retrieval_results.txt

Original Query:
How does network topology impact synchronization in LEO satellite networks?

Top 25 Relevant Paragraphs:

in satellite constellation also significantly affects the network performance, as it determines the basic network topology. In particular, existing non-GEO constellations like Iridium use a

in satellite constellation also significantly affects the network performance, as it determines the basic network topology. In particular, existing non-GEO constellations like Iridium use a

Network Characteristics of LEO Satellite Constellations: A Starlink-Based Measurement from End Users Sami Ma∗, Yi Ching Chou∗, Haoyuan Zhao∗, Long Chen∗, Xiaoqiang Ma†, Jiangchuan Liu∗ ∗School of Computing Science, Simon Fraser University, Canada †CSIS Department, Douglas College, Canada Emails: {masamim, ycchou, hza127}@sfu.ca; {longchen.cs, mxqcs}@ieee.org; jcliu@sfu.ca

Network Characteristics of LEO Satellite Constellations: A Starlink-Based Measurement from End Users Sami Ma∗, Yi Ching Chou∗, Haoyuan Zhao∗, Long Chen∗, Xiaoqiang Ma†, Jiangchuan Liu∗ ∗School of Computing Science, Simon Fraser University, Canada †CSIS Department, Douglas College, Canada Emails: {masamim, ycchou, hza127}@sfu.ca; {longchen.cs, mxqcs}@ieee.org; jcliu@sfu.ca

