Editing Satellite Internet access (section)

====Medium and low Earth orbits====
Medium Earth orbit (MEO) and low Earth orbit (LEO) satellite constellations do not have such long delays, as the satellites are closer to the ground. For example:
* The current LEO constellations of [[Globalstar]] and [[Iridium Satellite LLC|Iridium]] satellites have delays of less than 40&nbsp;ms round trip, but their throughput is less than broadband at 64&nbsp;kbit/s per channel. The Globalstar constellation orbits 1,420&nbsp;km above the Earth and Iridium orbits at 670&nbsp;km altitude.
* The [[O3b]] constellation orbits at 8,062&nbsp;km, with RTT latency of approximately 125&nbsp;ms.<ref>{{cite journal|arxiv=1407.2521|last1=Wood|first1=Lloyd|title=Revisiting elliptical satellite orbits to enhance the O3b constellation|journal=Journal of the British Interplanetary Society|volume=67|pages=110|last2=Lou|first2=Yuxuan|last3=Olusola|first3=Opeoluwa|year=2014|bibcode=2014JBIS...67..110W}}</ref> The network is also designed for much higher throughput with links well in excess of 1&nbsp;[[Data-rate units#Gigabit per second|Gbit/s]]. The next generation [[O3b mPOWER]] constellation shares the same orbit and delivers from 50&nbsp;Mbit/s to multiple gigabits per second to a single user.<ref>{{cite press release|url=https://boeing.mediaroom.com/2020-08-07-Boeing-to-Build-Four-Additional-702X-Satellites-for-SES|title=Boeing to Build Four Additional 702X Satellites for SES's O3b mPOWER Fleet|publisher=Boeing|date=7 August 2020|access-date=25 April 2021}}</ref>
* A study in 2021 showed that the [[Starlink]] satellites orbit at 550 km altitude, with an average RTT latency of 45&nbsp;ms.<ref>{{cite news|url=https://www.zdnet.com/article/starlink-is-better-than-its-satellite-competition-but-not-as-fast-as-landline-internet/|title=Starlink is better than its satellite competition but not as fast as landline internet|date=5 August 2021|access-date=26 March 2022}}</ref> Another study in 2022 showed that the latency of the Starlink network is 1.8&nbsp;ms to 22.8&nbsp;ms more than the latency of terrestrial networks according to a measurement study conducted in the Metro Vancouver area. <ref>{{Cite arXiv |last1=Ma |first1=Sami |last2=Chou |first2=Yi Ching |last3=Zhao |first3=Haoyuan |last4=Chen |first4=Long |last5=Ma |first5=Xiaoqiang |last6=Liu |first6=Jiangchuan |date=2022-12-27 |title=Network Characteristics of LEO Satellite Constellations: A Starlink-Based Measurement from End Users |class=cs.NI |eprint=2212.13697 }}</ref> Note that the exact measurement results can differ as the deployment of Starlink infrastructure varies across time and locations.

Unlike geostationary satellites, LEO and MEO satellites do not stay in a fixed position in the sky and from a lower altitude they can "see" a smaller area of the [[Earth]], and so continuous widespread access requires a constellation of many satellites (low-Earth orbits needing more satellites than medium-Earth orbits) with complex constellation management to switch data transfer between satellites and keep the connection to a customer, and tracking by the ground stations.<ref name="McK">[https://www.mckinsey.com/industries/aerospace-and-defense/our-insights/large-leo-satellite-constellations-will-it-be-different-this-time ''Large LEO satellite constellations: Will it be different this time?''] McKinsey & Company, 4 May 2020, Accessed 25 April 2021</ref><ref>[https://spacenews.com/divining-what-the-stars-hold-in-store-for-broadband-megaconstellations/ ''LEO and MEO broadband constellations mega source of consternation''] SpaceNews, 13 March 2018, Accessed 25 April 2021</ref>

MEO satellites require higher power transmissions than LEO to achieve the same signal strength at the ground station but their higher altitude also provides less orbital overcrowding, and their slower orbit speed reduces both [[Doppler effect|Doppler shift]] and the size and complexity of the constellation required.<ref>[http://interactive.satellitetoday.com/via/march-2019/the-gravity-of-space-debris/ ''The Gravity of Space Debris''] Via Satellite. March 2019, Accessed 25 April 2021</ref><ref>{{cite web |title=Satellites: LEO, MEO & GEO |url=https://www.atlantarf.com/Download_LEO_MEO_GEO.php |website=Atlanta RF |access-date=August 6, 2021 |archive-url=https://web.archive.org/web/20141003022149/https://www.atlantarf.com/Download_LEO_MEO_GEO.php |archive-date=2014-10-03 |date=October 29, 2013 |url-status=dead}}</ref>

Tracking of the moving satellites is usually undertaken in one of three ways, using:
* more diffuse or completely omnidirectional ground antennas capable of communicating with one or more satellites visible in the sky at the same time, but at significantly higher transmit power than fixed geostationary dish antennas (due to the lower gain), and with much poorer signal-to-noise ratios for receiving the signal 
* motorized antenna mounts with high-gain, narrow beam antennas tracking individual satellites
* [[phased array]] antennas that can steer the beam electronically, together with software that can predict the path of each satellite in the constellation.

In May 2022, [[Kazakhstan|Kazakhstani]] mobile network operator, [[Kcell]], and satellite owner and operator, [[SES (company)|SES]] used SES's [[O3b]] MEO satellite constellation to demonstrate that MEO satellites could be used to provide high-speed mobile internet to remote regions of Kazakhstan for reliable video calling, conferencing and streaming, and web browsing, with a latency five times lower than on the existing platform based on [[geostationary orbit]] satellites.<ref>[https://www.commsupdate.com/articles/2022/05/26/kcell-ses-demo-o3b-satellite-enabled-remote-mobile-services/ ''Kcell, SES demo O3b satellite-enabled remote mobile services''] Comms Update. 26 May 2022. Accessed 30 May 2022</ref><ref>{{cite press release|publisher=SES|date=25 May 2022 |url=https://www.ses.com/press-release/kcell-and-ses-successfully-demonstrate-cellular-network-connectivity-kazakhstan|title=Kcell and SES Successfully Demonstrate Cellular Network connectivity in Kazakhstan|access-date=30 May 2022}}</ref>