Joint optimization of Beam Placement and Shaping for Multi-Beam High Throughput Satellite systems using Gradient Descent

El mercat de les comunicacions per satèl·lit està canviant i la nova generació de satèl·lits tindrà nivells de flexibilitat i escalabilitat sense precedents: s'espera que els futurs Satèl·lits d'Alt Rendiment de múltiples feixos (HTS, per les sigles en anglès) puguin operar milers de feixos simultàniament, cadascun amb un conjunt de paràmetres completament dinàmics per sintonitzar. Això planteja nous reptes quan es tracta d'administrar eficientment la creixent quantitat de recursos. Dos d'aquests reptes estan vinculats a: la ubicació del feix (és a dir, definint la direcció de cada feix) i la forma del feix (és a dir, optimitzant la distribució de guany entre els usuaris coberts). Comprendre com explotar aquestes dues flexibilitats podria millorar l'eficiència, reduïr la potència requerida i permetre l'allotjament de nous usuaris al sistema. Per tant, aquesta tesi es centra en l'optimització conjunta de la posició i forma dels feixos.El mercado de las comunicaciones por satélite está cambiando y la nueva generación de satélites tendrá niveles de flexibilidad y escalabilidad sin precedentes: se espera que los futuros Satélites de Alto Rendimiento de múltiples haces (HTS, por las siglas en inglés) puedan operar miles de haces simultáneamente, cada uno con un conjunto de parámtetros completamente dinámicos para sintonizar. Esto plantea nuevos desafíos cuando se trata de administrar eficientemente la creciente cantidad de recursos. Dos de estos desafíos están vinculados a: la ubicación del haz (es decir, definiendo la dirección para cada haz) y a la forma del haz (es decir, optimizando la distribución de ganancia entre los usuarios cubiertos). Comprender cómo explotar estas dos flexibilidades podría mejorar la eficiencia, reducir la potencia requerida y permitir el alojamiento de nuevos usuarios en el sistema. Por lo tanto, esta tesis se centra en la optimización conjunta de la posición y forma de los haces.The satellite communications market is changing and new generation of satellites will have unprecedented levels of flexibility and scalability: future multi-beam High Throughput Satellites (HTS) are expected to be able to operate thousands of beams simultaneously, each with a set of fully-dynamic parameters to tune. This poses new challenges when it comes to efficiently managing the increasing amount of resources. Two of these challenges are linked to the beam placement (i.e., defining the pointing direction for each beam) and beam shape (i.e., optimizing the gain distribution among covered users) problems. Understanding how to exploit these two flexibilities could improve the efficiency, reducing the required RF power and enabling the accommodation of new users into the system. Thus, this Thesis focuses on the joint beam placement and shaping optimization.Outgoin

A Vision and Framework for the High Altitude Platform Station (HAPS) Networks of the Future

A High Altitude Platform Station (HAPS) is a network node that operates in the stratosphere at an of altitude around 20 km and is instrumental for providing communication services. Precipitated by technological innovations in the areas of autonomous avionics, array antennas, solar panel efficiency levels, and battery energy densities, and fueled by flourishing industry ecosystems, the HAPS has emerged as an indispensable component of next-generations of wireless networks. In this article, we provide a vision and framework for the HAPS networks of the future supported by a comprehensive and state-of-the-art literature review. We highlight the unrealized potential of HAPS systems and elaborate on their unique ability to serve metropolitan areas. The latest advancements and promising technologies in the HAPS energy and payload systems are discussed. The integration of the emerging Reconfigurable Smart Surface (RSS) technology in the communications payload of HAPS systems for providing a cost-effective deployment is proposed. A detailed overview of the radio resource management in HAPS systems is presented along with synergistic physical layer techniques, including Faster-Than-Nyquist (FTN) signaling. Numerous aspects of handoff management in HAPS systems are described. The notable contributions of Artificial Intelligence (AI) in HAPS, including machine learning in the design, topology management, handoff, and resource allocation aspects are emphasized. The extensive overview of the literature we provide is crucial for substantiating our vision that depicts the expected deployment opportunities and challenges in the next 10 years (next-generation networks), as well as in the subsequent 10 years (next-next-generation networks).Comment: To appear in IEEE Communications Surveys & Tutorial

