Quantifying technology infusion and policy impact on low earth orbit communication satellite constellations

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics; and, (S.M.)--Massachusetts Institute of Technology, Engineering Systems Division, Technology and Policy Program, 2004.Includes bibliographical references (p. 199-204).Technology infusion and policy implementation bring impacts to the trade space of complex engineering systems. This work describes in detail the frameworks for quantitative analyses on these impacts, demonstrates their use on the sample system, and presents the analysis results. The low earth orbit (LEO) communication satellite constellation system serves as the platform for carrying out the system trade space analysis. The system is reproduced in computer environment in the form of a multiple-input-output MATLAB model. The model contains multiple modules that incorporate the physics, economy, and policies of the real-world system. The inputs to the model are system design variables and the outputs are system performance, capacity, and cost. The Pareto optimal solution set of the baseline trade space is generated by the model using a full-factorial run that covers the entire design space. To simulate technology infusion, technical and cost attributes of four new technologies are quantified and infused into the system model. The infusion of technologies and combinations of technologies into the system is simulated. Policy implementation is simulated by changing the policy constraints in the model. The technology-infused trade space and policy-implemented trade space have new sets of Pareto optimal solutions. By comparing these solution sets with the baseline optimal solution set in the objective space, we can quantify the impact of technology infusion and policy impact. In conclusion, the methodologies of quantifying the impact of technology infusion and policy implementation on complex engineering systems is repeatable and has been tested against real-world systems.(cont.) The information generated demonstrates their usefulness to technology selection and policy decision-making processes.by Darren Datong Chang.S.M

Assessing the technical, economic and policy-centered feasibility of a proposed satellite communication system for the developing world

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics; and, (S.M.)--Massachusetts Institute of Technology, Sloan School of Management, Technology and Policy Program, 2005.Includes bibliographical references (p. 213-217).Satellite communication systems remain one of the most under utilized development mediums in less industrialized countries. This research proposes to establish a low cost satellite communications system tailored specifically for the developing world (+/- 30⁰ latitude). The technical, economic and policy related frontiers of the problem are integrated within a MATLAB based satellite communication constellation simulation which is used to assess the feasibility of the proposed satellite system. The analysis demonstrates that with technical advances that would allow higher capacity systems at lower costs and a renewed policy framework in line with the present state of the satellite system industry, it could be feasible to establish a low earth orbit satellite communications system for the developing world. The inputs to the satellite simulation are the proposed system's desired design variables and other relevant parameters. The outputs are system performance, capacity and cost. The Pareto optimal solution trade space is generated by the simulation model using a full-factorial run that probes the entire design space. The application of choice is short messaging services (SMS), chosen for its ability to provide proven connectivity at moderate costs. The capacity and cost of the most ideal Pareto architecture is contrasted against demand in the defined developing world region. The simulation also accounts for the necessary policy considerations and assesses the feasibility of the proposed system amidst the existing industry policy and regulatory framework. Additionally, data regarding the current economic standing of the region and how this forms an underlying basis for the digital divide is presented and assessed.(cont.) The policy and regulatory constraints on the acceleration of telecommunications development throughout the developing world are discussed. This thesis elaborates upon the need for a focus on design for affordability if satellite communication systems are to realize their immense potential for the delivery of needed social services to the world's marginalized.by Ayanna Terehas Samuels.S.M

Distributed satellite communications system design : first-order interactions between system and network architectures

