A range of new communications technologies are included up in the term ‘5G,' including new radio access technology and antennas operating in the low, mid and high bands of the radiofrequency spectrum, as well as more efficient approaches to beamforming. But what does 5G actually mean and what form factors will need to change to enable its adoption on aircraft, at airports and in maintenance or IT networks?
Initial radio specifications for the 5G new radio were formally introduced by the 3rd Generation Partnership Project (3GPP) a consortium of seven mobile telecommunications and wireless network standards organizations representing more than 700 telecommunications companies that also gave the world the air interface for 3G, 4G and 4G LTE networks. Signals for 5G networks are to run over new radio frequencies within one of either three different types of networks used by service providers including low-band (1 GHz and below), mid-band (1 GHz to 6 GHz) and high band (up to millimeter wave mmWave).
According to mobile networks industry trade group Global System for Mobile Communications Association (GSMA), current 5G networks that have been deployed are those which are considered to be 5G nonstandalone, meaning it is a radio architecture that builds on 4G LTE, whereas the type of high-speed low latency technology making headlines recently is 5G standalone (5G SA), which is expected to become increasingly available in the next two to three years.
Higher speeds enabled by the more capable air interface for 5G introduced by 3GPP are expected to, for example, reduce the time required for a smartphone to download or update a new application. According to Qualcomm's website, 5G is expected to deliver up to 20 Gigabits-per-second peak data rates and 100+ megabits per second average data rates, or enough speed and capacity to reduce the time it takes to download a two hour movie using today's 4G networks from an average of seven minutes to fewer than 10 seconds.
On the ground, some companies are already taking advantage of the 5G, though there is currently no cellular radio or antenna available that is capable of enabling 5G standalone connectivity on a commercial airliner. However, 5G research and development and initial use cases are occurring throughout aviation right now.
5G for Airplanes and Airports
"Towards the end of 2020, we will have sites built and we will start flight testing," said Mike Syverson, senior vice president of engineering at Gogo, whose company is developing new antennas and modems designed to enable the world's first in-flight connectivity (IFC) 5G air-to-ground (ATG) network by the end of next year.
Gogo's 5G network will only be available in North America, leverage the existing 250 towers in the region that enable its current 3G and 4G IFC networks. The 5G network will use unlicensed spectrum in the 2.4 GHz band, with a new modem and beam-forming technology providing the airplane-to-ground station link. The network will use licensed, shared and unlicensed spectrum across low, mid and high bands.
"Airspan is designing and building 5G vRAN base stations (ground towers) specifically for our 5G air-to ground (ATG) network," said Sanjeev Nagpal, director of product management for Gogo. "Connecting and maintaining a consistent connection with an aircraft traveling at 500+ miles per hour at altitudes of 35,000+ feet is incredibly challenging. Managing handovers from tower to tower with no drops and managing doppler effect are difficult on an aircraft moving at such high speeds and distances."
Some airports and aircraft maintenance providers have already taken steps to make some of those uses a reality in the near future as well. As an example, in February, Nokia deployed a 5G private wireless network that Lufthansa Technik used to enable collaborative virtual engine inspections between engineers at its shop in Hamburg and customers in other locations. Nokia deployed the network using its Digital Automation Cloud (DAC) end-to-end private wireless networking and edge computing platform.
Lufthansa Technik describes the 5G-enabled concept as its "Virtual Table Inspection" project, where airline maintenance engineers will not have to travel to their facility in Hamburg, instead they use the network for high-definition video trainings.
Nokia is using the same technology to enable the use of 5G at Brussels Airport, in partnership with Belgian mobile operator Citymesh.
"We can look on the potential of 5G in airports through a number of lenses," Fai Lam, transportation marketing director for Nokia, told Avionics.
From an IT operational perspective, Lam believes Wi-Fi is ‘good enough' for the current level of needs of passengers, guests and airport administrative purposes. However, deployment over large areas brings its own challenges around continuity of service. Also, data throughput and speeds possible with Wi-Fi do not provide the level of performance required for automation applications and to deliver Industry 4.0.
"By deploying a private wireless network over 5G the airport can operate a cable-free, autonomous network environment with its devices and third-party clients operating on a separate frequency from the public mobile networks," he said.
In April, the Federal Communications Commission's decision in April to unanimously approved Ligado's application to deploy a low-power terrestrial nationwide network in the L-band to support 5G and Internet of Things services (IoT).
On Apr. 17, 2020, the International Air Transportation Association (IATA) published a statement confirming its decision to join more than two dozen other aviation and non-aviation related organizations opposing the FCC's decision, expressing concern that the frequency band Ligado will use is adjacent to a band used by the Global Positioning System (GPS) and poses a strong risk of interference with GPS signals, including the potential interruption of GPS signals at low altitudes.
