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1
ALMEIDA, MARTA PUDWELL CHAVES DE. "RADIOPROPAGATION IN SATELLITE COMMUNICATION SYSTEMS." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 1996. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=9622@1.
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O desenvolvimento de sistemas de comunicações via satélite
requer a introdução de novas tecnologias e novas técnicas,
e o uso de freqüências elevadas superiores a 10 GHZ. Para
aplicações utilizando freqüências acima de 10 GHz, deve
ser considerada predominantemente a atenuação causada pela
chuva.
Este trabalho apresenta resultados intermediários de uma
campanha de medidas realizada no CETUC, na faixa de 12
GHz. Esta campanha foi iniciada em 1987 com a realização
de medidas radiométricas em diferentes regiões climáticas
do Brasil. Em 1995, foram adquiridos sistemas de recepção
de sinais de beacon de satélite. O principal objetivo das
medidas é a aquisição das distribuições estatísticas de
longo termo da atenuação causadas pela chuva, a serem
utilizadas no planejamento e dimensionamento de futuros
sistemas de comunicações via satélite. Além das
distribuições cumulativas de longo termo, são analisadas:
a variabilidade das distribuições ano a ano, as
estatísticas de pior mês, as características dinâmicas da
atenuação por chuva, a dependência da ocorrência de
atenuação com a hora do dia, a distribuição da taxa de
precipitação e a previsão da atenuação a partir da taxa de
precipitação.The development of satellite communication systems requires the introduction of new technologies and techniques as well as the use of high frequencies, above 10GHz. Above such frequencies, rainfall induced attenuation effects, which are strongly frequency dependent, become important as the main source of reliability impairment. Thid work presents the intermediate results from a measurements campaign at 12GHz. This campaign began in CETUC in 1987 with radiometric measurements on several different Brazilian climatic regions. In 1995, systems for receiving satellite beacon signal were acquired. The main objective of the satellite beacon measurements is to obtain the long term distributions of rainfall induced attenuation, which will be used to aid the planning and design of future satellite communication systems. Besides the long term distributions of attenuation, the following results will be sought out: year-to-year variability of the attenuation distributions,worst-month statistics, the dynamic characteristics of rainfall induced attenuation, the daily variation of the occurrence of attenuation events, rainfall rate distributions and the possibility of modelling the attenuation as a function of the rainfall rate.
2
Mohanty, Nirode C. "DEMAND ACCESS SATELLITE COMMUNICATION SYSTEMS." International Foundation for Telemetering, 1985. http://hdl.handle.net/10150/615594.
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International Telemetering Conference Proceedings / October 28-31, 1985 / Riviera Hotel, Las Vegas, NevadaA demand access Satellite Communication System for multiple users has been analyzed. A number of channels, m 1, of each satellites are necessary to coordinate the self-served users to allow access to a satellite having s channels. m depends upon traffic intensity and number of top priority users. A waiting time period for a Poisson arrival and exponential holding time M/M/s system for “preemptive resume” discipline has been derived. There is a significant reduction in waiting time in accessing the channel and in transmission time over other access schemes. There is no waiting time for a top priority user, either in accessing the channel or in transmitting its messages, when the appropriate number of order wires is used.
3
Paul, Jean R. "Communication platform for inter-satellite links in distributed satellite systems." Thesis, University of Surrey, 2011. http://epubs.surrey.ac.uk/770149/.
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A Distributed Satellite System (DSS) for space weather monitoring, in which satellites are able to exchange data via Inter-Satellite Links (lSL) and a master node communicates with ground is the target of this research. As design of satellite systems is dictated by economical and engineering factors, the use of readily available commercial wireless terrestrial network technologies for ISLs is an attractive prospect in distributed satellite systems. This work addresses the application of wireless terrestrial networking standards to DSS operating in Low Earth Orbits (LEO), which are affected by orbital dynamics. All communication factors such as range, antenna gain, velocity, etc. vary with time, and as a result adaptive on-board data processing and transmission techniques are necessary to provide system responsiveness to orbital effects. A novel analysis of the impact of satellite attitude on the antenna loss is carried out and the minimum beam width that ensures ISL is determined. A high performance System-On-Chip (SoC) computing platform capable of supporting the adaptive MAC method has been simulated, and then implemented on hardware. The SoC design features a IEEE802.11 wireless transceiver core developed to support ISL, which is controlled by a software application running on the LEON3 32-bit RISC processor. The SOC is implemented on an FPGA for dynamic reconfigurability purposes, and the wireless transceiver is designed with the aim of extending the communication range of traditional wireless networks to hundreds of kilometres. The range determination mechanism can be hard-coded or defined in software. The Space Wire protocol, which is becoming the de facto standard for on-board spacecraft networks, is not yet defined for wireless communications. A bridge is proposed allowing fault-tolerant intra-spacecraft Space Wire networks to communicate via inter-satellite links. An analysis of the hardware requirements is presented for medium date rate systems. This reveals that the IEEE802.11 transceiver, implemented as a hardware accelerator, has the capability to support the full range of data rate provided by SpaceWire links, and adds extra robustness to SpaceWire networks.
4
Ah-Thew, George Patrick. "Doppler compensation for LEO satellite communication systems." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape11/PQDD_0005/NQ42831.pdf.
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Zapata, Augusto J. "Analysis of maritime mobile satellite communication systems." Thesis, Monterey, California. Naval Postgraduate School, 1988. http://hdl.handle.net/10945/22890.
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Leelaratne, D. R. V. "Printed antennas for mobile satellite communication systems." Thesis, University of Kent, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.369608.
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Sabala, Ryan J. "Satellite Attitude Determination Using Laser Communication Systems." Ohio University / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1218636153.
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Alouini, Mohamed-Slim. "Impact of the atmosphere on K [subscript a]-Band satellite communication systems." Thesis, Georgia Institute of Technology, 1995. http://hdl.handle.net/1853/15364.
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9
Marzolini, Remo G. A. "Demodulator techniques in satellite communication systems for direct broadcast systems." Thesis, Open University, 1996. http://oro.open.ac.uk/57636/.
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This thesis is concerned with the FM demodulator techniques used in terrestrial TV receiver designs for Direct Broadcast Systems (DBS) from satellites. The various MAC/Packet schemes intended for DBS applications are described and the international standards that apply to them considered, with particular emphasis on the D2-MAC system. Noise in FM systems is discussed and a suitable threshold noise model is chosen for use in DBS TV demodulator systems. The characteristics of the various types of noise effects are considered in terms of their effect upon the TV picture. The threshold performance of a conventional FM demodulator for differing types of modulation is reviewed and it is shown how the threshold characteristic depends upon the nature of the modulation. The literature review carried out represents a significant component of the thesis and combines material from patent literature with more conventional source materials from professional journals, conferences, textbooks, etc. Some ten existing demodulator concepts that exhibit threshold extension characteristics are examined, and where relevant their potential performance in D2-MAC format systems is assessed. The demodulator characteristics that limit their performance in TV systems are identified. It is concluded that designing a threshold extension demodulator, with reliable operation, for all picture contents and for a wide range of input carrier-to-noise ratios, is a formidable task using existing design techniques. On the basis of this examination an adaptive threshold extension demodulator concept is proposed, that utilises information contained within the signal structure to achieve an improved performance over a wide range of input carrier-to-noise ratios and picture content. It is shown how the relevant signal structures may be derived from conventional (PAL, SECAM and NTSC), MAC format and all-digital television systems. Illustrations are given that show how the adaptive demodulator concept can be applied to certain existing threshold extension demodulators, enhancing their performance for television picture reception. Future trends in all-digital DBS TV systems intended ultimately for DBS applications are briefly discussed together with their demodlilation requirements.
10
Muratori, Erik. "Analysis of Space Communication Systems via Satellite Relaying." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2021. http://amslaurea.unibo.it/22837/.
