Rolland Vida

Adaptive sink mobility in event-driven multi-hop wireless sensor networks

Optimizing energy consumption in wireless sensor networks is of paramount importance. There is a recent trend to deal with this problem by introducing mobile elements (sensors or sink nodes) in the network. The majority of these approaches assume time-driven scenarios and/or single-hop communication between participating nodes. However, there are several real-life applications for which an event-based and multi-hop operation is more appropriate. In this paper we propose to adaptively move the sink node inside the covered region, according to the evolution of current events, so as to minimize the energy consumption incurred by the multi-hop transmission of the event-related data. Both analytical and simulation results are given for two optimization strategies: minimizing the overall energy consumption, and minimizing the maximum load on a specific sensor respectively. We show that by adaptively moving the sink, significant power saving can be achieved, prolonging the lifetime of the network.

Multi-hop wireless sensor networks with mobile sink

Energy efficiency is a very important goal in wireless sensor networks. In order to achieve it, many recent solutions use mobile sinks that move either randomly or along a predefined path. In this paper we propose an adaptive mobility solution; the sink moves inside the sensor network according to the current events, so as to minimize the energy consumption incurred by the multi-hop transmission of the event-related data.

Energy Efficiency in Wireless Sensor Networks Using Mobile Base Station

A sensor network consists of a large number of small, low-cost devices with sensing, processing and transmitting capabilities. The sensor nodes have limited battery power; therefore energy efficiency is a critical design issue. In this paper we propose to move the sink node, called Base Station (BS) so as to decrease the energy consumption of the whole network. We present two possible strategies to move the BS: the first one minimizes the average consumed energy, while the other one minimizes the maximum transmission energy for every active sensor. To evaluate the performance of the two strategies, we compare these with the case, when the BS is deployed in a fixed position. Simulation results show that the proposed processes can reduce energy consumption, thereby significantly extending the lifetime of the entire sensor network.

Techniques to improve scheduling performance in IEEE 802.15.3 based ad hoc networks

In this paper we propose new techniques to improve scheduling performance in time-slotted superframe based ad hoc networks. Such channel access technology is used in the IEEE 802.15.3 and 802.15.4 standards. Building on the performance analysis of previous proposals, we enhance the scheduling algorithms with flow state signaling and burst eligibility decision, so as to exploit the features of the 802.15.3 architecture. We show by simulation that the scheduling algorithms extended with these special mechanisms achieve higher performance, with better channel utilization and lower power consumption

Host Identity Specific Multicast

Multicasting is a key technology for both users and service providers as it enables important bandwidth savings, and thus lower costs, for content distribution and group communication. The current network level multicast solutions have several weaknesses. These issues are partly related to a problem embedded in the use of the IP addresses themselves. Currently an IP address is both an identifier of who I am and where I am. The host identity concept tries to solve this problem by introducing a new, unique identifier, the Host Identity Tag. This concept was used, up until now, mainly for unicast communications. In this paper we propose thus the host identity specific multicast (HISM) model; we present the architectural elements of the model, and show how it handles access control, mobility, and how it provides native network layer multicast support in mixed, IPv4-IPv6 environments.

Wireless Sensor Network Based Technologies for Critical Infrastructure Systems

This chapter presents an overview on how wireless sensor networks (WSN) can be used in critical infrastructure systems (CIS). First, the architecture of a typical sensor node is presented, and it is shown how these nodes can be grouped to form a network. Then, the requirements of a traditional WSN (such as low complexity, energy efficiency, scalability, or self-organization) are given, and those special requirements are highlighted that are characteristic to CIS: reliability, availability, real-time operations, security, etc. Currently available sensing and communication technologies that best fit these special requirements are also given. In the second part of the chapter some specific use cases are described: WSN for water system monitoring, electric power system monitoring, and nuclear reactor monitoring.

Event signature extraction and traffic modeling in WSNs

Motivated by earlier work on adaptive event forecasting, this paper proposes an iterative event signature extraction method for wireless sensor networks, and a probabilistic approach to model non i.i.d. (independent and identically distributed) aperiodic traffic. The model is validated on well described (collection included) real world measurements of various types, and it is then used to demonstrate the effectiveness of the proposed signature extraction method to support reliable event forecasting.Our scheme can continuously keep the event signature database low on artifacts, dynamically estimate the number of sequences and extract the signatures from noisy, overlapped events.The proposed solution is inspired by unsupervised competitive Hebbian learning used in self-organizing Kohonen maps. We evaluate the proposed solution analytically, but also empirically, by means of simulations.

Adaptive Event Forecasting in Wireless Sensor Networks

Since the emergence of the earliest wireless sensor networks (WSNs), a great deal of effort has been made to support target tracking applications. Although target tracking, or other services such as dynamic sleep scheduling or early warning systems require some level of event forecasting, there was little research on this topic, in spite of its importance. In this paper we formalize a framework for event forecasting based on fuzzy logic and propose an adaptive and scalable algorithm to predict events in the network. Moreover, for each forecast our solution provides a bounded confidence level based on learned time-space fuzzy signatures (TSS). We evaluate the proposed method by means of simulations and provide parameter sensitivity analysis as well.

RESERV: A Distributed, Load Balanced Information System for Grid Applications

Resource information systems are a key component of Computational Grids. Centralized information systems hamper scalability and reliability, and thus, completely distributed resource information systems, based on Distributed Hash Tables have been proposed. In some cases resource distribution might be highly uneven, load balancing of data becomes thus a crucial problem. However, current load balancing schemes cannot handle large amounts of data corresponding to a single resource type. In this paper we propose therefore RESERV, a distributed information system for Grid applications with a novel load balancing approach, able to handle extreme load unbalance.

GCAP: A New Multimedia Multicast Architecture for QoS

Despite its obvious suitability for distributed multimedia applications, multicasting has not yet found widespread application. Having analyzed shortcomings of todays approaches, we devise in the GCAP project a new endto-end transport architecture for multimedia multicasting that supports partial order and partial reliability. In this paper, we argue that, at the network layer, single-source multicasting (PIM-SSM) should be chosen. Consequently, our Monomedia Multicast protocol provides, along with reliability and QoS monitoring functionality, an ALM based multicast solution referred to as TBCP (Tree Building Control Protocol), to be used as back channel for SSM, e.g. for retransmission requests. On top of the Monomedia protocol, our Multimedia Multicast protocol handles multimedia sessions composed of multiple monomedia connections: The FPTP (Fully Programmable Transport Protocol) allows applications to specify, through its API, the (global) synchronization and (individual) reliability requirements within a multimedia session. Our group management approach is focused on group integrity.