Analysis and optimization of the satellite-to-plane link of an aeronautical global system

En aquest projecte s'ha analitzat i optimitzat l'enllaç satèl·lit amb avió per a un sistema aeronàutic global. Aquest nou sistema anomenat ANTARES està dissenyat per a comunicar avions amb estacions base mitjançant un satèl·lit. Aquesta és una iniciativa on hi participen institucions oficials en l'aviació com ara l'ECAC i que és desenvolupat en una col·laboració europea d'universitats i empreses. El treball dut a terme en el projecte compren bàsicament tres aspectes. El disseny i anàlisi de la gestió de recursos. La idoneïtat d'utilitzar correcció d'errors en la capa d'enllaç i en cas que sigui necessària dissenyar una opció de codificació preliminar. Finalment, estudiar i analitzar l'efecte de la interferència co-canal en sistemes multifeix. Tots aquests temes són considerats només per al "forward link". L'estructura que segueix el projecte és primer presentar les característiques globals del sistema, després centrar-se i analitzar els temes mencionats per a poder donar resultats i extreure conclusions.En este proyecto se ha analizado y optimizado el enlace satélite a avión para un sistema aeronáutico global. Este nuevo sistema, ANTARES, está diseñado para comunicar aviones y estaciones base mediante un satélite. Esta es una iniciativa europea en la que participan varias instituciones oficiales en aviación como el ECAC y es desarrollada en una colaboración europea de universidades y empresas. El trabajo llevado a cabo en este proyecto comprende básicamente tres aspectos. El diseño y análisis de la gestión de recursos. La idoneidad de usar corrección de errores en la capa de enlace y en caso que sea necesario diseñar una opción de codificación preliminar. Finalmente, estudiar y analizar el efecto de la interferencia co-canal en sistemas multihaz. Todos estos temas se consideran sólo en el "forward link". La estructura que sigue el trabajo es, primero presentar las características globales del sistema, luego centrarse y analizar los temas mencionados para finalmente dar resultados y extraer conclusiones.In this project it is analyzed and optimized the satellite-to-plane link of an aeronautical global system. This new upcoming system called ANTARES is intended for communicating airplanes and ground stations through a satellite system. This is a European initiative involving official institutions in terms of aviation such as the ECAC and developed in a European collaboration of universities and companies. The work carried out in the project comprehends basically three issues. The Radio Resource Management analysis and design. Analyze the suitability of using Link Layer-Forward Error Correction in the system and in case it is necessary design a preliminary coding option. Finally, study and analyze the effect of the co-channel interference in multibeam systems. All these issues are considered only for the forward link of the system. The structure of the project is as follows, first present the global characteristics of the system, then focus and analyze the mentioned subjects and finally give results and take conclusions on the work

Survey of Inter-satellite Communication for Small Satellite Systems: Physical Layer to Network Layer View

Small satellite systems enable whole new class of missions for navigation, communications, remote sensing and scientific research for both civilian and military purposes. As individual spacecraft are limited by the size, mass and power constraints, mass-produced small satellites in large constellations or clusters could be useful in many science missions such as gravity mapping, tracking of forest fires, finding water resources, etc. Constellation of satellites provide improved spatial and temporal resolution of the target. Small satellite constellations contribute innovative applications by replacing a single asset with several very capable spacecraft which opens the door to new applications. With increasing levels of autonomy, there will be a need for remote communication networks to enable communication between spacecraft. These space based networks will need to configure and maintain dynamic routes, manage intermediate nodes, and reconfigure themselves to achieve mission objectives. Hence, inter-satellite communication is a key aspect when satellites fly in formation. In this paper, we present the various researches being conducted in the small satellite community for implementing inter-satellite communications based on the Open System Interconnection (OSI) model. This paper also reviews the various design parameters applicable to the first three layers of the OSI model, i.e., physical, data link and network layer. Based on the survey, we also present a comprehensive list of design parameters useful for achieving inter-satellite communications for multiple small satellite missions. Specific topics include proposed solutions for some of the challenges faced by small satellite systems, enabling operations using a network of small satellites, and some examples of small satellite missions involving formation flying aspects.Comment: 51 pages, 21 Figures, 11 Tables, accepted in IEEE Communications Surveys and Tutorial

