Davide Di Palma

Agricultural Monitoring Based on Wireless Sensor Network Technology: Real Long Life Deployments for Physiology and Pathogens Control

Today Wireless Sensor Network are used into an increasing number of commercial solutions, aimed at implementing distributed monitoring and control system in a great number of different application area. In particular the agricultural scenario seems to be one of the most promising application area for WSN due to the necessity of proving the agricultural production chain in terms of precision and quality. This involves a careful system design, since requirements are very strict: battery life-time maximization,robustness, recovery strategies, network flexibility and reconfigurability. This paper shows and describes a practical case study, starting from a real problem and reaching the best architectural solution, with particular focus on the hardware implementation and communication protocol design. A real end-to-end solution has been implemented: several wireless nodes send environmental data every 15 minutes to a master node connected to a GPRS gateway board that forwards data to a remote server using TCP-IP standard protocol. The encouraging and unprecedented results achieved by this approach are supported by several pilot sites into different vineyard in Italy and in France, within which a great amount of environmental data have been collected and analyzed since two years and half.

Enhanced System Design Solutions for Wireless Sensor Networks applied to Distributed Environmental Monitoring

We study the performance of several search algorithms on unstructured peer-to-peer networks, both using classic search algorithms such as flooding and random walk, as well as a new hybrid algorithm proposed in this paper. This hybrid algorithm first uses flooding to find sufficient number of nodes and then starts random walks from these nodes. We compare the performance of the search algorithms on several graphs corresponding to common topologies proposed for peer- to-peer networks. In particular, we consider binomial random graphs, regular random graphs, power-law graphs, and clustered topologies. Our experiments show that for binomial random graphs and regular random graphs all algorithms have similar performance. For power-law graphs, flooding is effective for small number of messages, but for large number of messages our hybrid algorithm outperforms it. Flooding is ineffective for clustered topologies in which random walk is the best algorithm. For these topologies, our hybrid algorithm provides a compromise between flooding and random walk. We also compare the proposed hybrid algorithm with the fc-walker algorithm on power-law and clustered topologies. Our experiments show that while they have close performance on clustered topologies, the hybrid algorithm has much better performance on power-law graphs. We theoretically prove that flooding is effective for regular random graphs which is consistent with our experimental results.The adoption of wireless sensor networks (WSN) for wide area environmental monitoring is currently considered one of the most challenging application scenario for this emerging technology. The promise of an unmanaged, self-configuring and self-powered wireless infrastructure, with a continuously decreasing cost per unit, attracts the attention of both final users and system integrators, replacing previously deployed wired solutions and opening new business opportunities. This challenge might be afforded by resorting to a complete system level design to jointly address and optimize all the involved aspects. Besides, the design guide lines need to be inspired by the application requirements rather than technology driven. Following this approach, this paper presents an overall solution focusing both on node, network and remote user interface issues. The proposed platform in finally applied to a realistic user defined scenario oriented to agro-food production phase monitoring within GoodFood Integrated Project. The results of the validation phase presented highlight remarkable advantages both in terms of cost and complexity reduction and experienced QoS enhancement as well and, consequently, validating the WSN technology adoption.

Design and Application of Enhanced Communication Protocols for Wireless Sensor Networks operating in Environmental MonitorinDg

The adoption of Wireless Sensor Networks (WSN) for wide area environmental monitoring is currently considered one of the most challenging application scenario for this emerging technology. The promise of an unmanaged, self-configuring and self-powered wireless infrastructure attracts the attention of both final users and system integrators, replacing previously deployed wired solutions and opening new business opportunities. Even if many habitat monitoring applications usually do not provide for strictly real-time performances, however, smart power saving procedures have to be adopted, especially to increase the network lifetime. A common approach is to introduce a low power sleep mode, in which the nodes radio section is switched off. In adhoc networking scenarios, this definitely requires the adoption of synchronization procedures, properly scheduling the packet transmission time and avoiding both overhearing effects and collisions. In this paper, a novel class of MAC layer protocols, named STAR MAC, that aims at efficiently managing the nodes low power mode, is presented, and properly integrated within a routing scheme, according to the cross-layer design for minimizing the signaling overhead. The proposed solution is applied to a realistic user defined scenario oriented to agro-food production phase monitoring, highlighting remarkable advantages both in terms of cost and complexity reduction and QoS enhancement as well and, consequently, validating the WSN technology adoption.

Efficient MAC Protocols for Wireless Sensor Networks Endowed with Directive Antennas: A Cross-Layer Solution

This paper deals with a novel MAC layer protocol, namely, directive synchronous transmission asynchronous reception (D-STAR) able to space-time synchronize a wireless sensor network (WSN). To this end, D-STAR integrates directional antennas within the communications framework, while taking into account both sleep/active states, according to a cross-layer design. After characterizing the D-STAR protocol in terms of functional characteristics, the related performance is presented, in terms of network lifetime gain, setup latency, and collision probability. It has shown a remarkable gain in terms of energy consumption reduction with respect to the basic approach endowed with omnidirectional antennas, without increasing the signaling overhead nor affecting the setup latency.

