Emanuele Goldoni

Experimental analysis of RSSI-based indoor localization with IEEE 802.15.4

This paper presents a comparison between some of the most used ranging localization methods based on the Received Signal Strength Indicator (RSSI) in low-power IEEE 802.15.4 wireless sensor networks. In particular, the Trilateration, the Min-Max and the Maximum-Likelihood algorithms have been compared using only a limited number of reference nodes. In order to perform an exhaustive comparison we carried out tests in an indoor environment: dozens of RSSI values for every estimation have been gathered and cleaned from outliers values. Our results show that it is possible to some extent to obtain positioning information from nodes equipped with IEEE 802.15.4 radio modules, given the position and the number of reference nodes.

End-to-end available bandwidth estimation tools, an experimental comparison

The available bandwidth of a network path impacts the performance of many applications, such as VoIP calls, video streaming and P2P content distribution systems. Several tools for bandwidth estimation have been proposed in the last years but there is still uncertainty in their accuracy and efficiency under different network conditions. Although a number of experimental evaluations have been carried out in order to compare some of these methods, a comprehensive evaluation of all the existing active tools for available bandwidth estimation is still missing. This article introduces an empirical comparison of most of the active estimation tools actually implemented and freely available nowadays. Abing, ASSOLO, DietTopp, IGI, pathChirp, Pathload, PTR, Spruce and Yaz have been compared in a controlled environment and in presence of different sources of cross-traffic. The performance of each tool has been investigated in terms of accuracy, time and traffic injected into the network to perform an estimation.

Monitoring heritage buildings and artworks with Wireless Sensor Networks

Environmental monitoring is a crucial activity for preserving frescoes, historical structures, paintings, and artworks hosted both in exhibitions and storage rooms. Wireless Sensor Networks (WSNs) offer an unique opportunity for a pervasive and continuous tracking of microclimate conditions in historical buildings, where frescoed walls often refrain the deployment of data cables and electrical wires. Moreover, rising real-time alarms when environmental conditions are out of range, a WSN can have an active role in protecting and preserving the cultural heritage. To this aim, a new sensor network for indoor environmental monitoring has been developed in cooperation with the Soprintendenza per i Beni Storici Artistici ed Etnoantropologici per le province di Mantova, Brescia e Cremona and the proposed system has been deployed within the Alcova room of the Ducal Palace, Mantua. This article describes the main features of the developed monitoring system, as well as the results obtained from the testbed and the problems that need to be addressed when deploying a network within historical structures.

Real-time voice streaming over IEEE 802.15.4

Audio and video applications over wireless sensor networks have recently emerged as a promising research field. However, the limits in terms of communication bandwidth and transmission power have withstood the design of low-power embedded nodes for voice communication. In this work we describe the implementation details of an embedded system for the wireless broadcasting of audio signals over the low datarate IEEE 802.15.4 standard, which is widely adopted to build Wireless Personal and Sensor Networks. The resulting device has been developed from scratch by combining several techniques with the goal of obtaining the most suitable implementation on a low-cost and low-power 16-bit microcontroller. We used a realtime operating system, a well-known psychoacoustic model based on FFT signal decomposition and the Haar wavelet transform to create a novel audio compression algorithm targeted to embedded systems with limited computational capabilities. The result is a fully-functional embedded system which is able to stream voice in real-time over IEEE 802.15.4 with an acceptable audio quality.

REnvDB, a RESTful Database for Pervasive Environmental Wireless Sensor Networks

Every application of a Wireless Sensor Network (WSN) requires the data collected from sensor nodes to be reachable from the outside, in order to allow its processing and to obtain information from the monitored phenomena. Environmental protection and agriculture are examples of areas most likely to benefit from the deployment of WSNs. Devices equipped with temperature, humidity and light sensors could play a role in preserving the environment by providing early alerts and useful status information in real-time. Since such networks usually provide a huge amount of raw data, an easy way to organize, store and retrieve useful information is also needed. In this work we present REnvDB (RESTful Environmental DataBase), a novel database for Wireless Sensor Networks specifically designed for pervasive monitoring applications. The data model of the database is flexible enough to fulfill the requirements of most of the typical environmental monitoring systems. We also provided the database a RESTful interface, which can be used to expose the data collected by heterogeneous WSNs using the standard protocols of the World Wide Web. Thanks to its modular design and the use of metadata, the behavior of our RESTful interface can also be easily extended or modified according to the requirements and constraints of a specific context. Finally, the entire system has been implemented and tested in a real environment as part of a bigger project for the monitoring of an intensive agricultural field.

