From: **
STDS-802-11-TGbd -- Enhancements for Next Generation V2X.Task Group **
[mailto:STDS-802-11-TGBD@xxxxxxxxxxxxxxxxx] On
Behalf Of Joseph Levy
Sent: Wednesday, June 10, 2020
2:07 PM
To:
STDS-802-11-TGBD@xxxxxxxxxxxxxxxxx
Subject: Re: [STDS-802-11-TGBD]
NGV 20MHz M/O support
Hi
Joh, Friedbert, Rui, and All,
The
discussion on if 20 MHz is mandatory or optional for NGV, is independent from
the discussion of if 20 MHz will be allowed in specific regulatory regions for
the following reasons:
1.
If the regulatory rules in a
region do not allow 20 MHz operation, then the device will not enable 20 MHz
operation, this is independent of if it can support 20 MHz operation.
2.
Cars do not necessarily stay in
one regulatory region, hence a car may move between regulatory domains that ALLOW or do not ALLOW 20 MHz operation.
3.
Regulatory rules may change as
technology develops – but hardware capabilities are permanent.[RR] Well, don’t forget SDRs:^)))
4.
Making 20 MHz mandatory [RR] means that to be 802.11 conformant, a STA
MUST support 20MHz operation, and remember, you do not have to be 802.11 conformant
to get deployed in ITS! It does not mean a STA must always
transmit/receive 20 MHz – it only means it is capable of transmitting and
receiving 20 MHz when it is allowed/configured by higher layers to do so.
The
only reason in my view to make 20 MHz optional is to allow devices to be built
as 10 MHz only devices. Doing so may allow for a simple device to be
built, but we already have such a device specified in the current 802.11
standard. If we are going specify NGV STAs so that they have significant
new features relative to the current specification, I think adding a 20 MHz
PPDU compatible with the current 10 MHz PPDUs should be one of these
features. Therefore I think it should be
mandatory. Also, I don’t think adding such a 20 MHz PPDU would
significantly increase the complexity of a NGV STA.
[RR] Again, making it mandatory ONLY affects 802.11
conformance. OBU and RSU manufacturers are free to choose what they build into
their products.If they only want 10MHz channels, that’s all they’ll
build. The marketplace will decide whether all NGV modules have 20MHz
modes, or there are some that don’t for some economic reason presumably.
Cheers,
RR
Regards,
Joseph
From: ** STDS-802-11-TGbd -- Enhancements
for Next Generation V2X.Task Group ** <STDS-802-11-TGBD@xxxxxxxxxxxxxxxxx>
On Behalf Of John Kenney
Sent: Wednesday, June 10, 2020
4:07 PM
To:
STDS-802-11-TGBD@xxxxxxxxxxxxxxxxx
Subject: Re: [STDS-802-11-TGBD]
NGV 20MHz M/O support
Hi
Rui and All:
Rui,
thanks for starting this discussion.
I commented
on the 0.3 draft to make 20 MHz optional. I was thinking particularly
about the EU situation, which Friedbert has now confirmed. That alone
seems like a good reason for 20 MHz to be optional.
As
the US
spectrum situation is developing, DSRC/NGV may only have access to one 10 MHz
channel (sadly). Therefore, we might not be able to use the 20 MHz
capability here either if the FCC proposal is formalized. We may find
more ITS spectrum in the future. The 4.9 GHz band has been mentioned.
But, that is speculative and far from likely.
If
the FCC limits the ITS band to 30 MHz (5895-5925 MHz), there is also the
possibility of DSRC/NGV operating as unlicensed in the U-NII-4 band, or in
other U-NII bands, for less critical services. This has not been discussed
much. I can think of at least two paradigms for that:
A)
DSRC/NGV continues to use 10 MHz as the base channel width. In this case
the 20 MHz NGV capability could be used as well. This would be attractive
for existing DSRC implementations, e.g. New York
and Tampa pilot
sites and other large deployments. But, it's not clear if they will want to
given the lack of interference protection. Under this paradigm, 10 MHz
DSRC, 10 MHz NGV, and 20 MHz NGV would coexist well with each other, but not
with 20/40/80/160 MHz Wi-Fi should such devices be deployed in proximity.
B)
DSRC/NGV moves to a 20 MHz base channel width in the 5850-5895 MHz U-NII-4
band. DSRC already has a 20 MHz version, which chip sets support but is
not deployed (to my knowledge). 20 MHz DSRC would coexist well with
20/40/80/160 MHz Wi-Fi due to a common legacy preamble. Note that the 20
MHz version of NGV we are developing would not coexist well with 20/40/80/160
MHz Wi-Fi, because it uses two 10 MHz premables instead of a 20 MHz preamble.
If this paradigm is attractive, TGbd should consider specifying a second 20 MHz
format, using a 20 MHz preamble that would coexist with 20 MHz DSRC and
20/40/80/160 MHz Wi-Fi, and that would incorporate PHY/MAC enhancements
compared to DSRC. I believe Onn Haran has previously mentioned this
possibility. It is important to realize that this second 20 MHz format would
not be intended to coexist with the first 20 MHz format or with 10 MHz
DSRC/NGV. It would be more straight forward, I expect, than the first 20
MHz format.
I assume you meant 5925 and 5935MHz below …not 5825 and 5835.
RR
Dear
All,
from
the European point of view we actually only use 10MHz channels and only this
option is allowed based on the ITS regulation in the band between 5855MHz to 5825 MHz
(5835MHz
for Urban Rail)).
In
ETSI a multichannel concept is being developed and here actually only 10MHz
channels are considered.
Thus,
I would strongly recommend to keep the 20MHz bandwidth optional.
Friedbert
HI
All,
During
today’s call, we discussed about the mandatory and optional support of
NGV 20MHz PPDU and operation.
I
checked our meeting motion record, and there is no specific discussion to make
20MHz mandatory. I create this email thread for discussions on this topic.
According
to some discussions in today’s meeting, there are good reasons to make
20Mhz PPDU/operation optional. E.g. different countries/regions may have
different available spectrum and service planning for C2C communications. We
are ok to leave 20MHz PPDU/operation optional for 11bd, and let different
countries/regions to make the choice.
Thank
you,
Rui
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