Jiulong Ma, Xiaogang Qi, and Lifang Liu. 2017. An Effective Topology Design Based on LEO/GEO Satellite Networks. In International Conference on Space Information Network. Springer. Gérard Maral. 1994. The ways to personal communications via satellite. In International journal of satellite communications. Wiley Online Library. marine.rutgers.edu. 2001. Keplerian Elements. https://marine.rutgers.edu/cool/ education/class/paul/orbits.html. Florian Meyer. 2019. A new network design for the “Internet from space". https://ethz.ch/en/news-and-events/eth-news/news/2019/12/a-newnetwork-design-for-the-internet-from-space.html. NASA. 2008. Orbits and Kepler’s Laws. https://solarsystem.nasa.gov/resources/ 310/orbits-and-keplers-laws/. NASA. 2020. General Mission Analysis Tool. https://software.nasa.gov/software/ GSC-17177-1. NetworkX developers. 2020. NetworkX. https://networkx.github.io/. North American Aerospace Defense Command. 2020. https://www.norad.mil/. ns-3 Network Simulator. 2020. https://www.nsnam.org/. Pedro Silva. 2016. ns3-satellite. https://gitlab.inesctec.pt/pmms/ns3-satellite. Saheli Roy Choudhury. 2019. Super-fast internet from satellites is the next big thing in the space race. https://www.cnbc.com/2019/07/22/fast-internet-viasatellites-is-the-next-big-thing-in-the-space-race.html. Afreen Siddiqi, Jason Mellein, and Olivier de Weck. 2005. Optimal reconfigurations for increasing capacity of communication satellite constellations. In 46th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference. Kawsu Sidibeh. 2008. Adaption of the IEEE 802.11 protocol for inter-satellite links in LEO satellite networks. Ph.D. Dissertation. University of Surrey (United Kingdom). SNS3. 2020. https://www.sns3.org/content/home.php. SpaceX. 2016. SPACEX NON-GEOSTATIONARY SATELLITE SYSTEM. https: //fcc.report/IBFS/SAT-LOA-20161115-00118/1158350.pdf. SpaceX. 2019. SPACEX NON-GEOSTATIONARY SATELLITE SYSTEM. https: //fcc.report/IBFS/SAT-MOD-20190830-00087/1877671. 227 Exploring the “Internet from space” with Hypatia IMC ’20, October 27–29, 2020, Virtual Event, USA SpaceX FCC filing. 2017. SpaceX V-BAND NON-GEOSTATIONARY SATELLITE SYSTEM. https://licensing.fcc.gov/myibfs/download.do?attachment_key= 1190019. SpaceX FCC update. 2018. SPACEX NON-GEOSTATIONARY SATELLITE SYSTEM. https://licensing.fcc.gov/myibfs/download.do?attachment_key=1569860. SpaceX Starlink. 2017. https://www.spacex.com/webcast. David E Sterling and John E Hatlelid. 1991. The IRIDIUM system-a revolutionary satellite communications system developed with innovative applications of technology. In MILCOM 91-Conference record. IEEE. Telesat. 2018. Telesat’s responses - Federal Communications Commission. http: //licensing.fcc.gov/myibfs/download.do?attachment_key=1205775. Telesat. 2020. APPLICATION FOR MODIFICATION OF MARKET ACCESS AUTHORIZATION. https://fcc.report/IBFS/SAT-MPL-20200526-00053/2378318.pdf. Telesat. 2020. Telesat: Global Satellite Operators. https://www.telesat.com/. Liam Tung. 2020. SpaceX’s public beta of internet from space service coming by fall 2020. https://www.zdnet.com/article/elon-musk-spacexs-public-beta-ofinternet-from-space-service-coming-by-fall-2020/. Viasat. 2020. https://www.viasat.com/. Tanya Vladimirova and Kawsu Sidibeh. 2007. Inter-Satellite Links in LEO Constellations of Small Satellites. http://www.ee.surrey.ac.uk/m_ssc/research/vlsi/ intersatellite.html. Markus Werner, Axel Jahn, Erich Lutz, and Axel Bottcher. 1995. Analysis of system parameters for LEO/ICO-satellite communication networks. In IEEE Journal on Selected areas in Communications. ROBERT WIEDEMAN, ALLEN SALMASI, and Dennis Rouffet. 1992. GlobalstarMobile communications where ever you are. In 14th International Communication Satellite Systems Conference and Exhibit. AIAA. Lloyd Wood. 2001. Internetworking with satellite constellations. Ph.D. Dissertation. University of Surrey. Lloyd Wood. 2017. Satellite constellation visualization (SaVi). https://savi. sourceforge.io/. William W Wu, Edward F Miller, Wilbur L Pritchard, and Raymond L Pickholtz. 1994. Mobile satellite communications. In Proceedings of the IEEE. A GROUND STATION RELAYS Hypatia easily accommodates experimentation with constellations that eschew inter-satellite connectivity. In this scenario, ground station relays provide “bent pipe” connectivity with long-distance communication going up and down through satellites and GSes . To demonstrate this capability of Hypatia, we simulate a longlived TCP flow from Paris to Moscow over the first shell of Kuiper’s K1 shell (Table 1). We compare the behavior of the flow in two scenarios: (a) the constellation model used in the rest of the paper, i.e., with one GS-satellite link followed by a series of ISLs, followed by a satellite-GS link; and (b) without any ISLs, using only bent-pipe connectivity through GS relays. For the latter case, we add a grid of ground stations between Paris and Moscow such that there are multiple relays that can be chosen from. Fig. 16(a) and Fig. 16(b) show the situation at the start (𝑡= 0) for the two scenarios. Fig. 18(c) compares the path RTT over time for the two scenarios absent any traffic. As expected, the bent-pipe

