By the time a company is ready to run a media demo flight of a new technology the assumption is that the system will work as advertised. Still, as the SmartSky Citation Excel taxied for departure on a clear Florida morning a couple weeks ago there were questions to be answered and tests to be run. Armed with laptops, iPhones and a handful of helpful employees (plus a surprise device) we climbed up to cruising altitude and headed north, flying a circuit between Jacksonville and Savannah where the next generation air-to-ground (ATG) network is active to see if it would really hold up.
A couple hours later the results were incontrovertible: The system absolutely worked. We demonstrated multiple concurrent voice and video calls while streaming HD video in the background. Peak data speeds approached 20 megabits/second on both the forward and return links; not the fastest ever, but a significant amount of data consumed given only a handful of passengers on board. And it was more than just the speeds. The system showed off some advantages versus satellite and legacy ATG offerings that make it a compelling offering. Or will, once the towers are fully deployed.
Loving Lower Latency
In many ways the HD video test is an easy one. Given enough bandwidth that will work over nearly any link. Voice calls are a little harder because latency comes into play. The awkward quiet times between when one party stops talking and another hears the end of the conversation disappears as latency shrinks and the terrestrial systems deliver that far better than satellite-based communications. In one demonstration during the flight a pair of phones on a WhatsApp video call to each other revealed the significantly lower latency that SmartSky is able to achieve with its network.
That low latency can also make gaming a viable option in the sky. As part of the demonstration the company mounted an XBox in the cabin (the surprise device mentioned above). While most of us were working or simulating work activities on the system one SmartSky employee put up a solid Fortnite performance from the plane. That’s the sort of situation where high latency has a significant adverse effect. Remote desktop connections are similarly affected by high latency, though generally not as much fun to play with. While Brian was out collecting kills I connected to a pair of servers on the ground and performed network admin functions such as provisioning new users and managing backup jobs. The connections were steady and performed similar to a typical ground-based network.
Part of the low latency architecture is a multi-gateway strategy for the SmartSky network. For our short flight this did not come into play but as the network goes live that patented design means that traffic can flow across the closest terrestrial gateway and even switch between the egress points dynamically, minimizing latency and data transport costs. The company will start with a trio of gateways across the country but could expand that as network traffic grows. Chief Commercial Officer Nancy Walker explained, “Thanks to the highly virtualized nature of our network, we also have the unique ability to add additional egress points if or as needed, which basically is a function of traffic, cost of transport, and optimizing for low latency.”
From a raw performance perspective the multi-gateway strategy proves a winner. For implementations managed by third-party VARs it creates some interesting challenges. Many of those providers historically have actively managed monitored data flows to deliver performance reports and SLAs for aircraft owners. Traditionally this required all the data to pass through the VAR’s gateway when leaving the service provider network. Adding that extra backhaul is relatively insignificant on a satellite connection where latency is already near 1000 milliseconds. Adding it on a connection with an order of magnitude lower latency brings a noticeable hit to performance. SmartSky is working with its VARs to integrate their monitoring into the virtualized core infrastructure to alleviate those challenges.
Stressing the Return Link
After latency the return link – getting data off the aircraft – is generally seen as the second major challenge facing aircraft communication systems today. A heavy consumer entertainment focus meant initial efforts prioritized delivering content to the aircraft over the limited available radio spectrum. SmartSky’s use of the unlicensed 2.4 GHz space dramatically increases the spectrum available versus other ATG offerings and allows the company to promise return links speeds and latency congruent with the forward link.
Voice and video calls put a bit of strain on the return link, but after a base level of capacity is available those services are more latency dependent. Uploading a massive file is all about return link performance, however. My test was uploading a 700+ megabyte file to a server via SFTP. I ran that in the background, while continuing to use the other services on board and the transfer completed in just under 14 minutes.
That’s an average speed of 1 megabyte per second plus TLS overhead for a consistent period of time. Only when we landed and the operations center sent over the usage report for the flight did anyone notice that the return link traffic had been stressed so much; the upload did not interfere with the other activity on board.
The Patent Portfolio
What felt like a single, consistent connection in the sky proves to be a far more complicated engineering endeavor. SmartSky’s 4G/LTE architecture includes multiple components that are protected under a portfolio of more than 100 patents (nearly 200 if pending applications are included). President Ryan Stone is confident that the technology itself will prove sufficient to attract customers to the service, “We have software defined radios, software defined networking. That delivers network slicing and virtual private networks. On our low latency network those are easier to implement. We have beamforming; one beam talks to one plane at a time. There are things we are doing that are for running an efficient network but also makes it a more secure network.” Those technical developments are all part of what the company includes in the patent portfolio and Stone is clear that SmartSky will defend its intellectual property should others infringe upon it.
Our hour-long inflight connectivity session included a beam handoff roughly every 30 seconds. Managing those transitions without dropping the service is just one of the many solutions the company holds a patent for. Walker expanded on the beamforming technology’s role in the SmartSky network:
Beamforming in our system is one of the key technologies that enables our unique performance guarantees and enhances our ability to provide very secure communications. It is also what enables us to more precisely manage the traffic to and from each aircraft. The means to do this is highly proprietary in our system, though certain aspects are publicly disclosed in our patent portfolio, and as you experienced in flight, beam handoffs are seamless to the user experience. While the details are of course proprietary, we can say that our system does support a full and compelling user experience to multiple aircraft per site. Our solution is engineered to scale to the practical limits of the density of flight traffic in a given airspace, and this eliminates the scaling problem commonly experienced on the competition’s legacy ATG network.
The network will launch with more than 25,000 beams active across the country. SmartSky expects that even in the most dense flight corridors it will have sufficient beam and back-haul capacity to bring the currently anticipated customer fleet online. Should demand grow beyond current projections the company can increase signal density by carving out more cell sectors on towers. The fiber back-haul networks are also flexible, with what Walker describes as “simple and quick” adjustments to contracted capacity that allow for management of costs today and scalability into the future.
Getting to full deployment
While the overall connectivity experience was generally stable and speedy it was not 100% perfect; I did have a brief interruption in service at one point, where a couple remote connections dropped. Things quickly recovered, but it did happen. I also know that we were only connected to a single tower throughout the test flight. I expect that the tower transitions will operate smoothly but do not have first-hand experience with that aspect of the system. Finally, ours was the only plane online during the test period. SmartSky is confident that the technology will scale as necessary and the designs check out, but the company still must execute.
There’s also the challenge of getting the full complement of towers provisioned and online. Some of that is a hardware installation challenge and some of it is choosing when to increase link speeds and start paying for the infrastructure that isn’t quite being used by customers yet. Walker is adamant that the company will realize its goal of coming online later this year for the east coast and west coast corridors and filling in over the following months. JetSuiteX plans to be online in Q3/Q4, with hardware installing earlier if possible.