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È noto che l’uso di bande a RF con frequenze estremamente alte nei sistemi wireless per comunicazione digitale consente potenzialmente di raggiungere velocità di trasmissione dei dati molto elevate, rispetto a quelli ottenibili a frequenze più basse, a parità di tasso di errore. Ciò è vero in particolare per propagazione in spazio libero con antenne direttive. Tali bande di frequenza estremamente elevate sono tuttavia raramente impiegate nelle comunicazioni spaziali deep-space a causa della loro vulnerabilità ai disturbi atmosferici. Tuttavia, esse possono potenzialmente fornire diversi vantaggi nei collegamenti di telemetria deep-space nell'ambito di architetture “two-leg” con relay satellitare orbitante fuori dall'atmosfera terrestre. In tale configurazione, il collegamento da spazio remoto a relay, non influenzato dall’atmosfera terrestre, può utilizzare una banda di frequenze estremamente elevata (compatibilmente con vincoli di carattere tecnologico), mentre il collegamento da relay a ground station può utilizzare una banda più classica, ad esempio una delle bande raccomandate per comunicazioni near-Earth. Lo scopo della tesi è stato quello di confrontare le prestazioni di architetture “two-leg” con quelle ottenibili da un collegamento deep space diretto da spacecraft a ground, in banda X oppure in banda Ka. La valutazione è stata possibile attraverso la creazione di link budget accurati, che includono l'effetto dell'atmosfera e gli errori di puntamento, e analizzando le due diverse comunicazioni, mostrando in che condizioni è possibile avere un miglioramento delle prestazioni.
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Beyene, Dereje, and Befkadu Degefa. "Adaptive Antenna Arrays for Satellite Mobile Communication Systems." Thesis, Linnaeus University, School of Computer Science, Physics and Mathematics, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-191.
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Adaptive antenna arrays have a great importance in reduction of the effect of interference and increase the capacity for the mobile satellite communication. Interference and multipath fading remain a main problem for reception of signals. These two problems obviously affect the overall capacity. Adaptive antenna arrays in the handheld mobile apparatus will be the solution for the above two problems.
Satellite mobile communication is one of the growing fields in the communication area where terrestrial infrastructures are unable or ineffective to supply. Maritime, aeronautical and land mobile are some of the applications. During natural disasters where ground services are stopped, mobile satellite communications has great importance. Following the hurricane season, the Asian Tsunami and the devastating Haiti earthquake, mobile satellite communications had played a great role to fill the communication gaps. The satellites can be tracked automatically by adaptive antenna array when it moves in its orbital plane.
In this thesis the methods that how the adaptive antenna array combats interferers is presented and simulated using MATLAB software. The performance of the adaptive antenna array is evaluated by simulating the directivity pattern of the antenna and Mean Square Error (MSE) graph for different scenario like Signal to Interference Noise ratio (SINR), number of iterations, antenna array elements and convergence factor (μ), assuming the signals are coming from different Direction of Arrival (DOA).
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Karpinsky, Christopher J. (Christopher John) 1972. "Uplink multiple access techniques for satellite communication systems." Thesis, Massachusetts Institute of Technology, 1998. http://hdl.handle.net/1721.1/49644.
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Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1998.Includes bibliographical references (leaves 90-92).
by Christopher J. Karpinsky.
M.S.
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Lian, Keng Jin. "Adaptive Antenna Arrays for Satellite Personal Communication Systems." Thesis, Virginia Tech, 1997. http://hdl.handle.net/10919/36949.
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Since about the turn of the decade, several proposals have come forth for personal communication services implemented by means of multiple satellite systems. These satellite systems are similar to current terrestrial cellular technologies, which are still relatively new and have numerous technical problems associated with them. As a result, these satellite systems will also experience some of the similar problems. Two of such problems are the issue of multipath and interference. These problems may result in significant link degradation and affect overall capacity. To overcome this problem, adaptive antenna arrays on handheld terminals are proposed. This technique is believed to be better than omni-directional antennas which radiate in all directions. Adaptive antenna arrays have the ability to adapt to the changing environment and null out the interference. The LMS algorithm was investigated and used in the simulation of the adaptive array. The performance of the LMS array was discussed in detail. In the case of a multipath, an alternate approach was proposed where a diversity combiner is used to phase shift the multipath and combine the Signal of Interest and multipaths constructively.Master of Science
14
Talal, Mohammed. "Modem design for digital satellite communications." Thesis, Loughborough University, 1997. https://dspace.lboro.ac.uk/2134/7442.
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The thesis is concerned with the design of a phase-shift keying system for a digital modem, operating over a satellite link. Computer simulation tests and theoretical analyses are used to assess the proposed design. The optimum design of both transmitter and receiver filters for the system to be used in the modem are discussed. Sinusoidal roll-off spectrum with different roll-off factor and optimum truncation lengths of the sample impulse response are designed for the proposed scheme to approximate to the theoretical ideal. It has used an EF bandpass filter to band limit the modulated signal, which forms part of the satellite channel modelling. The high power amplifier (HPA) at the earth station has been used in the satellite channel modelling due to its effect in introducing nonlinear AMAM and AM-PM conversion effects and distortion on the transmitted signal from the earth station. The satellite transponder is assumed to be operating in a linear mode. Different phase-shift keying signals such as differentially encoded quaternary phase-shift keying (DEQPSK), offset quaternary phase-shift keying (OQPSK) and convolutionally encoded 8PSK (CE8PSK) signals are analysed and discussed in the thesis, when the high power amplifier (HPA) at the earth station is operating in a nonlinear mode. Convolutional encoding is discussed when applied to the system used in the modem, and a Viterbi -algorithm decoder at the receiver has been used, for CE8PSK signals for a nonlinear satellite channel. A method of feed-forward synchronisation scheme is designed for carrier recovery in CE8PSK receiver. The thesis describes a method of baseband linearizing the baseband signal in order to reduce the nonlinear effects caused by the HPA at the earth station. The scheme which compensates for the nonlinear effects of the HPA by predistorting the baseband signal prior to modulation as opposed to correcting the distortion after modulation, thus reducing the effects of nonlinear distortion introduced by the HPA. The results of the improvement are presented. The advanced technology of digital signal processors (DSPs) has been used in the implementation of the demodulation and digital filtering parts of the modem replacing large parts of conventional circuits. The Viterbi-algorithm decoder for CE8PSK signals has been implemented using a digital signal processor chip, giving excellent performance and is a cost effective and easy way for future developments and any modifications, The results showed that, by using the various studied techniques, as well as the implementation of digital signal processor chip in parts of the modem, a potentially more cost effective modem can be obtained.
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Botha, Jakobus Stephanus. "A reusable signal processing architecture for satellite based communication systems." Thesis, Stellenbosch : University of Stellenbosch, 2011. http://hdl.handle.net/10019.1/6503.
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Thesis (MScEng (Electrical and Electronic Engineering))--University of Stellenbosch, 2011.ENGLISH ABSTRACT: Keywords: digital signal processing, embedded systems, telecommunications, satellite technology. The rapid growth of the telecommunications industry is a worldwide phenomenon with people and computers generating and transmitting more and more information daily. Despite this growth, there are still areas in South Africa which lack terrestrial communications coverage. People inhabit these rural areas and their essential communication needs are not met. Satellite based communication coverage can provide a valuable service in these circumstances. In this thesis, the design of a satellite-based communications payload which makes use of software de ned radio techniques is presented in terms of the Open Systems Interconnect layer structure. A robust hardware platform using a space-quali ed on-board computer, a Xilinx Virtex-5 Field Programmable Gate Array (FPGA) and a Freescale digital signal processor (DSP) is designed, implemented and thoroughly tested. A device driver is designed for hardware and rmware components. A prototype ground station is also designed and constructed using a low-power PC, a Xilinx Spartan-3E FPGA, a Freescale DSP and radio frequency hardware. A wide range of testing methodologies were successfully utilised to deploy a functional system which is critically evaluated in the last chapter.