Jiulong Ma, Xiaogang Qi, and Lifang Liu. 2017. An Effective Topology Design Based on LEO/GEO Satellite Networks. In International Conference on Space Information Network. Springer. Gérard Maral. 1994. The ways to personal communications via satellite. In International journal of satellite communications. Wiley Online Library. marine.rutgers.edu. 2001. Keplerian Elements. https://marine.rutgers.edu/cool/ education/class/paul/orbits.html. Florian Meyer. 2019. A new network design for the “Internet from space". https://ethz.ch/en/news-and-events/eth-news/news/2019/12/a-newnetwork-design-for-the-internet-from-space.html. NASA. 2008. Orbits and Kepler’s Laws. https://solarsystem.nasa.gov/resources/ 310/orbits-and-keplers-laws/. NASA. 2020. General Mission Analysis Tool. https://software.nasa.gov/software/ GSC-17177-1. NetworkX developers. 2020. NetworkX. https://networkx.github.io/. North American Aerospace Defense Command. 2020. https://www.norad.mil/. ns-3 Network Simulator. 2020. https://www.nsnam.org/. Pedro Silva. 2016. ns3-satellite. https://gitlab.inesctec.pt/pmms/ns3-satellite. Saheli Roy Choudhury. 2019. Super-fast internet from satellites is the next big thing in the space race. https://www.cnbc.com/2019/07/22/fast-internet-viasatellites-is-the-next-big-thing-in-the-space-race.html. Afreen Siddiqi, Jason Mellein, and Olivier de Weck. 2005. Optimal reconfigurations for increasing capacity of communication satellite constellations. In 46th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference. Kawsu Sidibeh. 2008. Adaption of the IEEE 802.11 protocol for inter-satellite links in LEO satellite networks. Ph.D. Dissertation. University of Surrey (United Kingdom). SNS3. 2020. https://www.sns3.org/content/home.php. SpaceX. 2016. SPACEX NON-GEOSTATIONARY SATELLITE SYSTEM. https: //fcc.report/IBFS/SAT-LOA-20161115-00118/1158350.pdf. SpaceX. 2019. SPACEX NON-GEOSTATIONARY SATELLITE SYSTEM. https: //fcc.report/IBFS/SAT-MOD-20190830-00087/1877671. Exploring the “Internet from space” with Hypatia IMC ’20, October 27–29, 2020, Virtual Event, USA SpaceX FCC filing. 2017. SpaceX V-BAND NON-GEOSTATIONARY SATELLITE SYSTEM. https://licensing.fcc.gov/myibfs/download.do?attachment_key= 1190019. SpaceX FCC update. 2018. SPACEX NON-GEOSTATIONARY SATELLITE SYSTEM. https://licensing.fcc.gov/myibfs/download.do?attachment_key=1569860. SpaceX Starlink. 2017. https://www.spacex.com/webcast. David E Sterling and John E Hatlelid. 1991. The IRIDIUM system-a revolutionary satellite communications system developed with innovative applications of technology. In MILCOM 91-Conference record. IEEE. Telesat. 2018. Telesat’s responses - Federal Communications Commission. http: //licensing.fcc.gov/myibfs/download.do?attachment_key=1205775. Telesat. 2020. APPLICATION FOR MODIFICATION OF MARKET ACCESS AUTHORIZATION. https://fcc.report/IBFS/SAT-MPL-20200526-00053/2378318.pdf. Telesat. 2020. Telesat: Global Satellite Operators. https://www.telesat.com/. Liam Tung. 2020. SpaceX’s public beta of internet from space service coming by fall 2020. https://www.zdnet.com/article/elon-musk-spacexs-public-beta-ofinternet-from-space-service-coming-by-fall-2020/. Viasat. 2020. https://www.viasat.com/. Tanya Vladimirova and Kawsu Sidibeh. 2007. Inter-Satellite Links in LEO Constellations of Small Satellites. http://www.ee.surrey.ac.uk/m_ssc/research/vlsi/ intersatellite.html. Markus Werner, Axel Jahn, Erich Lutz, and Axel Bottcher. 1995. Analysis of system parameters for LEO/ICO-satellite communication networks. In IEEE Journal on Selected areas in Communications. ROBERT WIEDEMAN, ALLEN SALMASI, and Dennis Rouffet. 1992. GlobalstarMobile communications where ever you are. In 14th International Communication Satellite Systems Conference and Exhibit. AIAA. Lloyd Wood. 2001. Internetworking with satellite constellations. Ph.D. Dissertation. University of Surrey. Lloyd Wood. 2017. Satellite constellation visualization (SaVi). https://savi. sourceforge.io/. William W Wu, Edward F Miller, Wilbur L Pritchard, and Raymond L Pickholtz. 1994. Mobile satellite communications. In Proceedings of the IEEE. A GROUND STATION RELAYS Hypatia easily accommodates experimentation with constellations that eschew inter-satellite connectivity. In this scenario, ground station relays provide “bent pipe” connectivity with long-distance communication going up and down through satellites and GSes . To demonstrate this capability of Hypatia, we simulate a longlived TCP flow from Paris to Moscow over the first shell of Kuiper’s K1 shell (Table 1). We compare the behavior of the flow in two scenarios: (a) the constellation model used in the rest of the paper, i.e., with one GS-satellite link followed by a series of ISLs, followed by a satellite-GS link; and (b) without any ISLs, using only bent-pipe connectivity through GS relays. For the latter case, we add a grid of ground stations between Paris and Moscow such that there are multiple relays that can be chosen from. Fig. 16(a) and Fig. 16(b) show the situation at the start (𝑡= 0) for the two scenarios. Fig. 18(c) compares the path RTT over time for the two scenarios absent any traffic. As expected, the bent-pipe

