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| --- This message came from the IEEE 802.11 Working Group Reflector ---
Hi Minho, Thanks for your observations, very interesting. I probably need to think about this a lot more but I would point out that in your formula, the throughput
is not simply related to the channel capacity C and number of stations in the network. The problem is the overlapping stations from other networks on the same channel. Hence the formula becomes (1-P)*C/(N + O) where O is the number of STAs in other networks
on the same channel that are able to exert CCA on the wanted network. (Actually it gets worse than that when EDCA overhead is taken into account.) To keep O at a minimum, we need to organize our frequency re-use such that OBSS is kept at a minimum, but in
practice and in dense environments, this is not possible and the result is that we end up with a large area network with a very high value for N and (hopefully) small O. Using DSC we can contain the area and increase frequency re-use. Hence N can be made
smaller (by using a smaller cell size) and at the same time reduce the value of O. Hence, the original large network with high N is replaced by several smaller networks each with fewer STAs per network but with aggregate total of(high) N. Now a high number of STAs results in EDCA overhead. There is an overhead to EDCA which becomes worse as N exceeds CWmin and approaches the CWmax. Particularly
bad if QoS is used. It is therefore desirable to keep the number of active STAs in a network below a certain number related to CWmax. Hence, by restricting the area and the number of STAs in that area, we are better off. If the density of STAs is still
exceedingly high in the smaller cell network we have the ability to use more than one AP to cover that cell, each on separate channels, and again DSC can be used to restrict the area so as to get manageable numbers. Now I grant you this may not be straightforward to manage from the onset of setting up a particular area coverage, but I do believe that the DSC approach can
be used so as to maximize the efficiency – it is just a matter of getting the right values :>) If we desire to move to frequency re-use and a more cellular approach to capacity, then I do think that DSC has a lot to offer. I look forward to discussing with you in Dallas, maybe we could work on some actual figures/examples and see what comes out. Best regards Graham
From:
정민호 [mailto:minho@xxxxxxxxxx]
Hello Graham, Thank you a lot for the great introductory presentation today.
Let me revisit my comment with more detail.
As far as I understand, in Wi-Fi networks, per-user throughput can be roughly approximately given by (1-P ) *
C/N, where P, C, N refer to the frame loss rate, channel capacity, and the number of users within the carrier sensing range, respectively.
P mainly depends on the number of hidden nodes outside the carrier sensing range
and N is determined by the carrier sensing range and the area density of STAs within it.
FYI, specifically in HEW’s dense scenarios, it is hard to think that all the non-AP STAs are uniform in density for multi-BSS networks. So, optimal carrier sensing threshold of a DSC-capable STA for enhancing per-user throughput may be highly depending on the area density of STAs nearby the observing
STA and overall network conditions, which be hardly got because neither gathering STAs’ location info. nor AP-to-AP exchange of network conditions are easy now.
That is, my concern is that just heuristic operation of DSC (without consideration of sharing STAs’ location info. and network conditions info.) may have limited impact
on per-user throughput enhancement in HEW environments. Thank you. Best Regards, Minho From: *** IEEE stds-802-11 List *** [mailto:STDS-802-11@xxxxxxxx]
On Behalf Of Osama AboulMagd --- This message came from the IEEE 802.11 Working Group Reflector ---
Hello All, A HEW SG telecon is scheduled for Wednesday, October 30 at 10:00 ET. Please let me know if you plan a submission. Dial in information is given below. Thanks to Reza for arranging the webex. A tentative agenda is given below. Please let me know if you want to add an item to the agenda.
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Call the meeting to order
·
IEEE 802 and 802.11 IPR policies and procedure
·
Attendance Reminder. Please send an e.mail to
inoue.yasuhiko@xxxxxxxxxxxxx and/or
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·
https://mentor.ieee.org/802.11/dcn/13/11-13-1290-00-0hew-dynamic-sensitivity-control-for-hew.pptx
- Graham Smith (DSP Group)
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AoB
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have before proceeding with the teleconference. Regards; Osama -----Original Appointment----- Hi Osama, Below is the webex invite for HEW call on Oct 30, 10:00 ET. Reza Regarding WebEx
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