Transcript March 2002 doc.: IEEE 802.15-02/163r0 Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs) Submission Title: IEEE802.15.3: Modified Power Save GTS Date.

March 2002
doc.: IEEE 802.15-02/163r0
Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs)
Submission Title: IEEE802.15.3: Modified Power Save GTS
Date Submitted: 13 March, 2002
Source: Dr. William Shvodian
Company: XtremeSpectrum, Inc.
Address: 8133 Leesburg Pike, Suite 700, Vienna, VA 22182
Voice: 703-269-3047 , FAX: 703-269-3092 , E-Mail: [email protected]
Re: [ ]
Abstract: Proposal for Unified Power Save
Purpose: To provide a unified, simplified power save proposal
Notice: This document has been prepared to assist the IEEE P802.15. 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
Submission
Slide 1
Dr. William Shvodian
March 2002
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Overview
doc.: IEEE 802.15-02/163r0
Power save requirements
What’s wrong with current Power Save?
Unified Power Save Proposal
Unified Power Save Summary
Conclusion
Submission
Slide 2
Dr. William Shvodian
March 2002
PS Requirements
doc.: IEEE 802.15-02/163r0
• Power save is critical for battery
powered devices
• Power save needs to be as simple as
possible
• Power save DEVs need to go into and
out of a low power mode
Submission
Slide 3
Dr. William Shvodian
March 2002
Problems with Power Save
doc.: IEEE 802.15-02/163r0
• We now have two modes: APS and SPS
• Sub-rate SPS slots can result in blocking of
active streams while only using a fraction of
the available bandwidth
• SPS Next issue: May always be lagging and
is not really needed.
• It is unclear why a multiple devices need to
have all their GTS in the same sub-rate
superframes
• Asynchronous power save plus support for
sub-rate slots enable simple, effective power
save
Submission
Slide 4
Dr. William Shvodian
SPS Slot Blocking
March 2002
doc.: IEEE 802.15-02/163r0
• A small number of low rate GTS slots
can block all GTS slots for isochronous
streams for the piconet
CTR Interval = 8
Wake Beacon
SPS Slots
Submission
Slide 5
Dr. William Shvodian
March 2002
SPS with different wake interval
doc.: IEEE 802.15-02/163r0
• SPS slots could be assigned with a SPS Interval that
is less than the CRT Interval
• One problem with this is that SPS DEVs need to
wake up for beacons that it may not have any GTS
slots in.
• Another problem with this is that the SPS Interval is
determined when the SPS set is created and cannot
be changed. The total number of DEVs in the SPS
set or the SPS GTS slots will not be known in
advance.
CTR Interval = 8
SPS Interval
Submission
Slide 6
Dr. William Shvodian
March 2002
Sub-Rate Slot Spreading
doc.: IEEE 802.15-02/163r0
• Allowing the PNC to spread out sub-rate
GTS slots makes much better use of the
available resources!
• Power of 2 sub-rates ensure that sub
rate slots can be conveniently allocated.
CTR Interval = 8
Sub-rate Slots
Submission
Slide 7
Dr. William Shvodian
March 2002
Next Awake Beacon Issues
doc.: IEEE 802.15-02/163r0
• “PNC shall keep the next awake beacon for
that set updated at all times.”
• The PNC doesn’t know in advance when the
DEV will receive the frame with the SPS Next
value, so the superframe could be passed
before the intended DEV receives and
processes the command.
• Continuous calculation of Next Awake
Beacon is a waste of PNC resources.
– Given a single superframe number where a power
of 2 sub-rate slot is active and knowing the CTR
Interval it is trivial for a DEV to calculate the next
superframe where that slot will occur.
Submission
Slide 8
Dr. William Shvodian
March 2002
Replacement of Next Awake Beacon doc.: IEEE 802.15-02/163r0
• Add Active Beacon Number and CTR
Interval to Channel Time Status
command instead of Next Awake
Beacon in SPS.
Submission
Slide 9
Dr. William Shvodian
March 2002
Power Save CTR
doc.: IEEE 802.15-02/163r0
• Use a single bit to indicate if the
Channel time request is a power save
request or not.
– If the request is a power save request, it
shall continue to be allocated when the
DEV goes into power save mode.
– If it is not a power save request, it shall not
be allocated when the DEV goes into
power save.
Submission
Slide 10
Dr. William Shvodian
March 2002
Unified Power Save Summary
doc.: IEEE 802.15-02/163r0
• Use Sub Rate Slots for power save DEVs so
that the PNC can allocate slots without
unnecessarily blocking superframe channel
time.
• Replace the Next Awake Beacon concept
with Active Beacon Number and CTR Interval
in the Channel Time Status command
• Replace SPS with Sub-Rate Slots and Power
Save Channel time requests
• Require the PNC to send a channel time
status command to PS DEVs so they don’t
have to process all beacons.
Submission
Slide 11
Dr. William Shvodian
March 2002
Conclusions
doc.: IEEE 802.15-02/163r0
• Unified Power Save with Power Save
Sub Rate Slots can provide the
functionality of SPS without the
complexity or the superframe blocking
problems.
• If SPS has to stay in the standard as is,
please make it optional! Let the market
decide the need.
Submission
Slide 12
Dr. William Shvodian