LEO satellites have become a subject of extensive research in recent years, with a particular focus on advancing the performance of various systems and technologies. Starlink, the posterchild of LEO networks, continues to grow in its maturity and reach with > 2M subscribers as of September 2023 . Despite its growing popularity, there has been limited exploration into measuring Starlink’s performance so far. Existing studies either have a narrow scope, employing only a few vantage points  or focus on broad application-level operation  without investigating root-causes. Few studies have looked into the mobile behavior of Starlink and compared it to terrestrial cellular carriers . A few endeavors have attempted to unveil the operations of Starlink’s black-box network. Pan et al.  revealed the operator’s internal network topology from traceroutes, whereas Tanveer et al.  spotlighted a potential global network controller. The absence of global measurement sites poses a predominant challenge hampering a comprehensive understanding of Starlink’s performance. As we show in this work, Starlink’s performance varies geographically due to differing internal configurations and ground infrastructure availability. Some researchers have devised innovative methods to combat this. For example, Izhikevich et al. conducted measurements towards exposed services behind the Starlink user terminal, while Taneja et al.  mined social media platforms like Reddit to gauge the LEO network’s performance. Our

Similar observations about latency in LEO networks have already been made in other work . However, a new and surprising finding here is about the comparison of the constellations. Telesat has the fewest satellites, with less than a third of Kuiper’s and less than a fourth of Starlink’s, and yet it achieves the lowest latencies for most connections. Starlink’s latencies are also higher than Kuiper’s.

Similar observations about latency in LEO networks have already been made in other work . However, a new and surprising finding here is about the comparison of the constellations. Telesat has the fewest satellites, with less than a third of Kuiper’s and less than a fourth of Starlink’s, and yet it achieves the lowest latencies for most connections. Starlink’s latencies are also higher than Kuiper’s.

Starlink dishes in two countries and analyze the impact of globally synchronized “15-second reconfiguration intervals” of the satellite links that cause substantial latency and throughput variations. Our unique analysis paints the most comprehensive picture of Starlink’s global and last-mile performance to date. CCS CONCEPTS • Networks →Network measurement. KEYWORDS Starlink; Satellite communications; Internet measurements ACM Reference Format: Nitinder Mohan, Andrew E. Ferguson, Hendrik Cech, Rohan Bose, Prakita Rayyan Renatin, Mahesh K. Marina, and Jörg Ott. 2024. A Multifaceted Look at Starlink Performance. In Proceedings of the ACM Web Conference 2024 (WWW ’24), May 13–17, 2024, Singapore, Singapore. ACM, New York, NY, USA, 12 pages. https://doi.org/10.1145/3589334.3645328 Permission to make digital or hard copies of all or part of this work for personal or classroom use is granted without fee provided that copies are not made or distributed for profit or commercial advantage and that copies bear this notice and the full citation on the first page. Copyrights for components of this work owned by others than the author(s) must be honored. Abstracting with credit is permitted. To copy otherwise, or republish, to post on servers or to redistribute to lists, requires prior specific permission and/or a fee. Request permissions from permissions@acm.org. WWW ’24, May 13–17, 2024, Singapore, Singapore © 2024 Copyright held by the owner/author(s). Publication rights licensed to ACM. ACM ISBN 979-8-4007-0171-9/24/05...$15.00 https://doi.org/10.1145/3589334.3645328 1

