Thanks to the use of satellite technology, mobile personal telecommunications systems are able to provide communications simultaneously anywhere on the Earth's surface. The implementation of such systems raises several regulatory issues: after a brief explanation of the technical characteristics of different satellite systems in the first chapter, the second chapter will introduce the principles of space law relevant to satellite communications, with particular attention to the provisions which the development of global satellite telecommunication system could infringe. In the third chapter, there will be place for further analysis of international regulations established in the framework of the International Telecommunication Union and the World Trade Organisation, dealing more specifically with satellite telecommunications. The discipline established by the former organisation aims to the optimal management of the orbit and spectrum resources, particularly controversial because of the divergence of interests and exigencies of the member countries, whereas the latter intervened in the liberalisation of the telecommunication services, with the purpose to create an open environment for their diffusion. Furthermore, telecommunication activities are subjected to national regulation. The domestic discipline pertaining to global mobile satellite telecommunication services will be analysed in the fourth chapter, with particular attention to the U.S. Federal Communication Commission regulations and to the developments of Italian legislation in the light of the recent European initiatives in the field. National authorisation requirement conditions, in spite of the international effort toward regulatory harmonisation and liberalisation, are the key elements in the deployment of global mobile telecommunications services. National authorities should not continue to function solely on the basis of their national considerations, but be more flexible and open to cooperation, a

This thesis investigates the modelling of fade countermeasures (FCMs) for the design of geostationary Ka band digital satellite communication systems. The analysis focuses on a typical low-power low-rate very small aperture terminal application using adaptive forward error correction as a way of counteracting the high level of detected dynamic atmospheric fading. The management and performance of such systems is conditioned greatly by the ability of practical controllers at detecting the actual level of total signal attenuation. At 20 or 30 GHz, rain attenuation and tropospheric scintillation are the two major propagation effects of interest. Part of the solution relies on the consideration and integration of their random and dynamic nature in the design process. The finite response time of practical countermeasure systems is a source of performance degradation which can be minimised by the implementation of predictive control strategies. This is the focal point of this thesis. A novel on-line short-term predictor matched to the Ka band fading process is proposed. While the rain attenuation component is efficiently predicted, tropospheric scintillation is the source of the estimation error. To take this into account, a statistical model, based on an extension of the global fading model for rain and scintillation, is then developed so that long term performance of predictive countermeasures can be drawn. Two possible ways to compensate for scintillation-induced prediction errors, namely the fixed and variable detection margin approaches, are proposed, analysed and then compared. This is achieved by calculating the FCM utilisation factor, as well as the throughput and bit error rate performance of a typical Ka band system in the presence of dynamic fading within the context of predictive fade countermeasure control operations. In the last part of this thesis, the inclusion of instantaneous frequency scaling in the design of efficient FCM control schemes is investigated. This is applicable to systems using fade detection at a base frequency. In particular, a new statistical model, accounting for the impact of the stochastic temporal variations of rain drop size distribution on rain attenuation, is presented. This thesis further confirms that countermeasure systems are technologically viable. The consideration of more specific design problems does not change the overall validity of this statement. In this thesis, it is shown that a predictive FCM technique, based on readily available punctured convolutional codes, with their relatively modest coding gain, is sufficient to provide high link availability and user data throughput on a low-power low-rate in-bound VSAT link.

Deregulation, globalization, and commercialization are drastically changing the space industry. But commercial space activities entail considerable risks. This thesis is primarily an analysis of the risks that private entities in the space industry need to manage in order to be commercially successful. Due to the trend towards a buyer's market, satellite manufacturers increasingly have been forced to accept risks that do not fall within their traditional core business. Consequently, manufacturing companies become risk managers for a variety of legal space risks. Therefore, the legal framework for the commercial management of legal risks is analyzed and solutions to identified problems are offered. This thesis studies trends in contemporary risk management practices in the private sector, which is dominated by market forces. It is argued that risk management of legal issues should form an integral part of overall space project management, the rationale being that losses in any phase of space activities, while certain to occur, are uncertain in time and scale. This thesis, therefore, scrutinizes legal risk management throughout the life cycle of space projects. Few space applications have become commercially viable. Today, satellite navigation provided by the U.S. GPS is widely used, especially because it is free of direct charges. In Europe, a competing system, Galileo, is being developed. It will provide users with different service levels, ranging from free services to more reliable and accurate navigation services. As this system has both, public and commercial benefits, the industry is expected to participate in a Public Private Partnership for the Galileo satellite constellation. This thesis makes specific proposals to manage the legal risks of the Galileo project. At the same time, the allocation of legal space risks between the various parties is studied. The thesis of the author is that the management process, which is used to control technical space risks, can provide satellite manufacturers with a supportive analogy for dealing with legal space risks. Risks will be studied for all project phases of Galileo, i.e., the feasibility study, the establishment of specifications, development, manufacturing, the launch, operations, replenishment, and the final disposition of satellites.

