January 2011
doc.: IEEE 802.11-11/0060r1
Low Power Capability Support for 802.11ah
Date: 2011-01-17
Authors:
Name
Affiliations
Minyoung Park
Intel Corp.
Emily Qi
Intel Corp.
Submission
Address
Phone
th
2111 NE 25 Ave. 503 712 4705
Hillsboro OR 97229
email
[email protected]
[email protected]
Slide 1
Minyoung Park, Intel Corp.
January 2011
doc.: IEEE 802.11-11/0060r1
Abstract
• This presentation proposes low power capability
support for 802.11ah
Submission
Slide 2
Minyoung Park, Intel Corp.
January 2011
doc.: IEEE 802.11-11/0060r1
Previous Presentation on 802.11ah Usages
and Power Consumption Analysis
• Doc#: IEEE 802.11-10/1268r0
• Usages
– Smart metering (electricity, gas, water, …)
– Sensors (home, health, building, …)
– Collecting information from wireless sensing devices
• Traffic
– Low duty cycle: data may be collected every few minutes, hours, or days
– Small packet sizes: 10s or 100s of bytes
• Wireless sensing devices (Low-Power STAs)
– Battery powered and low-cost
– Multiple years of battery life
• Multiple years of battery life can be achieved by
– Low sleep state power consumption
– Low duty cycle
Submission
Slide 3
Minyoung Park, Intel Corp.
January 2011
doc.: IEEE 802.11-11/0060r1
Motivation
• AP does not know limited capabilities of Low-Power STAs
• AP does not treat Low-Power STAs differently from the other STAs
• Example: BSS Max Idle period (802.11v)
– AP has only one Max Idle period which allows the STAs to be associated for the Max
Idle period without sending any frames to the AP
Low-Power STAs which need to sleep for 10s of minutes
also need to wakeup and send frames to the AP
every 60 secs; otherwise they are disconnected
A single Max Idle Period = 60 secs
and need to reassociate when they wakeup.
STAs without low power constraint
Need to transmit frames to the AP every 60 secs
AP
• Low-Power STAs need to be treated differently from the other STAs
Submission
Slide 4
Minyoung Park, Intel Corp.
January 2011
doc.: IEEE 802.11-11/0060r1
Low Power Capability Support
• Provide low power capability support for Low-Power STAs
• Low Power Capability element
– A mechanism to exchange low power capability information between an AP
and Low-Power STAs so that the AP can treat the Low-Power STAs differently
from the rest of the other associated STAs
– Exchanged in (Re)Association Request/Response frames
– Format
Octets:
Element ID
Length
1
1
Low Power Capability Info
variable
Max Idle Period
Octets:
...
2
– Low Power Capability Info field
• Variable in length
• Example: Max Idle Period field
Submission
Slide 5
Minyoung Park, Intel Corp.
January 2011
doc.: IEEE 802.11-11/0060r1
Example: Max Idle Period
•
Max Idle Period field in Low Power Capability Info field
•
Low-Power STA asks the AP to use the Max Idle Period value set in the Low
Power Capability element in the (Re)Association Request frame
If the AP can support the Max Idle Period value in the (Re)Association Request
frame, the AP sets the same or a larger Max Idle Period value in the Low
Power Capability Info field in the (Re)Association Response frame
•
Low Power STAs can sleep
for 30 minutes without
being disconnected from the AP
Submission
AP applies different Max Idle periods for different classes of STAs
- STAs without low power constraint: 60 seconds
- Low-Power STAs: 30 minutes
AP
Slide 6
STAs without low power constraint
Need to transmit frames to the AP every 60 seconds
Minyoung Park, Intel Corp.
January 2011
doc.: IEEE 802.11-11/0060r1
Summary
• Wireless sensing devices in the 802.11ah usage model
–
–
–
–
Expected to be battery powered
Require multiple years of battery life
Low power consumption
Low cost
• Proposed low power capability support for Low-Power STAs
• Low Power Capability element
– Low-Power STAs provide their limited capability information to the AP
– The AP treats the Low-Power STAs differently from the other STAs to
support low power consumption
Submission
Slide 7
Minyoung Park, Intel Corp.