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2005.Includes bibliographical references (p. 159-165).Humanity now exists in the midst of the fast-moving Information Age, a period of history characterized by fast travel and even faster information transfer. As data becomes seemingly more valuable than physical possessions, the introduction of exciting applications for communications services becomes ever more critical for the success - and in some cases, survival - of businesses and even nations. While the majority of these innovations have occurred over cable and fiber, a number of the most socially significant have occurred due to the introduction of satellites. Terrestrial fiber and cable systems have a number of advantages, but the extent of their reach and the cost of installation - in terms of both capital and time - favor industrialized nations over more remote and underdeveloped communities. Even as satellites offer the only real chance for ultimate communications ubiquity and true global unity, there remains a significant cost-benefit barrier. Few commercial satellite systems have succeeded economically without first falling victim to bankruptcy. The upfront capital required to implement a satellite communications system is staggering, and historically satellite companies have failed to adequately match capacity and service options to the current and actual future demand. The design process itself is an inherent limiting factor to the achievable cost and performance of a system.(cont.) Traditionally, the first step toward designing satellite communication systems - as well as terrestrial, sensor web, and ad hoc networks - has been to specify the system topology (e.g., the orbits of the satellites and the locations of the ground stations) based on the desired market and then to design the network protocols to make the most of the available resources. Such a sequential process assumes that the design of the network architecture (e.g., protocols, packet structure, etc) does not drive the design of the system architecture (e.g., constellation topology, spacecraft design, etc). This thesis will show that in the case of Ka-band distributed satellite communication systems this fundamental assumption is not valid, and can have a significant impact on the success (cost, capacity, customer satisfaction) of the resulting satellite communication system. Furthermore, this thesis will show that how a designer values performance during the design and decision process can have a substantial impact on the quality of the design path taken through the trade space of possible joint architectures.by Jennifer E. Underwood.S.M

Reconfigurability in space systems : architecting framework and case studies

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2006.Includes bibliographical references (p. 247-257).Reconfigurability in engineered systems is of increasing interest particularly in Aerospace Systems since it allows for resource efficiency, evolvability, and enhanced survivability. Although it is often regarded as a desirable quality for a system, it has traditionally been difficult to quantitatively analyze its effects on various system properties in the early design stage. In order to allow for gaining an in-depth understanding of the various aspects of reconfigurability and its relationship with a system's architecture, a framework encompassing a set of definitions, metrics, and methods has been proposed. Two different modeling schemes, based on Markov models and controls theory, are first developed to show how the states and time aspects of reconfigurable systems can be naturally modeled and studied. An analytical model for quantifying the effect of reconfigurability on mission logistics, specifically spare parts demands, is formulated and it is shown through one specific example that reconfigurable parts can allow for 33-50% mass reduction. The system availability, however, becomes very sensitive to the reliability of the parts. Two case studies are then used for detailed illustration of the application of the developed framework.(cont.) In the first case study, the effect of reconfigurability on a fleet of planetary surface vehicles for a surface exploration mission are analyzed. It is found that a fleet of reconfigurable vehicles can allow for a mass savings of up to 27% and their expected transport capability degradation is almost three times lower as compared to a fleet of non-reconfigurable vehicles. In the second case-study, the reconfiguration of low earth-orbit communication satellite constellations is considered for evolving to higher capacity levels. It is found that reconfiguring a previously deployed constellation can be a viable option only for certain capacity levels and multi-payload launch capability scenarios. In addition to the high level 'ility' perspectives, a lower level design assessment is also carried out through a survey of 33 representative reconfigurable systems. It is found that on average, for commercial items the cost of reconfigurability is 35%, and the average useful state occupancy time is always at least 10 times the reconfiguration time of the system. Based on the illustrative results of the case studies, and generalization of empirical data, a few principles and guidelines for design for reconfigurability are proposed.by Afreen Siddiqi.Ph.D

Navigating the Deployment and Downlink Tradespace for Earth Imaging Constellations

Distributed Spacecraft Missions (DSMs) are gaining momentum in their application to Earth Observation (EO) missions owing to their unique ability to increase observation sampling in spatial, spectral, angular and temporal dimensions simultaneously. DSM design includes a much larger number of variables than its monolithic counterpart, therefore, Model-Based Systems Engineering (MBSE) has been often used for preliminary mission concept designs, to understand the trade-offs and interdependencies among the variables. MBSE models are complex because the various objectives a DSM is expected to achieve are almost always conflicting, non-linear and rarely analytical. NASA Goddard Space Flight Center (GSFC) is developing a pre-Phase A tool called Tradespace Analysis Tool for Constellations (TAT-C) to initiate constellation mission design. The tool will allow users to explore the tradespace between various performance, cost and risk metrics (as a function of their science mission) and select Pareto optimal architectures that meet their requirements. This paper will describe the different types of constellations that TAT-Cs Tradespace Search Iterator is capable of enumerating (homogeneous Walker, heterogeneous Walker, precessing type, ad-hoc) and their impact on key performance metrics such as revisit statistics, time to global access and coverage. We will also discuss the ability to simulate phased deployment of the given constellations, as a function of launch availabilities and/or vehicle capability, and show the impact on performance. All performance metrics are calculated by the Data Reduction and Metric Computation module within TAT-C, which issues specific requests and processes results from the Orbit and Coverage module. Our TSI is also capable of generating tradespaces for downlinking imaging data from the constellation, based on permutations of available ground station networks - known (default) or customized (by the user). We will show the impact of changing ground station options for any given constellation, on data latency and required communication bandwidth, which in turn determines the responsiveness of the space system

