1. WLAN Paging and Idle Mode
Month Year
Sept 2006
January 2007
WLAN Paging and Idle Mode
Authors:
Date:
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Emily Qi et al
Emily Qi et al

2. January 2007 Date:2006-09-8 Authors: Month Year Sept 2006
Emily Qi et al
Emily Qi et al

3. Month Year
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Abstract
This document describes the Idle Mode and WLAN Paging normative text proposal (doc 07/0060r0), supporting the Power Saving objective, REQ2010.
What’s new compared to doc 06/0943r6
Removed Paging Service Protection
Removed linkage to Mobility Domain, have only Paging Group
Changed Paging Indication bit-map to reduce the size of Beacon frames
Emily Qi et al
Emily Qi et al

4. Topics Motivation Idle Mode and Paging Concepts
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Topics
Motivation
Idle Mode and Paging Concepts
Protocol Overview and Feature Summary
Implementation Considerations
Summary
Emily Qi et al
Emily Qi et al

5. Month Year
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Motivation & Benefits
Extend standby hours for battery-powered devices such as handhelds and ultra mobile devices
Can benefit most devices
Reduce the network load (wired/wireless) as mobile STAs traverse BSSs
Reduces the AP & network resources used for maintaining network connectivity for STAs
Enable Paging in WLAN systems, supporting common applications in multi-radio devices
Emily Qi et al
Emily Qi et al

6. Unnecessary BSS Transition Scenario
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Unnecessary BSS Transition Scenario
BSS Transition
Data packets
Emily Qi et al
Emily Qi et al

7. Idle Mode and Paging Concepts
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January 2007
Idle Mode and Paging Concepts
Idle Mode: Save power and resources
Non-AP STA enters “deep sleep” if there is no outgoing/incoming traffic
Non-AP STA can notify the infrastructure that it is in Idle Mode
If non-AP STA roams out of the coverage area of an associated AP, non-AP STA doesn’t need to reassociate with a new AP when it is in “Idle Mode”
Paging: Wake non-AP STA to receive incoming frames
Infrastructure notifies (pages) the client if there is an incoming frame
Non-AP STA wakes up at a longer interval to check for incoming frames
Non-AP STA associates with an AP when it receives a “Page”
“Paging” is an established communications concept, deployed in cellular and other networks
Emily Qi et al
Emily Qi et al

8. Paging Concepts and Logical Entities
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Paging Concepts and Logical Entities
Paging Group - A group of BSSs in which non-AP STA can be paged
A non-AP STA must reassociate if it transitions to an AP in a different Paging Group
Provides a collection of BSSs which a non-AP STA may traverse without requiring re-association
Paging Server
Provides Paging Services and
Serves one or more Paging Groups
Emily Qi et al
Emily Qi et al

9. Example of WLAN Paging Architecture
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Example of WLAN Paging Architecture
Paging group #1
Paging Server #1 (
Paging Server #2
Paging group #3
Paging group #2
Emily Qi et al
Emily Qi et al

10. Paging & Idle Mode Feature Summary
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January 2007
Paging & Idle Mode Feature Summary
Paging Capability and Service Discovery
Paging Bit in Wireless Network Management Capabilities element
Paging Service element included in Beacon and Probe Response frames
Capability for a STA to Enter, Exit Idle Mode, provide Idle Mode Notification
Idle Mode Request Action Frame (non-AP STAAP)
Idle Mode Response Action Frame (AP non-AP STA)
Capability to Page a non-AP STA
Paging Indication element
Indicates which non-AP STAs in a Paging Group are being paged
Included in the Beacon frame at the Paging Interval
Included in the Probe Response frame in response to a non-AP STA Probe Request
Optional TGv Feature
Emily Qi et al
Emily Qi et al

11. Paging Advertising and Discovery
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Paging Advertising and Discovery
Wireless Network Management Capability element
Paging bit is set to 1 to indicate that Paging service is enabled by an AP or STA B0 B1 B2 B3 B4 B5 B6 B7
B8-B15
Multicast
Event Log
Diagnostics
Presence
FBMS
Proxy ARP
Collocated Interference
Paging Reserved
Bits: 1
Paging Service element
Advertise Paging Service and Paging Indication delivery information in Beacon and Probe Response frames
Element ID
Length
Paging Server ID
Paging Group ID
Paging Interval
DPIM Count
Octets: 1 6
Emily Qi et al
Emily Qi et al

12. Idle Mode Request/Response Action Frames include Idle Mode elements
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Idle Mode Request/Response Action Frames include Idle Mode elements
Idle Mode Request element
Element ID
Length
Request
Type
STA Address
Paging
Server ID
Group
Octets: 1 6
Request Type: Enter Idle Mode, Exit Idle Mode, Idle Mode Notification
Idle Mode Response element
Element ID
Length
Response
Status
STA
Address
Paging
Server
Group
Octets: 1 6 2
Response Types: Enter Idle Mode
Emily Qi et al
Emily Qi et al

