Business & GA, Commercial

The Race To Allow Airborne Cell Phone Use

By George Marsh | October 1, 2004
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What do many airline passengers want in a connectivity service? They want to be able to use their notebook computers and personal digital assistants (PDAs) to send and access e-mail and navigate the Internet and intranets while in flight. But, perhaps even more so, they want to operate their cell phones as though they were still on the ground — wherever they fly.

Using mobile phones safely throughout a flight requires technology that is only now emerging. In addition, e-mailing messages with large file attachments, surfing the Web and accessing private corporate networks at home or office speeds require a broadband "pipe" to the aircraft. And near-global coverage means satellite communication.

The SITA Team

Several companies are racing toward a solution that combines satellite communications and onboard networks. The front-runners are rival communication service providers SITA and ARINC, who announced plans at Farnborough 2004 and at the July Inmarsat Aeronautical Conference in Montreal, respectively.

SITA Inc. told journalists at Farnborough that it is forming a joint company with Tenzing Communications and airframer Airbus to take cabin connectivity this important step further. SITA’s in-flight passenger communications division will have an approximately 60-percent share of the joint venture, so far unnamed. It was set to be launched last month. The partners reportedly have put up between $50 million and $100 million to get the venture off the ground.

Backed by research, SITA and its partners started from the standpoint that:

  • Passengers wish to communicate using their own mobile phones, laptops and PDAs;

  • They prefer to do this using their own mobile phone, e-mail, Internet, text and private network service providers; and

  • They would like to be billed through their usual channels.

For their part, airlines want scalable solutions that they can deploy across a mixed fleet with minimal installation and operational cost, little drag or weight penalty, and maximum use of existing avionics and antennas. Airworthiness authorities need proof that passengers’ mobile devices will not affect safety critical aircraft systems. National telecommunications authorities want to know that transmissions from mobile phones at altitude will not "splash" across several base stations on the ground at once and disrupt cellular networks.

Meeting all these requirements is a tough call, but SITA, Tenzing and Airbus are confident that they can do it in time for a full product launch by late 2005 or early 2006. Initially, the joint company will offer traditional in-flight telephony, using fixed SITA Aircom phone installations on the aircraft. It will be a two-way, short-text messaging ("texting") service via the aircraft’s in-flight entertainment (IFE) system, plus e-mail and instant messaging from passengers’ own computers. (SITA already has launched a system with Emirates, which delivers SMS [short messaging service] via onboard Matsushita IFE equipment.)

By fall 2005 the SITA/Tenzing/Airbus service will start introducing Internet browsing and corporate network access capabilities. Finally, from mid-2006, passengers should be able to begin using their own mobile phones for calls and text messaging. This service will be provided via the well-established Inmarsat constellation of geostationary satellites. It will be available on both Airbus and Boeing aircraft — and eventually on regional and business jets, according to George Cooper, SITA’s senior vice president, airline operations and Aircom services. The partners expect typical international roaming rates to apply for mobile phone use, while laptop and PDA transactions will be billed on a usage basis.

To use their mobile phones in the air, passengers will have to link up to an onboard network. As soon as a phone is switched on, this network takes partial control of it. It will limit phone emissions to levels considered safe by the airworthiness authorities and instruct the phone to communicate only with an onboard base station. For this, the phone needs to emit only a fraction of a milliwatt rather than its usual power output of a couple of watts.

The base station, or picocell, can be low-power, too, since it communicates only with the onboard satcom equipment. It is the onboard base station and control technology–transparent to the user–that will enable mobile devices to be used in flight. The SITA system will be compatible with all phones using the GSM (global system for mobile communications) protocol, the world’s dominant mobile phone standard outside of North America.

Systems like the one designed for the SITA/Tenzing/Airbus service already have been shown to work. In May at the ILA exhibition in Berlin, for example, Germany’s aerospace research organization, DLR, demonstrated how calls from visitors’ GSM mobile phones could be passed via an experimental base station, and then via Inmarsat geostationary satellites, to a ground station at Oberpfaffenhofen. From there, calls were routed to ground fixed and mobile networks. The system controlled the power that the phones emitted and directed their calls to the base station rather than registering them with the normal terrestrial networks.

The demonstration also provided a parallel simulated Ku-band satcom path, showing that the system could work with satellites such as those on which Connexion by Boeing will rely. With an asymmetric Ku-band link of 144 Kbits/s down and 768 Kbits/s up, the user of a new-generation mobile phone would be able to send a short request for Web content and receive a rich media stream in return. In September, the system was due to be tested in an Airbus A340, using a GSM picocell.

