1. Satellite connectivity
Skills: none
IT concepts: geostationary, medium-Earth, and low-Earth orbit satellite characteristics, spectrum and licensing, satellite technology progress, important Internet-service satellite projects and some of their implications
This work is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 3.0 License.

2. Where does this topic fit?
Internet concepts
Applications
Technology (communication)
Implications
Internet skills
Application development
Content creation (images)

3. Low-Earth, medium Earth and geostationary satellite characteristics
Altitude (miles)
Latency (milliseconds)
Orbit time (hours)
LEO
< 1,200
20-25
Around 2
MEO
1,200-22,236
Around 12
GSO
22,236 24
Orbit characteristics calculator
Why is the geostationary satellite altitude exactly 22,236 miles while LEO and MEO are ranges?
Where would the moon fit in this picture?

4. Footprint of a proposed SpaceX Starlink satellite
Starlink is the trade name of SpacX’s proposed Internet-service satellite constellation.
All things being equal, will LEO, MEO or GSO satellites have the largest footprint?

5. Footprint example – LEO and VLEO
The signal is strongest when the satellite is directly overhead and fades as it moves away. When it gets too weak, the ground terminal automatically switches to another satellite with a better signal.
Where would the strongest signal would be within the footprint?

6. Geostationary orbit (GSO)
35,786 km (22,236 mi) and directly above the equator
Video broadcast and slow Internet
The satellite remains over the same point on the Earth since it rotates around the Earth exactly once per day.
Animate

7. Medium Earth Orbit (MEO)
1, ,236 miles
Global Positioning System and medium speed Internet
A relatively small constellation can insure full coverage of the Earth with multiple visible satellites. This animation shows the orbits of the GPS satellites and the number that are visible above the central US at a given time.
Animate
Source

8. Low-Earth Orbit (LEO) Under 1,200 miles
Earth imaging, science, fast Internet (?)
To be sure the entire Earth is covered at all times, many more satellites are needed.
This animation was prepared for Teledesic, which was formed in the 1990s, but failed because the technology was inadequate, Internet use was much less common and there was much less complementary terrestrial technology.
Animate

9. Ku-band: 12 to 18 gigahertz GHz Ka-band: 26.5 to 40 GHz
Spectrum
Ku-band: 12 to 18 gigahertz GHz
Ka-band: 26.5 to 40 GHz
V-band: 40 to 75 GHz
E-band: 60 to 90 GHz
Good news – higher frequency means faster transmission
Good news – higher frequency means smaller antennas
Bad news – higher frequency means more power or less distance
Best news – you only have to know the previous good/bad news, not the frequency bands
These statements are true given that other things remain equal. For example, more efficient

10. Licensed versus unlicensed spectrum
Each country controls its own spectrum and the International Telecommunication Union tries to keep it uniform. The ITU is a UN agency.
Did you apply to the FCC for a WiFi license? It WiFi is license-free.
WiFi is in the 2.4 and 5 GHz bands.
Do WiFi radios uses licensed or unlicensed spectrum?

11. Address the “digital divide”
Do all Internet users have the same quality of service?
Is there a digital divide within the United States?
If successful, LEO will have many applications – the big one is to bring the Internet to unserved people.
Source

12. Fewer, faster hops than fiber on long routes
Another hoped-for advantage
Los Angeles to Punta Arena, Chile
Source

13. Teledesic failed in the late 1990s, what has changed?

14. In 1945, Arthur C. Clarke proposed geostationary satellite communication (The vision)
“Fig. 2. Typical extra-terrestrial relay services. Transmission from A being relayed to point B and area C; transmission from D being relayed to whole hemisphere.”
Extra Terrestrial Relays, Arthur C. Clark, Wireless World, October 1945, pages
Clark is best known as a science fiction author. Check out the article on 2001 a Space Odyssey.
Arthur C. Clark also wrote 2001 a Space Odyssey

15. Technology progress – ground station equipment
The “dish” on the left could only establish a link to a satellite and it had to be precisely pointed at a geostationary satellite and transmission and latency were very slow.
Today’s “terminal” includes the antenna and a fast computer for switching between satellites as they move and interfaces for the Internet, mobile phone network and Wifi. It will be simple for a user to install.
Early geostationary satellite dish in rural India
Proposed low-Earth orbit satellite terminal with solar panels

16. Technology progress – communication
Beam forming
High speed
Laser between satellites

17. Technology progress – rocketry
Reusability
Payload increases
Milestones
Founded; 2002
First Falcon 1 demo flight; 2006
First Falcon 1 flight to orbit: 2008 …
First Falcon Heavy flight to orbit: 2018
First BFR flight to orbit: 2022 (est)
Payload to LEO (
Falcon 1: 470 kg (expendable)
Falcon 9: 13,150 kg
Falcon Heavy : 33,800 kg
BFR: 150,000 kg
Reuability of booster, second stage and fairing
Falcon 1: Expendable
Falcon 9: Partial reuse
Falcon Heave: Partial reuse
BFR: Full reuse
Elon Musk says they would have gone bankrupt had the 2008 Falcon 1 flight failed – it was their fourth attempt.

18. SpaceX Starlink status
Three leading contenders
four markets: Cloud service provider, mobile operators, air and sea, civil/government
O3b mpower press conference:
OneWeb status
SpaceX Starlink status
O3b status

19. LEO optimism

20. Summary
We have seen three types of satellite orbit – LEO, MEO and GEO – along with their characteristics, reviewed the technical progress that has made constellations of LEO and MEO Internet-service constellations possible and considered a few implications of their availability,

21. Track the progress of the Internet-service satellite projects here.
Resources
Track the progress of the Internet-service satellite projects here.

22. Self-study questions I mentioned three leading companies
Which one(s) is/are pursuing the consumer market?
Which one(s) is/are pursuing other markets?
What are some non-consumer markets for satellite connectivity
Which is best suited to the consumer Internet service market: LEO, MEO or GSO?
Which has a larger footprint: LEO, MEO or GSO?
Which has a longer latency time: LEO, MEO or GSO?
What is latency a measure of?