October 21, 2021 by Joe Ross, Senior Partner
Low Earth Orbit (LEO) satellite services have great promise for public safety communication. Historically, most satellite services have used what are referred to as Geostationary Earth Orbit (GEO). They’ve been in place for several decades and have delivered broadcast TV, marine communications, and broadband data. To continuously serve the same spot on Earth, GEO satellites must fly at an altitude of 26,000 miles. Unfortunately, it takes a long time for a radio signal to travel back and forth between Earth and a GEO satellite; there is substantial signal loss; and the satellite coverage cannot be focused on specific, smaller areas. So, there is a limited capacity, high latency, and large satellite antenna dishes are required to communicate back to these satellites. Some GEO services, like Sirius XM Radio can communicate directly to a small antenna, but they only communicate down to subscriber devices and do not need to communicate from the subscriber’s device back to the satellite. Therefore, the Sirius XM Radio satellite service only requires a small antenna to receive reliable coverage when in direct line of sight of the satellite.
LEO still uses satellites to transmit and receive information between earthbound devices and the satellites, but due to their proximity (usually somewhere between 500 km and 2000 km from Earth), the delay is much smaller, the signals are stronger, and each satellite can serve a much smaller geographic service area, allowing for massive reuse of radio spectrum. Because of these factors, there are numerous potential benefits for public safety. In exchange for delivering these benefits, an LEO satellite operator must have hundreds or thousands of satellites to serve regions of the Earth or the entire planet. With LEO, each satellite is flying overhead at speeds of tens of thousands of miles per hour, and the system must have at least one satellite in view at all times. Some of the subscriber devices have what are called “phased array” antennas that track the satellites. So while a GEO satellite is always at a fixed location longitudinally and on the equator (meaning that in the U.S. we point dishes south), LEO satellites are overhead. The promise of LEO is that you also do not have to steer the dish to the right satellite. They are constantly flying overhead and have line-of-sight (some may be able to deal with non-line-of-sight) with a subscriber’s antenna.
There are two basic service model offerings in the LEO space: direct to cell (D2C) and dedicated dish (or panel) and dedicated spectrum (DDS). To give you some context, here is a sampling of the broadband LEO projects that are currently underway:
|Lynk Global||D2C||Operational 2022|
|AST SpaceMobile||D2C||Equatorial - 2023
Global - 2024
|Starlink (SpaceX)||DDS||Commercial Oct 2021|
|OneWeb||DDS||Above 50th Parallel EO2021
For public safety, the core benefit of these low earth orbit solutions is emergency communication. In areas where there is no cell service, or where the cell networks are down, satellite communications can provide an important lifeline for a facility, vehicle, or, in the case of the D2C options, directly to a standard smartphone. The benefits of this should be clear. The major cellular carriers have widely varying levels of power backup on their cell sites. So, it might only take a four-to-eight-hour power outage in an area before the cell sites begin to lose battery power. If the power outage is prolonged, the carriers might struggle to refuel after 24 hours. And, in areas with high-winds or flooding, the cell equipment could be destroyed, taking a week to bring service back.
And then there are the parts of the country with no reliable service whatsoever. We all know how the carriers’ maps very generously show service (I’ll post on that later). Even in suburban areas, I find all kinds of dead spots outdoors. But in rural areas, there are vast areas that the carriers claim to be covered that are not, and then there are those remote areas where no carrier even claims service. These are areas where public safety still needs access to broadband data, and frankly, low-speed data would often suffice.
It’s in these situations that low-earth orbit satellite can thrive for public safety communications. It’s feasible that in a few years, mobile kits could be available for the dedicated dish solutions for communications or command vehicles that in turn could provide Wi-Fi service to nearby smartphones. Or, for those leveraging the FirstNet customer owned emergency deployable solutions, they could use high-speed, low latency backhaul to connect back to the internet. We helped a customer deploy a SatCoLT solution, and the geostationary satellite service is both slow and expensive (a guaranteed megabit for tens of thousands of dollars a year). The LEO solutions promise to deliver far greater speeds, at far lower costs (and hopefully with minimum speed commitments in the future to deliver public safety grade communication).
The direct to cellular solutions from AST SpaceMobile and Lynk Global are particularly interesting. For those, any first responder at hopefully any outdoor location in the country could use their smartphone to communicate at broadband speeds. These companies are making very bold claims about indoor use and high broadband speeds that I’ll opine on later, but even if they can deliver speeds fast enough to convey computer aided dispatch information, carry on push-to-talk or phone voice communications, enable text messaging, and identify unit location, many in the public safety community would consider that a success. If they can deliver reliable broadband speeds consistent with the FCC’s 5 and 1 megabits per second requirement for mobile broadband, that would be phenomenal.
These solutions have a long way to go. Even the Starlink service that has been providing its beta service for nearly a year, users are reporting issues of service outages (see here). As more satellites are launched, reliability should improve. But obstructions haunt the dedicated spectrum solutions as they require line-of-site with the satellite and often chimneys and trees can briefly obstruct the path. I’m confident that these providers will solve these problems and their solutions. I’m so bullish on this as a solution not just for public safety, that I made an investment in the only company (at least that I could find) that is publicly traded in this space, AST SpaceMobile.
Contact me at firstname.lastname@example.org if you have any feedback on this blog or if you’d like to find out more on how Televate can help you leverage LEO or GEO satellite solutions.