On-board beam generation for multibeam satellite systems

This paper aims at designing an onboard beam generation process for a hybrid onboard on-ground multibeam satellite architecture. The proposed method offers a good tradeoff between total throughput and feeder link bandwidth requirements compared with pure on-ground systems. Full frequency reuse among beams is considered, and the beamforming at the satellite is designed for supporting interference mitigation techniques. In addition, in order to reduce the payload cost and complexity, this onboard beamforming is assumed to be constant and the same for forward and return link transmissions so that the same array-fed reflector can be used for forward and return links, leading to a substantial reduction of the payload mass. To meet all these requirements, a novel robust minimum mean square error optimization is conceived. The benefits of the considered scheme are evaluated with respect to the current approaches both analytically and numerically. Indeed, we show that with the DVB-RCS and DVB-S2 standards, our proposal allows increasing the total throughput within a range between 6% and 15% with respect to other onboard processing techniques in the return and forward link, respectively.Peer ReviewedPostprint (author's final draft

Generalized multicast multibeam precoding for satellite communications

This paper deals with the problem of precoding in multibeam satellite systems. In contrast to general multiuser multiple-input-multiple-output cellular schemes, multibeam satellite architectures suffer from different challenges. First, satellite communications standards embed more than one user in each frame in order to increase the channel coding gain. This leads to the different so-called multigroup multicast models, whose optimization requires computationally complex operations. Second, when the data traffic is generated by several Earth stations (gateways), the precoding matrix must be distributively computed and meet additional payload restrictions. Third, since the feedback channel is adverse (large delay and quantization errors), the precoding must be able to deal with such uncertainties. In order to solve the aforementioned problems, we propose a two-stage precoding design in order to both limit the multibeam interference and to enhance the intra-beam minimum user signal power (i.e., the one that dictates the rate allocation per beam). A robust version of the proposed precoder based on a first perturbation model is presented. This mechanism behaves well when the channel state information is corrupted. Furthermore, we propose a per beam user grouping mechanism together with its robust version in order to increase the precoding gain. Finally, a method for dealing with the multiple gateway architecture is presented, which offers high throughputs with a low inter-gateway communication. The conceived designs are evaluated with a close-to-real beam pattern and the latest broadband communication standard for satellite communications.Peer ReviewedPostprint (updated version

Multibeam Joint Processing in Satellite Communications

Cooperative Satellite Communications (SatComs) involve multi-antenna satellites enabled for the joint transmission and reception of signals. This joint processing of baseband signals is realized amongst the distinct but interconnected antennas. Advanced signal processing techniques –namely precoding and Multiuser Detection (MUD)– are herein examined in the multibeam satellite context. The aim of this thesis is to establish the prominence of such methods in the next generation of broadband satellite networks. To this end, two approaches are followed. On one hand, the performance of the well established and theoretically concrete MUD is analysed over the satellite environments. On the other, optimal signal processing designs are developed and evaluated for the forward link. In more detail, the present dissertation begins by introducing the topic of multibeam joint processing. Thus, the most significant practical constraints that hinder the application of advanced interference mitigation techniques in satellite networks are identified and discussed. Prior to presenting the contributions of this work, the multi-antenna joint processing problem is formulated using the generic Multiuser (MU) Multiple InputMultiple Output (MIMO) baseband signal model. This model is also extended to apply in the SatComs context. A detailed presentation of the related work, starting from a generic signal processing perspective and then focusing on the SatComs field, is then given. With this review, the main open research topics are identified. Following the comprehensive literature review, the first contribution of this work, is presented. This involves the performance evaluation of MUD in the Return Link (RL) of multiuser multibeam SatComs systems. Novel, analytical expressions are derived to describe the information theoretic channel capacity as well as the performance of practical receivers over realistic satellite channels. Based on the derived formulas, significant insights for the design of the RL of next generation cooperative satellite systems are provided. In the remaining of this thesis, the focus is set on the Forward Link (FL) of multibeam SatComs, where precoding, combined with aggressive frequency reuse configurations, are proposed to enhance the offered throughput. In this context, the alleviation of practical constraints imposed by the satellite channel is the main research challenge. Focusing on the rigid framing structure of the legacy SatCom standards, the fundamental frame-based precoding problem is examined. Based on the necessity to serve multiple users by a single transmission, the connection of the frame-based precoding and the fundamental signal processing problem of physical layer multigroup multicasting is established. In this framework and to account for the power limitations imposed by a dedicated High Power Amplifier (HPA) per transmit element, a novel solution for multigroup multicasting under Per Anntenna Constraints (PACs) is derived. Therefore, the gains offered by multigroup multicasting in frame-based systems are quantified over an accurate simulation setting. Finally, advanced multicast and interference aware scheduling algorithms are proposed to glean significant gains in the rich multiuser satellite environment. The thesis concludes with the main research findings and the identification of new research challenges, which will pave the way for the deployment of cooperative multibeam satellite systems

