Providing affordable Internet access to rural populations in large developing countries to aid economic and social progress, using various non-conventional techniques has been a topic of active research recently. The main obstacle in providing fiber-optic based terrestrial Internet links to remote villages is the cost involved in laying the cable network and disproportionately low rate of return on investment due to low density of paid users. The conventional alternative to this is providing Internet access using geostationary satellite links, which can prove commercially infeasible in predominantly cost-driven rural markets in developing economies like India or China due to high access cost per user. A low-cost derivative of the conventional satellite-based Internet access system can be developed by utilizing an aging geostationary satellite nearing the end of its active life, allowing it to enter an inclined geosynchronous orbit by limiting station keeping to only east-west maneuvers to save fuel. Eliminating the need for individual satellite receiver modules by using one centrally located earth station per village and providing last mile connectivity using Wi-Fi can further reduce the access cost per user. A Ku band system design for rural India based on this concept, using an Intelsat 906 satellite is proposed in this thesis. The path of the satellite and the tracking requirements at village stations are determined. Components required for various blocks of the system are defined. Modulation schemes, FEC, data rates, number of customers to be served, link availability and outage statistics are presented. Quantitative analysis using link budgets and ITU rain models are provided. An optimized system design and a commercial deployment model are suggested which show the system is economically feasible. / Master of Science

Cette thèse présente une étude de faisabilité d'un récepteur faible coût et faible consommation pour l'extension du standard DVS-S à la mobilité. L'objectif de ce projet est de proposer de solutions pour lever les verrous technologiques quant à la réalisation d'un tel système en technologie CMOS 65 nm. Ce manuscrit de thèse articulé autour de quatre chapitres décrit toutes les étapes depuis la définition des spécifications du réseau d'antennes et de la chaîne de réception jusqu'à la présentation de leurs performances, en passant par l'étude de leurs architectures et de la conception des différents blocs. Suite à l'étude au niveau système et au bilan de liaison, le démonstrateur envisagé est constitué d'un réseau d'antennes (huit sous-réseaux de huit antennes microruban) suivi de la mise en parallèle de huit chemins unitaires pour satisfaire les exigences (Gain, facteur de bruit, rapport signal-à-bruit...) de l'application visée. Ce travail a abouti à la démonstration de la faisabilité d'une architecture innovante. Par ailleurs, nous avons aussi démontré sa non-application pour le standard DVB-S en raison des limitations en bruit de la technologie CMOS. Cependant des pistes existent pour améliorer le rapport signal-à-bruit du démonstrateur, à savoir l'utilisation d'un LNA (Low Noise Amplifier) avec une technologie compétitive en bruit et/ou d'un traitement du signal après la démodulation en bande par un processeur analogique. / This work focuses on the faisability of a low cost and low power receiver in order to extend the DVB-S standard to mobility. The objective of this project is to suggest solutions to overcome technological bottlenecks fot the realization of such a demonstrator with 65 nm CMOS technology. This report composed of four chapters, describes all steps from the specification definition to the performances of the antenna array and the receiver through the architecture study and the different blocks design. [...]

[pt] Neste trabalho, limites para a densidade de fluxo de potência equivalente produzida pelos lances de descida de sistemas de satélites nãogeoestacionários (não-GEO), operando na faixa de 3,7-4,2 GHz, são analisados. Estes limites visam proteger os receptores do Serviço Fixo por Satélite (FSS) das interferências produzidas por sistemas de satélites não geoestacionários, quando ambos operam na faixa de frequências considerada. A analise destes limites foi motivada pela Resolução 157 da Conferência Mundial de Radiocomunicações de 2015 (WRC-15), que ressalta a necessidade de estudos envolvendo aspectos técnicos e operacionais relativos à operação de sistemas não-GEO operando na faixa de frequências de 3,7 - 4,2 GHz de modo a permitir que esses sistemas possam operar nestas faixas de frequências assegurando, ao mesmo tempo, que os serviços primários existentes, entre eles o FSS, continuem protegidos. A importância do assunto fez com que este tópico fosse incluído na agenda da WRC-19. No trabalho, é inicialmente desenvolvida uma metodologia para a determinação de máscaras limitantes para a densidade de fluxo de potência equivalente produzida pelos lances de descida (epfd(descida)) de sistemas de satélites não-GEO. Esta metodologia foi utilizada na obtenção de duas máscaras baseadas, respectivamente, nos critérios de proteção das recomendações ITU-R S.1323 e ITU-R F.1495. Uma análise comparativa das máscaras de epfd(descida) obtidas foi feita considerando-se cinco constelações de satélites não-GEO do tipo Walker Delta, escolhidas adequadamente para cobrir um amplo conjunto de possibilidades. A análise utilizou, como base, o comportamento estatístico das margens associadas a cada uma das máscaras de epfd(descida) propostas. / [en] In this work, the limits for the equivalent power-flux density produced by the down-links of non-geostationary satellite systems (non-GSO), operating in the 3,7-4,2 GHz band are analyzed. These limits aim the protection of Fixed-Satellite Service (FSS) receivers, from the interferences produced by non-geostationary satellite systems, operating in the same frequency band. The analysis of these limits was motivated by Resolution 157 of the 2015 World Radiocommunication Conference (WRC-15), that recognized the need for studies on technical and operational aspects related to the operation of non-GSO systems operating in the 3,7-4,2 GHz frequency band, so that these systems can adequately operate in these frequency band while ensuring, at the same time, that the existing primary services, among them the FSS, remain protected. Due to its importance the topic was included in the agenda of the WRC-19. In this work, a methodology for the determination of limiting masks for the equivalent power-flux density generated by the down-links (epfd(down)) of non-GSO satellite systems is initially developed. This methodology was used to obtain two mask based, respectively, on the protection criteria of the ITU-R S.1323 and ITU-R F.1495 recommendations. A comparative analysis of the two obtained epfd(down) masks was made considering five Walker Delta type non-GSO satellite constellation, appropriately chosen to cover a wide set of possibilities. The analysis used, as a basis, the statistic behavior of the margins associated to each of the proposed epfd(down) masks.