Wireless Sensor Networks for On-Field Agricultural Management Process

Agriculture is one of the most ancient activities of man in which innovation and technology are usually accepted with difficulty, unless real and immediate solutions are found for specific problems or for improving production and quality. Nevertheless, a new approach of gathering information from the environment could represent an important step towards high quality and eco-sustainable agriculture. Nowadays, irrigation, fertilization and pesticides management are often left to the farmer’s and agronomist’s discretion: common criteria used to guarantee safe culture and plant growth are often giving a greater amount of chemicals and water than necessary. There is no direct feedback between the decision of treating or irrigating plants and the real effects in the field. Plant conditions are usually committed to sporadic and faraway weather stations that cannot provide accurate and local measurements of the fundamental parameters in each zone of the field. Also, agronomic models, based on these monitored data, cannot provide reliable information. On the contrary, agriculture needs detailed monitoring in order to obtain real time feedback between plants, local climate conditions and man’s decisions. The concept of precision agriculture has been around for some time now. Blackmore et al., in 1994 (Blackmore, 1994) defined it as a comprehensive system designed to optimize agricultural production by carefully tailoring soil and crop management to correspond to the unique condition found in each field while maintaining environmental quality. The early adopters during that time found precision agriculture to be unprofitable and the instances in which it was implemented were few and far between. Further, the high initial investment in the form of electronic equipment for sensing and communication meant that only large farms could afford it. The technologies proposed at this point comprised three aspects: Remote Sensing (RS), Global Positioning System (GPS) and Geographical Information System (GIS). RS coupled with GPS coordinates produced accurate maps and models of the agricultural fields. The sampling was typically through electronic sensors such as soil probes and remote optical scanners from satellites. The collection of such data in the form of electronic computer databases gave birth to the GIS. Statistical analyses were then conducted on the data and the variability of agricultural land was charted with respect to its properties. The technology, apart from being 1

Energy efficient MAC protocols for Wireless Sensor Networks endowed with directive antennas: a cross-layer solution

This paper deals with a novel MAC layer protocol, namely directive synchronous transmission asynchronous reception (D-STAR) able to space-time synchronize a wireless sensor network (WSN). To this end, D-STAR integrates directional antennas within the communications framework, while taking into account both sleep/active states, according to a cross-layer design. After characterizing the D-STAR protocol in terms of functional characteristics and antenna model, the related performance is presented, in terms of network lifetime gain, latency and collision probability. It has shown a remarkable gain in terms of energy consumption reduction with respect to the basic approach endowed with omnidirectional antennas, without increasing the signaling overhead nor affecting the set up latency.

An Energy Efficient Cross Layer Solution Based on Smart Antennas for Wireless Sensor Network Applications

Wireless Sensor Network deployment currently represents an affordable solution to some challenging application areas. This involves a careful system design with particular regard to the communications and control protocols. In the following, the benefits of adopting directive antennas, both in terms of energy saving and targets tracking are presented by integrating this feature into a novel MAC protocol (MD-STAR). Simulation results are also deeply provided, underlining higher performance of MD-STAR with respect to existing solutions, for different directive main lobe width and node density values.

Real-Time Monitoring of Volatile Organic Compounds in Hazardous Sites

Volatile Organic Compounds (VOCs) are largely used in many industries as solvents or chemical intermediates. Unfortunately, they include some components, present in the atmosphere, that can represent a risk factor for human health. They are also present as a contaminant or a by-product in many processes, i.e. in combustion gas stacks and groundwater clean-up systems. Benzene, in particular, shows a high toxicity resulting in a Time-Weighted Average (TWA) limit of 0.5 ppm, as compared, for instance, with TWA for gasoline, in the range of 300 ppm. Detection of VOCs at sub-ppm levels is, thus, of paramount importance for human safety and industrial hygiene in hazardous environments. The commonly used field-portable instruments for VOC detection are the hand-held Photo-Ionisation Detectors (PIDs), sometime using pre-filter tubes for specific gas detection. PIDs are accurate to sub-ppm, measurements are fast, in the range of one or two minutes and, thus, compatible with on-field operation. However, they require skilled personnel and cannot provide continuous monitoring. Wireless connected hand-held PID Detectors start being available on the market, thus overcoming some of the previously described limitations, but suffering for the limited battery life and relatively high cost. The paper describes the implementation and on-field results of an end-to-end distributed monitoring system integrating VOC detectors, capable of performing real-time analysis of gas concentration in hazardous sites at unprecedented time/space scale. The system consists of a Wireless Sensor Network (WSN) infrastructure, whose nodes are equipped with distributed meteo-climatic sensors and gas detectors, of TCP/IP over GPRS Gateways forwarding data via Internet to a remote server and of a user interface which provides data rendering in various formats and access to data. The paper provides a survey of the VOC detector technologies of interest, of the state-of-theart of the fixed and area wireless technologies available for Gas detection in hazardous areas and a detailed description of the WSN based monitoring system.

An Embedded Wireless Sensor Network System for Cultural Heritage Monitoring

The adoption of Wireless Sensor Networks(WSNs) for real time monitoring is currently considered one of the most challenging application scenario for this emerging technology. The promise of an unmanaged infrastructure, with a continuously decreasing cost per unit, attracts the attention of both final users and system integrator, opening new business opportunities. In Europe the necessity of preventing the deterioration of art and artifacts through control of the environment in storage and exhibition opens a novel application field for WSN. This involves a careful system design, since the application and the technology requirements are very strict. This paper describes a practical case study, starting from a real problem and reaching the best architectural solution with particular focus on the hardware implementation and communication protocol design. Finally, some tests and their results are presented to highlight the effectiveness and accurateness of the developed system.

Advanced Distributed Monitoring System for Agriculture based on Wireless Sensor Network Technology

Nowadays the precision farming concept is often related to new technologies, developed to give detailed information to improve farming production, while preserving the surrounding environment from a rash use of water and pesticides.