advantage of the semantic capabilities of ontologies at local domain level and the scalable P2P solutions at inter-domains level. Our proposed framework is founded on a new architecture based on peer-to-peer event-based communication system and using mainly a home box entity based on a global multimedia ontology. This domain ontology allows publishers and subscribers to use a common semantic space to characterise production and consumption of resources and services. Our approach can also be applied for similar large interconnected systems scenarios such as topic discovery with JNDI and service exchange with UDDI.