High speed train communications systems using free space optics

In this work, we propose a broad-band free space optical (FSO) wireless communications system for high-speed trains. The system consists of optical transceivers positioned outside the train and along the railway track. The train receivers are in the coverage area of base stations positioned along the railway track to ensure continuous link availability. In this paper, we present modelling of two cases for over-ground and underground train systems before embarking to practically implement the system in our research laboratory. Also discussed is the protocol for the data distribution along the track as well as the initial experimental demonstration of the proposed link

Modeling electromagnetic interference generated by a WLAN system onboard commercial aircraft

This work forms part of the project HIRF SE which is financially supported under the European Union 7th Framework Programme (FP7). The authors are solely responsible for the contents of the paper which does not represent the opinion of the European Commission.The growing demand for the utilization of personal electronic communication devices onboard commercial aircraft necessitates the assurance of safety by airline operators and regulators. This implies that the potential risks posed by the deployment of wireless communication systems on critical aircraft equipment must be carefully assessed and countermeasures taken when required. In this paper, a model based on a ray-tracing algorithm is developed to calculate the electromagnetic interference incident on the fuselage structure of a commercial airline. The source of interference is a 2.4 GHz data communications network. Two scenarios are considered; the first assumes a base station in the centre of the cabin while the second considers four base stations, transmitting at a lower power, distributed along the cabin. The model first determines the propagation map generated by the base stations. These results are used to establish the transmission power required by the personal mobile devices which is then employed to determine the propagation map of each device. The overall electromagnetic interference map incident on the fuselage resulting from the onboard wireless network is generated by vectorially combining the resulting propagation maps. Results for the two scenarios are presented.peer-reviewe

A Portable Wireless Particulate Sensor System for Continuous Real-Time Environmental Monitoring

Airborne particulate matter has been shown to be associated with morbidity and mortality, and may interfere with certain sensitive experiment. Understanding the levels and movements of particulate matter in an enclosed space can lead to a reduction in the impact of this material on health and experimental results. A system of environmental sensors including particulate matter, selected gasses, humidity, temperature, and pressure can be used to assist in tracking air movement, providing real-time mapping of potential contaminants as they move through a space. In this paper we present a system that is capable of sensing these environmental factors, collecting data from multiple dispersed nodes and presenting the aggregated information in real-time. The highly modular system is based on a flexible and scalable framework developed for use in aircraft cabin environments. Use of this framework enables the deployment of a custom suite of sensors with minimal development effort. Individual nodes communicate using a self-organizing mesh network and can be powered from a variety of sources, bringing a high level of flexibility in the arrangement and distribution of the sensor array. Sensor data is transmitted to a coordinator node, which then passes the time-correlated information to a server-hosted database through a choice of wired or wireless networks. Presentation software is used to either monitor the real-time data stream, or to extract records of interest from the database. A reference implementation has been created for the National Institutes of Health consisting of a custom optical particle counter and off-the-shelf sensors for CO2, CO, temperature, humidity, pressure, and acoustic noise. The total environmental sensing system provides continuous, real-time data in a readable format that can be used to analyze ambient air for events of interest