AFRIKAANSE OPSOMMING: Sleutelwoorde: syferseinverwerking, toegewyde stelsels, telekommunikasie, satelliettegnologie. Die vinnig groeiende telekommunikasieindustrie is 'n wêreldwye verskynsel waarin mense en rekenaars daagliks meer en meer data genereer. Ten spyte van die groei, is daar nog steeds gebiede in Suid-Afrika wat aan 'n gebrek van aardse kommunikasiedekking lei. Mense bewoon dié areas maar daar word nie aan hul noodsaaklike kommunikasiebehoeftes voldoen nie. Satelliet-gebaseerde kommunikasiedekking kan 'n waardevolle diens in hierdie omstandighede wees. Hierdie tesis beskryf die ontwerp van 'n ruimtegebaseerde kommunikasieloonvrag wat gebruik maak van sagteware-gede nieerde radiotegnieke aangebied in terme van die Open Systems Interconnect laagstruktuur. 'n Robuuste apparatuurplatform wat gebruik maak van 'n ruimte-gekwali seerde rekenaar, 'n Xilinx Virtex-5 Veldprogrameerbare Hek-Skikking (VPHS) en 'n Freescale syferseinverwerker is ontwerp, geïmplementeer en deeglik getoets. 'n Toestelbestuurder moes ontwerp word vir die apparatuur- en fermatuur-komponente. 'n Prototipe grondstasie is ook ontwerp en gebou met behulp van' n lae-krag PC, 'n Xilinx Spartan-3E VPHS, 'n Freescale seinverwerker en radiofrekwensie apparatuur. 'n Wye verskeidenheid van toetsmetodes is suksesvol benut om 'n funksionele stelsel te ontwikkel wat krities geëvalueer word in die laaste hoofstuk.
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Sammut, Anthony J. R. "Radio resource management for satellite personal communication networks." Thesis, University of Surrey, 1999. http://epubs.surrey.ac.uk/843349/.
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A novel flexible channel allocation scheme is proposed which is applicable to medium altitude, high diversity satellite personal communication systems with an interconnected ground control segment. The scheme is built upon the establishment of several temporal master-slave network hierarchies in distinct areas of the Earth, whereby the control of radio resources in each area is granted to a single network entity, the master, located at one of the network's fixed earth station sites. The master station is entrusted with the radio resource management functionality equivalent to a base station controller in GSM, whereas the slaves, which consist of all FES sites which control satellites that have a current connectivity with the master's area, share the functionality of a GSM base transceiver station with the satellites under their control. The master maintains a table of all channel allocations within its control area in real-time, its objective is to maximise the number of channels which can be provided in its area, in response to channel requests by users, subject to known interference criteria. It can achieve this by optimising the existing and future channel allocations through the use of predictive satellite coverage, spotbeam gain models and genetic algorithms. Radio resource related signalling between master and slave stations is performed through a dedicated terrestrial fibre-optic network which interconnects the FES sites, based upon GSM interface specifications which are adapted to account for the increased propagation delays and signalling load associated with the regional network. The potential capacity gain which is available through a centralised optimisation approach over a fixed channel allocation scheme is determined through simulation. The instantaneous capacity of each scheme is highly dependent on the traffic distribution and the positions of the satellites, which causes an analytical approach to be too restrictive or simplistic. The capacity gain estimation is performed over a time period for which several samples are taken and a powerful adapted genetic algorithm is applied to the NP complete problem to determine the maximum capacity. The flexible dynamic system, entitled the hybrid-centralised DCA scheme, is shown to have a raw capacity potential in excess of the FCA scheme under the traffic distribution scenario adopted.
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He, Xiaoping. "The signalling system in satellite personal communication networks." Thesis, University of Surrey, 1996. http://epubs.surrey.ac.uk/844181/.
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Recent advances in both satellite and terrestrial mobile communications technologies are now leading to the realisation of the dream of the global personal communications within a few years. Satellite systems, as a complement to terrestrial cellular systems, are introduced into the future Personal Communication Networks (S-PCN) to provide global coverage and to allow global roaming. The inter-working and the integration between the satellite and the terrestrial cellular systems (e.g. GSM system) are the key issues in developing the network architecture and designing the control functions and signalling protocols of satellite systems. This thesis focuses on the design of a satellite signalling control system. The coverage and link properties of ICO10 and LE066 satellite constellations, the representatives of low earth orbit (LEO) and medium earth orbit (MEO) satellite systems, are considered. A satellite specific network architecture is proposed to accommodate the requirements of satellite dynamics and resource control function. The physical layer of satellite signalling links are designed to cope with the specific features of LEO or MEO satellite air-interfaces. In order to overcome problems specific to LEO or MEO satellite systems and to provide call set-up control function, three important signalling protocols are proposed for the S-PCNs. The priority based fast access scheme is designed for the satellite random access channel allowing low access delay for the call set-up related access packets, even when the channel load is high. The satellite diversity based paging approach is proposed to optimize the paging performance. The modified selective re-transmission (M-SRT) and Go-Back-N (M-GBN) protocols are proposed to cope with the transaction type transmission on the dedicated control channel. Simulation results have shown siginficant improvement of the M-SRT and M-GBN protocols in call setup delay. Two protocols are also compared in the aspects of implementation complexity and call set-up performance. Finally, the integration scenarios between satellite and GSM system have been examined for S-PCN in the call handling related functions and associated signalling protocols. The GSM higher layer signalling protocols are tailored to provide the call control related functions. The optimum integration scenario is derived under the criterion of minimum modifications to the GSM higher layer signalling protocols and minimum complexities of the control functions.
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Leitao, M. J. M. "Propagation factors affecting the design of satellite communication systems." Thesis, University of Bradford, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.355235.
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Higuchi, Nathan K. "UHF Applications for Radar and Pico-Satellite Communication Systems." Thesis, University of Hawaii at Manoa, 2002. http://hdl.handle.net/10125/6948.
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This thesis first discusses the design, fabrication, and test results of UHF preamplifier designed to operate from 400 to 500 MHz. The preamplifier integrates a single-pole double-throw (SPDT) switch, tapped-line interdigital filter, balanced low-noise amplifier, and gain stage in a compact, multilayer package. The switch and amplification stages are realized on one layer, and the stripline filter is realized on a second layer. The circuit board dimensions measure 4 inches x 1.25 inches x 0.12 inches. One hundred eight units were manufactured. The preamplifier has a 3-dB bandwidth of 100 MHz, 31 dB gain, 3 dB noise figure, and 30.6 dBm output third-order intercept. The second part of the thesis discusses the CubeSat project at the University of Hawaiʻi and presents an analysis on the radiation pattern of the active antenna on the cube satellite. The analysis for the active antenna compares two antenna models to the measured results of a 4x4 grid oscillator. The first approximation model is a rectangular aperture spaced away from a mirror, and the second model is a dipole array spaced from a mirror. Two simulation experiments are presented to show how the spacing between the grid and mirror compares to the measured data and which antenna model more accurately predicts the radiation pattern.xi, 78 leaves
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De, Gaudenzi Riccardo. "Code division multiple access for satellite personal communication systems /." Noordwijk : ESA, 1999. http://www.gbv.de/dms/goettingen/303779977.pdf.
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Polaha, James Henry. "An analysis of low-earth-orbit-satellite communication systems." Thesis, Virginia Polytechnic Institute and State University, 1989. http://hdl.handle.net/10919/74533.
