1. January, 2002
doc.: IEEE /xxxr0
January, 2002
Project: IEEE P Working Group for Wireless Personal Area Networks (WPANs)
Submission Title: [EPS Talking Points]
Date Submitted: [23 January, 2002]
Source: [Mark E. Schrader] Company [Eastman Kodak Co.]
Address [1447 Saint Paul St., Rochester, NY, , USA]
Voice:[ ], FAX: [ ],
Re: [PM Discussion Illustrating the Points.]
[If this is a response to a Call for Contributions, cite the name and date of the Call for Contributions to which this document responds, as well as the relevant item number in the Call for Contributions.]
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Abstract: [Illustrations and Summary Points]
Purpose: [Show functionality and PNC implementation]
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 P
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Mark E. Schrader, Eastman Kodak>
Mark .E Schrader, Eastman Kodak

2. January, 2002
doc.: IEEE /xxxr0
January, 2002
In the course of discussing power management in the MAC conference calls, various members suggested criteria for evaluating proposed PM methods that would make for a superior standard, while being consistent with this committee’s overall requirements. The following is an unofficial list of the criteria that came out of the MAC conference calls.
Mark E. Schrader, Eastman Kodak>
Mark .E Schrader, Eastman Kodak

3. Primary Power Save Requirements
January, 2002
doc.: IEEE /xxxr0
January, 2002
Primary Power Save Requirements
Allow power sensitive DEVs to save power or sleep as much as possible, not park etc.
Primary requirement: A DEV shall be allowed to not listen for multiple superframes, and then listen only to a beacon unless the CTAs in that beacon tell the DEV to listen to a time slot. This sequence repeated over and over is defined as “sleep mode” (or extended power save, EPS, mode).
The PM scheme shall not decrease the PNCs doze time significantly.
The PM scheme shall require minimal DEV interaction with the PNC when in sleep mode.
Mark E. Schrader, Eastman Kodak>
Mark .E Schrader, Eastman Kodak

4. Synchronization Criteria
January, 2002
doc.: IEEE /xxxr0
January, 2002
Synchronization Criteria
Synchronization is supported and not required by a station setting up its sleep mode.
We shall support three or more DEVs communicating with each other while in sleep mode.
A new DEV may join and communicate synchronously with other sleep mode devices.
Or a device may choose its own sleep mode parameters rather than synchronizing to an existing sleep mode.
Mark E. Schrader, Eastman Kodak>
Mark .E Schrader, Eastman Kodak

5. Cost and Performance Criteria
January, 2002
doc.: IEEE /xxxr0
January, 2002
Cost and Performance Criteria
The PM method shall not significantly impact the cost, complexity, and performance of the MAC.
The PM method shall not degrade the performance of the piconet.
By example: If N devices each want a time one slot in every 30 superframes, the PNC shall be capable of not overloading a single superframe with all N time slots in fulfilling that request.
High rate devices shall operate in the presence of sleep mode devices without being impacted.
Mark E. Schrader, Eastman Kodak>
Mark .E Schrader, Eastman Kodak

6. January, 2002
doc.: IEEE /xxxr0
January, 2002
Burst Criteria
Transitions from sleep to “full power mode” shall be fast, and vice versa.
Fast means within the time required for the PNC to respond to one command to the PNC.
“full power mode” is with all CTA slots restored and sending data as before sleep mode.
This enables burst data from power sensitive devices (e.g. remotely operated cameras with motion detection capability) to start quickly.
Mark E. Schrader, Eastman Kodak>
Mark .E Schrader, Eastman Kodak

7. January, 2002
doc.: IEEE /xxxr0
January, 2002
Flexibility Criteria
Devices shall be able to save power individually. “I am going into sleep mode!”
Devices shall be able to save power synchronously as a group. “We are going into sleep mode now.” (“...because I know best, and you gave me the authority switch your mode”).
Devices in sleep mode shall be able to only listen to beacons and have no time slots, or send the occasional packet of data.
Mark E. Schrader, Eastman Kodak>
Mark .E Schrader, Eastman Kodak

8. January, 2002
doc.: IEEE /xxxr0
January, 2002
The current method fulfills all of the previous criteria and functionality. It is designed to meet the very high expectations of the MAC subcommittee and this standards body -- to manage power both very effectively and very efficiently.
Mark E. Schrader, Eastman Kodak>
Mark .E Schrader, Eastman Kodak

9. How It Works and Why It Works This Way
January, 2002
doc.: IEEE /xxxr0
January, 2002
How It Works and Why It Works This Way
Mark E. Schrader, Eastman Kodak>
Mark .E Schrader, Eastman Kodak

10. Channel Time Allocations
January, 2002
doc.: IEEE /xxxr0
January, 2002
Channel Time Allocations
A stream is initiated with QoS parameters that are mapped one-to-one to equivalent channel time request, CTRB fields.
Each stream connection request or channel time request that is accepted by the PNC, results in at least one channel time allocation, CTA owned by the DEV that “originates” that stream connection
Mark E. Schrader, Eastman Kodak>
Mark .E Schrader, Eastman Kodak

11. January, 2002
doc.: IEEE /xxxr0
January, 2002
Allocation Types
There are two types of streams/CTAs, that can be originated by a DEV, an ACTIVE stream/CTA or an EPS stream/CTA.
The PNC switches between CTA types when the DEV, that originated the stream, switches modes.
The following figure shows the relationship between CTA types and PM modes.
Mark E. Schrader, Eastman Kodak>
Mark .E Schrader, Eastman Kodak

