SUMMARYThis paper introduces architectures for next-generation high throughput satellite (HTS) systems comprising various satellite payload options, ground terminal advances, and scalable system-level software control and management techniques. It describes a model to estimate aggregate system capacity as a function of radio band, available spectrum, spot beams, waveforms, and payload capability, including antenna size, power, and digital/ analog connectivity across various links and availability objectives. This system model has been used to evaluate aggregate capacity of representative Ka-Band low earth orbit and geosynchronous orbit systems. A system implementation approach is described for next-generation HTS systems based on widely used Industry standards. Modulation and coding techniques are based on Digital Video Broadcasting -S2 extensions (DVB-S2X), which comprises spectrally efficient modulation schemes combined with low-rate codes. Several implementation technologies are analyzed related to configurable onboard payload and ground-based, software-defined resource control and management, key enablers of next-generation HTS systems. Basic architectural building blocks are introduced for design of end-to-end systems across low earth orbit, medium earth orbit, and geosynchronous orbit satellite constellations, with and without onboard processing and inter-satellite links, and including several efficient scenarios to achieve lossless handovers.

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Despite some predictions of the total demise of next generation satellite systems, a working Ka-band regenerative satellite system has been built and it is called SPACEWAY TM*. SPACEWAY provides a two-way broadband "Internet in the Sky" IP network over satellite. It utilizes on-board regenerative processing and on-board packet switching with one-hop mesh connectivity between satellite terminals in its spot beams. This paper discusses the SPACEWAY system, its overall architecture, its network services, and its capabilities as built. It describes how the pieces of SPACEWAY are layered together to provide a complete set of end-user IP networking services. SPACEWAY has completed its system design, system deployment, and system testing for service availability in 2007. SPACEWAY implements the internationally approved ESTI/TIA/ITU standard called Regenerative Satellite Mesh-A (RSM-A) used for twoway single-hop regenerative mesh communications. This paper further discusses how SPACEWAY can be leveraged for a low-risk DoD-grade satellite system providing communications-on-the-move (COTM), information assurance (IA), virtual private networks (VPNs), and policy management.

Mega satellite constellations in low earth orbit (LEO) will provide complete global coverage; rapidly enhance overall capacity, even for unserved areas; and improve the quality of service (QoS) possible with lower signal propagation delays. Complemented by medium earth orbit (MEO) and geostationary earth orbit (GEO) satellites and terrestrial network components under a hybrid communications architecture, these constellations will enable universal 5G service across the world while supporting diverse 5G use cases. With an unobstructed line-of-sight visibility of approximately 3 min, a typical LEO satellite requires efficient user terminal (UT), satellite, gateway, and intersatellite link handovers. A comprehensive mobility design for mega-constellations involves cost-effective space and ground phased-array antennas for responsive and seamless tracking. An end-to-end multilayer protocol architecture spanning space and terrestrial technologies can be used to analyze and ensure QoS and mobility. A scalable routing and traffic engineering design based on software-defined networking adequately handles continuous variability in network topology, differentiated user demands, and traffic transport in both temporal and spatial dimensions. The spacebased networks involving mega-constellations will be better integrated with their terrestrial counterparts by fully leveraging the multilayer 5G framework, which is the foundational feature of our hybrid architecture.

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