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There is an ever increasing need for low-cost communication systems in the world. One such system, low-earth-orbit satellites, can provide store-and-forward, as opposed to real time, communication for many earth stations. The advantages and disadvantages of such a system is presented. Material covering protocols and communications architectures is elaborated upon for the use of amateur radio communications. Doppler shift and its effect on satellites in low-earth-orbit is examined. Efficiency and throughput of the Amateur X.25 Protocol will be explored. The last chapter entails the analysis of the PACSAT experiment.Master of Science
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Tiainen, Arttu. "Inter-Satellite Link Antennas : Review and The Near Future." Thesis, Luleå tekniska universitet, Rymdteknik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-62541.
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The emerging trend in distributed spacecraft systems of using multiple spacecraft which share functions as opposed to independent spacecraft has given opportunities for missions previously infeasible. Inter-satellite link (ISL) communications provide a direct link within the space segment without need of an intermediate ground segment to relay the data. As the distributed spacecraft systems (DSS) have become less exotic and more complex, the need and demand for inter-satellite antenna systems has increased and the requirements for the antenna systems more diverse and become more demanding. This document is a research of the antennas currently used for ISL, already flown or will be launched in the near future. While the emphasis is strongly in the antennas, the other parts of the ISL communications sub-systems are observed. To limit the scope of the work, optical cross links are not observed in this document. ISL used only for very close proximity, such as several kilometres, are given only limited scope as the main challenges on those do not involve antennas. Furthermore, the major emphasis is given to systems which can be seen as commercially important. This document is divided in five main sections and the conclusions. In the first section the features and the challenges of ISLs are described. In the second section a parametrisation system for antennas is defined and this system is used in following sections to describe the ISL sub-systems and antenna used in them. The third part is a survey of recently flown space missions with ISLs. The fourth section is a survey on the missions which are scheduled to fly in near future and a brief survey of the solutions offered by satellite service providers and manufacturers. Due to the limited technical data available, the fourth section contains far more reverse engineering and assumptions than the survey on legacy missions. The fifth section describes the several families of ISL suitable antennas under development and discusses about several topics which relate to the ISL antenna development. In this part also are defined several example antenna specifications and the applications of those. The study concludes that antennas suitable for inter-satellite links are not inherently different from ground segment communication antennas of the S/C. The major difference is the need for greater coverage, which can be attained by multiple antenna elements, beam steering or antenna pointing. Specific considerations are needed to be taken into account and often the use of ISLs will increase the technical challenges, but it can provide solutions for problems which cannot be solved otherwise.çDie sich abzeichnende Entwicklung von Einzelsatellitensysteme hin zu Systemen mit einer Vielzahl an Plattformen gleicher Funktionalität, eröffnet Möglichkeiten für die Durchführung von Missionen die bisher als nicht praktikabel/undurchführbar bewertet wurden. Inter-satellite Link (ISL) Kommunikation stellt eine direkte Verbindung zwischen den einzelnen Komponenten eines Raumsegments zur Verfügung ohne auf ein zwischengeschaltetes Bodensegment zur Datenübertragung angewiesen zu sein. Die gestiegene Anwendungshäufigkeit und Komplexität von Distributed Spacecraft Systemen (DSS) bringen eine Erhöhung der Nachfrage bezüglich Antennen für die inter-satelliten Kommunikation mit sich, wobei die Anforderungen an diese vielfältiger und anspruchsvoller geworden sind. Diese Abschlussarbeit stellt eine Untersuchung bezüglich Antennensystemen dar, welche in der Vergangenheit, der Gegenwart sowie der nahen Zukunft ihre Verwendung in der ISL fanden und finden werden. Während auch die anderen Bestandteile eines ISL Kommunikation Subsystems betrachtet werden, liegt der Schwerpunkt der Studie maßgeblich auf den Antennen selbst. Um den Rahmen der Arbeit zu wahren wird auf die Betrachtung optischer Kommunikationssysteme verzichtet. Bei inter-satellite Link Systemen die zur Datenübertragung über kurze Distanzen von nur einigen Kilometern benutzt werden liegen die Herausforderungen nicht bei den Antennen, weswegen diese nur bedingt untersucht werden. Weiter werden besonders die Systeme betrachtet welche als wichtig für die kommerzielle Anwendung erachtet werden können. Diese Arbeit ist in insgesamt sechs Abschnitte unterteilt. Im ersten Kapitel werden zunächst die Eigenschaften und die Herausforderungen bezüglich ISLs erläutert. Ein System zur Parametrisierung von Antennen wird im zweiten Kapitel definiert um es in den folgenden Abschnitten zur Beschreibung der ISL Subsysteme anzuwenden. Eine Analyse der Instrumentierung vergangener Weltraummission mit ISL Systemen wird im dritten Kapitel durchgeführt, die Betrachtung zukünftiger Missionen erfolgt in Kapitel 4. Da für Letztere nur begrenzt technische Daten zur Verfügung stehen, beinhaltet das vierte Kapitel weitaus mehr Reverse Engineering und Annahmen als die Untersuchung abgeschlossener Missionen. Im fünften Kapitel werden verschiedenen, für die inter-satellite Kommunikation geeigneten Antennentypen beschrieben und unterschiedliche Themen bezüglich der ISL Antennenentwicklung diskutiert. Weiter werden in diesem Abschnitt verschiedene Antennenspezifikationen definiert und entsprechende Anwendungsbeispiele beschrieben. Im letzten Teil werden die gefundenen Erkenntnisse abschließend diskutiert. Die Untersuchung zeigt dass Antennen welche für die inter-satelliten Kommunikation geeignet sind, sich grundsätzlich nicht von gängigen Antennen zur Bodensegmentkommunikation des S/C unterscheiden. Der Hauptunterschied liegt in der Notwendigkeit einer größeren Abdeckung. Dies kann durch eine größere Anzahl von Antennenelementen, Strahlsteuerung oder Antennenausrichtung erreicht werden. Systemspezifische Erwägungen müssen in Betracht gezogen werden wobei die Anwendung von ISL Systemen die technischen Herausforderungen/Anforderungen erhöht. Im Gegenzug ermöglicht sie Lösungen für Probleme die auf andere Weise nicht behandelt werden können.
Une nouvelle tendance est apparue dans les systèmes décentralisés des satellites, consistant à utiliser plusieurs satellites qui partagent des fonctionnalités, plutôt que des satellites indépendants. Cela a rendu possible des missions qui étaient précédemment irréalisables. Le lien inter-satellite (ISL) permet en effet de communiquer directement dans l’espace, sans devoir utiliser le segment sol pour transmettre les données. Alors que les systèmes décentralisés des satellites (DSS) sont devenus moins exotiques et plus complexes, la nécessité et la demande de systèmes d’antennes inter-satellite se sont développées et les exigences pour les systèmes d’antennes se sont diversifiés et sont devenus plus contraignants. Ce document réalise une étude des différentes antennes actuellement utilisées pour le ISL, dont certaines sont déjà opérationnelles et d’autres seront lancées prochainement. Tandis qu’il met fortement l’accent sur les antennes en ellesmêmes, il étudie aussi les autres parties des sous-systèmes de communication ISL. Néanmoins, pour limiter la portée du document, les réticulations optiques ne sont pas abordées. De même, les ISLs utilisés pour les communications à faible portée, de l’ordre de quelques kilomètres, ne sont que brièvement évoquées, étant donné que les défis majeurs concernant ceux-ci n’impliquent pas les antennes. Au delà de ça, ce document met surtout l’accent sur les systèmes qui peuvent être vu comme commercialement importants. Ce document est divisé en cinq sections, en plus de la conclusion. Dans la première section sont décrit les caractéristiques et les challenges des ISLs. Dans la seconde section, un système de paramétrage pour les antennes est défini et ce système est utilisé dans les sections suivantes pour décrire les sous-systèmes ISLs ainsi que les antennes associées. La troisième partie donne un aperçu des récentes missions spatiales lancées avec ISLs. La quatrième section étudie quant à elle les missions prochainement programmées et donne un bref aperçu des solutions offertes par les fournisseurs et fabricants des services satellitaires. Dû à la limitation des donéees techniques disponibles, cette section est principalement basée sur l’ingénierie inverse et des hypothèses, comparé aux missions déjà lancées et discutées en section 3. Finalement, la cinquième section décrit les différentes familles d’antennes ISL sous développement et discute de plusieurs sujets liés à leur développement. Elle définit aussi plusieurs exemples de spécifications d’antennes, et les applications associées. L’étude conclut que les antennes adaptées pour les liens inter-satellite ne sont pas très différentes des antennes de communication au sol du satellite, la plus grande différence étant la nécessité d’une plus grande couverture réseau. Celle-ci peut être atteinte via l’utilisation de plusieurs antennes, l’orientation du faisceau ou le pointage de l’antenne. Des considérations particulières doivent être prises en compte et souvent, l’utilisation des ISLs augmente les défis techniques. Néanmoins, cela constitue une solution à des problèmes qui ne peuvent pas être résolus autrement.
