Low Earth orbit (LEO) satellites are deployed between ~400 and 2,000 km above the surface of the Earth. At this altitude, LEO satellites deployed for broadband communications purposes experience a significant advantage with respect to round-trip (~3 milliseconds) and inter-satellite latency, compared to MEO and GSO satellites.
The primary disadvantages of being deployed in LEO include experiencing some atmospheric drag leading to loss of orbit, and shorter life spans of the satellites (e.g. the planned life time for the Oneweb microsatellite is 7 years).165 Also, due to their high apparent angular velocity, LEO satellites have a smaller “dwell” time (in which the object is visible to one part of the Earth).
In order to overcome these challenges, satellite operators are required to use a constellation of satellites (with multiple orbits that differ with respect to location and time) to provide global coverage and visibility.
Despite the significant latency advantages of LEO, there are currently no commercial LEO satellite operators providing broadband communication services to consumers. Factors such as the number of satellites required to provide continuous coverage over a defined area, and the costs of satellite build, launch and replacement, have been historically prohibitive to the successful deployment of LEO satellites for commercial internet services.166
Recently, there has been renewed interest in this technology fueled by rapidly growing global internet connectivity demands and advances in satellite technology (e.g. smaller size and mass, antennae technology, and configurable radio-frequency payload systems) and practices (i.e. mass production) that have significantly reduced satellite production costs. As well, the demonstration by Space Exploration Technologies (also known as SpaceX) of a recovery of a first stage (SpaceX Falcon 9) rocket,167 along with advances in multiple small satellite launchers, will lead to significant satellite launch cost savings.
Three companies have emerged as having significant interest in bringing LEO satellite based commercial internet services to market: OneWeb LLC, LeoSat and SpaceX.
OneWeb LLC has plans to launch a satellite constellation of 648 LEO (1,200 km from Earth) Ku-Band microsatellites (< 150 kg) starting in late 2017, along with 250 spare satellites. The target price to produce each satellite is less than $500,000.168 OneWeb has established partnerships with Airbus (satellite production), MacDonald, Dettwiler and Associates (satellite antenna subsystem production), Virgin Galactic (deployment launches), Arianespace (Soyuz deployment launches) and Qualcomm (chip / electronics technology) to develop this technology. OneWeb is designed to provide up to 50 Mbps of effective bandwidth,169 a path latency below 30 milliseconds, and end-to-end latency below 50 milliseconds, which is similar to terrestrial fibre, DSL or cable modem service latencies170 (Figure 17).
Figure 17. OneWeb LLC satellite technology communications overview. Terrestrial networks
will provision internet to OneWeb terrestrial gateways, which will relay data to LEOS, and onwards to
user terminals. From the user terminal, consumers will be able to access the internet through direct
connection or via 3G, 4G LTE or Wi-Fi technologies.171
By 2018 or 2019, LeoSat LLC hopes to launch between 78 and 108 high-throughput Ka-band satellites into LEO (1,400 km from Earth) for global internet and data transfer services. Each satellite will have a bandwidth of 20 Gbps and an end-to-end latency time of less than 140 milliseconds.172, 173 LeoSat is partnering with Thales Alenia Space for the LEO constellation, which will provide high-speed, low-latency and highly secure communications and bandwidth for business operations in the telecom backhaul, oil & gas exploration, and maritime and international business markets.174
SpaceX also intends to launch a large constellation of small satellites for the purpose of providing a low-latency, high-capacity internet service with global coverage. It plans to launch ~4,000 satellites (300-400 kg) into LEO, and intends to begin testing its broadband antenna communications platform (primary payload) in late 2016 when it launches two identical Ku-Band demonstration satellites (MicroSat-1a and -1b) into a 625 km orbit.175 This will be the first of six-to-eight planned demonstration satellites that will inform the final LEO constellation design.
There is significant interest and potential to provide affordable and reliable internet service to remote and rural communities via satellite technologies. In Alberta, the SuperNet could play a key role in providing internet service providers wholesale access to middle-mile infrastructure to link upstream internet sources with terrestrial-based satellite gateways. Similarly, throughout the rest of Canada, affordable wholesale access to long-range backhaul fibre networks fed by satellite technologies will be critical to providing economical high-speed broadband services to consumers in rural and remote communities.
References
165. Gunter Krebs. OneWeb 1,...,900. Gunter’s Space Page. Accessed 10 June 2016.
166. Gunter Krebs. BATSAT (Teledesic T1). Gunter’s Space Page, 17 April 2016. Accessed 10 June, 2016.
167. Peter B. de Selding. SpaceX’s reusable Falcon 9: What are the real cost savings for customers? Space News. 25 April 2016. Accessed 18 May 2016.
168. Peter B. de Selding. Competition To Build OneWeb Constellation Draws 2 U.S., 3 European Companies. Space News. 19 March 2015. Accessed 18 May, 2016.
169. Mark Holmes. Greg Wyler Talks OneWeb. Satellite Today. 9 March 2015. Accessed 18 May, 2016.
170. CRTC. Transcript, Hearing April 25, 2016. Line 15296. Accessed 18 May 2016.
171. Qualcomm. OneWeb Global Communications Network. Accessed 18 May, 2016.
172. Leosat. Interview with Mark Rigolle, 16 September 2015. Accessed 10 June, 2016.
173. Space News. Why Leosat’s leaving Internet for the masses to Oneweb, 10 March 2015. Accessed 18 May, 2016.
174. Leosat. Interview with Cliff Anders, 9 September 2015. Accessed 18 May 2016.
175. Federal Communications Commission [U.S.]. SpaceX Purpose of Equipment. Accessed 18 May 2016.