Engineers with the SITA/Tenzing/Airbus team are confident that the control overlay will enable passenger phones to operate without detriment either to onboard flight systems or to the ground cellular infrastructure. The system also will control the output from CDMA (code division multiple access) phones that North American passengers might switch on. (CDMA is the American mobile phone protocol.) The new company will work closely with Airbus in gaining clearance and certification for the onboard network.

Passengers initially will benefit from Tenzing’s current e-mail system, offered by the in-flight phone service provider. They will access it by plugging their laptops into a seat-back phone jack.

Working With Inmarsat

The SITA-led team will have good access to emerging broadband satellite communications. SITA, which is basically owned by numerous airlines and operates on their behalf, worked closely with Inmarsat from 1985 to 1990 on the development of aviation industry standards for the first aircraft satellite communications system. In turn, SITA and Inmarsat contributed to the International Civil Aviation Organization’s (ICAO’s) definition of an aircraft-satellite communications standard.

Since then, SITA has provided service via Inmarsat, keeping pace with the latter’s aeronautical service evolution through the classic Aero series to today’s Swift64 standard. Swift64, achieved by using advanced payloads on Inmarsat’s present third-generation satellites, enables SITA to offer a mobile ISDN (integrated services digital network) circuit mode service at 64 Kbits/s and a mobile "always on" packet data service, sharing 64 Kbits/s. This "halfway broadband" capacity is sufficient to provide, for example, live video, radar imagery or captured JPEG images along with full-duplex voice.

During the 2005-2006 time-frame, Inmarsat plans to orbit a new fourth-generation satellite constellation. The Inmarsat 4s’ enhanced payloads will enable the organization to launch its Swift Broadband service, providing a dedicated 64-Kbit/s voice/ISDN capability in circuit-switched mode and, for Internet/intranet capability, a 432-Kbit/s packet switched service per channel. Coupling channels together can raise bandwidth to 864 Kbits/s.

New broadband avionics inevitably will be developed to benefit from these higher data rates. SITA is in discussions with several avionics suppliers, says Cooper, adding that the final selection of a system partner "may still be weeks or months away." The selected organization will be required to exploit advanced electronics to combine higher capacity with reduced size, so that less room is taken up on the aircraft.

For the many airlines that already use current Inmarsat-capable equipment for cockpit communications and in-seat telephony, equipping for Swift Broadband should require only an avionics upgrade and not a complete aircraft retrofit. This typically would include a new transceiver, the picocell base station and, for short-haul aircraft, a new antenna.

Unlike the steerable Aero H antenna installed on many long-haul aircraft, the new antenna can be fixed (non-steerable) since a short-haul aircraft is likely to spend most of its time within the footprint of a single spot beam. This reduces antenna size, complexity and cost. Patrick Gavin, executive vice president-customer services at Airbus, estimates that it will be possible to install the required new avionics over three nights when an aircraft is out of service.


Competing against the SITA team is a second alliance, formed last year by ARINC Inc. and Norway’s Telenor AS. The two partners appear poised to select an avionics supplier. Over the past several months they have made a significant breakthrough by developing a way to handle GSM calls across a classic satcom link. This means airlines currently equipped for Inmarsat services will not have to purchase new communications systems. They can simply add the ARINC/Telenor system.

This system is designed to be software- upgradeable to accommodate new messaging systems, such as Swift64, B-GAN or Ku-band systems. ARINC and Telenor were to have demonstrated a system allowing mobile phone use, at the World Airline Entertainment Association conference and exhibition in Seattle, in September. The companies plan to bring broadband connectivity to airliner cabins by early 2006.

Graham Lake, ARINC vice president and managing director for Europe, the Middle East and Africa, declared at the latest Inmarsat aeronautical users’ conference in Montreal, "it’s no longer a question of whether mobile phones will be used on aircraft — it’s more a question of when."

Lake said, "when" probably will be 12 to 18 months from now. The alliance, like its competitor, is working on an intelligent controller/picocell-based network to ensure safe mobile phone use in the air.

"We view the ability to literally ‘roam’ onto an aircraft and seamlessly use a mobile phone for voice and SMS messaging as a near-term reality," says Telenor chief technical officer Berit Svendsen. "We will provide a comprehensive Aero-GSM fleet solution without the need for a significant investment in new communications infrastructure."

