1. Submission Title: IEEE802.15.3: Overview of Power Save Proposal.
September 2001
Project: IEEE P Working Group for Wireless Personal Area Networks (WPANs)
Submission Title: IEEE : Overview of Power Save Proposal.
Date Submitted: 19 September, 2001
Source: Jay Bain Company: Time Domain
Address: 7057 Old Madison Pike
Voice: , FAX: ,
Source: Mark E. Schrader Company: Eastman Kodak Co.
Address: 4545 East River Road, Rochester, NY
Voice: , FAX: ,
Abstract: This provides an overview of additional proposals on Power Management for incorporation into the draft 0.8. Text is in 01/430r0
Purpose: To provide information and solicit comments on proposed power management updates
Notice: This document has been prepared to assist the IEEE P It is offered as a basis for discussion and is not binding on the contributing individual(s) or organization(s). The material in this document is subject to change in form and content after further study. The contributor(s) reserve(s) the right to add, amend or withdraw material contained herein.
Release: The contributor acknowledges and accepts that this contribution becomes the property of IEEE and may be made publicly available by P802.15
Jay Bain Time Domain, Mark Schrader Eastman Kodak

2. Topics of proposal (mostly from 01/425r0 and editor notes in d0.7)
September 2001
Topics of proposal (mostly from 01/425r0 and editor notes in d0.7)
Wake-on-WPAN – Jay Bain
Unused bits in CTA to indicate mode and next active SF – Mark Schrader
Null-CTA element – Mark Schrader
Current EPS state in device information request – John Barr
Definitions of EPS and related terms – Jay Bain
Jay Bain Time Domain, Mark Schrader Eastman Kodak

3. September 2001
Wake on WPAN
Transition from EPS to Active mode in an EPS DEV develops MLME-POWERMGT.indication primitive.
Structure in place in d0.7,
Add tie between the 7.5.x commands changing modes or indication of data and the clause 6 primitives. Add this text in clause 8.
Consider addition of means for enable/disable of the indication as a PIB item.
Add differentiation of Wake to consider the three CTA characters (awake, EPS, momentary)
Jay Bain Time Domain, Mark Schrader Eastman Kodak

4. CTA Mode SST/NAB Switch
September 2001
Unused CTA Bits
CTA Mode
SST/NAB Switch
Jay Bain Time Domain, Mark Schrader Eastman Kodak

5. Outline Issues from previous proposal New CTA bits definitions
August 2001
Outline
Issues from previous proposal
New CTA bits definitions
Advantages
Impact
Jay Bain Time Domain, Mark Schrader Eastman Kodak

6. August 2001
Issue1
There is no explicit indication in the CTA element if it is an AWAKE or an EPS type. There is a difference:
If EPS CTA then the DEV will not be awake for each beacon
If AWAKE CTA then the DEV will be awake
Jay Bain Time Domain, Mark Schrader Eastman Kodak

7. September 2001
Issue 2
When a station is sleeping there is no beacon info. communicated about the state of the DEV. Information:
Is it in EPS mode or AWAKE mode?
When will the source be waking up or simply having its next time (low QoS) slot?
For destination DEVs losing beacons/synchronization
For a station wanting to establish a stream
Jay Bain Time Domain, Mark Schrader Eastman Kodak

8. September 2001
Issue 3
CTA elements are added and omitted from the header depending on whether the DEV has a slot (or will be awake) in that superframe. This may be more work for the PNC then always having the CTA element and modifying the values of CTA fields periodically.
Jay Bain Time Domain, Mark Schrader Eastman Kodak

9. Current CTA Element Fields
September 2001
Current CTA Element Fields
Destination DEV address = 1B
Source DEV address = 1B
Slot Start Time = SST = 2B
Stream ID = 1B
Unused = 1B
Jay Bain Time Domain, Mark Schrader Eastman Kodak

10. Proposed Use of Two Unused CTA Bits
September 2001
Proposed Use of Two Unused CTA Bits
Bit 0: CTA Element Type & DEV Mode
0 = AWAKE CTA Element Type
1 = EPS CTA Element Type
Bit 1: SST/NAB Field Definition
0 = The field is the Slot Start Time, SST, as in previous slide and the current draft D07, p78.
1 = Next Active Beacon, NAB. The field is defined as, the 2 LSB’s of the beacon number, of the next superframe in which the DEV will have a time slot (or if asleep, wake up).
Jay Bain Time Domain, Mark Schrader Eastman Kodak

11. Result of These Changes
September 2001
Result of These Changes
An AWAKE DEV with a time slot every N superframes will always have a CTA element.
A device that is asleep (EPS mode) will always have a CTA element.
Other DEVs reading the a CTA element always know the mode of that DEV, and either the slot time or the beacon number of the next time slot.
Jay Bain Time Domain, Mark Schrader Eastman Kodak

12. September 2001
What is the Impact?
CTA element values will not change any more often than before. Important for the “CTA change bit”.
CTA adds/deletes will occur less often then before.
The PNC will post the:
CTA mode associated with a CTA element.
next SF in which a slot will occur if it is not in this SF.
Jay Bain Time Domain, Mark Schrader Eastman Kodak

13. Impact Tradeoff: CTA Position
September 2001
Impact Tradeoff: CTA Position
CTA elements with Bit 1 set to 1, NAB CTAs, are positioned as the first entries in the beacon.
Pro: Computing the time slot durations of SST CTAs will be uniform for all SST CTAs and NAB CTAs will be easily located.
Con: CTA elements will have to be moved by the PNC when Bit 1, changes state.
Jay Bain Time Domain, Mark Schrader Eastman Kodak

14. September 2001
CTA elements with Bit 1 set to 1, NAB, are positioned in the same place as the same element with Bit 1 set to 0, SST.
Pro: All CTA elements are always in the same order and position in the Beacon.
Con: The duration of the time slot specified by a SST CTA, which is located just before a NAB CTA, requires finding the next SST CTA element in the sequence. (The slot duration is the difference between the two successive slot start times.) = more complex algorithm.
Jay Bain Time Domain, Mark Schrader Eastman Kodak

15. Global Advantages The mode is always posted.
September 2001
Global Advantages
The mode is always posted.
Network robustness and synchronization will be improved:
If: hhThhhThhhDhhh
Then: the next beacon will be enough to restore the lost beacon information regardless of mode or QoS.
Minimal additional PNC overhead.
Jay Bain Time Domain, Mark Schrader Eastman Kodak

16. Null CTA Element September 2001
Jay Bain Time Domain, Mark Schrader Eastman Kodak

17. September 2001
Definition
The null CTA element is a SST CTA element with the same slot start time as the next SST CTA element listed in the beacon. It is used to indicate that a sleeping device is awake on this superframe to listen to the beacon, but does not have a time slot allocated.
Jay Bain Time Domain, Mark Schrader Eastman Kodak