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. July 2011
doc.: IEEE /xxxxr0
Abstract
The target of this presentation is to provide some considerations on Max Idle Period extension for ah power save.
ZTE Corporation
ZTE Corporation

3. Transmission Characteristics of 11ah Use Case [1]
No.
Use Cases
STA/AP communication
Traffic type
STA Capacity 1a
Smart Grid
2-way (meter data & control)
Continuous/periodic/burst
6000 1c
Environ./Agri. Mon.
2-way (monitoring data and control; mostly monitoring)
Periodic, event-based
300 1d
Industrial Process Automation
Periodic (0.1s~100s), Burst
500 1e
Indoor Healthcare System 50 1f
Healthcare/Fitness
Periodic: few 100 bytes every minute
Event-based: few 100 bytes per event
50 (multi-story center can have higher density) 1g
Home/Building Automation/Control
50~100 1h
Temperature Sensor Network
5~20 3a
Outdoor Extended Range Hot Spot
Burst/permanent 3b
Outdoor Wi-Fi for Cellular Offloading
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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.
All of STAs in the BSS are deployed the same Max Idle Period by the AP;
The length of Max Idle Period is less than 1 day (~18.64hrs)
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5. Problems of support both mobile devices and sensors
In current BSS Max Idle Period management scheme, all of STAs in the BSS are deployed the same Max Idle Period by the AP.
If 11ah sensors are set to the same value of several minutes as mobile phone,
It will be a big power consumption for 11ah battery-powered sensors.
There may be a large number of keep-alive messages occupy the channel resources frequently, channel access competition and access delay may be a big problem.
To save power of sensors in these use cases, AP should support multiple max idle period management scheme
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6. 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,
STA could sleep longer than 18hrs to save more power, without sending keep-alive frame every 18hrs.
By keep association with AP, if emergency situation happens, STA can quickly wake up and report important data to AP.
Besides, STA can response to event-based query/control message
from AP by periodically listen to TIM message.
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ZTE Corporation

7. Power Save for very long transmission duty cycle (~days)
July 2011
doc.: IEEE /xxxxr0
Power Save for very long transmission duty cycle (~days)
One of the simply solution is to enlarge the unit of Max Idle Period, e.g. from ‘1000TU’ (1s) to ‘10000TU’ (10s), so that the length of Max Idle Period will be extended from ~18.64hrs to ~186hrs (7.75days) .
Idle Options:
ZTE Corporation
ZTE Corporation
ZTE Corporation

8. Summary
Multiple Max Idle Period management extension for Support both mobile devices and sensors
Very long Max Idle Period management 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.
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9. Reference
[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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10. Straw Poll 1
Do you support the concept of very long Max Idle Period (~days) extension for better support related 11ah use cases? Y: N: A:
Slide 10
ZTE Corporation
Minyoung Park, Intel Corp.

11. Straw Poll 2
Do you support the concept of very long Max Idle Period (~days) by simply change the unit of Max Idle Period, so that the length of Max Idle Period will be extended longer than ~18hrs? Y: N: A:
Slide 11
ZTE Corporation
Minyoung Park, Intel Corp.

12. backup
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13. Power Save for very long transmission duty cycle (~days)
July 2011
doc.: IEEE /xxxxr0
Power Save for very long transmission duty cycle (~days)
If the sensor is disassociated with AP until requirement of burst data transmission
Num of STAs
Authentication and association time (s) 50
1.2073
100
1.8012
200
2.6550
500
4.6366
900
1000
12.345
1500
2000
2500
3000
To meet the requirement,
successful and faster association process is needed to satisfy the delay requirement and security requirement for these time-sensitive and life/property-related important data transmission, especially for burst data transmission by large number of STAs at the same time due to emergency event happens such as fire disaster.[3]
AP also needs to check the status of sensor or query sensor occasionally. How disassociated- STA quickly responses to this event-based query/control message from AP ?
ZTE Corporation
ZTE Corporation