Proceedings of the Second International Mobile Satellite Conference (IMSC 1990)

Presented here are the proceedings of the Second International Mobile Satellite Conference (IMSC), held June 17-20, 1990 in Ottawa, Canada. Topics covered include future mobile satellite communications concepts, aeronautical applications, modulation and coding, propagation and experimental systems, mobile terminal equipment, network architecture and control, regulatory and policy considerations, vehicle antennas, and speech compression

Dynamic frequency assignment for mobile users in multibeam satellite constellations

Els nivells de flexibilitat i escalabilitat mai vistos de la propera generació de sistemes de comunicació per satèl·lit exigeixen nous algorismes de gestió de recursos que s'adaptin a contextos dinàmics. El futur entorn dels serveis de comunicació per satèl·lit estarà definit per un nombre més gran d'usuaris, una gran part dels quals correspondrà a usuaris mòbils com avions o vaixells. El repte addicional que introdueixen aquests usuaris és abordar la incertesa espai-temporal que es presenta en forma de retards, canvis en la seva trajectòria, o tots dos. Atès que els usuaris mòbils constituiran un segment important del mercat, els operadors de satèl·lits prioritzen l'aprofitament dels avançats sistemes digitals per desenvolupar estratègies flexibles d'assignació de recursos que siguin robustes davant de les bases d'usuaris dinàmiques. Un dels problemes clau en aquest context és com gestionar l'espectre de freqüències de manera eficient. Mentre que nombroses solucions aborden escenaris d'assignació de dinàmica freqüències, el nivell addicional de complexitat que presenten els usuaris mòbils no ha estat prou estudiat, i no és clar si els nous algorismes d'assignació de freqüències poden abordar la incertesa espai-temporal. Concretament, sostenim que els canvis inesperats en la posició dels usuaris introdueixen noves restriccions en l'assignació de freqüències que els algoritmes la literatura podrien no ser capaços de complir, especialment si les decisions s'han de prendre en temps real i a escala. Per solucionar aquesta limitació, proposem un algorisme de gestió dinàmica de freqüències basat en programació lineal entera que assigna recursos a escenaris amb usuaris tant fixos com mòbils, tenint en compte la incertesa espai-temporal d'aquests últims. El nostre mètode inclou tant la planificació a llarg termini com l'operació en temps real, una sinergia que no ha estat prou explorada per a les comunicacions per satèl·lit i que és crítica quan s'opera sota incertesa. PLos niveles de flexibilidad y escalabilidad nunca vistos de la próxima generación de sistemas de comunicación por satélite exigen nuevos algoritmos de gestión de recursos que se adapten a contextos dinámicos. El futuro entorno de los servicios de comunicación por satélite estará definido por un mayor número de usuarios, una gran parte de los cuales corresponderá a usuarios móviles como aviones o barcos. El reto adicional que introducen estos usuarios es abordar la incertidumbre espacio-temporal que se presenta en forma de retrasos, cambios en su trayectoria, o ambos. Dado que los usuarios móviles constituirán un segmento importante del mercado, los operadores de satélites dan prioridad al aprovechamiento de los avanzadas sistemas digitales para desarrollar estrategias flexibles de asignación de recursos que sean robustas frente a las bases de usuarios dinámicas. Uno de los problemas clave en este contexto es cómo gestionar el espectro de frecuencias de forma eficiente. Mientras que numerosas soluciones abordan escenarios de asignación dinámica de frecuencias, el nivel adicional de complejidad que presentan los usuarios móviles no ha sido suficientemente estudiado, y no está claro si los nuevos algoritmos de asignación de frecuencias pueden abordar la incertidumbre espacio-temporal. En concreto, sostenemos que los cambios inesperados en la posición de los usuarios