1. WLAN Paging for Power Saving
Month Year
May 2006
May 2006
WLAN Paging for Power Saving
Date:
Authors:
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Emily Qi et al, Intel Corp.
Emily Qi et al

2. Month Year
May 2006
May 2006
Abstract
This document outlines a WLAN Paging proposal in support of Power Saving objective in accordance with REQ2010.
Emily Qi et al, Intel Corp.
Emily Qi et al

3. Agenda Power Saving Goal Power Consumption Issues
Month Year
May 2006
May 2006
Agenda
Power Saving Goal
Power Consumption Issues
Power Saving Analysis
WLAN Paging Concept
WLAN Paging Protocol
Emily Qi et al, Intel Corp.
Emily Qi et al

4. May 2006
Power Saving Goal
Enables 300+ hours of standby operation for handheld and Ultra Mobile PC (UMPC) to support applications, such as VoIP over WLAN
Emily Qi et al, Intel Corp.

5. Power Consumption Issues
May 2006
Power Consumption Issues
Overhearing
Scanning overhead
Power consumption during idle
The number of reassociations
The total system power
Emily Qi et al, Intel Corp.

6. Introducing WLAN Paging
May 2006
Introducing WLAN Paging
STA “deeply sleeps” or “shuts down” if there is no outgoing/incoming traffic
STA wakes up at a time interval (e.g. 2.1s) to check if there is incoming traffic
STA doesn’t need to associate with AP when it is in “deep sleep” mode and roaming across APs.
If STA roams out of the coverage area of the last known associated AP when STA wants to be “active”, STA will re-associate with a new AP
Emily Qi et al, Intel Corp.

7. PC Power Consumption w/WiFi
Month Year
May 2006
May 2006
Power Saving Analysis
PC Power Consumption w/WiFi
System
Scanning
Idle
Misc (filtering,DTIM, PS-Poll, re-association, etc)
Total (mw/hour)
Active
10W
700mW
100mW
N/A
10800mW
With Paging
300mW
10mW
40mW
450mW
Emily Qi et al, Intel Corp.
Emily Qi et al

8. WLAN Paging Concept Logical Entities: Paging Mode : Paging Domain
Month Year
May 2006
May 2006
WLAN Paging Concept
Logical Entities:
Paging Domain
Paging Service Controller
Paging Group
Paging Mode :
Discovery and Registration
Initialization
Operation
STA wakes up for Paging scan at the Paging interval (e.g. 2.1s)
APs in the Paging Group advertises Paging Indication Message
Termination and STA reassociates with an AP.
Emily Qi et al, Intel Corp.
Emily Qi et al

9. Paging Logical Entities
May 2006
Paging Logical Entities
Paging Domain
A set of BSSs within the same ESS, identified by a Paging Domain ID
Paging Service Controller
Provides Paging Service for a set of BSSs in the Paging Domain.
Paging Group
A logical group to offer a contiguous coverage region in which STA can be paged
The paging groups should be large enough so that most STAs will remain within the same paging group most of the time, and small enough such that the paging overhead is reasonable.
Emily Qi et al, Intel Corp.

10. Discovery and Registration
Month Year
May 2006
May 2006
Discovery and Registration 1
Paging Info (paging interval, PD_ID, PG_ID, timestamp)
Beacon and Probe
Paging_Reg_REQ()
(Paging_ID,
Security Context, and etc) 2
Paging_Reg_RSP()
Emily Qi et al, Intel Corp.
Emily Qi et al

11. Paging Mode Initialization
May 2006
Paging Mode Initialization
(Paging Mode profile)
Paging_Init_REQ()
(Init Paging and
Presence Update)
Paging_Init_RSP() 3
(Paging Context:
Last sync BSSID, Security Context, Paging Interval, … )
Emily Qi et al, Intel Corp.

12. Paging Scan & Presence Update
Month Year
May 2006
May 2006
Paging Scan & Presence Update
The STA wakes up and Paging Scans at Paging Interval
- Active/Passive: Synchronization – channel, timestamp, PG_ID …. 4 5
If PG_ID is different from the STA’s previous PG_ID, or Presence update timer (keep-alive) is expired, the STA will:
- Send Presence Update
Sync-up paging timer and paging interval
Keep alive exp
Presence update()
Emily Qi et al, Intel Corp.
Emily Qi et al

13. May 2006
Paging
Incoming packets 6
APs in the Paging Group Uni-cast /Broadcast <(Protected) PIMs>
STAs sync-up paging timer and paging interval
If the STA is paged, the STA might want to terminate the Paging mode and re-associate to a selected AP. Otherwise, the STA will be remain in paging mode.
Emily Qi et al, Intel Corp.

14. WLAN Paging Protocol Paging Capability Discovery
May 2006
WLAN Paging Protocol
Paging Capability Discovery
Paging Registration REQ/RSP
Keying protocol
Paging Initialization REQ/RSP
Paging Un-Initialization REQ/RSP
Presence Update REQ/RSP
Paging Mechanism
Unicast
Broadcast
Multicast using PG
Emily Qi et al, Intel Corp.

15. Protected Paging Indication
May 2006
Protected Paging Indication
STA MAC Address
Paging Event Type
Sequence Number
Key ID
MIC
Octets: 6 1 2 8
STA MAC Address indicates the Mobile station that is paged
Paging Event type field indicates the traffic type: VoIP, IM, etc …
The Sequence Number field enables replay protection.
The Key ID field identifies the Integrity Pairwise Temporal Key (IPTK) between the Paging Controller and STA used to compute the MIC.
The MIC field shall contain a message integrity code calculated over all of the preceded fields
Any message integrity code, such as AES in CMAC mode, or SHA-1 in HMAC mode, will do.
Emily Qi et al, Intel Corp.

16. Proposed Key Hierarchy
Month Year
May 2006
May 2006
Proposed Key Hierarchy
PSPMK := KDF (KDK, “Paging Service” || STA MAC address || Paging Domain ID || length of the key)
IPTK:= KDF(PSPMK, Random_Num_STA || Random_Num_LS || length of the key);
Emily Qi et al, Intel Corp.
Emily Qi et al

17. Paging Key Distribution
Month Year
May 2006
May 2006
Paging Key Distribution
Emily Qi et al, Intel Corp.
Emily Qi et al

18. May 2006
Feature Summary
Paging Domain and Paging Service Controller for Paging Management
Paging Capability Discovery and Paging Service Registration for Paging Service Enabling
Paging Scan at Paging Interval (e.g. 2.1s) for power efficiency
802.11v Presence update and Paging Group for bandwidth efficiency
Protected Paging Indication for forgery protection
Emily Qi et al, Intel Corp.

19. References 06/349r0 Idle Mode Operation for IEEE 802.11v (Jin et al)
May 2006
References
06/349r0 Idle Mode Operation for IEEE v (Jin et al)
06/363r0 Standby Time Improvement (Meylan et al)
05/1073r1 Advanced Power Introduction (Kneckt et al)
05/1075r0 Broadcast and Multicast Enhancements (Jokela et al)
Emily Qi et al, Intel Corp.