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Lomotey, Charles. "Strategies to Recover from Satellite Communication Failures." ScholarWorks, 2019. https://scholarworks.waldenu.edu/dissertations/7032.
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In natural and manmade disasters, inadequate strategies to recover from satellite communication (SATCOM) failures can affect the ability of humanitarian organizations to provide timely assistance to the affected populations. This single case study explored strategies used by network administrators (NAs) to recover from SATCOM failures in humanitarian operations. The study population were NAs in Asia, the Middle East, Central Africa, East Africa, and West Africa. Data were collected from semistructured interviews with 9 NAs and an analysis of network statistics for their locations. The resource-based view was used as the conceptual framework for the study. Using inductive analysis, 3 themes emerged from coding and triangulation: redundancy of equipment, knowledge transfer, and the use of spare parts to service the SATCOM infrastructure. The findings showed that the organization's use of knowledge, and collaboration among NAs and nontechnical staff improved the organization's ability to recover from SATCOM failures. The implication of this study for social change was the reduced cost of satellite services due to the efficient use of the bandwidth. These savings can be channeled into the purchase of vaccines, shelter, and the improvement in the quality of water and sanitation for displaced persons in humanitarian disasters, which improve the organization's delivery of humanitarian services to the affected populations in the disaster.
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Bramwell, Jonathan Richard. "The use of digital signal processing in satellite communication." Thesis, University of Plymouth, 1988. http://hdl.handle.net/10026.1/2479.
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The recent emphasis on Information Technology has increased the need for methods of data communications with a greater interest in the areas of Satellite communications. Data communications over a satellite can be easily achieved by the use of excessive power and bandwidth but efficient management of the satellite resource requires more elegant means of transmission. The optimum modulator and demodulator can be described by mathematical expressions to represent the physical processes that are required to transmit and receive a signal. Digital Signal Processing circuits can be use to implement these mathematical functions and once correctly designed are not susceptible to variations in accuracy and hence can maintain an accurate representation of the mathematical model. This thesis documents an investigation into the algorithms and techniques that can be used in the digital implementation of a Satellite Data Modem. The technique used for carrier phase recovery and data decoding is a major variation on a method proposed by Viterbi and Viterbi and relies on Phase Estimation instead of the more common carrier regeneration techniques. A computer simulation of this algorithm and its performance is described and the overall performance of the simulation is compared to theoretical analysis and experimental performance of a Multi-Data Rate Satellite Modem covering data rates in the range 16 Ksymbol/sec to 256 Ksymbol/sec in both the BPSK and QPSK data formats.
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Meenan, Christopher. "Advanced mobility management techniques for satellite mobile communication networks." Thesis, University of Surrey, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.388995.
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Aguis, Andreas-Albertos. "Antennas for handheld satellite personal communicators." Thesis, University of Surrey, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.298142.
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Valadon, Cyril. "Advanced CDMA receiver architectures for satellite multimedia communications." Thesis, University of Surrey, 1999. http://epubs.surrey.ac.uk/843442/.
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Future mobile broadband communication systems aim to provide a wide range of multimedia services (telephony, video conferencing, audio and video broadcasting, etc.) to a large number of users. In order to achieve a global coverage and reach remote users, satellite is foreseen to be a key component in the development of such networks. When compared to first-generation mobile satellite communication systems, these future satellite networks will need to provide significantly higher data rates whilst achieving very low bit error probability values. In order to keep the mobile user terminal as well as on-board processing complexity as low as possible, it is important to reach the required quality of service with very low values of the signal-to-noise ratio. Hence, particular attention must be paid to the design of the air interface of these future satellite systems. The use of CDMA presents a number of advantages for mobile communication systems, and hence CDMA technology has recently received a lot of attention for both second generation and future terrestrial multimedia systems. However, less effort has been put into the design of CDMA solutions for satellite communications. Moreover, good air interface designs for terrestrial systems do not necessarily translate into efficient solutions for the satellite environment. Hence, different techniques aimed at improving the performance of CDMA satellite systems are proposed in this thesis. First, the performance of S-CDMA, which reduces the level of MAI by co-ordinating the transmission of the different users, is analysed in satellite fading channels. Comparisons with the more conventional A-CDMA are provided and the impact on the transmission quality of imperfect power control, synchronisation errors and pulse shaping is assessed. In order to meet the very tight requirements set for multimedia services, FEC coding is required. Hence, the performance of S-CDMA in fading channels is presented for different channel coding techniques. The performance of the different schemes is characterised with both power and spectral efficiency and comparisons are made. In order to reduce the performance degradation due to the MAI, it is also possible to use multiuser detection algorithms at the receiver. In this thesis, the performance of MUD algorithms using an ANN architecture is analysed in satellite fading channels. Different training strategies and algorithms are considered and the performance of the ANN receivers is compared to that of the conventional correlator as well as other MUD algorithms. Finally, a number of different multi-rate spreading techniques are proposed and their respective complexity is discussed and compared. The power fluctuations caused by these different multi-rate spreading techniques are analysed in order to evaluate their performance in the satellite non-linear channel.
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Qi, Ronggang. "Mulicarrier demultiplexing and VLSI implementation for satellite communications systems." Thesis, University of Surrey, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.308476.
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Al-Khaled, Fahad Sulaiman. "Efficient radio channel assignment techniques for mobile satellite communication networks." Thesis, University of Newcastle Upon Tyne, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.391293.
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Karacaoglu, Ulun. "MIC an MMIC active filters for satellite and mobile communication." Thesis, King's College London (University of London), 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.286349.
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Ollars, Emil. "Design and characterization of a radio receiver for satellite communication." Thesis, Luleå tekniska universitet, Institutionen för system- och rymdteknik, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-87007.
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Due to the increase in volume and speed of data transmissions in recent years, the demand for high-speed satellite communication solutions has increased. This thesis investigates the possibility of making a receiver for satellite radio based on an Analog Devices ADC evaluation board. To do this, evaluation boards for each component were acquired and tested individually before connecting them. The system components include an I/Q demodulator, a local oscillator, and an ADC. Using these components a system design for the radio receiver has been proposed, and its performance analyzed. The SNR of the designed system was measured to26 dB. This performance was deemed to be sufficient for a signal using the BPSKmodulation scheme.
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Anderson, Paul David. "Array design and beamforming for satellite earth terminals." Diss., Georgia Institute of Technology, 1997. http://hdl.handle.net/1853/15357.
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Mertzanis, Ioannis. "QOS provisioning for broadband satellite-ATM multimedia networks." Thesis, University of Surrey, 1999. http://epubs.surrey.ac.uk/773030/.
