Dan Stefan Tudose

Home automation design using 6LoWPAN wireless sensor networks

Wireless sensor and actuator networks (WS&ANs) are a new technology based on networks of small radio-enabled embedded devices that are being deployed in areas such as environmental monitoring, vehicle tracking, building management, body monitoring and other applications. Power sources for network nodes are often limited, which imposes restrictions on hardware resources and their use by the underlying embedded software. We propose a new wireless sensor network architecture that is especially designed for the task of home automation. Our system relies on a low power WS&AN that employs energy harvesting techniques to maximize node lifetime and an embedded residential gateway that offers user interaction and secure connectivity to the outside world. The advantages of our system are its scalability, low power, self sufficiency and versatility.

Mobile sensors in air pollution measurement

In this paper we present a mobile system for air quality and pollution measurement suited for the urban environment. We designed, tested and built a reliable measurement device that can acquire information about the air quality of its surroundings, store it in a temporary memory buffer and periodically relay it to a central on-line repository. Real-time gathered data can be freely accessed by the public through an on-line web interface. Users can select and view different gases and concentrations overlapped on a map of the city.

Task Scheduling in Wireless Sensor Networks

This paper discusses a scheduling algorithm for the sub-tasks of an application in a Wireless Sensor Network. With the next generation of sensor networks, task-based systems are needed to provide services to entities outside the network. Allocation of tasks on different wireless nodes must take into account energy constraints, compatibility of tasks to a given node or topology and must be in agreement with the purpose of the network. The problem described in this paper requires maximizing network lifetime and satisfying these allocation constraints. The solution proves to be correct though in some cases it can lead to algorithmic complexity, such that further work on an approximation algorithm might be indicated.

Energy Independent Wireless Sensor Network Design

Battery powered wireless sensor nodes (WSN) are rarely efficient from the point of view of life time, development and maintenance cost. In this context, energy harvesting techniques are used more and more, coupled with super capacitors, in order to mitigate the costs and increase the lifetime. This paper presents the results of powering Sparrow v3, a wireless sensor node, from super capacitors charged by a solar panel. The experimental results show that this system may operate in an autonomous mode, using only the power provided by the photovoltaic cells. The novelty of this setup is represented by its small solar panel, combined with super capacitors which have a smaller capacity than other similar systems. A highly optimized code had to be implemented in order to achieve the energy autonomy goal.

Rectifier Antenna Design for Wireless Sensor Networks

Wireless Sensor Networks (WSNs) is a technology which is increasingly implemented in a multitude of data acquisition, data processing, and control applications. A rectifier antenna, or rectenna is a device used to convert radio frequency energy into electrical energy through the use of a rectifier circuit attached directly to a regular antenna. For most purposes, rectennas are used for microwave energy transmission, due to their high efficiency in converting microwaves into electrical energy. In this paper, we study the efficiency of rectifier antennas in harvesting energy and their applicability for powering Wireless Sensor Nodes.

Low-Cost Air Quality System for Urban Area Monitoring

With the worldwide urban population following a continuous growth, more individuals expose themselves to a less healthy environment by inhaling polluted urban air. The current pollution measurement techniques make use of automated monitoring stations that are usually installed in certain key points around the city but can only provide coarse-grained air quality reports as well as not being able to indicate the sources of the air polluting agents. As traffic related air pollution cannot be traced to a single location, there is the need for a new approach which has the capacity of measuring fine-grained air quality that can reflect any detailed variations that may be caused by traffic jams. In this paper, we intend to offer a solution by implementing a low-cost air quality system using mobile sensing for monitoring the variance of gaseous pollutants in metropolitan areas.

Analysis of Software AES in SparrowE Wireless Sensor Networks

Wireless sensor networks are a cheap and versatile solution for monitoring various environments. The data gathered by these sensors is often used in research projects and science experiments. It is necessary to ensure that a certain level of security and protection is instated for the transmitted data. Current software security methods implemented on wireless sensor networks do not necessarily take into consideration the lifetime and autonomy of the nodes. This paper presents an analysis of a software AES implementation on SparrowE wireless sensor nodes and shows a comparison between the viability of such a method with regard to hardware AES.

Enablement of CoAP Stack on Sparrow Wireless Sensor Network

As smart embedded devices tend to become more and more ubiquitous, interconnecting these gadgets with the existing network infrastructure by using simple application layer protocols is highly needed. This article presents a new approach for a specialized web transfer protocol widely available in the Internet of Things used in conjunction with a set of newly designed wireless sensor nodes. The application layer protocol is using an IPv6 over Low power Wireless Personal Area Networks (6LoWPAN) stack in order to facilitate the interconnection of a group of constrained devices with other networks.

Energy-efficient user interaction with an off-grid building

This paper describes the design of energy-efficient wide spectrum mechanisms and protocols to capture context information and employ actuation to close the feedback loop. The project described in this article focuses on harvesting energy from the environment through as many ways as possible, and efficiently using the harvested energy in off-grid buildings, dynamically adapting the consumption to currently available energy levels. The main energy sources to be used for harvesting are: solar energy, wind energy, wasted wireless communication energy and hydro energy. Through its web and Android interfaces, the project offers functionalities such as analyzing energy harvesting efficiency, monitoring building-wide energy consumption, setting up profiles and managing consumers individually.