39137. Jonathan C McDowell. 2020. The low earth orbit satellite population and impacts of the SpaceX Starlink constellation. The Astrophysical Journal Letters 892, 2 (2020), L36. Brandon Craig Rhodes. 2011. PyEphem: astronomical ephemeris for Python. Astrophysics Source Code Library (2011), ascl–1112. Qingqing Tang, Zesong Fei, Bin Li, and Zhu Han. 2021. Computation offloading in LEO satellite networks with hybrid cloud and edge computing. IEEE Internet of Things Journal 8, 11 (2021), 9164–9176. Jiang Wenjuan and Zong Peng. 2010. An improved connection-oriented routing in LEO satellite networks. In 2010 WASE International Conference on Information Engineering, Vol. 1. IEEE, 296–299. 42

starlink LEO satellite signals IEEE Trans. Aerosp. Electron. Syst., to be published, doi: 10.1109/TAES.2021.3113880.

Performance measurements. Satellite-based connectivity has been in operation at least for couple of decades . However, as compared to satellites on geosynchronous earth orbit (GSO), LEO satellite systems struggled to commercially take o￿in the past . Thus, a signi￿cant proportion of works focus on GSO, more speci￿cally on satellites on the circular geosynchronous orbit called Geostationary equatorial orbit (GEO), to optimise the link latencies and achieve protocol enhancements. Bene￿ts of protocol improvements at application level like HTTP/1.1 to HTTP/2 , QUIC  were also investigated. The works in the past are therefore limited to performance measurements with GEO satellites. Modelling and simulation. LEO satellite studies have focussed mostly on theoretical models exploring opportunities to improve the 5G connectivity , handover performance , optimal channel reservations , e￿cient beamforming , performance of navigation systems , IoT devices  etc.. Performance of protocols in the simulated LEO environments are also studied . More recently, Kassing et al.  developed a packet-level LEO network simulator based on ns-3. Designs of new constellations  and in-orbit computing  are also proposed to tackle the disparate requirements from a variety of applications. This work bridges the gap between these two categories of research e￿orts by conducting the ￿rst measurement study (along with ) on the commercial LEO satellite network, Starlink. Our measurement study sheds light on the unique characteristics of the new Internet from space provided by this megaconstellation of LEO satellites and provides two datasets that can be utilized to equip LEO simulations with real-world data which would enable rapid design and development of di￿erent network protocols. 3

We presented a network topology for global constellations of interconnected LEO satellite internet networks that supports a low-cost, location-oriented routing scheme. We demonstrate that ×Grid has fewer hops between common routes than conventional +Grid configurations. The ×Grid topology orients ISLs to the direction of motion, allowing client state information to be handed off to direct neighbors. Additionally, the routing scheme atop ×Grid facilitates the selection of appropriate return node knowing only the estimated RTT. We demonstrate efficacy of ×Grid and the routing scheme through simple simulations. In this simulation we show that ×Grid alone delivers approximately 20% more packets due to reduced latency in the number of hops, and that our routing scheme performs similarly to plain ×Grid while never dropping packets due to handoff. ACKNOWLEDGEMENTS This work was supported by an Internet Society (ISOC) Foundation grant. The views and conclusions contained herein are those of the authors and should not be interpreted as necessarily representing the official policies or endorsements, either expressed or implied, of ISOC. 41 LEO-NET ’23, October 6, 2023, Madrid, Spain Joseph McLaughlin, Jee Choi, and Ramakrishnan Durairajan

