José Antonio Gay-Fernández

PROPAGATION ANALYSIS AND DEPLOYMENT OF A WIRELESS SENSOR NETWORK IN A FOREST

A complete study for the deployment of a wireless sensor network in a forest based on ZigBee is presented in this paper. First, due to the lack of propagation models for peer to peer networks in forests, propagation experiments were carried out to determine the propagation model. This model was then used for planning and deploying an actual wireless sensor network. The performance of the network was compared with the expected theoretical behavior to extract some conclusions that are presented in the paper. Finally, some general conclusions, as an estimation of the minimum number of routers necessary to cover a given area, are extracted from the experiments and presented in the paper.

Peer to Peer Wireless Propagation Measurements and Path-Loss Modeling in Vegetated Environments

The use of wireless networks is continuously increasing, as well as extending to new purposes and new environments, mainly outdoor oriented and some of them at vegetation media. Although there are multiple propagation studies at wireless network frequency bands within vegetation scenarios, most of them are focused on classical base station to mobile terminal configuration. The main aim of this research is to provide a propagation study for the three most commonly used wireless network frequencies: 2.4, 3.5 and 5.8 GHz in a peer to peer configured system, where both, the transmitter and the receiver are located at the same low heights, within vegetation media, including forests and meadows.

A Complete Traceability System for a Wine Supply Chain Using Radio-Frequency Identification and Wireless Sensor Networks [Wireless Corner]

Radio-frequency identification (RFID) technology provides an effective tool for managing traceability along food supply chains. This is because it allows automatic digital registration of data, and therefore reduces errors and enables the availability of information on demand. A complete traceability system can be developed in the wine production sector by joining this technology with the use of wireless sensor networks for monitoring at the vineyards. A proposal of such a merged solution for a winery in Spain has been designed, deployed in an actual environment, and evaluated. It was shown that the system could provide a competitive advantage to the company by improving visibility of the processes performed and the associated control over product quality. Much emphasis has been placed on minimizing the impact of the new system in the current activities.

Radio-Electric Validation of an Electronic Cowbell Based on ZigBee Technology

The tracking of cows in large, extensive farms, as well as the possibility of checking on some veterinary data in real time, could open new business horizons for meat producers. A proposal for an electronic cowbell is presented, in order to provide an inexpensive technical solution for the exploitation of such free-running cattle. The idea is based on Zig Bee technology, which a rapidly developing technology. Different rural environments have been analyzed from propagation measurements, and an estimate of the number of network nodes (or “motes”) and the cost of the system is presented.

Short-Term Modeling in Vegetation Media at Wireless Network Frequency Bands

This paper presents a short-term analysis of the radio propagation channels within vegetation media at the most commonly used wireless network frequency bands: 2.4, 3.5, and 5.8 GHz. Fading effects underlying this short-term analysis would determine whether the radio channel could support a stable link or not. The configuration used in this study is a peer-to-peer system, where the transmitter and the receiver are located at low heights inside several vegetation media, including forests and meadows. The distribution function that best fits the received power was determined to be Weibull, and the evolution of its parameters was studied as the distance between transmitter and receiver increases.

Radioelectric propagation in mature wet forests at 5.8 GHz

Measurements in two different mature forests have been performed, considering a pine forest and a eucalyptus forest. The peer-to-peer scenario used responds to the current needing of radio data for network planning: there exist much information about propagation in vegetation in base station to mobile terminal (master-slave) configurations, but there is a lack in peer-to-peer configurations. The current trends in wireless networking in open environments, with growing interest to sensor networks, support the performing of such research work.

Peer to peer propagation in vegetation media for wireless sensor networks

The extension of wireless communication systems and their application in rural environments, require radio propagation models adapted to this situations: presence of vegetation (both trees and shrubs), low transmitted powers, or peer to peer configurations. This work presents the results of a large radio propagation measurement campaign, conducted in different vegetation environment, with low antenna heights, and tuned to frequencies assigned to wireless networks: 2.4, 3.5 and 5.8 GHz bands.

Analysis of Spatial Diversity in Both Transmitter and Receiver on Low-Height Links at Forests

This work focuses on radio wave propagation within forested environments, at 5.8 GHz. Concretely, we explore the advantages of implementing spatial diversity in reception or even in both ends for improving the strength of the received signal in such environments, which could be useful in applications such as vehicle-to-infrastructure, vehicle-to-vehicle, or emergency communications. Measurements gathered at both evergreen and deciduous forests sustain the thesis. Once processed, the results support the proposal of implementing a spatial diversity technique in reception or in both ends using a 2 × 4 (or 2 × 2) scheme in order to improve the connectivity at 5.8 GHz band within forests. In fact, we estimated a gain due to spatial diversity in reception of 5 dB and 2 dB at evergreen and deciduous forests, respectively, and 16 dB or 5 dB when implementing at both ends.

Evolution of received power time-variability range with distance at deciduous forests

Forests are scenarios where more and more radio communication systems are going to be installed. Propagation models in such environments are needed, but most of them are focus on the static long-term behavior. This contribution analyses short-term activity in an oak tree forest. The focus is put on the range of measured received powers at each measurement location, and how it varies with distance as receiver moves deeper into the forest. The presence of foliage seems to increase the variability of the received power with time at a fixed location, but it also increase the rhythm at which this range grows with distance between transmitter and receiver. Besides, the variation range grows faster with distance in OLoS conditions than in LoS.

Using Weibull distribution to modeling short-term variations in decidious-forested radio channels

Radio propagation within forests has been typically studied in terms of long-term (or mean) behavior. However, short-term time variations could limit the use of radio systems in such environments. This contribution is focused in the use of Weibull distribution to model short-term variations in radio channels within deciduous tree forests. We also analyze the effect of the distance between transmitter and receiver, providing a model to predict such random effects in received power.