Air-Ground-Air communications in Mission Critical scenarios

In-flight communications have always fascinated me. While earlier the only possibility was to use Satellites, a hot topic for in the last few years has been Air-Ground-Air communications.

Some of you may remember that couple of years back Ericsson showed an example of using LTE in extreme conditions. The video below shows that LTE can work in these scenarios.



Now there are various acronyms being used for these type of communications but the one most commonly used is Direct-Air-to-Ground Communications (DA2GC), Air-to-Ground (A2G) and Ground-to-Air (G2A).

While for short distance communications, LTE or any cellular technology (see my post on Flying Small Cells) may be a good option, a complete solution including communication over sea would require satellite connectivity as well. As I have mentioned in a blog post before, 75Mbps connectivity would soon be possible with satellites.

For those interested in working of the Air-Ground-Air communications, would find the presentation below useful. A much detailed ECC CEPT report from last year is available here.

Direct Air-to-Ground Communication – Broadband for Planes from Zahid Ghadialy

The next challenge is to explore whether LTE can be used for Mission Critical Air Ground Air communications. 3GPP TSG RAN recently conducted study on the feasibility and the conclusions are as follows:

There is a common understanding from companies interested in the topic that:

1. Air-to-Ground communications can be provided using the LTE standards (rel-8 and beyond depending on the targeted scenarios).
2. 3GPP UE RF requirements might need to be adapted
3. It may be possible to enhance the performance of the communications with some standards changes, but these are in most cases expected to be non-fundamental optimizations
4. Engineering and implementation adaptations are required depending on the deployment scenario. In particular, the ECC report [1] comments that from implementation point of view synchronization algorithms are to be modified compared to terrestrial mobile radio usage in order to cope with high Doppler frequency shift of the targeted scenario. In addition, some network management adaptations might be needed. From engineering perspective the Ground base station antenna adjustment has to be matched to cover indicated aircraft heights above ground up to 12 km by antenna up-tilt. It is also expected that the inter-site distances would be dominated by the altitudes to be supported [5].
5. A2G technology using legacy LTE has been studied and successfully trialed covering different kinds of services: Surfing, downloading, e-mail transmission, use of Skype video, audio applications and Video conferencing. Related results can be found in several documents from ECC and from companies [1], [2], [3]. The trials in [1] and [2] assumed in general a dedicated spectrum, and the fact that the communications in the aircraft cabin are using WIFI or GSMOBA standards, while LTE is used for the Broadband Direct-Air-to-Ground connection between the Aircraft station and the Ground base station.
6. It is understood that it is possible to operate A2G communications over spectrum that is shared with ground communications. However, due to interference it is expected that the ground communications would suffer from capacity losses depending on the deployment scenario. Therefore, it is recommended to operate A2G communication over a dedicated spectrum.
7. It can be noted that ETSI studies concluded that Spectrum above 6 GHz is not appropriate for such applications [4].
8. LTE already provides solutions to allow seamless mobility in between cells. Cells can be intended for terrestrial UEs and cells intended for A2G UEs which might operate in different frequencies.
9. Cell range in LTE is limited by the maximum timing advance (around 100km). Larger ranges could be made possible by means of implementation adaptations. 

Texting and Internet being trialled on flights

BMI is piloting mobile internet and texting services on planes, but frequent flyers need not get up in arms about getting stuck next to chatty people, as the airline has wisely chosen to leave out voice calls.

The service, from OnAir, will be trialled for six months on just one plane – an Airbus A320, which flies between Heathrow and Moscow. Passengers will be able to use SMS, email and internet on mobiles, PDAs and laptops with GSM SIM cards or dongles.

Peter Spencer, managing director of BMI, said: “It opens up an exciting new era of travellers being able to stay in touch by text message and email whilst in the air.

The pilot project isn’t just about testing the tech or the take-up, however. “The trial will help us address some of the social and etiquette issues regarding the use of mobile communications devices inflight and provide valuable customer feedback which will be at the heart of deciding how the service is developed and rolled out across the remainder of our mid haul fleet,” Spencer said.

“We have chosen not to implement the voice call option as part of the trial,” he added.

On the other side of the world, Delta Air Lines officially launched Aircell's Gogo Inflight Internet service on six of its aircrafts. In-flight Internet initially will be available on five MD-88 aircraft flying Delta Shuttle routes between New York's LaGuardia Airport and Boston's Logan and Washington's Reagan airports plus one Boeing 757 flying throughout Delta's domestic system, with service spreading to other Delta routes as additional aircraft are introduced.

"In-flight Internet access is one of the most popular requests we receive from our customers," noted Tim Mapes, Delta's senior vice president of marketing. To celebrate the launch, Delta passengers traveling on the Gogo-equipped MD-88 Shuttle aircraft will be treated to a holiday surprise with complimentary access to Gogo during a Dec. 16 - 31, 2008 promotional period.

A "WiFi hotspot" decal will be prominently displayed adjacent to the boarding door of the MD-88 aircraft so customers will know Gogo Inflight Internet service is available on their flight. In addition, a Delta-Gogo instructional card will be available in each seatback, providing details on how to sign up for the service. Gogo representatives and Delta employees will be available at all three Delta Shuttle-served airports throughout the promotional period to provide information and assistance to customers traveling during this timeframe.