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. 

Update on Public Safety and Mission Critical communications

Its been a while since I wrote about Public Safety and Mission Critical communications, so here is a quick summary.

Iain Sharp have a good overview of whats happening in the standards in the LTE World Summit back in June. Embedded below is his complete presentation.

LTE Standards for Public Safety – an independent analysis from Zahid Ghadialy

There is another slightly older presentation that I also thought was worthwhile adding here.

There is a lot of discussion centred around the use of commercial networks for mission critical communications, mainly die to cost. While this may make sense to an extent, there should be procedures put in place to give priority to public safety in case of emergency.

Tech Trend for Next Generation Critical Communications from Zahid Ghadialy

We are planning to run a one day training in Jan 2015 on public safety. If this is of interest to you then please get in touch with me for more details.

x-o-x-o-x-o-x-o-x-o-x-o-x
After the post someone brought these links to my attention so I am adding them below:

• Mission-Critical PTT Set for LTE Release 13, Release 12 Freeze Likely in 2015
• 3GPP News: LTE Mission Critical Applications
• 3GPP News: Delivering Public Safety Communications with LTE
• 3GPP SA6 - Mission-critical applications
• 3GPP-OMA-ETSI Critical Communications Workshop, August 26-27, 2014

Taking 5G from vision to reality

This presentation by Moray Rumney of Agilent (Keysight) in Cambridge Wireless, Future of Wireless International conference takes a different angle at what the targets for different technologies have been and based on that what should be the targets for 5G. In fact he has an opinion on M2M and Public safety as well and tries to combine it with 5G. Unfortunately I wasnt at this presentation but from having heard Moray speak in past, I am sure it was a thought provoking presentation.

Taking 5G from vision to reality from Zahid Ghadialy

All presentations from the Future of Wireless International Conference (FWIC) are available here.

Push to talk (PTT) via eMBMS

I was talking about push to share back in 2007 here. Now, in a recent presentation (embedded below) from ALU, eMBMS has been suggested as a a solution for PTT like services in case of Public safety case. Not sure if or when we will see this but I hope that its sooner rather than later. Anyway, the presentation is embedded below. Feel free to add your comments:

eMBMS for Public Safety from Zahid Ghadialy

3GPP Public Safety focus in Rel-12

Public Safety is still a hot topic in the standards discussion and on this blog as well. Two recent posts containing presentations have been viewed and downloaded like hotcakes. See here and here.

3GPP presented on this topic in the Critical Communications World that took place last month. The following is from the 3GPP press release:

The ’Critical Communications World’ conference, held recently in Paris, has focused largely on the case for LTE standardized equipment to bring broadband access to professional users, by meeting their high demands for reliability and resilience.

Balazs Bertenyi, the 3GPP SA Chair, reported on the latest status of the first 3GPP features for public safety, in particular those covering Proximity services (Direct mode) and Group call. He spoke of the need to strike a balance between more or less customisation, to make use of commercial products while meeting the specific requirements for Public Protection and Disaster Relief (PPDR).

To ensure that these needs are met, Balazs Bertenyi called for the wholehearted participation of the critical communications community in 3GPP groups, by sending the right people to address the technical questions and obstacles that arise during the creation of work items.

A presentation and video from that event is embedded below:

LTE Standards for Public Safety – 3GPP view from Zahid Ghadialy

For more details see here.

LTE for Public Safety Networks

The last presentation on this topic couple of months back has reached nearly 7K views so here is another one from a recent article on the same topic from IEEE Communications Magazine

Public Safety Communications using LTE

Public Safety Communications using LTE from Zahid Ghadialy