13. Paging Indication Paging Indication element
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Paging Indication
Paging Indication element
Element ID
Length
Paging ID
List
Octets: 1
1– 252
The Paging ID List includes a list of Paging IDs of non-AP STAs being paged. Thus the length of the element is a function of the number of non-AP STAs being paged.
Frames containing Paging Indication:
Beacon frame, only when DPIM count is 0
Probe Response frame
Emily Qi et al
Emily Qi et al

14. January 2007
Example Message Flow
Emily Qi et al

15. Example: Idle Mode and Paging Scenario
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Example: Idle Mode and Paging Scenario
SIP_INVITE (for STA1)
Paging Group 1
Paging Group 2
Paging Server
Paging IDs
Paging
Exit Idle Mode
Page STA
SIP_INVITE (for STA1)
Enter Idle Mode
BSS transition
Enter Idle Mode
Data packets
Idle Mode messages
Emily Qi et al
Emily Qi et al

16. Implementation Considerations
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Implementation Considerations
Let’s talk about “Complexity”
Layer 3 Application Impacts
Paging Impact on Beacon Frames
Configuration and Deployment
Paging Server - AP protocol
Emily Qi et al
Emily Qi et al

17. Protocol Functionality Distribution
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Protocol Functionality Distribution
Client STA Impact
2 Action Frames, 4 paging information elements, contents
NOT complex!
AP Impact
2 Action Frames, 4 paging information element, contents
AP-Paging Server Protocol (out of scope)
Paging Server
Paging Service Management effectively resides here; Paging Server maintains list of idle mode non-AP STAs MAC Address, Paging Group ID, Paging ID, Paging Server ID, Home APs, and Idle Mode Notifications
NOT Complex!
Emily Qi et al
Emily Qi et al

18. Layer 3 Application Impacts
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Layer 3 Application Impacts
SIP and other Keep-Alive messages are periodically generated by clients
SIP Client sends periodic (configurable interval, typically 60 seconds – 1 hour)
An idle-mode-enabled client will need to exit Idle Mode, send the SIP Keep-alive, re-enter idle mode, potentially resulting in additional required associations.
Wireless LAN Solutions
Configure larger keep alive intervals for wireless systems
Provide a network based proxy-SIP client (e.g. at Paging Server). 
Entering idle mode results in dropping the SIP connection
Emily Qi et al
Emily Qi et al

19. Paging Impact on the Beacon
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Paging Impact on the Beacon
Current design for notification of Paging IDs – Include Paging IDs in the Beacon
The length of the element is a function of the number of STAs being paged.
Paging List included only when DPIM = 0, e.g. every 2 seconds (20 Beacon frames)
When no non-AP STAs are being paged, the Paging Indication element is not included.
Example – 10 Paging IDs, x 2 octets = average of 1 octet per Beacon
Using data from 06/1726r2, 100 STAs, 2call/sta/hour/5 min calls = 1 call every 18 seconds; 2000 STAs, 20 calls every 18 seconds, approx 2 Paging IDs per Paging Interval (Paging interval = 2 seconds)
Alternative designs considered for indicating that a non-AP STA is being paged
TIM-like bitmap; bitmap likely sparsely but randomly populated
Hash of list + list of IDs
Additional suggestions welcome
Emily Qi et al
Emily Qi et al

20. Configuration and Deployment
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Configuration and Deployment
Configure and deploy a Paging Server
Assign Paging Server ID
Define Paging Groups
(RADIUS server is MUCH more complex)
Configure APs
Assign Paging Group, Paging Server ID
Configure TGv capabilities
AP-Paging Server Protocol
Configure STA
Emily Qi et al
Emily Qi et al

21. Paging Server - AP Protocol
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Paging Server - AP Protocol
Out of Scope for TGv
AP delivers Idle Mode Request Element to Paging Server
Paging Server Delivers Idle Mode Response Element to AP
Paging Server Delivers list of Paging IDs to APs
Packet transfer from previous Home AP to current Home AP
AP to AP Communication (out of scope)
Drop at the previous Home AP and let the network application retransmit
Emily Qi et al
Emily Qi et al

22. Summary Idle Mode and Paging proposal enables Using
January 2007
Summary
Idle Mode and Paging proposal enables
Extend battery standby hours for handheld and ultra mobile devices
Enable Paging in WLAN systems, supporting common applications in multi-radio devices
Using
Straightforward protocol extensions.
Emily Qi et al

23. Motion Adopt the normative text in 07/0060 into TGv draft 0.07.
January 2007
Motion
Adopt the normative text in 07/0060 into TGv draft 0.07.
Emily Qi et al

24. Thank You! January 2007 Month Year Sept 2006 Emily Qi et al