Change is in the air over Europe, in the shape of a concerted attempt by Inmarsat and the European Space Agency to turn satellite communications into a wide-open field for quick and economic development of new applications and services. The result could be to make satellite phones as ubiquitous as ordinary ground-based mobile phones – and one of the first places to feel the impact should be the airline cockpit.
A nine-month, €4.2 million ($4.6 million) feasibility study approved in July 2015 – with €2 million from ESA, €1.9 million from prime contractor Inmarsat and the other €300,000 coming from sub-contractors Space Engineering Italy, Airbus Defence & Space and RUAG Switzerland – aims to identify technologies, in space and on the ground, that could become standard hardware and software architecture for sat-com equipment and applications. Broadly, this Inmarsat Communications Evolution (ICE) project will attempt to define a smaller, lower-cost satellite-enabled radio terminal as well as modular components – off-the-shelf chips, essentially – that could cheaply and easily be incorporated into various electronic devices.
Inmarsat’s vision is to define a standard sat-com chip that could, say, easily sit on an ordinary GSM phone circuit board to turn what would otherwise be an ordinary phone into a satellite-capable device. The company is focusing this ICE effort on architecture, without attempting to envision the service environment that may follow. It is also hoping that partner and user feedback will inform the design of its next generation of satellites, Inmarsat-6, which are being planned for launch from 2020 and will have to have the technological flexibility to cope with evolving demands over 15 or more years in service.
It may not be overstating the case to imagine that this and other initiatives under way may set off an explosion of satellite-enabled communication and broadband services akin to the leap beyond voice and text that came on the ground when iPhones and other smartphones started to supplement or replace ordinary “dumb” mobiles.
Timing a Heathrow arrival to seconds means course corrections mid-Atlantic
High Level/REX Shutterstock
SAFETY FIRST
According to Inmarsat’s chief technology officer Michele Franci, however, ICE is mainly about safety services, rather than in-flight connectivity for passengers. As such, the drive is to “remodel” the ground-based elements of the L-band network, the 1-2 GHz range of the radio spectrum that supports services ranging from GPS to ADS-B aircraft tracking and GSM mobile phones as well as Inmarsat, Iridium, Lightsquared and Thuraya satellite terminals. In aviation, most of the impact will be in the cockpit.
L-band is significant, as it is more reliable than the Ku-band services – such as Inmarsat’s own Global Xpress – that are starting to provide the in-cabin broadband capable of streaming movies and other high-throughput applications.
Critically, Franci wants to come out of this nine-month study having defined an alternative to Inmarsat’s BGAN satellite radio/phone terminals. That means much smaller and lighter – about the size of a credit card and maybe the thickness of “two or three” – and much cheaper than the $20,000-50,000 cost of a BGAN set. A small, modular software-defined radio unit, he believes, could be cheap enough to be accessible to any aircraft operator, even for general aviation aircraft. And, where he describes BGAN today as a “very closed system”, Franci wants to reach a point where a new generation of terminals could make satellite the primary cockpit communications link, replacing the traditional VHF radio that prevails today.
The programme is related to another Inmarsat-ESA project, known as IRIS Precursor. That programme, which passed its final design review in July 2015 and is now moving into full development, will eventually provide for satellite transmission of air traffic management communications in Europe’s next-generation SESAR ATM system.
SESAR is about making European ATM more efficient, in large part to fit a growing amount of traffic into finite sky space. And, notes Franci, VHF networks are reaching saturation – the only way to go is up, so to speak, and that means satcoms.
REACH OUT
The potential impact is wide-reaching. Mary McMillan, Inmarsat’s vice president of aviation services, points out that before satellites made the now common ADS-B position beacons possible, aircraft had to maintain separation of 100nm (185km) along their flight track and 4,000ft vertically – a “bubble of separation” 200nm across and 4,000ft deep. But with even the minimum ADS-B frequency of 14min or 15min, that safety zone has been cut to “30-30”: 30 miles fore/aft and horizontally, and 1,000ft deep – effectively tripling the available airspace over the Atlantic.
But in an ATM world ruled by SESAR and the USA’s NextGen systems, operators envision timing an arrival at London Heathrow to within just a few seconds, to fly the shortest, most efficient flightpath. To do that, notes McMillan, it will be necessary to make flightpath and speed adjustments “halfway across the Atlantic”. Such continuous “4D” flight tracking (three dimensions of space and one of time) can only be achieved by satellite.
And such a delicately balanced network of hundreds of aircraft will depend on much more than frequent position updates. Aircraft in flight will have to be in continuous communication with each other and with ATM systems. The current generation of Inmarsat-4 satellites, says Franci, are doing some of this “machine to machine” communication, but they were not designed for it. The Inmarsat-5 satellites being launched now were designed five years ago, and while Inmarsat-6s may well be designed to manage large streams of data, ICE is at root about more efficient use of satellite resources – which will always be limited.
That efficiency takes two forms. First of all is security: for safety systems, communications must be assured, reliable and always available. Ku-and Ka-band links can play a role, but L-band, which is less susceptible to failures such as rain fade, has to be the backbone of the system.
Second is the time-critical nature of each particular message. For voice transmissions, real-time is necessary. For some other messages, a delay of a few seconds is tolerable. Airlines may also like to receive some messages – affecting their on-ground maintenance planning, say – where a delay of minutes is acceptable.
The system, then, will have to automatically make decisions of time sensitivity based on the nature of the message and the density of message traffic. Over airports, where there are many aircraft operating in safety-critical modes, some messages will have to be prioritised at the expense of others that – over the ocean, say – would be transmitted with little or no delay.
To make the most of a spacecraft’s bandwidth resources – and current L-band services are only using about 40MHz, a very narrow frequency range – messages will need to be delivered in a “random” way. There will need to be continuous management of the spectrum available, with messages split up to maintain a constant stream while ensuring high-priority messages travel in real time. Franci talks about reducing spectrum waste in terms of “less overhead” – for example, doing away with the “pings” and “handshakes” that currently are used to identify the parties in machine-machine messaging.
Fortunately for airlines that would like to quickly get more of the benefits of space-enabled communications, it should not be necessary to wait either for the long-delayed SESAR or NextGen programmes, or for Inmarsat-6. Franci expects to have a solution and partners identified and ready to begin full-scale development of terminals and software by summer 2016 – which could see cockpit upgrades from some time in 2017.
Source: FlightGlobal.com