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This work is motivated by the current trends in future broadband communication networks. On the one hand, the latest developments and experimentation with the Asynchronous Transfer mode (ATM) technology shows that that ATM is going to be the future transport mechanism in many private and public networks. This is driven by the need to efficiently support a large population of widebandlbroadband users with different data traffic characteristics and certain Quality of Service (QoS) guarantees. On the other hand, the interest in satellites and their role in the future broadband multimedia communications systems, has grown considerably since they can very quickly and economically extend the boundaries of the terrestrial mobile and fixed networks coverage. On-board satellite signal regeneration and' ATM-like' switching is part of the latest experimental developments by many payload manufacturers. In this thesis, the focus is on the Grade of Service (GoS) and QoS provisioning in future broadband satellite multimedia systems by introducing new means for their performance evaluation. The investigation includes modelling techniques for both Geostationary (GEO) and non-GEO systems. An extensive set of representative results derived analytically and by simulation are presented assuming different mixed traffic scenarios. A new methodology for the Available Bit Rate (ABR) service class capacity estimation and the CAC strategy that needs to be adopted in S-ATM systems is developed. Moreover, the performance evaluation of bandwidth reservation techniques for non-GEO satellite constellations is investigated and new rules for maintaining specified GoS performance are proposed. This work contributes towards the definition of a satellite network infrastructure that best satisfies the requirements of an integrated solution with Broadband-Integrated Services Digital Network (B-ISDN).
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Alawadi, Tareq A. "Investigation of the effects of cloud attenuation on satellite communication systems." Thesis, Cranfield University, 2012. http://dspace.lib.cranfield.ac.uk/handle/1826/7991.
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The aim of this project is to investigate the attenuation due to clouds at 20-
50GHz; to develop an accurate long-term prediction model of cloud attenuation
applicable to slant-path links and evaluate the impact of cloud attenuation
dynamics on the design of future portable EHF earth-space systems. Higher
frequencies offer several advantages, for example, greater bandwidth and
immunity to ionospheric effects. The EHF band is being targeted for the launch
of earth-space communication systems to provide global delivery of bandwidthintensive
services (e.g. interactive HDTV, broadband internet access and
multimedia services, television receive-only, etc.) to portable terminal units.
Since spectrum shortage and terminal bulk currently preclude the realization of
these breakthrough-broadband wireless communication services at lower
frequencies, a better understanding is needed in order to optimize their usage.
One major obstacle in the design of EHF earth-space communication systems
is the large and variable signal attenuation in the lower atmosphere, due to a
range of mechanisms including attenuation (and scattering) due to clouds and
rain, tropospheric scintillation caused by atmospheric turbulence and variable
attenuation by atmospheric gasses. In particular, cloud attenuation becomes
very significant at EHF.
In this thesis, we start with an overview of literature review in the first chapter.
Followed next by the theory and description of accepted-up to date- cloud
attenuation models in the field (chapter 2). Then followed up by a description of
the pre-processing, validations, sources and assumptions made in order to
conduct the analysis of the cloud attenuation in this work (chapter 3).
Afterwards, a comprehensive analysis of Meteorological and local tropospheric
degradation was carried out (chapter 4). That was followed by an overview of
cloud fade statistics and suggested methods to counter their effects (chapter 5).
And finally the improved cloud attenuation model and the enhancement of the
currently accepted cloud attenuation model (ITU-R 840.4) by terms of validating
the effective temperature concept and ways of acquiring it (chapter 6).
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Thesnaar, Emile Jacobus. "Development of a radiation resistant communication node for satellite sub-systems." Thesis, Stellenbosch : Stellenbosch University, 2014. http://hdl.handle.net/10019.1/86510.
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Thesis (MEng)--Stellenbosch University, 2014.ENGLISH ABSTRACT: Within a complex electronic system, sub-system communication forms the backbone of the functionality of any satellite. It allows multiple processors to run simultaneously and data to be shared amongst them. Without it, a single processor would have to control the entire satellite. Not only would such a design then be overly complicated, but the processor would also not have sufficient capacity to service all the components efficiently. Furthermore the detrimental effects that radiation have on integrated circuits are well documented and can be anything from a single bit flip to a complete integrated circuit failure. If not repaired, a failure on a sub-system communication bus could lead to the loss of the entire satellite. Die goal is to create more radiation resistant Controller-Area-Network (CAN) node. Since a full triple modular redundant design will have a large footprint and high power consumption, a combination of techniques will be applied and tested. The goal is to achieve improved footprint utilisation over triple modular redundancy, while still maintaining good resistance to Single Event Upsets (SEU). By applying simulation, it was sufficiently proven that the implementation of the individual techniques used functioned according to expectations. These techniques included error detection and correction using Hamming Codes, single event transient filter and triple modular redundancy. Having applied these mitigation techniques, the footprint of the CAN controller increased by only 116%. Simulation showed that the Error Detection and Correction and Triple Modular Redundancy worked effectively with the CAN controller, and that the CAN controller could function as originally intended. Using radiation testing, the design proved to be more resistant to SEUs than the unmitigated CAN controller. It was thus shown that through using a combination of mitigation techniques, it is possible to develop an optimal design with a high level of resistance against Single Event Upsets, utilizing a smaller footprint than implementing Triple Modular Redundancy.
AFRIKAANSE OPSOMMING: Sub-stelsel kommunikasie vorm die basis van die funksionaliteit in ’n komplekse elektroniese stelsel soos ’n satelliet. Dit skep die vermoë om veelvoudige verwerkers gelyktydig te laat funksioneer en inligting tussen hulle te deel. Sonder sub-stelsel kommunikasie, sal ’n enkele verwerker die hele sateliet moet beheer. Dit sal nie net die hele ontwerp oorkompliseer nie, maar die verwerker sal ook nie genoeg kapisteit hê om al die komponente effektief te diens nie. Die newe-effekte van bestraling op geïntegreerde stroombane is goed gedokumenteer en kan wissel van ’n enkele omgekeerde bis, tot die vernietiging van die geïntegreerde stroombaan. Indien die fout in die kommunikasiestelsel nie herstel word nie, kan dit lei tot die verlies van die hele sateliet. Die doel is om ’n meer bestraling bestande Controller-Area-Network (CAN) nodus te skep. Aangesien ’n volle drie-dubbele-modulêre-oortollige ontwerp ’n baie groot area beslaan en hoë krag verbruik het, gaan ’n kombinasie van versagting tegnieke toegepas en ge-evalueer word. Die doel is om beter area benutting as die drie-dubble-modulêre-oortollige ontwerp te kry, terwyl ’n goeie weerstand teen foute behoue bly. Deur middel van simulasies is voldoende bewyse gelewer dat die implimentasie van die individuele versagting tegnieke soos verwag funktioneer. Hierdie tegnieke sluit in, fout opsporing en regstelling deur middel van Hamming kodes, enkele geval oorgangs verskynsel filter asook drie-dubbele-modulêre-oortollige ontwerp. Nadat versagting meganismes toegepas is, het die area verbruik van die CAN beheerder toegeneem met slegs 116%. Simulasies het bewys dat Fout Opsporing en Regstelling en Drie-Dubbele-Modulêre-Oortollige ontwerp tegnieke binne die CAN beheerder korrek funktioneer, terwyl die CAN beheerder self funktioneer soos dit oorspronklik gefunksioneer het. Deur middel van bestralingstoetse, is dit bewys dat die ontwerp meer bestand is teen foute geïnduseer deur bestraling as die onbeskermde CAN beheerder. Dit is dus bewys dat deur gebruik te maak van verskeie versagting tegnieke dit moontlik is om ’n optimale ontwerp te implimenteer, met ’n hoë weerstand teen foute, maar met ’n laer area verbruik as die van ’n Drie-dubbele-Modulêre-Oortollige ontwerp.
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Al-Dalakta, Emad Yacoub Qeryaqos. "PAPR and ICI reduction techniques for OFDM based satellite communication systems." Thesis, University of Newcastle upon Tyne, 2012. http://hdl.handle.net/10443/1528.