Cockpit systems such as Terrain Avoidance and Warning Systems (TAWS) use GPS signals to accurately display position reports to pilots, according to Noppadol Pringvanich, IATA's Head ATM Engineering & Aviation Radio Spectrum.
"Even though the satcom system is mainly used in oceanic operations, the pilot needs to make sure it is working before the aircraft departs. But if you have a Ligado station near the airport, it may cause interference. If you cannot lock on your satcom, you cannot verify that the system is operational so you may not be able to depart. This will have costly operational and retrofitting implications," he said in IATA's statement.
5G for Low-Altitude Airspace
As the concept of unmanned traffic management (UTM) becomes increasingly defined by civil aviation regulators on a region-by-region basis, could 5G serve as a medium for data and information sharing between drones or electric air taxis, air traffic and wireless network service providers in the future?
"I think the larger issue now is actually the fact that you need an almost 100 percent reliable high-bandwidth connection to track non-cooperative aircraft," Alex Harmsen, CEO of Iris Automation, told Avionics.
Harmsen's company, a Silicon Valley-based startup, has been working on an onboard collision avoidance system that – for the first time – will power an FAA-sanctioned flight beyond an unmanned aircraft operator's visual line of sight (BVLOS) without assistance from visual observers (VOs) or expensive ground-based radar systems.
With an onboard system like Iris' Casia, drones are able to make decisions in near-real-time and without streaming megabits of high-resolution video and sensory information to command-and-control facilities on the ground, meaning such a system – combined with UTM that derives information from ground-based sources – can be operated at low density without needing the bandwidth and reliability of 5G networks.
"If you don't have that reliability and low latency, then it becomes almost impossible to get anyone to trust that your system can reliably provide real-time avoidance," Harmsen told Avionics. "This is also true for ground-based radar. The reliability of your system is only as good as the radio/comms link."
Working through 3GPP, telecommunications providers have helped the FAA develop metrics that can be used to measure the reliability of wireless connections between drones and ground receivers, according to Jennifer Richter, a partner at Akin Gump who has worked extensively with the telecom industry.
"Over a dozen data points were agreed upon with the hope that participants in the [UAS] Integration Pilot Program, or other private testing, could test use of the wireless networks for UAS communications and provide common data back to the FAA for evaluation," Richter told Avionics. "The FAA remains interested to acquire this type of data and understand the safety case for using wireless networks to support UAS operations."
NASA is also interested in the potential data sharing and other use cases 5G could enable in low altitude airspace. The agency's Aeronautics Research Mission Directorate is sponsoring multiple activities to address communications, navigations systems (CNS) needs in what it describes as the Advanced Air Mobility (AAM) market.
Through its Grand Challenge series launched in August last year, NASA intends to bring together companies involved in emerging air transportation systems to help inform requirements and best practices for UAM operations, including Federal Aviation Administration certification requirements for electric and hybrid-electric aircraft.
"NASA is exploring CNS architectures and technologies for AAM that will satisfy safety-critical service requirements for high-volume, high-density operations in and around urban airspace," Davis Hackenberg, NASA's Advanced Air Mobility project manager, told Avionics. "These new services will attempt to combine the assured reliability and consistent performance of existing CNS systems with the blistering pace of wireless innovation in non-aviation markets like LTE/5G and satellite communications. These industries continue to push the limits of spectral efficiency and network capacity, and NASA is looking for opportunities to adopt, where possible, or adapt these services for AAM operations."
On Dec. 8, 2020, the FCC will hold a public spectrum auction designed to help further facilitate the use of 5G in the U.S. Within the 3.7-4.2 GHz band, the FCC is allocating the 3.7-4.0 GHz portion of the band for mobile use, and 280 megahertz from 3.7-3.98 GHz band will be auctioned by the FCC for wireless services in the contiguous United States. Commissioners expect the auction to generate tens of billions of dollars.
Whether or not some of the spectrum acquired in that auction provides 5G enablement for low altitude operations remains to be seen, however, the aerospace industry will be ready when it is. Max Fenkell, director of unmanned and emerging technologies at the Aerospace Industries Association, told Avionics member organizations concerned with ensuring various cellular and broadcast communication options are available but not mandated, allowing different missions to have different requirements.
"When you look at any operation, whether it's UAS, future urban air mobility … the FAA hasn't set the safety case is for the mission yet," Fenkell said. "Once we understand the safety case, then we can understand what the spectrum requirements should be for it."
Fenkell expects the vast majority of small UAS will function on unlicensed spectrum, using Bluetooth or WiFi, but larger aircraft at higher altitudes will use dedicated spectrum, more similar to current manned aviation and the Automatic Dependent Surveillance – Broadcast (ADS-B) system employed by air traffic controllers. Meanwhile, telecommunications providers are awaiting definitive regulatory guidance from the FCC and FAA to begin building infrastructure that will enable future low altitude air traffic systems.
"When it's all said and done, the aerospace and defense industries will likely be the number one user of 5G technologies," Fenkell said.