ANALISIS RUGI-RUGI LINTASAN PADA SATELIT IRIDIUM YANG BEROPERASI PADA FREKUENSI UPLINK 1650 MHz

PADA SATELIT IRIDIUM YANG BEROPERASI PADA FREKUENSI UPLINK 1650 MHz. Rori Arkan Ibadillah Kartiko ArdimWidodo Sotyohadi [email protected] Abstrak Satelitiridium merupakan satelit dengan orbit rendah dan merupakan salah satu type satelit LOW (Low Earth Orbital). Konstelasi satelit iridium terdiri dari 66 satelit aktif di orbitnya, yang menyediakan pelayanan suara dan data ke telepon satelit, pager dan transceiver terintegrasi di seluruh permukaan bumi. Rugi-rugi lintasan (dB) didefinisikan sebagai perbedaan antara daya yang di transmisikan dengan daya yang diterima. Yang disebabkan oleh karakteristik media perantara serta adanya pengaruh lingkuangan cuaca,dll. Penelitian untuk mengetahui rugi-rugi lintasan pada satelit iridium dengan Uplink 1650 MHz pada kondisi lingkungan dan cuaca yang ada diperlukan untuk mengetahui feasibility system komuikasi tersebut. Hasil pengukuran daya terima melalui antenna penerima yang dihubungkan dengan sebuah spectrum analyzer dibandingkan dengan hasil perhitungan teoritis daya terima dalam dB. Dari kedua hasil tersebut dilakukan Analisa dan evaluasi terhadap perbedaan yang ada. Dalam penelitian dikaji terhadap tiga buah satelit iridium yaitu satelit iridium 32,45,dan 60 serta di kaji juga terhadap kondisi cuaca cerah dan mendung. Lokasi penelitian ini dilakukan di Gedung workshop Teknik elektro ITN malang kampus 2. Hasil Analisa menunjukkan semakin besar jarak maka daya terima makin kecil, yang berarti juga rugi-rugi lintasan semakin besar. Terdapat perbedaan hasil pengukuran dengan teoritis 2 – 4 dB. yang disebabkan antara lain factor cuaca, redaman atmosfer,serta gain dari gain antenna penerima. Sedangkan untuk kondisi cuaca cerah dan mendung, daya terima satelit iridium tidak begitu berbeda. Kata kunci:satelit iridium, rugi-rugi lintasa, feasibility system,daya terima. ANALISIS RUGI-RUGI LINTASAN PADA SATELIT IRIDIUM YANG BEROPERASI PADA FREKUENSI UPLINK 1650 MHz. Rori Arkan Ibadillah Kartiko ArdimWidodo Sotyohadi [email protected] Abstract Iridium satellite is a satellite with low orbit and is one type of satellite LOW (Low Earth Orbital). The iridium satellite constellation consists of 66 active satellites in its orbit, which provide voice and data services to satellite phones, pagers and integrated transceivers across the entire surface of the earth. Track losses (dB) are defined as the difference between the transmitted power and the received power. Which is caused by the characteristics of the intermediary media and the influence of the weather environment, etc. Research to determine the path losses on iridium satellites with Uplink 1650 MHz on existing weather and environmental conditions is needed to determine the communication feasibility system. The measurement results of receiving power through the receiving antenna connected to a spectrum analyzer compared to the results of theoretical calculations of acceptability in dB. From the two results, an analysis and evaluation of the differences was carried out. In the study studied three iridium satellites, i.e. iridium 32.45 and 60 satellites and also studied the conditions of sunny and cloudy weather. The location of this research was carried out at the Electrical Engineering Workshop in ITN campus 2. The analysis results showed that the greater the distance, the smaller the receiving power, which meant the greater the loss of the track. There are differences in the measurement results with theoretical 2-4 dB. caused by weather factors, atmospheric attenuation, and gain from the receiver antenna gain. As for sunny and cloudy weather conditions, the reception of iridium satellites is not so different. Keywords: iridium satellite, track loss, feasibility system, receiving power

