Global Area Network Research Articles

A wideband circular polarization antenna for portable INMARSAT BGAN terminal applications

AbstractA low profile, wideband, and portable antenna has been designed and fabricated for Inmarsat broadband global area network (BGAN) land mobile terminal applications. The purpose of the antenna was to provide a low‐cost and easy‐fabricated solution with wide bandwidth and high performance. The proposed antenna is composed of the stacked corner‐truncated patches with sequential rotation oblique feed and a serial feeding network. Good antenna characteristics are achieved over the BGAN operating bands. The measurement results for return loss, gain, axial ratio, and radiation pattern confirm the integrity of the simulation results. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 2354–2357, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24643

On the applications of the space time premise when exploiting location diversity of multiple antenna sites

This paper presents novel techniques to exploit the spatial dimension and the space time (ST) premise in a Large Scale Communication Networks LSCN(s). These techniques are based on an encapsulation framework aimed at enforcing an artificial none line of sight (NLOS) condition. The framework integrates the spatially diverse multiple antenna sites (MAS); composing parts of an LSCN into joint transmission/reception systems. The location diversity of these MAS provides for exploiting the spatial dimension whether for multiplexing gain, diversity gain and/or array gain. Whereas multiplexing gain is best exploited in multi input multi output (MIMO) architectures to boost spectrum efficiency; diversity and array gains lend themselves to equally useful applications e.g., in VSAT technology; array/diversity gain can improve the uplink efficiency to satellite, diversity gain may resolve uncertainty issues in HF link, etc. This paper develops a framework for exploiting MIMO in a network to network communications. It also outlines possible applications of location diversity of MAS in LSCNs. Selected scenarios include terrestrial satellite networks, VSAT network topologies, HF communications and broadband global area networks (BGAN).

A Study of Delays in Making Tide Gauge Data Available to Tsunami Warning Centers

Abstract This short note provides conclusions of a study of the various factors that determine the delay between tsunami arrival at a tide gauge station and data being made available at tsunami warning centers. The various delays involved include those associated with the tide gauge hardware and measurement methods and with the form of telemetry employed. It is shown that the most widely used form of telemetry in existing tsunami networks (meteorological satellite data collection platforms) can be improved upon significantly with the use of modern telemetry alternatives [notably Inmarsat’s Broadband Global Area Network (BGAN)], enabling faster, more frequent, more secure, and higher bandwidth transmissions of tide gauge data.

Land vehicular propagation channel characterization of BGAN system

AbstractThis paper summarizes the results of a measurement campaign, which set out to characterize Inmarsat's broadband global area network extension (BGAN‐X) L‐band land vehicular (LV) channels as a function of elevation angle and candidate antenna systems. Measurements were conducted with three types of directional antennas on motorway routes around London using Inmarsat's Indian Ocean Region (IOR), Atlantic Ocean Region‐East (AOR‐E) and Atlantic Ocean Region‐West (AOR‐W) satellite transmissions, corresponding to elevation angles of, respectively, ∼7.5°, ∼13° and ∼30°. Simultaneous recordings of data on two types of directive receivers enabled correlation of several channel parameters. Statistics were used to refine a baseline model that derived BGAN‐X LV channel parameters by scaling the statistics obtained from an omni‐directional antenna receiver. The measurements demonstrate that Ricean mean and Ricean factor vary significantly over the chosen routes at elevation angles below ∼13°. Further, the Doppler shift of the direct path can be predicted accurately. A qualitative analysis indicates that the multi‐path Doppler spread is generally (not always) caused by uniform scattering around the vehicle over short distances and undergoes spatial filtering due to the receiver antenna. A technique was established to derive statistics of a two‐state Markovian channel model at any specified fading threshold by gathering tracking system state, thereby allowing one to ascertain service expectations and operational parameters such as connection time‐out of a packet‐switched system or reliability threshold of a circuit‐switched system. The technique was used to identify and select appropriate routes, particularly for the IOR and the AOR‐W regions. Data analysis is in progress to establish the reason for the slow variations of signal mean at low‐elevation angles in Ricean conditions and to derive appropriate statistical models. Furthermore, image processing of the video recordings is expected to reveal the extent of optical and RF fades correlation. Copyright © 2008 John Wiley & Sons, Ltd.

Real time sea level data transmission from tide gauges for tsunami monitoring and long term sea level rise observations

The authors present the development and implementation of a ‘tsunami enabled’ tidegauge which allows real time data to be returned from almost anywhere on Earth. At itscentre is a low power, embedded Linux platform, which performs the data logging andcommunications. This is attached to a radar and pressure sensors that are queried overa serial interface. Telemetry is through the Inmarsat Broadband Global Area Network(BGAN) system which allows a bi-directional broadband connection over Ethernet,permitting remote reconfiguration when required, and faster, more frequent tide gaugedata. Data transmission is over an internet connection with files containing one minutevalues from three sensors returned every five minutes

Efficient IP‐multicast via Inmarsat BGAN, a 3GPP satellite network

AbstractThis paper outlines a number of challenges associated with supporting IP‐multicast services efficiently across the Inmarsat Broadband Global Area Network (BGAN) 3GPP‐based satellite network operating over the Imarsat‐4 satellite constellation. The paper presents a network architecture that extends the 3GPP reference architecture to allow IP‐multicast to be delivered when the Core Network is in a 3GPP Release‐4 (non‐MBMS compliant) configuration.This paper further extends the service and system concepts defined in 3GPP MBMS to provide improved flexibility and accountability, and improved scalability and efficiency when operating with the Inmarsat‐4 BGAN TDM/TDMA air interface.This paper describes a number of radio resource management techniques that were deployed in a test system and the validation testing that was undertaken to support multimedia distribution and VoIP‐based netted communications applications. The tuning of application and system behaviour to achieve acceptable performance is described in outline. Copyright © 2007 John Wiley & Sons, Ltd.

