1. WLAN Paging and Idle Mode
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WLAN Paging and Idle Mode
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Emily Qi et al
Emily Qi et al

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Abstract
This document outlines a WLAN Paging and Idle normative text proposal (doc#06/0943r2) in support of Power Saving objective in accordance with REQ2010.
This is a merged proposal of WLAN Paging (06/656r0, Qi et al) and Idle Mode Operation (06/349r0, Jin et al).
Emily Qi et al
Emily Qi et al

3. Agenda Power Saving Goal Power Consumption Analysis
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Agenda
Power Saving Goal
Power Consumption Analysis
WLAN Paging and Idle Mode Concept
WLAN Paging Protocol
Emily Qi et al
Emily Qi et al

4. Month Year
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Power Saving Goal
Extend standby hours for handheld and Ultra Mobile PC (UMPC) to support applications such as VoIP over WLAN
Emily Qi et al
Emily Qi et al

5. Power Consumption Issues
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Power Consumption Issues
Overhearing broadcast/unicast messages at Rx
Scanning Overhead for AP Selection
Number of BSS transitions while roaming
OS wakes up to call supplicant
Derives the keys: PMKR1 and PTK
Sends and receives authentication and reassociation messages
Emily Qi et al
Emily Qi et al

6. Introducing Idle Mode and WLAN Paging
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Introducing Idle Mode and WLAN Paging
Idle Mode : STA enters “deep sleep” if there is no outgoing/incoming traffic
STA wakes up at a longer “sleep” interval (e.g 2.1s) to check if there is any incoming frame
If STA roams out of the coverage area of the last known associated AP, STA doesn’t need to reassociate with a new AP when it is in “idle mode”
WLAN Paging: Infrastructure will “find” the client if there is incoming traffic
STA will reassociate with a new AP when it receives the notification of incoming traffic from infrastructure
Emily Qi et al
Emily Qi et al

7. WLAN Paging and Idle Mode Concept
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WLAN Paging and Idle Mode Concept
Paging Concepts
Paging Domain (PD)
PD is a set of BSSs within the same ESS
Paging Group (PG)
PG is a logical group of APs in which STA can be paged
A PD comprises one or more PGs
Paging Server
Provides Services: Paging and Keying
Can be in the AP or a separate network entity
Paging Procedures
Paging Capability Discovery and Advertising
STA Enter/Exit/Update Idle Mode
APs periodically broadcast Paging Indication
STA wakes up to receive paging indication
Paging Service in AP
Paging Service in a separate network entity
Emily Qi et al
Emily Qi et al

8. STA Operations STA enters Idle Mode Idle Mode Operation
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STA Operations
STA enters Idle Mode
The STA sends Idle Mode Request (enter) to its current AP for Paging Service Request (known as Home AP)
Paging Server sends Idle Mode Response (succeed/or fail) with Idle mode keep-alive timer along with keying materials if Paging Service Protection is enabled
The Home AP keeps the STA alive until paging server receives Exit Idle Mode Request
Idle Mode Operation
Paging Scan: STA wakes up to receive Paging Indication
Passive Paging Scan and Active Paging Scan
Idle Mode Update
Keep-alive Update before keep-alive timer expires
Paging Group ID update when the STA roams into a new Paging Group
STA exits Idle Mode
If a STA hears a paging, the STA exits the idle mode and scans channel to associate with an AP
If it is still in the home AP area, no reassociation is required
Emily Qi et al
Emily Qi et al

9. Infrastructure Operation
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Infrastructure Operation
Paging Server can be in the AP (distributed) or in a separate network entity (centralized)
Paging Server maintains the paging service information for the STA in Idle mode
STA MAC Address, Paging Group ID, Home AP (not needed if paging service is in the AP)
Home AP maintains state for the Idle Mode STA
If there is an incoming packet for the STA in Idle Mode, Home AP notifies the Paging Server to
Find out the current paging group where STA belongs
Request all of APs in the Paging Group to page the STA
Emily Qi et al
Emily Qi et al

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Paging Scan
Paging Scan: STA wakes up to receive Paging Indication
Passive Paging Scan
Listen to Beacon Scan and Broadcast Paging Indication Frame
Active Paging Scan
STA sends Probe Request to the visiting AP
The visiting AP responds with Probe Response including the Paging Indication Element
STA wakes up
If the STA is still with the same BSS, the STA will wait for Paging Indication broadcast frame
Beacon PI PI PI PI
Home AP
Paging Interval (e.g. 2.1s)
Beacon PI PI
Visiting AP
Paging Interval (e.g. 2.1s)
If the STA moves to a visiting AP, the STA scans for a new beacon and sync up with the new DPIM drifting time, or STA sends Probe Request to request the last PI element from the visiting AP.
SIFS
Emily Qi et al
Emily Qi et al

11. Example of STA Operating at Idle Mode
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Example of STA Operating at Idle Mode
Emily Qi et al
Emily Qi et al

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WLAN Paging Protocol
Paging Capability and Paging Service Discovery (Beacon/Probe Response
Paging Indication
Broadcast Action Frame
Probe Response
Idle Mode Request and Response (unicast)
Enter Idle Mode
Exit Idle Mode
Idle Mode Update for Paging Group ID and Keep-alive
Emily Qi et al
Emily Qi et al

13. WLAN Paging Message Flow
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WLAN Paging Message Flow
Emily Qi et al
Emily Qi et al

14. Feature Summary Idle mode operation to extend STA standby hours
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Feature Summary
Idle mode operation to extend STA standby hours
WLAN paging to wake up STA in order to receive incoming traffic
Paging Server for deployment flexibility and scalability
Paging Group for bandwidth efficiency and scalability
Paging Service Protection for forgery protection between STA and Paging Server
Emily Qi et al
Emily Qi et al

15. References 06/349r0 Idle Mode Operation for IEEE 802.11v (Jin et al)
July 2006
References
06/349r0 Idle Mode Operation for IEEE v (Jin et al)
06/656r0 WLAN Paging for Power Saving (Qi et al)
Emily Qi et al

16. Month Year
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Motion
Move to include normative text in document 06/0943r2 into the TGv draft.
Mover:
Second:
Results:
Emily Qi et al
Emily Qi et al