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Multi-carrier systems such as orthogonal frequency division multiplexing (OFDM) are significantly affected by peak-to-average-power ratio (PAPR). Unfortunately, the high PAPR inherent to OFDM signals envelopes will occasionally drive high power amplifiers (HPAs) to operate in the nonlinear region of their characteristic curve. The nonlinearity of the HPA exhibits amplitude and phase distortions, which cause loss of orthogonality among the subcarriers (SCs), and hence, inter-carrier interference (ICI) is introduced in the transmitted signal. The ICI power is proportional to the amplitude of the signal at the amplifier input and it may cause a considerable bit error rate (BER) degradation. A plethora of research has been devoted to reduce the performance degradation due to the PAPR problem inherent to OFDM systems. Some of the reported techniques such as amplitude clipping have low-complexity; on the other hand, they suffer from various problems such as in-band distortion and out-of-band expansion. Signal companding methods have low-complexity, good distortion and spectral properties; however, they have limited PAPR reduction capabilities. Advanced techniques such as coding, partial transmit sequences (PTS) and selected mapping (SLM) have also been considered for PAPR reduction. Such techniques are efficient and distortionless, nevertheless, their computational complexity is high and requires the transmission of several side information (SI) bits. In this thesis, a new low-complexity scheme is proposed based on the PTS that employs two inverse fast Fourier transforms (IFFTs) and two circulant transform matrices, in order to reduce complexity and improve the system performance. Furthermore, the low-complexity scheme is simplified by omitting one of the circulant transform matrices in order to reduce both the computational complexity and the number of SI bits at the cost of a small reduction in PAPR and BER performance. It is well known that, accurate PAPR estimation requires oversampling of the transmitted signal, which in turn results in increased complexity. More importantly, minimising the PAPR does not necessarily minimise the distortion produced by the nonlinearity of the HPA. Therefore, minimising PAPR does not necessarily imply that the BER will be minimised too. Efficient and less complex schemes for BER reduction of OFDM systems in the presence of nonlinear HPA and/or carrier frequency offset (CFO) are proposed. These proposed techniques are based on predicting the distortion introduced by the nonlinearity of HPA and/or CFO. Subsequently, techniques such as the PTS and SLM are invoked to minimise the distortion and BER. Three distortion metrics are adopted in this thesis: inter-modulation distortion (IMD), peak interference-to-carrier ratio (PICR) and distortion-to-signal power ratio (DSR). Monte Carlo simulations will confirm that the DSR and PICR are more reliable than the PAPR and IMD for selecting the coefficients of the PTS and SLM to minimise the BER. Furthermore, complexity analyses demonstrate that the proposed schemes offer significant complexity reduction when compared to standard PAPR-based methods. A closed form solution for accurate BER for the OFDM signals perturbed by both the HPA nonlinearity and CFO was derived. Good agreement between the simulation results and the theoretical analysis can be obtained for different HPA parameters and CFOs. Finally, efficient approaches to reduce the impact of nonlinear power amplifiers with respect to the BER of OFDM systems are proposed. These are approaches based on: the well-established PAPR schemes, a power amplifier model and a simple single point cross correlator. The optimum phase sequence within the proposed approaches is selected by maximising the correlation between the input and output of the power amplifier model. Simulation results have confirmed that the BER using the proposed approaches is almost identical to the DSR, while the complexity is reduced significantly for particular system configurations.
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Deambrogio, Lina <1979>. "Enabling Techniques and Algorithms for Integrated Communication and Navigation Satellite Systems." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2012. http://amsdottorato.unibo.it/4336/1/Deambrogio_Lina_Tesi.pdf.
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This thesis presents the outcomes of my Ph.D. course in telecommunications engineering. The focus of my research has been on Global Navigation Satellite Systems (GNSS) and in particular on the design of aiding schemes operating both at position and physical level and the evaluation of their feasibility and advantages.
Assistance techniques at the position level are considered to enhance receiver availability in challenging scenarios where satellite visibility is limited. Novel positioning techniques relying on peer-to-peer interaction and exchange of information are thus introduced. More specifically two different techniques are proposed: the Pseudorange Sharing Algorithm (PSA), based on the exchange of GNSS data, that allows to obtain coarse positioning where the user has scarce satellite visibility, and the Hybrid approach, which also permits to improve the accuracy of the positioning solution.
At the physical level, aiding schemes are investigated to improve the receiver’s ability to synchronize with satellite signals. An innovative code acquisition strategy for dual-band receivers, the Cross-Band Aiding (CBA) technique, is introduced to speed-up initial synchronization by exploiting the exchange of time references between the two bands. In addition vector configurations for code tracking are analyzed and their feedback generation process thoroughly investigated.
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Deambrogio, Lina <1979>. "Enabling Techniques and Algorithms for Integrated Communication and Navigation Satellite Systems." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2012. http://amsdottorato.unibo.it/4336/.
Full textAbstract:
This thesis presents the outcomes of my Ph.D. course in telecommunications engineering. The focus of my research has been on Global Navigation Satellite Systems (GNSS) and in particular on the design of aiding schemes operating both at position and physical level and the evaluation of their feasibility and advantages.
Assistance techniques at the position level are considered to enhance receiver availability in challenging scenarios where satellite visibility is limited. Novel positioning techniques relying on peer-to-peer interaction and exchange of information are thus introduced. More specifically two different techniques are proposed: the Pseudorange Sharing Algorithm (PSA), based on the exchange of GNSS data, that allows to obtain coarse positioning where the user has scarce satellite visibility, and the Hybrid approach, which also permits to improve the accuracy of the positioning solution.
At the physical level, aiding schemes are investigated to improve the receiver’s ability to synchronize with satellite signals. An innovative code acquisition strategy for dual-band receivers, the Cross-Band Aiding (CBA) technique, is introduced to speed-up initial synchronization by exploiting the exchange of time references between the two bands. In addition vector configurations for code tracking are analyzed and their feedback generation process thoroughly investigated.
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Icolari, Vincenzo Riccardo <1989>. "Cognitive-Based Solutions to Spectrum Issues in Future Satellite Communication Systems." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2017. http://amsdottorato.unibo.it/7907/1/icolari_vincenzoriccardo_tesi.pdf.
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With particular attention to Satellite Communications (SatComs), cognitive-based solutions are investigated. With cognitive-based solutions we refer to all those techniques that aim at improving spectrum utilization of the available spectrum and rely on the knowledge of the environment in which the systems operate. As a matter of fact, an improved spectrum utilization enables higher throughput capacities that will satisfy the future markets and demands of an increasingly connected world.
Throughout the thesis, several techniques are proposed, developed, and assessed with respect to specific scenarios of interest. Particular focus has been put on spectrum awareness techniques for system coexistence, and on spectrum exploitation techniques for an improved efficiency in terms of resource utilization.
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Hartigan, Patrick Francis. "Forecasting of radiowave attenuation on earth-space links." Thesis, Coventry University, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.332325.
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Zhao, Wei. "Handover techniques and network integration between GSM and satellite mobile communication systems." Thesis, University of Surrey, 1997. http://epubs.surrey.ac.uk/2322/.
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Harrell, Andre T. "Wireless technology via satellite communications for peacekeeping operations." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2001. http://library.nps.navy.mil/uhtbin/hyperion-image/01Sep%5FHarrell.pdf.
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Thesis (M.S. in Information Systems Technology)--Naval Postgraduate School, September 2001.Thesis advisor(s): Tri T. Ha, Nancy Roberts. Includes bibliographical references (p. 85-87). Also available online.
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Begum, Sahena. "Reliable broadband satellite-integrated network design through propagation and networking solutions." Thesis, University of South Wales, 2009. https://pure.southwales.ac.uk/en/studentthesis/reliable-broadband-satelliteintegrated-network-design-through-propagation-and-networking-solutions(aa71347b-031f-437d-9da0-6e8432e19630).html.
