5G, the fifth-generation broadband cellular network technology standard, has been controversial in the aviation context, to put it very mildly. Its enhanced mobile broadband (eMMB) evolves connectivity beyond 4G for ever-hungrier devices, including those that make up the Internet of Things. Speeds match terrestrial fibre broadband, and the prospect of that connectivity in every passenger pocket and mobile-connected piece of equipment is exciting. But what went wrong with the US rollout, and what does it mean for aviation?
By and large, there are two strands to the relationship between aviation and 5G. The first — or the good news — is substantial package of connectivity benefits that improved connectivity brings to the industry, especially at airports and when it comes to air-to-ground communications. But the second — the bad news — is that the shambolic rollout of 5G near airports in the United States has tarnished the reputation of what will, eventually, be a vital technological tool that the industry will use. It has also raised serious questions of regulator effectiveness.
The base problem is that the spectrum the US regulator auctioned off for 5G cellular use is close to the 4.2–4.4 GHz band that has long been allocated to the aeronautical radionavigation service, including aircraft radar altimeters and corresponding ground equipment, known as the ARNS band. And that could cause potentially catastrophic interference.
So why do this in the first place?
When it’s used right, 5G is a big technological leap
5G’s benefits to aviation are based both on better connectivity within the industry and better connectivity in passengers’ pockets. Speeds of 50 Mbps to 1000 Gbps are possible, and that simply changes the game when it comes to a connected industry.
Martin Smillie, SITA’s vice president for the communications & data exchange portfolio, tells us that “With the arrival of 5G, connectivity will be much more fluid and flexible. The new networks will enable massive data flows, providing secure, real-time, predictive, and historic views of airport operations. This will make collaboration between airports, airlines, ground handlers, air traffic managers, and concession holders easier and more effective.”
Airside, landside and within the terminal, 5G is an enabler for technologies like smart energy management or water usage, sensor-activated lights, ground vehicle tracking, connected hangars, digitalised passenger parking, intelligent public transportation, and much more.
“The result will be the intelligent monitoring of queues throughout the airport and tracking and controlling of autonomous vehicles that assist passenger journeys,” Smillie says. “Vehicles on the ramp will be served by connected smart tugs and baggage carts. Wheelchairs, mobile kiosks, and robotic assistants will be controlled remotely. Ground services staff do their jobs more effectively by extending coverage. Pilots and onboard crew can also receive real-time data and updates on their devices, even while inside the plane. Airlines can offload aircraft diagnostic and operational data. 5G allows the use of IoT to provide predictive data to be informed of potential crisis earlier, and remote HD video to better handle situations even on the apron where traditional public or wired networks may not provide coverage.”
Of course, all of this 5G benefit requires coverage. And that, putting it lightly, has been complicated — particularly in the United States.
Textbooks will be written on the US 5G rollout situation
When the US Federal Communications Commission auctioned off C-band frequencies between 3.7-4.2 GHz, an inherent question of interference arose, given the usage of the 4.2–4.4 GHz ARNS band for aircraft navigation.
Almost immediately, various actors within (and outside) the aviation industry started flagging this major potential problem — which could have resulted in major groundings to avoid disaster. Matters came to a head in late 2021 and into January 2022, with a flurry of FAA statements and airworthiness directives.
After a six-month moratorium on deployment near airports from January 2022, wireless operators agreed in June to “continue with some level of voluntary mitigations for another year”. Airlines and other operators will retrofit them with radio frequency filters, which usually take a matter of a few hours to install.
But how did all this come about?
We spoke with Airlines for America, the US airline trade body, which has been almost unprecedentedly unilateral in its ongoing approach on the subject [PDF].
Airlines for America communications manager Hannah Walden tells us that “US airlines are continuing efforts to implement a permanent 5G solution, while ensuring the highest level of safety in the skies. We remain in routine communication with all stakeholders and the federal government as we work together to deploy new service in a manner that allows this 5G spectrum and aviation to coexist safely.”
This coexistence is particularly complicated in the US. In most countries, this potential conflict was solved by using frequencies further away from aviation usage, operating 5G with markedly lower power levels, adding antenna placement requirements, implementing airport exclusion zones, and more. In the US, however, the Federal Communications Commission allowed both higher power level implementation and allowed greater usage of the frequencies closer to the ARNS band. The prospect of interference with radio altimeters is potentially catastrophic.
“As the US airline industry works to actively install the required aircraft modifications,” A4A says, “we remain in close communication with the federal government, telecommunications companies, manufacturers and other stakeholders to achieve our shared goal of working to safely implement additional 5G service, so that the United States remains a world leader in both safety and technological innovation.”
Information provided by A4A highlights the differing regulatory approaches taken. Internationally, buffer zones were implemented, antennas tilted downwards to reduce interference, and power levels are lower. Under European regulators, the 3.4–3.8 GHZ band is used, with an additional 100 MHz (0.1 GHz) separation compared with that in the US, while permitted power levels are also 23% lower. In the UK, A4A says, permitted power levels in the 3.805–4.195 GHz band are 99% lower. In South Korea, 5G is limited to 3.42-3.7 GHz and permitted power is 95% lower. In Japan, there is a 5G ceiling of 4.1 GHz and macro cell power level limits are 96% lower. In Australia, the spectrum is “even farther away from the radio frequency band used by radio altimeters. The power levels permitted are 76% lower than those allowed in the US”, says A4A.
All in all, it seems that, when good governance in the public interest happens, 5G has been rolled out swiftly and effectively. But it is a cautionary tale. Work to join up regulators, especially those with overlapping responsibilities, must happen — and certainly before a future 6G technology generation.
Author: John Walton
Published: 20th September 2022
;
