Le 25/09/2019 à 16:13, Alexandre Petrescu a écrit :
Hi
Le 20/09/2019 à 04:23, Sharon Barkai and Dick Roy ([RR]) wrote:
[...]
*/[RR] This is a really long story, however, C-V2X is being specified
as an alternative to US DSRC, not as a cellular access technology
since that’s already available and deployed. The reason LTE Release
14 and successors is being specified has nothing to do with its
lineage as a child of cellular; in fact, it is provably a square peg
being forced into a round hole and we all know how that generally
ends up, and that’s a story for another day/*
The 5G evolution is supposed to match the latency of peer to peer WiFi.
When that matches, WiFi will have leaped forward to below
100micro-second latency. This was so (cellular catching up with a
leaping forward WiFi latency) since the invention of WiFi 20 years ago,
and it wont change. It's a constant of evolution.
*/[RR] 5G is nothing but hype at the moment
Here is a more precise status, according to my personal understanding.
This obviously differs from many people's understandings, who may be
more knowledgeable.
In France, frequencies for use in 5G radio would start to be discussed
now in September, with allocation towards December. The allocation is
similar, but not quite like, the process that was used for 3G: auction
sales. The differences from 3G are: (1) it is not expected to generate
huge revenues for gov't and (2) some sales, like of the 3.5GHz band,
would actually be a re-allocation from what was previously allocated to
wimax operators (e.g. SDH in France) and to City Authority (like Mayor)
in places where there was no operator).
Obviously, until these frequencies are allocated one cant really talk
about 5G deployment on public roads, even if...
If one wants to talk about 5G like when talking a higher bandwidth and
lower latency than 4G, then one assumes 4G to be 50ms latency and
2Mbit/s bandwidth. One can talk then about 25ms latency and 10Mbit/s,
and claim that to be 5G. But it is not 5G. It is just another Class or
Category of 4G. In theory, one can still be 4G and run at 1Gbps (e.g.
Category 16).
Also, one can talk about a higher bandwidth outdoors network by running
802.11 WiFi on 5.4 GHz and, why not, at 5.9GHz.
Colleagues call these 'acrobatics 5G'.
This is when one wonders: what is 5G anyways? with its associated
question: why was the predecessor of 5G called 'LTE' (Long Term
Evolution), or where is the long term? Is 5G LTE?
With respect to other countries, I heard two recent announcements, about
Spain and Germany.
They both claim 5G is deployed in the respective areas.
This claims 15 cities in Spain on June 15th, by Vodafone:
https://www.xataka.com/empresas-y-economia/red-5g-comercial-vodafone-espana-tiene-fecha-lanzamiento-15-ciudades-15-junio
This claims 5 cities in Germany, but it does not say when, by Deutsche
Telekom:
https://www.telekom.de/start/netzausbau?wt_mc=alias_1070_netzausbau
As hardware for end users, this is the situation now:
- there is no 5G smartphone for sale in France. I guess it is the same
in more countries. If it were different, it would be an isolation
easily spot by many.
- iphone 11 just launched features 'Gigabit-class LTE' and 'LTE
Advanced' but no '5G'. They run on 'LTE Bands' which are your typical
frequencies below 5GHz for cellular communications, but nowhere like a
26GHz of 5G. No such band is called a '5G band'.
Further details after searches of public documents:
iphone 11 pro understands a 5G frequency band:
it is specified to understand several frequency bands, among which also
TD-LTE Band number 42, which is 3400MHz - 3600MHz. This band is a 5G
band. Part of this band (3490MHz - 3600MHz) is being considered for
allocation by regulator ARCEP. It has not yet been allocated, but under
discussion.
ARCEP considers to also allocate Band 43 at 3600MHz - 3800MHz, for 5G.
But this band is not covered by iphone 11 specs.
ARCEP is silent about the range 3400MHz-3490MHz. I suspect there might
be some errors here.
iphone 11 pro also understands TD-LTE Band 46 at 5150 MHz - 5925 MHz,
which covers WiFi 5.4GHz and 802.11-OCB at 5.9GHz. I suspect there
would be some clashes here between deployed Road-Side Units and iphones.
For highways and roads requirements, ARCEP seems to plan to require the
licensee to cover them by December 2025. And the required bandwidth is
between 50mbit/s to 100Mbit/s and 10ms latency. These figures are
obviously little incitative, because 2025 is very late, 50mbit/s is what
4G already does and 10ms is much higher than 1ms 802.11-OCB today.
On another hand, ARCEP requires the 5G licensee to support IPv6,
starting end of 2020. (in French: "Le titulaire est tenu de rendre
son réseau mobile compatible avec le protocole de routage IPv6
à compter du 31décembre2020."). This means that by that time, if IPv6
under its form IPv6-over-OCB does not see a huge deployment compared to
just 802.11-OCB WSMP, it might be that IPv6-over-5G on routes would be
more likely. Which may raise a question of the potential usefulness of
a spec IPv6-over-5G.
So, this is to say that where I live it is not very clear how these
things will unfold.
Alex
- one can buy off the shelf modules, like miniPCIe (I have a list) that
go very high in terms of bandwidth, well beyond what normal 4G would
do, but couldnt really use them at that high parameters.
Alex
and simply matching the latency would be no reason to switch from
DSRC to another access technology for V2V safety, though nothing
prevents the addition of 5G NR access technologies in ITS stations
(aka OBUs) for other uses. /*
I agree.
[...]
Alex
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