Commercialization of space activities particularly harnessing satellites for telecommunication in the 1970's is perhaps the most dynamic development of the twentieth century comparable only to the industrial revolution of the seventeenth century. The possibilities of civilian applications of satellite technology confined to its military use until the recent past has raised urgent questions of policy and regulations both nationally and internationally. / The main objective of the thesis is to review the development of satellite telecommunication with particular reference to India. The thesis assesses the present access status and the regulatory regime, analyzes general challenges of deregulation including concerns of national security, fair competition, equal opportunity for service providers and manufacturers and above all consumer protection. It examines the how the Canadian CRTC and American FCC are addressing the current challenge posed by rapid technological developments and consequent convergence of telecommunications and broadcasting as well as lessons India could learn from the Canadian and American experiences. Finally suggestions are made for a possible logical direction for India's future telecom policy, in particular and the commercialization of space activities, in general.

Three studies of precipitable water using the Global Positioning System are presented. The first study finds that precipitable water in Hawaiʻi is best described by a lognormal distribution. The long-term average value of precipitable water declines exponentially with height, but the dispersion of precipitable water declines more linearly. The change in skewness of the distributions is also linear, although in this case it increases with elevation. The second and third studies use GPS meteorology to investigate a climatological and a meteorological event respectively. First, the effect of the 1997-1998 El Nino on precipitable water in the western tropical Pacific is studied and found to be consistent with a model relating the formation of an anomalous high-pressure ridge to the El Nino episode. Finally, the details of the precipitable water field for the Kaʻu Storm, November 2000 are examined. The results highlight the role of topography in controlling the location of convection, The observed correlation between the precipitable water and rainfall is used to generate estimates of rainfall based on GPS data, Comparing the GPS precipitable water estimates with those from a weather model indicates that the underestimates of rainfall produced by the weather model are probably due to correlated underestimates of precipitable water. / Thesis (Ph. D.)--University of Hawaii at Manoa, 2002. / Mode of access: World Wide Web. / Includes bibliographical references (leaves 62-66). / Electronic reproduction. / Also available by subscription via World Wide Web / ix, 66 leaves, bound ill. 29 cm

Thesis (Ph. D.)--University of Hawaii at Manoa, 1991. / Includes bibliographical references (leaves 152-154) / Microfiche. / xvi,154 leaves, bound ill. 29 cm

The western North Atlantic population of the northern right whale (Eubalaena glacialis) was severely depleted by whaling over the last century. Despite over fifty years of protection, fewer than four hundred individuals are believed to exist in the North Atlantic. Relatively little is known about the diving behavior, respiratory physiology, or diel activity of these whales, although such information could be useful in predicting population abundance and distribution in relation to food or environmental variables. Dive behavior data can be collected visually, but collection is limited to daylight hours, calm weather, and fortuitous encounters with study animals. Satellite-monitored radio tags offer the opportunity to collect data on individual whales' diving behavior continuously, over long distances and periods of time, and at relatively low cost. Thirteen North Atlantic right whales were tagged and monitored in the Gulf of Maine between 1989 and 1991. One male was tagged in 1989; two adult males, six adult females (two with calves) and one juvenile were tagged in 1990; one adult female (with a calf) and two juveniles were tagged in 1991. The duration of monitoring for the whales varied from <1 day to 43 days. Characteristics of the radio tags were different over each year in order to evaluate different attachment mechanisms and methods of collecting and summarizing data for dive duration, dive frequency, and time submerged. These data were then used to describe the dive behavior and to predict aspects of the respiratory physiology for these whales. The number of dives, their duration, and the time submerged varied considerably among individual whales and between years. Over all, the whales spent 79% of their time underwater. However, most dives were short (i.e., 95% were <14 min; the mean dive duration was 92.3 sec), although dives of 30-40 min duration were observed for several individuals. In general, the number of dives a right whale made was inversely related to the average duration of its dives within a time interval. Furthermore, over a given time interval, the number of times a whale dove was a better predictor of the percent time it was submerged than was the average duration of its dives. There was no evidence of diel variation in dive behavior (i.e., number of dives, average dive duration, or percent time submerged) among these whales. Age, sex, and reproductive status may have affected dive behavior, although these trends were not statistically significant due to the small number of study animals and individual behavioral variability. Males tended to dive more often and averaged shorter dives than females. Females with calves dove more often and averaged shorter dives than females without calves. Juvenile females dove less often but averaged longer dives than adult males or females with calves. It was predicted that the aerobic dive limit of an "average" right whale was approximately 14 min. Ninety-five percent of the dives recorded for the 11 monitored right whales were < 14 min. Furthermore, there was no evidence of recuperative periods (i.e., prolonged periods at the surface) after long dives. These observations were consistent with the idea that the North Atlantic right whales dove within their aerobic scope. They further suggest that physiological parameters alone probably have little influence on dive characteristics, except to set an upper limit on the duration of a dive. Satellite telemetry provides an opportunity to monitor the movements and behavior of free-ranging animals, and overcome many of the short-comings associated with traditional, human-based visual techniques for tracking and studying such animals. Although the tags used in this study were prototypes and varied in their design from year to year, several right whales were monitored simultaneously and were tracked over thousands of kilometers. Advances in tag miniaturization, attachment, and software will likely extend the time tags stay attached and the detail of the behavioral and environmental variables that can be monitored. As testimony to the power of this technology, this application of satellite telemetry to monitor great whales yielded one of the most extensive, long-term, continuously-monitored data sets yet recorded on the diving behavior of a baleen whale. / Graduation date: 1993