The strategic evolution of systems : principles and framework with applications to space communication networks

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2009.Cataloged from PDF version of thesis.Includes bibliographical references (p. [369]-377).Complex systems in operation are constrained by legacy; in other words, the existing properties, structure, components, protocols, software, people and etc. that are inherited over time. This inheritance heavily influences the type and timing of feasible and available changes to the system, the effectiveness and desirability of their impact while accounting for uncertainty, and the future constraints imposed as a result. This thesis introduces the Strategic Evolution of Systems, a novel framework for evolving complex systems that directly addresses legacy challenges during system operation within the context of space communication networks. The framework - perspective, position, plan and pattern - is based on Mintzberg's "emergent" interpretation of strategy. This thesis also presents several unique ideas including the concept of option lock-out, or the tendency to lose access to potentially desirable regions of the architectural space when exercising a transition; an energy analogy to model static architecture value; an entropy-based formulation to evaluate the desirability, or dynamic multidimensional value, of an architecture by considering the structural and temporal space of possible transitions; and the application of the entropy-based formulation to define the overall desirability of an architecture as its position, or current situation (favorable or unfavorable) relative to accessible alternatives, in order to identify the most advantageous immediate transition. A key contribution of this thesis is a method to value legacy in a physical non-market traded system, including a demonstration of its application to a system in which benefits and costs are nonmonetary in nature.(cont.) Other important contributions include a change exposure tool, referred to as a Strategic Advantage Map, to visualize the near- and long-term impact of immediate transitions relative to legacy. Here, an architecture's position relative to the legacy system can be thought of as the region of entropy space it occupies (evaluated over time and uncertainty). The more dominating this region of position entropy is, the more desirable the architecture. For monetary-based systems, a second change exposure tool includes an "Iceberg Exposure,"which maps the exposure of net present value for each accessible transition option relative to a neutral no-gain-no-loss line, resulting in a graph resembling an iceberg. The visualization tools allow decision makers to quickly evaluate the impact (risk/opportunity) of change, based on their concept of desirability. Case studies include a historical look at the NASA Deep Space Network for insight into legacy and complex system evolution, a demonstration of the Strategic Evolution of Systems framework for a global commercial satellite communication system, and an illustration of the method extended to non-monetary systems for the deployment of communication assets to support manned exploration of Earth's moon. The satellite system case study introduces an extended market model that evaluates the attainable business segments in a global satellite communications system by integrating estimates of the global distribution of market demand, observed traffic statistics, and calculations of the resulting steady-state network performance.(cont.) This thesis will show how to use the framework and principles for evaluating a system's current position as well as how to update the evaluation as time progresses. The satellite communication case study will provide one example where the methodology enables identification of the optimal transition path over the system's operational life. It will become evident that the choice of horizon time and the use of debiasing factors can have significant influence on the results. Future study on properly identifying and constructing these variables is strongly recommended. Finally, the ideas and tools presented in this thesis may be used to compare preferred systems to suggested alternatives in order to justify expenditures or to initiate research and development programs.by Jennifer E. Manuse.Ph.D

Telecommunications Networks

This book guides readers through the basics of rapidly emerging networks to more advanced concepts and future expectations of Telecommunications Networks. It identifies and examines the most pressing research issues in Telecommunications and it contains chapters written by leading researchers, academics and industry professionals. Telecommunications Networks - Current Status and Future Trends covers surveys of recent publications that investigate key areas of interest such as: IMS, eTOM, 3G/4G, optimization problems, modeling, simulation, quality of service, etc. This book, that is suitable for both PhD and master students, is organized into six sections: New Generation Networks, Quality of Services, Sensor Networks, Telecommunications, Traffic Engineering and Routing

Bibliography of Lewis Research Center technical publications announced in 1992

This compilation of abstracts describes and indexes the technical reporting that resulted from the scientific and engineering work performed and managed by the Lewis Research Center in 1992. All the publications were announced in the 1992 issues of STAR (Scientific and Technical Aerospace Reports) and/or IAA (International Aerospace Abstracts). Included are research reports, journal articles, conference presentations, patents and patent applications, and theses