19-10-2022 | By Robin Mitchell
Recent proposals in the US to open the 12GHz spectrum to 5G operators have left SpaceX and other satellite broadband providers in a fury. What challenges does space satellite communication face, why are the proposals deeply concerning for satellite broadband providers, and why should these bands be left alone for satellite users only?
Throughout human history, man has developed different methods of communication. The spoken word has allowed humans to convey information to each other in a standardised format, while the written word has allowed an individual’s thoughts to endure the test of time. Smoke signals would enable groups of people to communicate over larger distances, and the invention of mail services allowed for this communication to span across continents. Eventually, the discovery of electricity and the invention of the telegram allowed for messages to be instantly transmitted across a country, and the radio opened human communication to the very edge of space itself.
Satellites provide mankind with extraordinary opportunities such as geolocation, imaging, and connectivity, but their high altitudes mean that radio waves are currently the only practical solution for establishing a reliable connection. While lasers are being explored, the high relative speed of orbiting satellites makes it difficult to track, aim, and fire a beam of light that the orbiting satellite can detect.
However, not just any radio frequency can be used as the Earth’s atmosphere absorbs large portions of the electromagnetic spectrum. Long-wave radio waves, infrared, UV, X-ray, and Gamma are all blocked by the atmosphere, which leaves radio wavelengths between 1cm and 10m as the only viable options. Considering that many other terrestrial services also run on the bands, satellite communication systems are left with a handful of frequency bands which lie between 1GHz and 40GHz.
The vast distance between satellites and their respective ground stations requires a large antenna with powerful transmitters, but because satellites are limited in size, signals from satellites can be very weak. As such, receivers on the ground need to be either very large or very sensitive, and this makes them vulnerable to interference. Therefore, it is essential that satellite bands are controlled with the use of licenses to prevent unauthorised transmissions that may interfere with satellite communication.
Recently, a US satellite broadcaster, Dish Network, in partnership with Dell Technologies, has requested the FCC to upgrade its radio license to allow it to also use the 12GHz spectrum to provide terrestrial 5G networks to customers. The two companies have stated to the FCC that their plan to integrate 5G terrestrial networks would not interfere with others using the band and, as such, should be allowed to proceed. Data submitted to the FCC by RS Access (who was backed by Michael Dell from Dell technologies) has suggested that if allowed, less than 1% of current satellite terminals using non-geostationary orbit systems would be affected. In cases where interference is causing issues, the two have stated mitigation techniques that will help, but exactly how quickly these methods could be enacted is not clear.
Now, when this proposal was submitted to the FCC, SpaceX and other satellite broadband providers have outright rejected the claims made by Dish Network and Dell Technologies and have expressed deep concern about how opening the 12GHz spectrum to 5G networks would affect their system performance. To help back the concerns made by SpaceX, another satellite broadband service provider, OneWeb, submitted its own study on the matter and has concluded that terrestrial 5G networks would be detrimental to satellite broadband providers. Another broadband company, DIRECTV, also backed claims made by SpaceX with concerns that the proposed plans would also disrupt their services.
In response to the claims made by SpaceX and other satellite broadband providers, Dish Network hit back with claims that counter-evidence to their license request has been based on poor assumptions. But a third-party investigation by SAVID determined that the power calculations done by SpaceX were in favour of Dish by a factor of four, but the data presented by Dish was underestimated by a factor of 40. Furthermore, SAVID determined that base stations built by Dish would undoubtedly cause signal degradation and therefore limit the bandwidth provided by satellite broadband providers. As such, SAVID has called for the FCC to reject the proposed 5G plans.
In cases like this, one hopes that those working at the FCC are clever enough to understand the presented data and have the technical knowledge to make educated decisions. If the FCC allows 5G networks to operate in the 12GHz spectrum, this wouldn’t be the first time such an organisation has made a major blunder. It was only a year ago that 5G installations had to be halted as it was found that 5G networks were using the same frequencies as those used by autopilots on planes. As such, a 5G network near an airport can potentially confuse a landing plane about its true height, and this could be disastrous in thick fog and bad weather.
In the case of satellite technologies, usable frequencies for satellites are already limited enough as it is, and there are plenty of other radio frequency spectrums that 5G installations can take advantage of. Furthermore, keeping the satellite frequencies restricted to satellites also helps for future-proofing. If these frequency bands are opened to terrestrial services, it may be difficult to introduce new satellite technologies as they could interfere with the existing terrestrial services.
Overall, it is a pretty stupid idea to open up the 12GHz to terrestrial services when considering that 5G services will become local and that satellites already face enough challenges as is.