Performance measurements. Satellite-based connectivity has been in operation at least for couple of decades . However, as compared to satellites on geosynchronous earth orbit (GSO), LEO satellite systems struggled to commercially take off in the past . Thus, a significant proportion of works focus on GSO, more specifically on satellites on the circular geosynchronous orbit called Geostationary equatorial orbit (GEO), to optimise the link latencies and achieve protocol enhancements. Benefits of protocol improvements at application level like HTTP/1.1 to HTTP/2 , QUIC  were also investigated. The works in the past are therefore limited to performance measurements with GEO satellites. Modelling and simulation. LEO satellite studies have focussed mostly on theoretical models exploring opportunities to improve the 5G connectivity , handover performance , optimal channel reservations , efficient beamforming , performance of navigation systems , IoT devices  etc.. Performance of protocols in the simulated LEO environments are also studied . More recently, Kassing et al.  developed a packet-level LEO network simulator based on ns-3. Designs of new constellations  and in-orbit computing  are also proposed to tackle the disparate requirements from a variety of applications. This work bridges the gap between these two categories of research efforts by conducting the first measurement study (along with ) on the commercial LEO satellite network, Starlink. Our measurement study sheds light on the unique characteristics of the new Internet from space provided by this megaconstellation of LEO satellites and provides two datasets that can be utilized to equip LEO simulations with real-world data which would enable rapid design and development of different network protocols. 3

SpaceX, Amazon, and others plan to put thousands of satellites in low Earth orbit to provide global low-latency broadband Internet. SpaceX’s plans have matured quickly, such that their underdeployment satellite constellation is already the largest in history, and may start offering service in 2020. The proposed constellations hold great promise, but also present new challenges for networking. To enable research in this exciting space, we present Hypatia, a framework for simulating and visualizing the network behavior of these constellations by incorporating their unique characteristics, such as high-velocity orbital motion. Using publicly available design details for the upcoming networks to drive our simulator, we characterize the expected behavior of these networks, including latency and link utilization fluctuations over time, and the implications of these variations for congestion control and routing. CCS CONCEPTS • Networks →Network simulations; Network performance analysis; Network dynamics; Topology analysis and generation; Packet-switching networks. KEYWORDS Low Earth orbit satellite, LEO, Internet broadband constellation, LEO network simulation, LEO network visualization ACM Reference Format: Simon Kassing∗, Debopam Bhattacherjee∗, André Baptista Águas, Jens Eirik Saethre, Ankit Singla. 2020. Exploring the “Internet from space” with Hypatia. In ACM Internet Measurement Conference (IMC ’20), October 27– 29, 2020, Virtual Event, USA. ACM, New York, NY, USA, 16 pages. https: //doi.org/10.1145/3419394.3423635 1

SpaceX, Amazon, and others plan to put thousands of satellites in low Earth orbit to provide global low-latency broadband Internet. SpaceX’s plans have matured quickly, such that their underdeployment satellite constellation is already the largest in history, and may start offering service in 2020. The proposed constellations hold great promise, but also present new challenges for networking. To enable research in this exciting space, we present Hypatia, a framework for simulating and visualizing the network behavior of these constellations by incorporating their unique characteristics, such as high-velocity orbital motion. Using publicly available design details for the upcoming networks to drive our simulator, we characterize the expected behavior of these networks, including latency and link utilization fluctuations over time, and the implications of these variations for congestion control and routing. CCS CONCEPTS • Networks →Network simulations; Network performance analysis; Network dynamics; Topology analysis and generation; Packet-switching networks. KEYWORDS Low Earth orbit satellite, LEO, Internet broadband constellation, LEO network simulation, LEO network visualization ACM Reference Format: Simon Kassing∗, Debopam Bhattacherjee∗, André Baptista Águas, Jens Eirik Saethre, Ankit Singla. 2020. Exploring the “Internet from space” with Hypatia. In ACM Internet Measurement Conference (IMC ’20), October 27– 29, 2020, Virtual Event, USA. ACM, New York, NY, USA, 16 pages. https: //doi.org/10.1145/3419394.3423635 1

• We lay out the case for building network analysis tools for upcoming LEO networks. As a first step towards meeting this need, we develop Hypatia, an analysis framework capturing the orbital dynamics of LEO networks. • We use regulatory filings by the largest three planned LEO networks to evaluate and visualize their networks. • Using packet-level simulations, we analyze the behavior of individual end-end connections across such networks in terms of their changing latencies and path structure, and show how this impacts congestion control negatively, even in the absence of any competing traffic. • Further, by simulating traffic constellation-wide, we show that the changes in path structure result in a difficult problem for routing and traffic engineering, as the utilization of paths and links is highly dynamic. • Hypatia’s visualizations aid intuition about the structure of satellite trajectories and their impact on a constellation’s behavior, and pin-point traffic hotspots in the network and show their evolution over time. Satellite networking played an important role in laying the foundations of the Internet, and may again provide the impetus for substantial and exciting changes. We hope that Hypatia will serve as an enabler for that work. Hypatia’s source code is available online , together with our visualizations . 2

