Long Distance Wireless Sensor Networks: simulation vs reality

Wireless sensor networks allow unprecedented abilities to observe and understand large-scale, real-world phenomena at a fine spatial-temporal resolution. Their application in Developing Countries is even more interesting: they can help solve problems that affect communities. One of the limitations of current wireless sensors is the communication range, with most devices having 100 meters as maximum limit. In contrast, many applications require long-range wireless sensor network where nodes are separated by large distances, giving the advantage of being able to monitor a vast geographic area. In this paper we will present the results of simulations and of experiments carried out using off-the-shelf equipment over distances ranging from 300m to 12km. The results show that long distance wireless sensor networks (LDWSN) are possible and that the quality of these links is high

Planning and Deploying Long Distance Wireless Sensor Networks:The Integration of Simulation and Experimentation

Wireless sensor networks allow unprecedented abilities to observe and understand large-scale, real-world phenomena at a fine spatial-temporal resolution. Their application in Developing Countries is even more interesting: they can help solve problems that affect communities. One of the limitations of current wireless sensors is the communication range, with most devices having 100 meters as maximum range. In contrast, many applications require long-range wireless sensor network where nodes are separated by large distances, giving the advantage of being able to monitor a large geographic area. In this paper we will present the results of an integrated approach combining a planning step using simulations and an experimental step carried out using off-the-shelf equipment over distances ranging from 600m to 12km. The results reveal that the simulation results agree with experimentation and show that long distance wireless sensor networks (LDWSN) are possible and that the quality of these links is high. Finally, we discuss the relative efficiency of our solution in terms of range compared to other wireless sensor networks

Experimental Evaluation of Radio Transceivers for Sensor Networks in Harsh Environments

This poster describes the experiments performed with Waspmote devices using different 802.15.4/ZigBee transceivers in harsh conditions over distances ranging from hundreds of meters up to tens of kilometres

Experimental Evaluation of Interference Mitigation on The 2.4 GHz ISM band Using Channel Hopping

Both research and practice have revealed that sensor devices running the 802.15.4 on their MAC layer may be competing for wireless communication on the 2.4 GHz ISM band with Wi-Fi, Bluetooth and other proprietary devices. Building upon a SunSPOT development platform, we evaluate the impact of channel hopping on interference mitigation in the 2.4 GHz ISM band and propose a channel hopping model that may be used to mitigate interference under different indoor WSN deployment scenarios. The results obtained by using a wireless sensor network where the sensor nodes are placed at different distances from an interference source and using different power levels agree with previous experimental works on interference in the 2.4GHz band and reveal that (1) channel hopping can improve the performance of WSNs when deployed in Wi-Fi collocating environments and (2) among the different parameters, the received signal strength indication (RSSI) is the most relevant for WSN performance evaluation in collocating Wi-Fi environments

Broadened T-cell Repertoire Diversity in ivIg-treated SLE Patients is Also Related to the Individual Status of Regulatory T-cells

Intravenous IgG (ivIg) is a therapeutic alternative for lupus erythematosus, the mechanism of which remains to be fully understood. Here we investigated whether ivIg affects two established sub-phenotypes of SLE, namely relative oligoclonality of circulating T-cells and reduced activity of CD4 + Foxp3+ regulatory T-cells (Tregs) reflected by lower CD25 surface density.Octapharma research funding; Fundação para a Ciência e a Tecnologia postdoctoral fellowships: (SFRH/BPD/20806/2004, SFRH/BPD/34648/2007); FCT Programa Pessoa travel grant

Design of a flexible and reliable gateway to collect sensor data in intermittent power environments

The development of a wireless sensor network (WSN) gateway is challenging for sites where limited infrastructures lead to frequent power shortages and and network unreliability. In this paper we present a low-power, low-cost, 802.15.4 and 802.11 compatible solution which uses open source software to meet local conditions. Using the SunSPOT motes on a system which is mostly platform independent, our system is based on the Fox embedded Linux board and equipped with a USB flash drive and a USB WiFi adapter. The system can be solar-powered, and the results of a solar system design are presented. All the hardware components are available off-the-shelf and are easy to assemble. We conclude that our system is preferred for applications in remote areas, where a stable power supply and a reliable network infrastructure are lacking. Furthermore, it can be used to extend the range of wireless sensor networks by layering a network of long range motes above islands of low range motes

On the design of a Water Quality Wireless Sensor Network (WQWSN): an Application to Water Quality Monitoring in Malawi

More than one billion people lack access to safe drinking water in the world. Providing a way to measure automatically water quality will help tackle this problem. This paper presents the design of a water quality measuring system and proposes a prototype implementation of a water quality wireless sensor network (WQWSN) as a solution to this challenging problem. When applied to developing countries, the design and implementation of such a system must take into consideration the difficult environment in which it will operate. An application to water quality measurement in Malawi reveals the relevance of using our novel solution to mitigate two challenging issues: energy consumption of the system and the inter-networking problem

On the relevance of Open Wireless sensors for NGN

Open Wireless Sensors are based on the Open Source Software and Open Source Hardware paradigms. The code used to program them and the information about the hardware design are freely released. We present the main characteristics of Open Wireless Sensor Networks (OWSNs) and report on two examples with the experimental results revealing the performance of OWSNs in terms of link quality and battery life. We demonstrate the relevance of using OWSNs in Next Generation Networks by showing the advantages of the Open Source model when applied to Wireless Sensor networks in terms of cost, personalisation and independence from a single entity as compared to proprietary solutions

Community Sensor Networks: An Application to Pollution Maps

Air pollution is a widely recognized threat to our health and the environment in which we live, and can seriously hamper visibility. As currently implemented, air pollution monitoring is based on environmental monitors sparsely deployed at a relatively small number of fixed locations by governmental organizations to develop maps revealing pollution patterns across cities. This lack of pollution monitoring coverage needs to be addressed through complementary technologies, systems and strategies. This paper proposes the use of community sensor networks for the measurement and distribution of air pollution levels. It also proposes the web-based publication of the resulting pollutions maps to promote public participation in the fight against the health and environmental challenges associated with air pollution. The main contributions of this paper are twofold. Firstly, we extend a recently proposed Ubiquitous Sensor Networking (USN) architecture proposed by the ITU in the context of the Internet of the Things (IoT) to propose the main networking architecture behind community sensor networks. Secondly, building upon off-the-shelf sensor devices and existing web services, we present the experimental results and pollution maps built in the city of Cape Town in South Africa as a proof of concept on how community sensor networks can be built using least cost equipment and how pollution maps can be derived from the pollutant levels collected through these networks