Last week at work, we released a report titled "UK Spectrum Usage & Demand". The only time most people hear about spectrum is when there are some auctions going on. Often a small chunk of spectrum gets sold off for billion(s) of dollars/pounds and these surely make a headline. As I recently found out, 50% of spectrum in UK is shared and 25% is license exempt.
Anyway, this first edition of the report focuses on Public Mobile, Utilities, Business Radio and Space/Satellites. Space is becoming an important area of focus here as it is a significant contributor to the UK economy.
Anyway, the report is embedded below and is available to download from here:
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.
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:
Air-to-Ground communications can be
provided using the LTE standards (rel-8 and beyond depending on the
targeted scenarios).
3GPP UE RF requirements might need to be
adapted
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
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].
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.
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.
It can be noted that ETSI studies concluded
that Spectrum above 6 GHz is
not appropriate for such applications [4].
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.
Cell range in LTE is
limited by the maximum timing advance (around 100km). Larger ranges could
be made possible by means of implementation adaptations.
While we have talked about different LTE categories, especially higher speeds, we have not yet discussed Category-0 or Cat-0 for M2M.
A recent news report stated the following:
CAT-1 and CAT-0 are lower speed and power versions of the LTE standard which dramatically extend the addressable market for carriers and chip makers alike. They introduce new IoT targeted features, extend battery operation and lower the cost of adding LTE connectivity.
“While chipsets supporting these lower categories are essential for numerous applications, including wearable devices, smart home and smart metering, there has been an industry development gap that we had anticipated two years ago,” said Eran Eshed, co-founder and vice president of marketing and business development at Altair. “We’ve worked hard to address this gap by being first to market with true CAT-1 and 0 chipsets featuring a power/size/cost combination that is a massive game-changer.”
Ericsson has an interesting presentation that talks about LTE evolution for cellular IoT. While Rel-12 Cat-0 would use the normal allocated bandwidth (upto 20MHz), Rel-13 plans further enhancements to save even more power by reducing the bandwidth to 1.4Mhz. Another possible saving of power comes from the use of Half Duplex (but its optional). There is a very interesting presentation from Mstar semiconductors on half duplex that I have blogged about here. Anyway, the presentation from Ericsson is here:
When we talk about 50 billion M2M devices, a question that I regularly ask is how many of them will be using cellular and how many will use other technologies. Its good to see that my skepticism is shared by others as well, see the tweet below.
Nokia has also got an interesting whitepaper on this topic which talks about optimizing LTE and the architectural evolution that will lead cellular LTE to become a compelling technology so that it can be widely adopted. That paper is embedded as well below.
