--- This message came from the IEEE 802.11 Working Group Reflector ---
Graham,
I didn’t mean to say that “we do not actually need CCK anymore”. What I meant was that if we did not have CCK, we would not invent it. Even though the role it plays (single-tone mode that is not as terribly inefficient as DSSS) is useful,
any new mode we might design would have the problem that there would be no installed base, so it just wouldn’t be worth the trouble (I think).
As it is, CCK does exist, it does have this moderately useful role, and whatever else we might say, it does score highly on the installed base front. Why touch it? It would create more problems for implementers to remove it than to leave
it the way it is.
Regards,
Sean
From: G Smith <gsmith@xxxxxxxxxxxxxxxxxxx>
Sent: Tuesday, January 24, 2023 11:59 AM
To: STDS-802-11@xxxxxxxxxxxxxxxxx
Subject: Re: [STDS-802-11] CCK should it be Deprecated?
--- This message came from the IEEE 802.11 Working Group Reflector ---
Hi Mike, Sean, Thomas and Harry,
I understand the general view that there are devices out there that are 11b only, but I was hoping to get a response from a supplier of company that is actually making such products. Then the question would be if the DSSS/CCK chipset is
so essential, (i.e. they need 11 Mbps) or, if in future a DSSS/OFDM would be just as good if not better (possibly restricted to 12 or 24 Mbps), or, indeed, if they tend, in practice, to use DSSS only?
Given that it would be about 8 years notice, who actually would be affected? As Sean points out, we actually do not need CCK anymore and deleting it would, in my mind, also make the lists of supported data rates, for example, much cleaner.
I have no more to present, but maybe delay this discussion until Sponsor Ballot and see what comes up?
I was thinking of presenting at a Plenary (mid week) to get full exposure, but that can’t happen until March and I do not want to delay 11me at all.
Thanks
Graham
--- This message came from the IEEE 802.11 Working Group Reflector ---
Hi All,
Thank you all for your feedback on this issue.
So Graham, with respect to your comment. How do you want to proceed? Do you have anything more to present? I'll add this CID to the agenda for the Jan 27th meeting if that works for you.
--- This message came from the IEEE 802.11 Working Group Reflector ---
Graham, Thomas, all,
I have to agree with Thomas on this. If CCK didn’t exist, we would certainly not invent it. As it is, though, it has a very definite use, and as long as that is true, there doesn’t
seem to be much point in deprecating it.
Regards,
Sean
--- This message came from the IEEE 802.11 Working Group Reflector ---
I think a technical justification might be that some STA implementations achieve their very low power consumption and/or complexity requirements by only supporting DSSS/CCK.
Whether or not those device types actually need data bandwidths higher than 2 Mbps may be less relevant, given DSSS can only achieve that tput if the medium is otherwise completely
idle, and (per my earlier note) the AP might want to send frames to that STA at rates higher than 2 Mbps even if the STA doesn’t need to transmit at those rates itself.
Thanks Thomas,
I suppose the question is whether we feel that we should start to discourage use of CCK? I think in technical terms it is not now needed, so maybe we should just start the process
rolling?
Deprecating does just that.
Graham
Thanks for this discussion.
As I mentioned when this was discussed in REVme, there are some relatively recent chipsets in the market that only support 11b (up to 11 Mbps) targeting very low power IoT applications.
So it is not obvious we can forecast a date at which all 11b-only STAs will be end-of-life.
I also noted that WFA’s Optimized Connectivity specification (publicly available on their website) specifies a minimum beacon rate of 5.5 Mbps (i.e. a CCK rate) in 2.4 GHz to help
minimize management frame airtime overhead. While in practice many APs that certify for this program might configure use of OFDM beacon rates by default (e.g. 6 Mbps or above), such APs that need to interoperate with 11b-only STAs would necessarily be configured
to use 5.5 Mbps CCK instead.
Given continued use of CCK rates in the field is expected for some time, I don’t see see a clear justification for deprecating them from the standard.
--- This message came from the IEEE 802.11 Working Group Reflector ---
Thanks Harry,
My only response is that we were seeking to see if that really was the case. Are there enough 11b only, relying on CCK, out there in the field and remember it would be 8 years
before it is obsolete and that does not mean that CCK has to be removed, just that interoperability with every device is not guaranteed. The DSSS 1 , 2 Mbps is retained of course.
Graham
My guess is that if there are 11b-only devices still hanging around after all these years, the manufacturer is not going to want to upgrade them, even if OFDM provides similar performance.
Also, if there is a customer who still uses an 11b-only WiFi deployment to this day after all these years, they likely have a good reason for not upgrading to OFDM, and will not
want to change anything.
Further, the amount of real estate and power consumed by a working CCK implementation is so minimal compared to the rest of the modem, why would modern chipsets bother ripping it
out, given they would have to subject the chip to a series of tests to verify they didn’t accidentally break something.
--- This message came from the IEEE 802.11 Working Group Reflector ---
In 802.11me we are discussing Clause 16 and CCK. There is a proposal to make CCK “deprecated”. This is the first step to making it “Obsolete”.
Please look at the following presentation and I would be very interested to hear any viewpoints or comments.
The presentation makes the case that there is no basic need for CCK as the OFDM 6 and 12Mbps are more than suitable to be used rather than CCK 5.5 and 11 Mbps, and that there is
no need for the extra modem that is required.
Anyhow, please do read the presentation and please do comment either to the reflector or directly to me.
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