Cellular Via Satellite

Conventional base stations give us good cellular coverage in populated areas where traffic levels justify the investment in infrastructure. However large areas of land, such as much of Canada’s far north, will never justify regular terrestrial base stations. Satellite Phones work well but are expensive. New technology is now being tested that could enable satellites to work with regular cellphones.

By Peter Aggus

Peter, as a radio engineer & technology management consultant, has developed innovative & cost-effective solutions for clients in many industries.

The Problem

Much of the Earth’s surface has a need for cellular coverage but does not have the traffic levels to justify the investment. In many cases, such as across the oceans or in mountainous areas, there’s almost no traffic, yet users want cellular-level service at similar cost to regular cellular.

Current Solutions

Until now, in areas with no cellular coverage, people can use satellite technology. Geosynchronous satellites, such as Inmarsat, can provide near global coverage – at a high price. Low Earth Orbit (LEO) satellites have added lower cost options – but they still require special (expensive) handsets and have a high call cost.

Cellular companies extend their coverage to cover long highway routes in remote areas (or even urban areas with difficult terrain) through the use of lower cost small ‘Remote Base Stations’, linked back to a parent main cell site by fibre.

Experimental Solutions

Experiments have been done using this same concept to extend the technology to an aerial platform, using a balloon, airship or drone to provide service to a specific location. Rather than a fibre connection, the link is by radio. Amusingly, they call this radio over radio.

Technically, this could extend to putting the remote unit on a satellite – although that would require a fleet with massive numbers of low orbit satellites … which is exactly what companies like SpaceX have been launching to support global satellite internet.

In early January 2024, Starlink launched the first six Direct to Cell capable satellites. On January 8th, in partnership with T-Mobile in the US, they achieved a historic milestone by using the service to transmit text messages to a conventional cellphone. Radio regulations limit this service to using T-Mobile’s licensed spectrum in their authorized service area – so currently just the US. In April 2023, Rogers announced that it would be the Canadian partner with Starlink – so we expect soon to hear that they have completed a similar technology demonstration in Canada.

The first stage only offers SMS (text) communication – but even that limited service will be a complete game changer for Canada’s far north. If all goes well, the technology will advance to testing voice and data communications using LTE (4G and 5G compatible) later in 2025.

A different technology is being tested by Apple. All iPhones are able to send SOS text messages to 911 with voice callback using the cellular networks but the latest iPhones are equipped with a satellite frequency so, if they have no cell reception, their emergency SOS communications can be relayed via satellite. That service is not planned to offer non-emergency calls because the satellite frequency used is only approved for SOS use.

The Future

SMS uses very limited capacity and sends simple short messages for many users in sequence, multiple times if needed until receipt is confirmed. Voice and data expect much more capacity, and this limits how many simultaneous calls the ‘cell’ can handle – as indeed does the satellite’s available power. The cellphone will need good constant visibility of the sky for voice communication to work. We will watch with interest how the Starlink service develops.

No costs have yet been discussed – we are just at the technology demonstration phase of this exciting new service. Regulators have yet to decide the terms under which the service might be offered – will we see all carriers fighting to get their competing services operating, or will sanity prevail and give us a jointly managed roaming service available to all cellphone users?

If you’d like to discuss how to include these emerging technologies into your IT Strategic Plan, or to comment on this article, please email me at peter.