1. Consideration on Max Idle Period Extension for 802.11ah Power Save
July 2011
doc.: IEEE /xxxxr0
Consideration on Max Idle Period Extension for ah Power Save
Date:
Authors:
ZTE Corporation
ZTE Corporation

2. John Doe, Some Company Authors: doc.: IEEE 802.11-yy/xxxxr0 Month Year
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John Doe, Some Company

3. John Doe, Some Company Authors: doc.: IEEE 802.11-yy/xxxxr0 Month Year
ZTE Corporation
John Doe, Some Company

4. Motivation
In this presentation, we discuss the power save for 11ah use cases with Very long reporting interval and little downlink control message transfer, for example,
Gas detector only need to transfer alarm message & data to AP, the detector potentially may sleep several days or even longer.
In some smart grid use cases, meters report the data with very long period (more than one day) for only charge requirement.
Current 11v BSS Max Idle Period management scheme couldn’t satisfy the requirements of these 11ah use cases.
The length of Max Idle Period is less than 1 day (~18.64hrs)
All of STAs in the BSS are deployed the same Max Idle Period by the AP;
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5. Power Save for very long transmission duty cycle (~days)
July 2011
doc.: IEEE /xxxxr0
Power Save for very long transmission duty cycle (~days)
Current length of BSS Max Idle Period is only ~18.64hrs (16bit with unit of 1000TU).
Suppose AP supports longer max idle period (~days) with ultra low sleep power consumption, the benefit of power save will be:
STA could sleep longer than 18hrs to save more power, without sending unnecessary keep-alive frames.
The power consumption of un-expective deferral time for sending these unnecessary keep-alive messages according to channel access competition will be avoided.
The additional (re) association process due to unsuccessful transmissions of unnecessary keep-alive frame in time.
ZTE Corporation
ZTE Corporation

6. Very Long Max Idle Period Extension
July 2011
doc.: IEEE /xxxxr0
Very Long Max Idle Period Extension
One of the simply solution is to change the unit of Max Idle Period larger than 1000TU(1s).
For Example, using one or two bits to indicate two or four types of different units, if the indication shows that the unit is 10000TU(10s), the length of Max Idle Period will be extended from ~18.64hrs to ~186hrs (7.75days) . B1
Unit
1000TU 1
10000TU
B1B2
Unit 00
1000TU 01
10000TU 10
TBD 11
ZTE Corporation
ZTE Corporation

7. Multiple Max Idle Periods Extension for Support multiple device categories
In current BSS Max Idle Period management scheme, although AP can separately indicates a Max Idle Period for every STA by association response or re- association response, AP couldn’t obtain the STA’s information about Max Idle Period deployment such as STA’s preference or application type. Therefore, all of STAs in the BSS are deployed the same Max Idle Period by the AP.
In different 11ah sensor applications, reporting intervals may vary from seconds/minutes to hours/days. If 11ah sensors with long reporting intervals are set to the same short value as 11ah sensors with short reporting intervals, or are set to the same short value as mobile phones (e.g. 5 minutes) in convergence scenario,
Lots of unnecessary keep-alive messages will waste resource and power for 11ah sensors with long reporting intervals.
Transmission of a large number of keep-alive messages may induce channel access competition and access delay problem.
Since battery-powered sensors usually required the life time about several years, different max idle period for different device categories (including for each STA) needs to be considered.
ZTE Corporation

8. Potential Method for Support Multiple Max Idle Periods
Step1:
AP advertises its capability of whether it support “very long Max Idle Period”;
Step2 :
STA includes its preferred Max Idle Period value or device category in the (Re) Association Request frame for obtaining the device specific Max Idle Period value from AP
Step3:
The AP decides the Max Idle Period value regarding to AP’s capability and the
STA’s preferred Max Idle Period or device category, and indicates the value to
the STA in the (Re)Association Response frame
Note: If the STA doesn’t like the received Max Idle Period value from the AP, the STA can either drop the association, or the STA gets dissociated by the AP timing it out because the STA does not send the keep-alive message in time.
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9. Summary
Very long Max Idle Period extension (~days) for support related 11ah use cases
One of the simply solution is to change the unit of Max Idle Period, so that the length of Max Idle Period will be extended longer than ~18hrs.
Multiple Max idle Periods extension for Support multiple device categories (including for each STA)
Potential method:
1) AP advertises its capability of whether it support “very long Max Idle Period”;.
2) 11ah STA indicates its preferred Max Idle Period value or device category to the AP in the (Re) Association Request frame
3) The AP decides the Max Idle Period value regarding to AP’s capability and the STA’s preferred Max Idle Period or device category, and indicates the value to the STA in the (Re)Association Response frame
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10. References
[1] ah-potential-compromise-of ah-use- case-document [2] v-2011 [3] ah-performance-evaluation-of-multiple-STAs’- authentication-and-association-process [4] ah-power-saving-mechanism-consideration-for ah-framework [5] ah-low-power-capability-support-for ah
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11. Straw Poll 1
Do you agree that BSS Max Idle Period shall be able to set to a longer value (~days) by changing the unit of Max Idle Period larger than 1000 TU (1s) (the sleep interval unit extension method is TBD) ? Y: N: A:
Slide 11
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12. Straw Poll 2
Do you agree that the AP shall be able to support multiple Max Idle Periods？ Y: N: A:
Slide 12
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