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Satellites will play an indispensable role in the deployment of commercial networks to meet an increasing demand for supporting multimedia services at high data rates. Next generation satellite systems, operating at high frequency bands offer large bandwidth and are able to provide broadband services. To interface satellite links with existing terrestrial networks for providing communication access to a variety of users directly, several performance issues need to be addressed. Current thesis presents a technically viable satellite-integrated network model that is efficient in carrying broadband services to users over a wide scattered area. Accurate prediction of attenuation level is necessary for a reliable network model to operate with required service availability. Long term rainfall data has been analysed to characterise attenuation level at a selected region such as Dhaka. It is shown that rainfall is highly seasonal and attenuation level is quite high during monsoon. However, the seasonal behaviour of rainfall can be exploited to improve the link availability. Radar and rain gauge measurements at Sparsholt are also used to find rain cell size distribution, which is an important factor in site diversity implementation to combat severe rain fade. It is found that convective rain cell has extension in the region of 10 km. The network model is designed with dimensioning the effective bandwidth to support a number of users over the satellite link by taking into account the multimedia traffic characteristics. Concatenated coding, a robust coding scheme is implemented to improve the link quality at a level required to deliver broadband services. The ITU-T performance objectives of 7.5×10 for CLR and 1.4×10 for CER over satellite links are met at a required Eb/No of 2.95 dB and 2.88 dB respectively. Different enhancement mechanisms for optimum TCP performance are implemented to combat the large propagation delay associated with a satellite link. It is revealed through the simulation that TCP performance over a satellite link is as efficient as terrestrial links with these enhancement mechanisms Finally, the overall performance of the designed network is evaluated through link budget analysis and simulation. An innovative downlink power control strategy has been implemented to maintain the link during the rainiest months. The interference level due to high power satellite transmission in the designed system is also calculated to protect other existing communication links sharing the same frequency bands. A feasible broadband network designed with characterising propagation as well as networking issues will efficiently deliver broadband communication services to a large population promptly and in a cost-effective manner. Such a network solution will be in the realm of current R & D towards broadband satellite networks.
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Gremont, Boris Christian. "Fade countermeasure modelling for Ka band digital satellite links." Thesis, Coventry University, 1997. http://curve.coventry.ac.uk/open/items/d85e8a85-635c-d024-3737-d1205f235596/1.
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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.
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Kassianides, Constantinos N. "A study of the effects of scintillation on digital satellite communication systems." Thesis, University of South Wales, 2002. https://pure.southwales.ac.uk/en/studentthesis/a-study-of-the-effects-of-scintillation-on-digital-satellite-communication-systems(19190903-59f8-4350-9a59-2d2a70e1a623).html.
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The growth of satellite communication industry and the need to offer new and better services, to compete with optical fiber systems, have driven the satellite industry to search for higher bandwidth and improved cost of services. Higher frequency bands, such as Ka and V-band, came into play. These frequency bands have the advantage of efficient use of spectrum, the ability to transfer data at much higher rates, and the use of smaller antennas resulting in lower cost for the user. A major drawback though, is the severity of propagation impairments. Scintillation becomes important for low-fade margin systems operating at high frequencies and with low elevation angles and therefore must be taken into account in the design of satellite communication systems. The first part of the thesis deals with the analysis of beacon data and presentation of various statistics, namely short and long-term distributions of scintillation amplitudes and intensity. Their correlations with meteorological parameters are also presented. A dynamic model of tropospheric scintillation is developed, which permits the generation of scintillation time series based on known scintillation characteristics, such as spectral shape and probability density function. The model employs readily obtainable input parameters (antenna diameter, path elevation angle, frequency, ground temperature and humidity) and yields statistics that compare extremely well with existing prediction models as well as measured scintillation data (up to the fourth moment). Important applications of the new model are for simulating the performance of scintillation-degraded communication links and predicting required scintillation fade margins. The second part of the thesis investigates the effects of scintillation on digital satellite communication systems using simulations implemented in COSSAP. Simulation results show that the higher the order of the modulation that is being used, the larger is the effect of scintillation on the bit error rate performance of the link. In the third part of the thesis, fade mitigation techniques to overcome the effects of scintillation fading are discussed. Analysis of an adaptive modulation system using three modulation techniques is presented and its advantages demonstrated. The adaptive system can be used to mitigate scintillation fading and at the same time increase the capacity of the system, decreasing system outage time through an efficient utilisation of available resources. In the last part, data transfer scenarios in VSAT systems incorporating adaptive modulation, ARQ and adaptive up-link power control are presented. The implementation of the adaptive system in a COSSAP simulation platform is discussed and individual adaptive components are simulated and presented in detail.
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Yenice, Yusuf E. "Effects of atmospheric turbulence on ground-satellite optical communications and countermeasures." Thesis, University of Surrey, 1999. http://epubs.surrey.ac.uk/843086/.
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The theoretical advantages of ground-satellite optical communication systems can only be exploited, if means can be found to circumvent the limitations due to atmospheric effects. Atmospheric turbulence dominates the analysis and design of these links. The effects of atmospheric turbulence on the performance of ground-satellite optical communication systems and possible countermeasures are investigated in this thesis. The design and analysis of any optical system operating in the atmosphere requires empirical investigations of atmospheric turbulence conditions at the system's location. Stellar observations provide a useful and convenient means for this purpose in the case of ground-satellite optical communications. The available techniques are reviewed. The experimental setup for a particular technique is described and initial results are presented. We were involved in the first ever ground-satellite optical communication experiments conducted between Japanese Engineering Test Satellite VI and a ground station in Tokyo. One issue which has not yet been satisfactorily resolved is the probability density function (PDF) of intensity fluctuations. It was theoretically shown that the PDF approaches a negative exponential in the very strong turbulence region. Experimental evidence is presented in support of this prediction. The ETS-VI experiment results also confirm that too large a beam size can have significantly deleterious effects on fading performance. Early analyses predicted drastic reductions in uplink on-axis scintillation variance with increasing beam size. As the beam size is increased, the scintillation variance gradient off the beam centre becomes large, and eventually the limitation of the first-order theory is exceeded. An explicit limit on the beam size is identified in this thesis: the beam radius must not exceed a third of the coherence scale. Analyses also predict that appropriately converging the beam results in less scintillation compared to a collimated beam. During the ETS-VI experiment we were not able confirm this prediction. Supplements to the first-order theory also suggest that converging beams behave very similarly to collimated beams. This makes the uplink beam size the single most important adjustable parameter. Possible countermeasures to the atmospheric turbulence effects are identified and reviewed separately for the downlink and the uplink. It is emphasized that uplink transmitter beam size is a crucial design parameter and its optimum value changes continuously according to changing turbulence conditions along the propagation path. A previous study concluded that the optimum beam size is of the order of the coherence scale. It is shown that the optimum size is critically dependent on beam wander and pointing accuracy, and can in fact be much smaller. A novel countermeasure is proposed in which the uplink transmitter beam size is controlled in real time in response to measured turbulence parameters to maximize mean intensity and minimize fluctuations at the satellite receiver.
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Suvannapattana, P. "Analysis and design of user terminal antennas for mobile satellite communications." Thesis, University of Surrey, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.326196.
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Doumi, Tewfik Lahcene. "A simulator for the narrow band satellite mobile radio channel." Thesis, University of Bradford, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.304181.
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Wada, Tadahiro, Takaya Yamazato, Masaaki Katayama, and Akira Ogawa. "A New M-ary/SSMA Scheme Applicable in LEO Satellite Communication Systems." IEEE, 1996. http://hdl.handle.net/2237/7781.
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Özmizrak, F. Nur. "Investigation of practical strategies for reducing intermodulation effects in satellite communication systems." Thesis, University of Ottawa (Canada), 1986. http://hdl.handle.net/10393/5247.
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