Recent trends in IP/NGEO satellite communication systems: transport, routing, and mobility management concerns

科研費報告書収録論文(課題番号:17500030/研究代表者:加藤寧/インターネットと高親和性を有する次世代低軌道衛星ネットワークに関する基盤研究

Firmware de seleção de célula para redes 5G não-terrestres

The integration of satellite technology in 5G will enable networks to become more ubiquitous and reliable, extending coverage to previously underserved areas and making the network more resilient to natural catastrophes. The nonterrestrial networks (NTN) are expected to co-exist with the current terrestrial infrastructures, sharing much of the same requirements. This in turn will allow the User Equipment to connect to both, opening up new use cases and possibilities. The intent of this dissertation is to design a firmware that prepares these devices to take advantage of this new paradigm. This firmware implements an extended, radio access and backhaul-aware cell selection scheme, that chooses either to connect to terrestrial or non-terrestrial cells. The selection is based on metrics, such as, the latency and packet loss of the link, in addition to the traditional signal strength indicators. Testing the solution required deploying an end-to-end 5G network which includes not only a gNodeB (gNB) capable of simulating the propagation delay induced by long distances but also a terrestrial node. This deployment uses the OpenAirInterface (OAI) 5G software stack. With the use of this testbench, the implemented firmware was tested against key network degradation scenarios. These scenarios include, for example, the total failure of the terrestrial gNB and the steady increase of latency. The results show that this use of the firmware might help upkeep the quality of service for the User Equipment using it.A integração de tecnologias satélite nas redes 5G vai permitir que estas se tornem mais seguras e omnipresentes, estendendo a cobertura de forma a abranger áreas remotas e tornando estas redes mais resilientes contra catástrofes naturais. É expectado que as redes não-terrestres venham a coexistir com as atuais redes terrestres, partilhando os mesmos requisitos. Por sua vez isto vai permitir que os terminais se conectem a ambos, abrindo assim novas possibilidades e casos de uso. Com esta dissertação pretende-se projetar um firmware que prepare estes dispositivos para tomar partido deste novo paradigma. Este firmware funciona como uma versão estendida, ciente do backhaul, do esquema de cell selection, de forma a que este possa decidir entre conectar cells terrestres ou não terrestres. Esta decisão é informada por métricas como a latência e a perda de pacotes da ligação, além dos indicadores de força de sinal tradicionais. Para a validação desta solução foi necessário a instalação de uma rede 5G end-to-end que incluísse tanto um gNodeB (gNB) capaz de simular atraso de propagação induzido pelas longas distâncias, tal como um nó terrestre. Esta instalação usa o OpenAirInterface (OAI), uma implementação da stack 5G. Usando esta testbench, a implementação do firmware projetado foi testada face a cenários de degradação da rede. Estes incluem, por exemplo, a falha total do gNB terrestre ou um aumento crescente da latência. Os resultados obtidos mostram que o uso deste firmware poderá ajudar a manter a qualidade de serviço de um terminal que o utilize.Mestrado em Engenharia de Computadores e Telemátic

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

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

Proceedings of the Fifth International Mobile Satellite Conference 1997

Satellite-based mobile communications systems provide voice and data communications to users over a vast geographic area. The users may communicate via mobile or hand-held terminals, which may also provide access to terrestrial communications services. While previous International Mobile Satellite Conferences have concentrated on technical advances and the increasing worldwide commercial activities, this conference focuses on the next generation of mobile satellite services. The approximately 80 papers included here cover sessions in the following areas: networking and protocols; code division multiple access technologies; demand, economics and technology issues; current and planned systems; propagation; terminal technology; modulation and coding advances; spacecraft technology; advanced systems; and applications and experiments