An Open Architecture for Distributed Malware Collection and Analysis

Honeynets have become an important tool for researchers and network operators. However, the lack of a unified honeynet data model has impeded their effectiveness, resulting in multiple unrelated data sources, each with its own proprietary access method and format. Moreover, the deployment and management of a honeynet is a time-consuming activity and the interpretation of collected data is far from trivial. HIVE (Honeynet Infrastructure in Virtualized Environment) is a novel highly scalable automated data collection and analysis architecture we designed. Our infrastructure is based on top of proven FLOSS (Free, Libre and Open Source) solutions, which have been extended and integrated with new tools we developed. We use virtualization to ease honeypot management and deployment, combining both high-interaction and low-interaction sensors in a common infrastructure. We also address the need for rapid comprehension and detailed data analysis by harnessing the power of a relational database system, which provides centralized storage and access to the collected data while ensuring its constant integrity. This chapter presents our malware data collection architecture, offering some insight in the structure and benefits of a distributed virtualized honeynet and its development. Finally, we present some techniques for the active monitoring of centralized botnets we integrated in HIVE, which allow us to track the menaces evolution and timely deploy effective countermeasures.

Wireless Passive Sensors for Remote Sensing of Temperature on Aerospace Platforms

This paper is devoted to the feasibility study of a wireless sensing system, mainly based on passive surface acoustic wave sensors, for remote measurement of temperature aboard space platforms. The use of passive sensors is particularly attractive since they need no battery and are robust in extreme environments, as they contain no active electronic circuits. The main objective of this paper is the complete characterization of the wireless system environment, in order to determine the main fundamental limits of this technology from a communication theory point of view. Preliminary experimental measurements are used for defining the main environment parameters, validating some of the theoretical limit computations, and proving the space application feasibility.

Low-Complexity Localization and Tracking in Hybrid Wireless Sensor Networks

Localization in Wireless Sensor Networks (WSNs) is an important research topic: readings come from sensors scattered in the environment, and most of applications assume that the exact position of the sensors is known. Due to power restrictions, WSN nodes are not usually equipped with a global positioning system—hence, many techniques have been developed in order to estimate the position of nodes according to some measurements over the radio channel. In this paper, we propose a new technique to track a moving target by combining distance measurements obtained from both narrowband IEEE 802.15.4 and Ultrawideband (UWB) radios, and then exploiting a novel speed-based algorithm for bounding the error. This process is applied to a real dataset collected during a measurement campaign, and its performance is compared against a Kalman filter. Results show that our algorithm is able to track target path with good accuracy and low computational impact.

PRISM: A Novel Protocol for Real-Time Synchronous Acquisitions in WSNs

Wireless Sensor Networks are often considered as low-rate asynchronous systems for distributed monitoring. However, there are several real-time and high data-rate applications where the traditional behavior of WSNs could give raise to channel sharing problems, thus limiting the usefulness of this technology for these emerging fields. This article proposes and discusses PRISM (Protocol for Real-tIme Synchronous Monitoring), a novel protocol for real-time synchronous acquisitions in single-hop and multi-hop wireless sensor networks. The PRISM protocol allows to define the maximum number of nodes, the requirements on the network synchronization and the data-rate in a flexible manner in order to accommodate for different types of acquisitions. Its performance has been studied theoretically through numerical simulations. Moreover, the protocol has been tested in a fully-working wireless monitoring system based on the IEEE 802.15.4 physical standard. Results show the effectiveness and the efficiency of the proposed protocol.

W-TREMORS, a wireless monitoring system for earthquake engineering

Wireless Sensor Network is an emerging technology which can significantly reduce the cost and the time needed to monitor the conditions of civil structures. This work presents W-TREMORS, a new wireless sensing system for high-frequency distributed data acquisition. Our sensor network is based on the low-power and low-data rate standard IEEE 802.15.4, and we used inexpensive hardware. Nevertheless, the system meets requirements imposed by Structural Health Monitoring applications thanks to an efficient use of hardware resources and adopting a novel communication protocol which optimize bandwidth utilization. In addition, we developed a complete software architecture to integrate the Wireless Sensor Network with an existing measurement system. Our prototype WSN was tested through shaking tests in a controlled environment to validate the approach, and to identify problems which should be addressed before using the system on real-world buildings. Preliminary results show that our solution can effectively monitor seismic events providing high reliability and good performances.