Satellite-based communications networks can provide personal communications services to markets that are unable to be serviced by terrestrial wireless networks, such as maritime, aviation, military, developing countries and remote industry. Traditional Geostationary Earth Orbit (GEO) satellite communications suffer from high transmit power requirements and long delays. In comparison, Low Earth Orbit (LEO) satellite communications do not suffer these problems, and therefore promise to provide high-quality communications services to small handheld terminals. The convergence of traditional voice, data, fixed, and mobile communications networks, has prompted the extension of common terrestrial networking protocols into terrestrial wireless and satellite networks. The research presented in this thesis focuses on the Asynchronous Transfer Mode (ATM) extensions required to support the frequent satellite handovers that occur in LEO satellite networks. / During the late 1990s, the standards organisation known as the ATM Forum drafted a Wireless ATM (WATM) specification, which included the handover procedures for use in terrestrial WATM networks. It is advantageous to broaden the use of the terrestrial handover procedures to handover scenarios in a LEO satellite network, based on the Iridium constellation, and specifically focuses on the Quality of Service (QoS) provided during handover. / The first contribution of this thesis (Chapter 4) is the identification of a number of performance deficiencies within the ATM forum handover procedures when used in a typical LEO satellite network. The performance deficiencies were identified through analysis of the handover signalling and functionality used in the handover procedure, and were quantified through simulation of the handover procedure (Chapter 7) using the OPNET Modeler discrete event simulation tool. The performance deficiencies result in significant and unacceptable ATM cell loss and increases in ATM cell delays, which have the potential to cause a significant user perceived interruption in communications during handover. / The primary cause of poor performance in the ATM Forum handover procedure is the lack of ATM functionality to specifically control the handover of ATM cells from the existing ATM connection to the new ATM connection. The second contribution (Chapter 5) is the specification of novel ATM-attuned signalling and functionality to improve this aspect of the handover. The new functionality allows an incremental handover of ATM cells to be performed which, in combination with the new signalling messages to support this process, eliminates the potential for ATM cell loss and minimises the increases in ATM cell delay. / The third contribution of this thesis (Chapter 6) is the specification of two new handover procedures, which exploit the novel ATM signalling and functionality described above, to provide a lossless low-delay handover in a LEO satellite network. / The fourth and final contribution (Chapter 7) is the simulation and performance analysis of the ATM Forum handover procedure in a LEO satellite network based on the Iridium constellation. As far as I am aware, there are no other published attempts of its kind, thus making it a unique contribution amongst the literature. Iridium is currently the most sophisticated LEO satellite network in use today, and although it is a narrowband system, the constellation characteristics are suitable for use in a future broadband system. The OPNET Modeler discrete event simulation tool was used to create a satellite ATM simulation model, implementing the ATM Forum handover procedure, and the two new handover procedures specified in Chapter 6. Handover performance was methodically simulated using a comprehensive set of handover scenarios (i.e. handover geometries), ranging from single-user single-connection scenarios to scenarios involving hundreds of users and connections. The handover performance was analysed with respect to the ATM Cell Loss Ratio (CLR) and Cell Delay Variation (CDV) parameters, which are the primary indicators of handover performance, and with respect to the handover latency, which is a secondary indicator of performance. The performance of the ATM Forum handover procedure was shown to severely fail both the recommended ATM and WATM performance objectives in the majority of handover scenarios, rendering it unsuitable for use in a LEO satellite ATM network. Conversely, the new handover procedures suffer no ATM cell loss, and in the vast majority of handover scenarios minimise the increases in ATM cell delay. Hence, the new handover procedures are ideally suited for use in a future broadband LEO satellite ATM network. / Thesis (PhDTelecommunications)--University of South Australia, 2004.

Thesis (MEngineering)--University of South Australia, 2001

Thesis (M.S.)--Kutztown University, 1989. / Source: Masters Abstracts International, Volume: 45-06, page: 2701. Typescript. Includes bibliographical references (leaves 60-62).