• We lay out the case for building network analysis tools for upcoming LEO networks. As a first step towards meeting this need, we develop Hypatia, an analysis framework capturing the orbital dynamics of LEO networks. • We use regulatory filings by the largest three planned LEO networks to evaluate and visualize their networks. • Using packet-level simulations, we analyze the behavior of individual end-end connections across such networks in terms of their changing latencies and path structure, and show how this impacts congestion control negatively, even in the absence of any competing traffic. • Further, by simulating traffic constellation-wide, we show that the changes in path structure result in a difficult problem for routing and traffic engineering, as the utilization of paths and links is highly dynamic. • Hypatia’s visualizations aid intuition about the structure of satellite trajectories and their impact on a constellation’s behavior, and pin-point traffic hotspots in the network and show their evolution over time. Satellite networking played an important role in laying the foundations of the Internet, and may again provide the impetus for substantial and exciting changes. We hope that Hypatia will serve as an enabler for that work. Hypatia’s source code is available online , together with our visualizations . 2

characterizing the network performance of emerging LEO megaconstellations. However, constructing a hybrid constellation that integrates satellites working in various kinds of orbit (e.g., LEO, GEO and MEO) to collaboratively provide global network access, is another blooming picture in the evolution of SNs. We will extend STARPERF to model and profile such kind of hybrid SNs in the future. Authorized licensed use limited to: Tsinghua University. Downloaded on February 26,2025 at 02:54:36 UTC from IEEE Xplore.  Restrictions apply. Improving the fidelity of STARPERF. Like other recent works that study on the network performance of emerging

trum adaptation and multiplexing , or the time consumed by a real satellite dish to detect PHY connectivity changes. Future work. Satellite Internet mega-constellations are still evolving rapidly. New constellation designs are constantly being proposed, and existing constellation schemes are constantly being updated. In our future work, we will follow the evolution and deployment of realistic satellite Internet constellations. In particular, we will track the latest constellation information to update STARRYNET’s open database, calibrate the constellation models and further improve the fidelity of the STARRYNET framework. Moreover, based on these implinew network techniques tailored for ISTNs, e.g., practical and resilient satellite routing protocols in the future. Our latest research progress on STARRYNET will be updated on the website: https://github.com/SpaceNetLab/StarryNet. 9

trum adaptation and multiplexing , or the time consumed by a real satellite dish to detect PHY connectivity changes. Future work. Satellite Internet mega-constellations are still evolving rapidly. New constellation designs are constantly being proposed, and existing constellation schemes are constantly being updated. In our future work, we will follow the evolution and deployment of realistic satellite Internet constellations. In particular, we will track the latest constellation information to update STARRYNET’s open database, calibrate the constellation models and further improve the fidelity of the STARRYNET framework. Moreover, based on these implinew network techniques tailored for ISTNs, e.g., practical and resilient satellite routing protocols in the future. Our latest research progress on STARRYNET will be updated on the website: https://github.com/SpaceNetLab/StarryNet. 9