What exactly is airborne personal communications?

The paper discusses BGAN (broadband global area network) service from Inmarsat carried by their latest 14 satellites allows data rates of up to about 500kbps per channel in both uplink and downlink. In view of the greater capability and more flexible use, costs can be dramatically reduced, thereby bringing affordable access to many more people. The Thales satellite communications transmitter receiver for the satellite link. The equipment is designed to be compact while providing the required capability for the Inmarsat BGAN system.

The ITER CODAC conceptual design

CODAC orchestrates the activity of 60–90 Plant Systems in normal ITER operation. Interlock Systems protect ITER from potentially damaging operating off-normal conditions. Safety Systems protect the personnel and the environment and will be subject to licensing. The principal challenges to be met in the design and implementation of CODAC include: complexity, reliability, transparent access respecting security, a high experiment data rate and data volume since ITER is an experimental reactor, scientific exploitation from multiple Participant Team Experiment Sites and the long 35-year period for construction and operation. Complexity is addressed by prescribing the communication interfaces to the Plant Systems and prescribing the technical implementation within the Plant Systems. Plant Systems export to CODAC all the information on their construction and operation as “self-description”. Complexity is also addressed by automating the operation of ITER and of the plasma, using a structured data description of “Operation Schedules” which encompass all non-manual control, including Plasma Control. Reliability is addressed by maximising code reuse and maximising the use of existing products thereby minimising in-house development. The design is hierarchical and modular in both hardware and software. The latter facilitates evolution of methods during the project lifetime. Guaranteeing security while maximising access is addressed by flow separation. Out-flowing data, including experimental signals and the status of ITER plant is risk-free. In-flowing commands and data originate from Experiment Sites. The Cadarache Experiment Site is equated with the Remote Experiment Sites and a rigorous “Operation Request Gatekeeper” is provided. The high data rates and data volumes are handled with high performance networks. Global Area Networks allow Participant Teams to access all CODAC data and applications. Scientific exploitation of ITER will remain a human as well as technical challenge, to find methods of effectively combining the experience and observations of a geographically distributed research team.

Sacred groves: potential for biodiversity management

Existing global protected area networks have two shortcomings: (1) they do not cover certain habitats, and (2) local people often resent their formal management. Here, we show that communities around the world traditionally protect natural sites that are dedicated to ancestral spirits or deities. Such sites cover a wide variety of habitats and are often located in biodiversity rich regions. Case studies on sacred groves show that these small forest patches play an important role in biodiversity conservation. Furthermore, natural sacred sites are maintained through traditional methods of community based conservation that do not require governmental involvement. Incorporating these sites into conservation networks could enhance the effectiveness of protected areas by covering a wider variety of habitats and by harnessing the support of local people. In this article, we discuss current threats to sacred groves that need to be addressed through management approaches. More research on the ecology and underlying socioeconomic mechanisms of natural sacred sites is required to fully reveal their potential for biodiversity conservation.

And it BGAN to happen [broadband global area network

Inmarsat's ambitious project for a satellite-based broadband mobile solution is making slow but steady progress. London-based Inmarsat has promised a broadband global area network (BGAN) service, planned for mid-2005. In many respects, this Inmarsat service is already in place today, operating through leased capacity on the giant Thuraya satellite, which serves 99 countries including the whole of the Middle East, all of Europe and much of Northern Africa and the rest of the near-East. This so-called "regional BGAN" system is itself quite spectacular; but nothing like as sophisticated as Inmarsat's all-singing, all-dancing BGAN service, designed to supply satellite-based broadband access to users almost anywhere on the planet, at affordable rates and speeds comparable to GPRS.

Network performance and integrity enhancement with optical path layer technologies

Path layer technologies will play a key role in the development of a powerful and failure resilient B-ISDN. So far, they have been based on electrical technologies. This paper highlights WDM/FDM techniques and demonstrates that optical paths can greatly enhance the path layer capability and, therefore, the network performance. It is also shown that effective network failure restoration can be achieved with optical paths. The applicability of the wavelength path (WP) technique to global area networks is revealed by comparing different optical path realization techniques. WPs are applied to the national backbone network example to evaluate the required number of wavelengths, and to identify optical cross-connect node requirements. It then proposes a new optical path concept: the virtual wavelength path (VWP). In the VWP scheme, wavelengths are assigned on a link-by-link basis. In other words, the wavelength assigned to a wavelength path has only local significance. Significant benefits of the VWP such as the simplified path accommodation design within a transmission facility network and the reduced number of wavelengths needed, are elucidated. An optical cross-connect node architecture that enables the VWPs is also proposed. The architecture allows the VWP concept to be realized with commercially available optical technologies. The optical path layer concept proposed exploits and consolidates the layered transport network architecture and optical technologies, and will open up new opportunities for creating a B-ISDN that is bandwidth abundant and has a high degree of integrity.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>