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| --- This message came from the IEEE 802.11 Working Group Reflector ---
Hi Mark, Thanks for your comments. Please find my response inline.
I hope other people will jump in and offer their views. Regards; Osama. From:
*** IEEE stds-802-11 List *** [mailto:STDS-802-11@xxxxxxxx]
On Behalf Of Hamilton, Mark --- This message came from the IEEE 802.11 Working Group Reflector ---
HEW folks, You may have been there, or heard about, my questions during the closing plenary in Los Angeles about the draft PAR being put forward by the HEW SG. At the time, Bruce clarified
that the agenda item at the time was to get the draft PAR into the process for review, and that my questions would be better asked during the review. So, I am putting them forward here, now, instead of taking the time during that plenary session, in an interest in getting it clarified before/at the Beijing meeting. 1.
I am wondering about the band restrictions. To quote from the draft PAR: “This amendment defines operations in frequency bands between 1 GHz and 6 GHz.” It was confirmed at the plenary that
the intent is to not cover the TV white space bands. These leads me to two questions:
a.
The PAR talks about making changes to both/either MAC and PHY. If the MAC is changed, how are those changed envisioned to be band-specific? This seems to me to be some combination of cumbersome
in the text (a lot of added “If such-and-such MIB attribute is true” language around all of the changes), and complex and unnecessary restriction in implementations to only use the new features if the specified bands are in use.
b.
If there are changes to the PHY, for example the 11ac PHY (which is specifically called out as focus for the improvements, per the PAR), will those changes not be reflected in the 11af PHY
(which is currently an intentional “copy” of the 11ac PHY)? This again seems unnecessary and an unfortunate complication for implementations. [osama] I believe the intention
of the group members is to produce a new PHY clause rather than tweaking clause 22. I think the PAR is clear in saying that the improvement will be relative to 11ac and 11n under the same scenarios, rather than saying introduce changes to 11ac PHY. For example
if some of the technologies discussed in the SG, e.g. UL MU MIMO, are introduced in HEW, do you think they should be added to 11af?
It seems to me that 11af TG did a good job producing clause 23 (a modified version of clause 22), but it is not clear the intention was to track all the changes in future amendments. It will be a heavy burden on future work. I also would like to point
out that initially 11af was proposing to use 11n PHY (draft D1.0), not 11ac, which supports my assertion that the intention wasn’t to track changes to be introduced by future amendments. [osama] The focus of the group
(as well as the motion to start the SG) is on the 2.4 and 5 GHz bands where most (if not all) of WLAN deployments are. Issues related to the band selection was discussed in the SG during the January meeting. Some favored to be specific about the bands of interest
and state 2.4 and 5 GHz explicitly in the PAR scope. Others preferred to keep the door open to if and when new bands become available. Hence the language in the PAR. There was no intention to go back and
modify everything that was done before. 2.
I also wonder about the language discussing mobility.
a.
The PAR has this bullet: “Outdoor operation is limited to stationary and pedestrian speeds.” (In the section 5.2.b extended comments at the bottom – which is an excellent addition, by the
way – this made the PAR one of the most clear about its intent in recent memory!) There seems to be no matching discussion of indoor operation while mobile. [osama] My understanding is we
needed to qualify the outdoor speeds only. Indoor speeds are probably straightforward and are not different from what is in 11n and 11ac channel models.
b.
Between the above sentence, and the specific mention of mobile devices as a target stakeholder, I am assuming that some aspect of mobility is being considered as part of the problem set of
the scope. Although, I don’t see any other discussion that clarifies this. (As many of you know, I am very interested in mobility performance, and would like to understand if there is overlap or other relationship to the proposed work.) If mobility factors
are to be considered, I believe more language describing that is needed in the PAR. If mobility is not going to be considered, I don’t understand the discussion of (outdoor) mobility speeds, and suggest that bullet be changed to say that mobility is not being
considered. [osama] I believe the qualification
of the outdoor speeds was mainly introduced to affect the channel models the group is developing. While not an expert in mobility, I am sure that mobility means more than just channel models. As far as I remember there hasn’t been discussion in the SG on supporting
mobility (anyone can correct me if I am wrong). I think the bullet is appropriate the way it is to serve its intended purpose. I also note that the word “mobility” wasn’t mentioned anywhere in the PAR. Thanks for any clarification on these items.
Mark Hamilton _______________________________________________________________________________
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