12. Switching Between Extended Power Save and ACTIVE Modes
January, 2002
doc.: IEEE /xxxr0
January, 2002
Switching Between Extended Power Save and ACTIVE Modes
Mark E. Schrader, Eastman Kodak>
Mark .E Schrader, Eastman Kodak

13. Why not just ask for new CTAs?
January, 2002
doc.: IEEE /xxxr0
January, 2002
Why not just ask for new CTAs?
Normal (ACTIVE) CTA’s have timing parameters that can be used by only one stream.
Suppose that an EPS mode DEV A sleeps 6 superframes, and then has one slot, and repeats this pattern.
It is impossible for DEV B to tell the PNC that it wants to sleep and communicate in phase with DEV A using a standard (ACTIVE) channel time request.
Mark E. Schrader, Eastman Kodak>
Mark .E Schrader, Eastman Kodak

14. A Low Complexity Solution
January, 2002
doc.: IEEE /xxxr0
January, 2002
A Low Complexity Solution
The EPS Set is equivalent to a shared version of the Allocation Period part of the channel time request.
The DEV now can say “I request the same timing as the other members of the EPS Set”
It is no more difficult for the PNC then asking it for two independent channel time allocations, both with unrelated parameters.
The slot width and jitter are private in both cases and computed from the CTRB parameters.
Mark E. Schrader, Eastman Kodak>
Mark .E Schrader, Eastman Kodak

15. January, 2002
An abbreviation used in this document: AP is defined as the Allocation Period field of the Channel Time Request Block used by the PNC to create CTA elements in the beacon.
Mark E. Schrader, Eastman Kodak>

16. How CTAs are Specified in ACTIVE Mode & EPS Mode
January, 2002
doc.: IEEE /xxxr0
January, 2002
How CTAs are Specified in ACTIVE Mode & EPS Mode
CTRB
CTRB AP
EPS Set N AP
slot allocation period
slot allocation period
ACTIVE CTA
EPS CTA
AP = Allocation Period field of CTRB of the Channel Time Request Command
Mark E. Schrader, Eastman Kodak>
Mark .E Schrader, Eastman Kodak

17. Yes but what about the AP in EPS mode?
January, 2002
doc.: IEEE /xxxr0
January, 2002
Yes but what about the AP in EPS mode?
CTRB
EPS Set N AP
slot allocation period ?!
EPS CTA
Claim: The Allocation Period field in the CTRB (AP) enables critical EPS functionality with minimal PNC overhead.
Mark E. Schrader, Eastman Kodak>
Mark .E Schrader, Eastman Kodak

18. Definition of AP Field in EPS Mode
January, 2002
doc.: IEEE /xxxr0
January, 2002
Definition of AP Field in EPS Mode
The AP specifies how many slot allocation periods (specified by the EPS Set) to count before putting in the specified non-zero channel time allocation.
This is not hard for a PNC to do. It is one counter function per EPS CTA. It can be done in firmware.
Whenever the AP value is 1, the specified time slot is always used as in ACTIVE mode
Mark E. Schrader, Eastman Kodak>
Mark .E Schrader, Eastman Kodak

19. The EPS AP Reduces PNC Overhead.
January, 2002
doc.: IEEE /xxxr0
January, 2002
The EPS AP Reduces PNC Overhead.
Example: 25 PDAs to communicate
Each PDA asks for a source slot at a rate of 1 per every 12 SFs. The EPS Set used was set to a period of 3 superframes. Thus, AP = 4 will give 1 slot per 12 superframes.
The PNC will distribute the 25+ slot requests among 4 possible superframes randomly -- no superframe overloading and very small PNC overhead compared with any alternative method.
All PDAs can sleep 2 superframes at a time.
Any PDA will be able to have a stream to any other PDA at this rate.
Mark E. Schrader, Eastman Kodak>
Mark .E Schrader, Eastman Kodak

20. By using the same EPS Set and AP value, the PNC overhead is minimized.
January, 2002
EPS AP Continued
By using the same EPS Set and AP value, the PNC overhead is minimized.
In a large piconet situation where each device of the type PDA the PNC might restrict the value of AP and what EPS set it would use by the PNC rather than each device being able to select arbitrary timing parameters.
The PNC burden for this synchronized network with power save is less than a non-synchronized network without power save.
Mark E. Schrader, Eastman Kodak>

21. EPS AP for Very Long Slot Periods
January, 2002
doc.: IEEE /xxxr0
January, 2002
EPS AP for Very Long Slot Periods
Applications requiring very long times between EPS slot allocations may require the DEV to just listen to some intermediate beacons. This allows it to receive momentary data and management commands from the PNC.
The EPS allocation period in the CTRB is all that is required to implement this function.
Mark E. Schrader, Eastman Kodak>
Mark .E Schrader, Eastman Kodak

22. Controlling Complexity and Performance
January, 2002
Controlling Complexity and Performance
Mark E. Schrader, Eastman Kodak>

23. Add number of EPS Sets supported by PNC to capabilities list.
January, 2002
Add number of EPS Sets supported by PNC to capabilities list.
Add min and max delay to switch modes to PNC capabilities.
Assign MTS slots in EPS mode consistent with max delay-to-switch-modes capability of PNC.
Combine the three “switch” commands to one command with one or two parameters.
Change dual use CTRB field to two fields.
Mark E. Schrader, Eastman Kodak>