introducen nuevas restricciones en la asignación de frecuencias que los algoritmos la literatura podrían no ser capaces de cumplir, especialmente si las decisiones deben tomarse en tiempo real y a escala. Para solventar esta limitación, proponemos un algoritmo de gestión dinámica de frecuencias basado en la programación lineal entera que asigna recursos en escenarios con usuarios tanto fijos como móviles, teniendo en cuenta la incertidumbre espacio-temporal de estos últimos. Nuestro método incluye tanto la planificación a largo plazo como la operación en tiempo real, una sinergia que no ha sido suficientThe unprecedented levels of flexibility and scalability of the next generation of communication satellite systems call for new resource management algorithms that adapt to dynamic environments. The upcoming landscape of satellite communication services will be defined by an increased number of unique users, a large portion of which will correspond to mobile users such as planes or ships. The additional challenge introduced by these users is addressing the spatiotemporal uncertainty that comes in the form of delays, changes in their trajectory, or both. Given that mobile users will constitute an important segment of the market, satellite operators prioritize leveraging modern digital payloads to develop flexible resource allocation strategies that are robust against dynamic user bases. One of the key problems in this context is how to manage the frequency spectrum efficiently. While numerous solutions address dynamic frequency assignment scenarios, the additional layer of complexity presented by mobile users has not been sufficiently studied, and it is unclear whether novel frequency assignment algorithms can address spatiotemporal uncertainty. Specifically, we argue that unexpected changes in the position of users introduce new restrictions into the frequency assignment, which previous algorithms in the literature might not be able to meet, especially if decisions need to be made in real-time and at scale. To address this gap, we propose a dynamic frequency management algorithm based on integer linear programming that assigns resources in scenarios with both fixed and mobile users, accounting for the spatiotemporal uncertainty of the latter. Our method includes both long-term planning and real-time operation, a synergy that has not been sufficiently explored for satellite communications and proves to be critical when operating under uncertainty. To fulfill the problem’s scope, we propose different strategies that extend a state-of-the-art frequency management algOutgoin

System Modelling and Design Aspects of Next Generation High Throughput Satellites

Future generation wireless networks are targeting the convergence of fixed, mobile and broadcasting systems with the integration of satellite and terrestrial systems towards utilizing their mutual benefits. Satellite Communications (Sat- Com) is envisioned to play a vital role to provide integrated services seamlessly over heterogeneous networks. As compared to terrestrial systems, the design of SatCom systems require a different approach due to differences in terms of wave propagation, operating frequency, antenna structures, interfering sources, limitations of onboard processing, power limitations and transceiver impairments. In this regard, this letter aims to identify and discuss important modeling and design aspects of the next generation High Throughput Satellite (HTS) systems. First, communication models of HTSs including the ones for multibeam and multicarrier satellites, multiple antenna techniques, and for SatCom payloads and antennas are highlighted and discussed. Subsequently, various design aspects of SatCom transceivers including impairments related to the transceiver, payload and channel, and traffic-based coverage adaptation are presented. Finally, some open topics for the design of next generation HTSs are identified and discussed.Comment: submitted to IEEE Journa