At Satellite 2018 last month in Washington DC, everyone in the satellite industry talked up how 5G deployments and satellite could work together. It was funny and sad at the same time, since I haven’t heard a lot of discussion in the wireless industry – the guys actually spending money to get 5G out the door – on how to integrate satellite broadband into terrestrial networks.
Depending on who you talk to in the cellular infrastructure marketing machine this week, there are three big use cases for 5G. Case one is a massive Internet of Things (IoT) framework, communicating with millions to billions of devices. Satellite has a role to play here, since it is already connecting “things” that move – planes, trains, automobiles, ships, and cruise lines, but you don’t really need 5G definitions and overhead to do IoT today. Plus there’s a good bit of IoT legacy/installed base stacked up over the two decades since Iridium and ORBCOMM rolled into the IoT/M2M.
Broadband communications is the second use case, with the two most highly touted specs for 5G being multi-gigabit broadband speeds and low latency. This is where existing satellite broadband services run into a brick wall. Established, long-used geosynchronous earth orbit (GEO) services run signals between the ground and satellites 22,300 miles above the earth. Relaying a signal through a GEO satellite between point A and B adds over half a second (540 milliseconds) of latency due to the distance involved – before we get into overhead from routing and other network elements.
Target goal for 5G network latency is 1 to 2 milliseconds, but will likely run single digits. Typical performance on a 4G LTE, last generation, old and busted wireless network is 50 milliseconds – or less than one-tenth the time a single hop through a GEO satellite takes.
The third use case is for real-time control of things, be it drones or factories or robots, according to Ericsson a while back.
If latency matters, geosynchronous satellites have little to no role to play in a 5G broadband network. Satellite firms have long brushed off latency as being a factor for consumers or businesses, but that’s like hearing phone companies once saying “You’ll only need a megabit; nobody knows what you can do with 10 Mbps.”
People aren’t dumb. Once they get a taste for better service, they’ll opt for the service with the best features and characteristics. If they actually NEED those services, such as low latency, they will pay extra to get them.
However, GEO services aren’t the only game in town. Medium earth orbit (MEO) and low earth orbit (LEO) services deliver lower latency than GEO. O3b mPOWER, a division of SES, positions its fleet of satellites at an altitude of around 5,000 miles above the Earth’s surface, giving the company a stated round trip latency of less than 150ms through its network. MEO-style networks with satellites located between 1,200 miles and 5,000 miles above the earth get us into the ballpark where satellite becomes useful for voice and data services without paying a “latency penalty.”
LEO communications networks, the new hotness in the satellite industry, should drop latency to between 25 to 50ms, depending on which provider you talk to and how close you fly to Earth. While 25 to 50ms isn’t exactly a 5G single digit latency promise, it’s probably good enough for most real-time communications applications, including voice and gaming.
The flip side to lower-flying satellites is needing more of them for worldwide coverage. A GEO satellite out at 22,300 miles circles the globe at the same speed as the world turns – so it remains “fixed” above one point while it is moving. A lower flying satellite will only be overhead for a few minutes at any point on the earth. If you want 24-hour coverage at any point on the earth using LEO, you need to have a group of satellites positioned out so as one goes out of range, another is approaching.
SpaceX, OneWeb, and Telesat are all in the process of building LEO networks. Telesat plans to launch a paltry 120 satellites for its phase one network. OneWeb’s phase one network will be 648 satellites while SpaceX is planning a whopping 4,425 satellites for its initial constellation. All three networks are expected to reach full operational capacity in the early 2020s.
When the marketing hype clears, cellular networks could benefit by using MEO and LEO broadband services to extend coverage in underserved and unserved areas. SoftBank’s investments and work with OneWeb and Sprint suggest the two firms could use OneWeb’s LEO network to enhance Sprint’s rural coverage across the U.S.
Talk of 5G and satellite being best buddies, however, is more hype and less reality, depending on what the definition of 5G is on any given day. The wireless (cellular) industry and carriers are the ones who are going to define requirements, terms of engagement, and write checks at the end of the day.
Does satellite have a role in expanding cellular networks? Yes, especially low latency services such as O3b and the crop of forthcoming LEO networks. Is satellite good enough to support 5G deployments? It’s hard to say, since cellular companies are setting the latency bar high (well, low) and are just starting to grapple with how 5G services are going to be deployed – as well as defining what 5G really means.