The ARINC/Telenor technology will address the airspace as a virtual GSM country, simplifying mobile addressing and connectivity during the flight. Current terrestrial GSM roaming charges are being used for end-user pricing models. An onboard management system will enable the phone facility to be shut down during flight over countries where airborne cellular use still is not permitted. Cabin crews also will be able to pre-empt the satcom system in the event of an aircraft operational emergency.

ARINC and Telenor expect to launch broadband service in the commercial air transport market at about the same time as their competitor. Like the SITA consortium, they intend to exploit established satcom equipment but also will offer alternative pathways. Customers, they say, will be able to use the Inmarsat L-band satcom systems that equip more than 3,000 aircraft worldwide and will be able to exploit the Swift Broadband system, when it arrives. But ARINC also will offer its SKYLink broadband system, which already is being installed in Gulfstream models and is available for other corporate aircraft.

SKYLink, first demonstrated at last year’s National Business Aviation Association (NBAA) meeting and convention, relies on leased Ku-band transponders orbiting on existing SES GLOBAL family satellites. "We now have one satellite that covers North America and serves the bizjet market," says Bob Thompson, senior director ARINC Satellite Services. "For the commercial market we plan to expand with a satellite covering North America, extending out along the North Atlantic flight tracks, and one covering Europe and the Middle East. They will be activated in the third quarter of 2005." Messaging will be transmitted between the satellites and ARINC’s ground-based hub antenna in Carlsbad, Calif., which, in turn, will transfer the data to and from the company’s headquarters in Annapolis, Md., via the ARINC network.

SKYLink utilizes Ku-band satcom technology, which includes an integrated transceiver/router and a tracking antenna subsystem developed in partnership with Rantec Microwave Systems. The router, made by Cisco Systems, is hardened and can be connected to multiple locations on the aircraft, including wireless access points. This allows passengers to use their Wi-Fi (wireless fidelity) -equipped laptops.

On the ground, a new gateway unit will act as the interface between the satellite ground stations and national cellular networks. "The SKYLink off-aircraft data rate is 128 Kbits/s, and the data rate to the aircraft is up to 3.5 Mbits/s," Thompson adds. "This performance is remarkable, considering that the entire system weighs just 35 pounds [15.8 kg], including the 12-inch [30.5-cm] mechanically steered dish antenna, which weighs just 12 pounds [5.4 kg]."

The SKYLink system for airliners will be larger but offer the same service. Instead of the Rantac antenna, which fits in a bizjet’s vertical stabilizer, ARINC plans to offer a low-profile antenna that can be installed atop the fuselage. The company is evaluating three antenna designs, all of which will track Ku-band satellites accurately and control the transmission energy from aircraft to satellite in order to avoid interference with established users of Ku-band services. Taking information from an ARINC 429 bus, the highly maneuverable system can determine the aircraft’s pitch, roll and yaw, and turn the antenna accordingly, says Thompson. "It can make corrections [to track satellites] at a rate of 30 degrees per second."

All told, the SKYLink system for commercial aircraft will weigh 150 pounds (68 kg) with power supply. The system’s power requirement is 350 watts. ARINC anticipates certification by the first quarter of 2006.

Once SKYLink is installed on an aircraft, it can be distributed to one or many onboard users via the aircraft’s wired or wireless local area network. ARINC believes there are thousands of corporate aircraft that could gain from having the system. And now, with Telenor, it anticipates a healthy air transport business, as well. ARINC also plans to expand its SKYLink service to include live TV, movies, games and, for the flight crew, gatelink communications and a wireless link for electronic flight bags.

Other Contenders

Satellite operator Globalstar has, with wireless specialist Qualcomm, tested a CDMA-based in-flight phone system on American Airlines aircraft. Though less endowed with bandwidth than SITA’s or ARINC’s systems, this solution offers a capacity of 15 simultaneous calls with a single picocell, a figure that could be increased by adding picocells. The partners say their solution could be adapted to work with GSM phones.

Other emerging systems leverage existing ground-based wireless networks to provide continental-only coverage, avoiding more expensive satcom solutions. These systems also avoid the latency issue–the slight time lag experienced when communicating via satellites–which can inhibit the spontaneity of two-way conversations. Verizon Airfone, AirCell and SkyWay Aircraft are offering such terrestrially based systems for use within North America. Similar solutions could be possible for large contiguous territories such as China, Russia and Australia.

Airline-supplied passenger phones have not caught on. But now phones are poised to make an in-flight comeback. If regulatory fears are finally allayed, passengers soon will be able to stay connected during all phases of flight.

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