A New Paradigm for Non-Geosynchronous Satellite Communications and Radio Astronomy Systems

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Spectrum is a precious natural resource for various active (transmit and receive) and passive (receive only) wireless systems, both of which provide several benefits to the society. However, phenomenal growth of active wireless systems and related spectrum allocations have caused less spectrum observation opportunities and greater chances of radio frequency interference (RFI) for passive wireless systems. One of the expansions of active wireless systems that deserves a special attention is the emergence of large-scale non-geosynchronous orbit (NGSO) satellite communication systems (SCSs). The prospects of such large-scale SCSs impose a distressing RFI situation to passive wireless systems such as radio astronomy system (RAS). Radio astronomy enables study of the universe, astro-physics and astro-chemistry as well as testing of the laws of fundamental physics, thus its growth is crucial for advancing science and knowledge discovery. The existing spectrum allocation/access paradigm is difficult to accommodate mutual growths of RAS and NGSO SCS. The purpose of this project is to develop a new paradigm for RAS and NGSO SCS where both types of systems can coexist and expand beyond what is achievable in the existing paradigm. Instead of viewing large-scale NGSO SCSs as a threat of RFI, this project views them as an opportunity to develop an integrated large-scale NGSO-SCS and NGSO-RAS system that can provide space-based RAS observation services, in addition to their main communication services. By enabling a large-scale NGSO-RAS, the proposed paradigm will open a new era for RAS with numerous enhanced capabilities and observation opportunities. This can lead to new exciting science discoveries on a larger scale. On the other hand, some spectrum originally allocated to RAS can be re-purposed for active wireless systems, thus stimulating more wireless applications and business opportunities for active wireless systems. The overall spectrum utilization efficiency will also be substantially enhanced.This project introduces a new paradigm of spectrum access for RAS and NGSO SCS by means of transforming a large-scale NGSO SCS into an integrated large-scale NGSO-SCS and NGSO-RAS. This is different from the current paradigm where RASs implemented on ground are prone to RFI caused by SCSs, and conflicting spectrum needs from both SCSs and RASs cannot be resolved. To have broader applicability, the project considers three types of integrated systems: i) a system with all dual-purpose satellites (each with SCS and RAS receivers), ii) a system with a mixture of dual-purpose satellites and single-purpose SCS-only satellites, iii) a system with a mixture of single-purpose SCS-only satellites and single-purpose RAS-only satellites. For each type of the integrated systems, further detailed technical developments are as follows: 1) The project will develop innovative approaches for spectrum access and resource allocation needed for the new paradigm. The project will also study new achievable performance in terms of RAS data rate, SCS data rate, and outage performance. Furthermore, promising deployment scenarios and recommended changes of frequency allocation rules will be investigated for the new paradigm. 2) The project will study new capabilities of the proposed large-scale NGSO-RAS under several deployment scenarios and practical constraints. In addition, novel solutions to enable RAS observations in the bands assigned to higher-orbit satellite systems will also be developed. 3) The project will develop efficient data transport strategies for both delay-sensitive SCS data and space-borne delay-insensitive RAS data under several deployment scenarios and optimization metrics. Joint design of resource allocation and data transport will also be developed for further performance improvement.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.