for optimizing the performance of modern satellite networks, as listed below. • (i) Emerging mega-constellations indeed offer low-latency opportunities for long-distance communications if ISLs are deployed, especially for communications between different continents. The attainable network performance can be significantly affected by the concrete constellation design. Satellites working on lower orbits may provide lower latency due to the shortened route length. However, lower orbits are also faster with a higher orbital velocity, which is more likely to cause intermittent network connectivity and higher jitter. Thus, the constellation design and network policies should be jointly optimized to support various upper applications. • (ii) The orbital decision and the scale of satellites can significantly affect the resilience of the constellation. An even constellation design (e.g., Starlink) has more nodes with Authorized licensed use limited to: Tsinghua University. Downloaded on February 26,2025 at 02:54:36 UTC from IEEE Xplore.  Restrictions apply. 0 10 20 30 40 50 60 Latency (ms) 0 0.5 1 CDF NewYork<-->Beijing StarLink OneWeb Telesat 0 10 20 30 Latency (ms) 0 0.5 1 CDF London<-->Beijing StarLink OneWeb Telesat 0 10 20 30 Latency (ms) 0 0.5 1 CDF Beijing<-->Sydney StarLink OneWeb Telesat 0 10 20 30 40 50 Latency (ms) 0 0.5 1 CDF NewYork<-->London StarLink OneWeb Telesat 0 20 40 60 80 100 Latency (ms) 0 0.5 1 CDF Sydney<-->NewYork StarLink OneWeb Telesat 0 10 20 30 40 Latency (ms) 0 0.5 1 CDF London<-->Sydney StarLink OneWeb Telesat Fig. 6: Area-to-area attainable latency on various mega-constellations. The area-to-area path is calculated by the shortest path identification algorithm, using the number of hops as the routing metric. NY<->BJ LD<->BJ BJ<->SN NY<->LD SN<->NY LD<->SN 0 10 20 Throughput(Gbps) StarLink OneWeb Telesat Fig. 7: Throughput obtained under different constellations. 0 0.02 0.04 0.06 0.08 0.1 Betweenness 0 0.5 1 CDF

characterizing the network performance of emerging LEO megaconstellations. However, constructing a hybrid constellation that integrates satellites working in various kinds of orbit (e.g., LEO, GEO and MEO) to collaboratively provide global network access, is another blooming picture in the evolution of SNs. We will extend STARPERF to model and profile such kind of hybrid SNs in the future. Authorized licensed use limited to: Tsinghua University. Downloaded on September 02,2024 at 10:45:02 UTC from IEEE Xplore.  Restrictions apply. Improving the fidelity of STARPERF. Like other recent works that study on the network performance of emerging

for optimizing the performance of modern satellite networks, as listed below. • (i) Emerging mega-constellations indeed offer low-latency opportunities for long-distance communications if ISLs are deployed, especially for communications between different continents. The attainable network performance can be significantly affected by the concrete constellation design. Satellites working on lower orbits may provide lower latency due to the shortened route length. However, lower orbits are also faster with a higher orbital velocity, which is more likely to cause intermittent network connectivity and higher jitter. Thus, the constellation design and network policies should be jointly optimized to support various upper applications. • (ii) The orbital decision and the scale of satellites can significantly affect the resilience of the constellation. An even constellation design (e.g., Starlink) has more nodes with Authorized licensed use limited to: Tsinghua University. Downloaded on September 02,2024 at 10:45:02 UTC from IEEE Xplore.  Restrictions apply. 0 10 20 30 40 50 60 Latency (ms) 0 0.5 1 CDF NewYork<-->Beijing StarLink OneWeb Telesat 0 10 20 30 Latency (ms) 0 0.5 1 CDF London<-->Beijing StarLink OneWeb Telesat 0 10 20 30 Latency (ms) 0 0.5 1 CDF Beijing<-->Sydney StarLink OneWeb Telesat 0 10 20 30 40 50 Latency (ms) 0 0.5 1 CDF NewYork<-->London StarLink OneWeb Telesat 0 20 40 60 80 100 Latency (ms) 0 0.5 1 CDF Sydney<-->NewYork StarLink OneWeb Telesat 0 10 20 30 40 Latency (ms) 0 0.5 1 CDF London<-->Sydney StarLink OneWeb Telesat Fig. 6: Area-to-area attainable latency on various mega-constellations. The area-to-area path is calculated by the shortest path identification algorithm, using the number of hops as the routing metric. NY<->BJ LD<->BJ BJ<->SN NY<->LD SN<->NY LD<->SN 0 10 20 Throughput(Gbps) StarLink OneWeb Telesat Fig. 7: Throughput obtained under different constellations. 0 0.02 0.04 0.06 0.08 0.1 Betweenness 0 0.5 1 CDF