Space-Air-Ground Integrated 6G Wireless Communication Networks: A Review of Antenna Technologies and Application Scenarios

A review of technological solutions and advances in the framework of a Vertical Heterogeneous Network (VHetNet) integrating satellite, airborne and terrestrial networks is presented. The disruptive features and challenges offered by a fruitful cooperation among these segments within a ubiquitous and seamless wireless connectivity are described. The available technologies and the key research directions for achieving global wireless coverage by considering all these layers are thoroughly discussed. Emphasis is placed on the available antenna systems in satellite, airborne and ground layers by highlighting strengths and weakness and by providing some interesting trends in research. A summary of the most suitable applicative scenarios for future 6G wireless communications are finally illustrated

Future benefits and applications of intelligent on-board processing to VSAT services

The trends and roles of VSAT services in the year 2010 time frame are examined based on an overall network and service model for that period. An estimate of the VSAT traffic is then made and the service and general network requirements are identified. In order to accommodate these traffic needs, four satellite VSAT architectures based on the use of fixed or scanning multibeam antennas in conjunction with IF switching or onboard regeneration and baseband processing are suggested. The performance of each of these architectures is assessed and the key enabling technologies are identified

Automatic Tuning of Silicon Photonics Millimeter-Wave Transceivers Building Blocks

Today, continuously growing wireless traffic have guided the progress in the wireless communication systems. Now, evolution towards next generation (5G) wireless communication systems are actively researched to accommodate expanding future data traffic. As one of the most promising candidates, integrating photonic devices in to the existing wireless system is considered to improve the performance of the systems. Emerging silicon photonic integrated circuits lead this integration more practically, and open new possibilities to the future communication systems. In this dissertation, the development of the electrical wireless communication systems are briefly explained. Also, development of the microwave photonics and silicon photonics are described to understand the possibility of the hybrid SiP integrated wireless communication systems. A limitation of the current electrical wireless systems are addressed, and hybrid integrated mm-wave silicon photonic receiver, and silicon photonic beamforming transmitter are proposed and analyzed in system level. In the proposed mm-wave silicon photonic receiver has 4th order pole-zero silicon photonic filter in the system. Photonic devices are vulnerable to the process and temperature variations. It requires manual calibration, which is expensive, time consuming, and prone to human errors. Therefore, precise automatic calibration solution with modified silicon photonic filter structure is proposed and demonstrated. This dissertation demonstrates fully automatic tuning of silicon photonic all-pass filter (APF)-based pole/zero filters using a monitor-based tuning method that calibrates the initial response by controlling each pole and zero individually via micro-heaters. The proposed tuning approach calibrates severely degraded initial responses to the designed elliptic filter shapes and allows for automatic bandwidth and center frequency reconfiguration of these filters. This algorithm is demonstrated on 2nd- and 4th-order filters fabricated in a standard silicon photonics foundry process. After the initial calibration, only 300ms is required to reconfigure a filter to a different center frequency. Thermal crosstalk between the micro-heaters is investigated, with substrate thinning demonstrated to suppress this effect and reduce filter calibration to less than half of the original thick substrate times. This fully automatic tuning approach opens the possibility of employing silicon photonic filters in real communication systems. Also, in the proposed beamforming transmitter, true-time delay ring resonator based 1x4 beamforming network is imbedded. A proposed monitor-based tuning method compensates fabrication variations and thermal crosstalk by controlling micro-heaters individually using electrical monitors. The proposed tuning approach successfully demonstrated calibration of OBFN from severely degraded initial responses to well-defined group delay response required for the targeted radiating angle with a range of 60◦ (-30◦ to 30◦ ) in a linear beamforming antenna array. This algorithm is demonstrated on OBFN fabricated in a standard silicon photonics foundry process. The calibrated OBFN operates at 30GHz and provide 2GHz bandwidth. This fully automatic tuning approach opens the possibility of employing silicon OBFN in real wideband mm-wave wireless communication systems by providing robust operating solutions. All the proposed photonic circuits are implemented using the standard silicon photonic technologies, and resulted in several publications in IEEE/OSA Journals and Conferences

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