Transcript August 2001 doc.: IEEE 802.15-01/315r3 Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs) Submission Title: IEEE802.15.3: Overview of Power Save.

August 2001
doc.: IEEE 802.15-01/315r3
Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs)
Submission Title: IEEE802.15.3: Overview of Power Save Proposal.
Date Submitted: 14 August, 2001
Source: Jay Bain
Company: Time Domain
Address: 7057 Old Madison Pike
Voice: 256 922 9229 , FAX: 256 922 0853, E-Mail: [email protected]
Source: Mark E. Schrader
Company: Eastman Kodak Co.
Address: 4545 East River Road, Rochester, NY 14650-0898
Voice: 716-781-9561 , FAX: 716-781-9533, E-Mail: [email protected]
Abstract: This provides an overview of proposed incorporations in the draft standard relating to power
management.
Purpose: To provide information and solicit comments on proposed power management
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
Jay Bain Time Domain, Mark Schrader Eastman Kodak
August 2001
doc.: IEEE 802.15-01/315r3
Overview of MAC Power Save
Provide the protocol structure that
will allow a range of applications
the greatest opportunity to save
power.
Submission
Slide 2
Jay Bain Time Domain, Mark Schrader Eastman Kodak
August 2001
doc.: IEEE 802.15-01/315r3
Revision changes
• Changes from R1 to R2
– Add shoulds and shalls to text on beacon length,
QoS,
– Add chart of EPS savings
– Add table of comparison of approaches
• Changes from R2 to R3
– Multiple sourcing
– Update proposal changing beacon content,
synchronization, initialization, and dual QoS
profiles
Submission
Slide 3
Jay Bain Time Domain, Mark Schrader Eastman Kodak
August 2001
doc.: IEEE 802.15-01/315r3
Possible operating scenarios
• The mode with greatest power saving is
OFF!
• If off won’t do -- Associate with a
network and then:
– Take advantage of characteristics of
contention free period – reduce power in
slots not assigned to a device. (RPS)
– Take advantage of higher layer inactivity reduce power by skipping several beacons
and superframes. (EPS)
Submission
Slide 4
Jay Bain Time Domain, Mark Schrader Eastman Kodak
August 2001
doc.: IEEE 802.15-01/315r3
The enemies of power saving
• Constant high throughput requirements.
• Time to progress from startup to data
movement.
• Failure by higher layers to correctly structure
requirements for service
• Real characteristics of PHY and MAC
• Poor environmental conditions resulting in
lost packets and use of lower transmission
rates
Submission
Slide 5
Jay Bain Time Domain, Mark Schrader Eastman Kodak
August 2001
doc.: IEEE 802.15-01/315r3
Beacon
RPS Operation
Contention Free Period
Contention
Access
Period
Period of Reduced Power Opportunity
• PNC may be an RPS device
• Stay awake for
–
–
–
–
Beacon
CAP
Assigned receive slot
Assigned send slot with
activity
• Consider receive slot as
empty after 25% of duration
Submission
Slide 6
• Slot location
– Higher layers make
realistic RPS QoS
requirement known to
device
– PNC required to make
best effort to locate
assigned slot nearest
beacon
Jay Bain Time Domain, Mark Schrader Eastman Kodak
August 2001
doc.: IEEE 802.15-01/315r3
Sender: EPS  AWAKE, Slot Allocations 1
AWAKE
Sender &
Receiver
wake to
beacon,
read null
CTA.
No traffic
Indicated
Beacon
Beacon
EPS Mode
Submission
Mode
Sender: PNC
“AWAKE Mode
Declaration” in
CAP, receive
ACK. Switch at
end of EPS
interval
EPS Mode
Sender: In beacon on last data
packet, “EPS Mode Declaration” in
CAP to PNC and receive ACK.
PNC returns to sending null CTAs
at the EPS Mode rate.
Contention Free Period
Other Members’ Slots
Slide 7
Sender & Receiver wake to
beacon with AWAKE Mode
CTAs set by PNC. Send first
data packet in assigned slot. A
high rate AWAKE allocations
shown
Jay Bain Time Domain, Mark Schrader Eastman Kodak
August 2001
doc.: IEEE 802.15-01/315r3
Sender: EPS  AWAKE, Slot Allocations 2
AWAKE Mode Allocation: One Slot (blue) in Every 10 Superframes.
Sender &
Receiver wake to
beacon, read null
CTA. No traffic
Indicated
Submission
Mode
AWAKE Mode
Beacon
Beacon
Beacon
EPS Mode
EPS
Sender: Transmits
PNC “AWAKE Mode
Declaration” in CAP,
receives ACK. The
mode switches on next
scheduled EPS Mode
slot superframe.
Slide 8
Contention Free Period
Other
Members’
Slots
Sender & Receiver
wake to beacon with
AWAKE Mode CTA (with
slot) set by PNC, Send
first data packet in
assigned slot. An
identical-to-EPS-Mode
rate is shown.
Sender: Transmits PNC
“EPS Mode Declaration”
in CAP, receives ACK.
The mode switches on
next scheduled AWAKE
Mode slot superframe.
Jay Bain Time Domain, Mark Schrader Eastman Kodak
August 2001
doc.: IEEE 802.15-01/315r3
Sender: EPS  AWAKE, Slot Allocations 3
AWAKE
Sender &
Receiver
wake to
beacon, and
data is sent
in EPS mode
allocated
slots.
Beacon
Beacon
EPS Mode
Submission
Mode
Sender: PNC
“AWAKE Mode
Declaration” in CAP,
receive ACK. Switch
at end of EPS
interval
EPS Mode
Sender: In beacon on last data
packet, “EPS Mode Declaration” in
CAP to PNC and receive ACK.
PNC returns to sending null CTAs
at the EPS Mode rate.
Contention Free Period
Other Members’ Slots
Slide 9
Sender & Receiver wake
to beacon. data is sent in
AWAKE Mode allocated
slots
Jay Bain Time Domain, Mark Schrader Eastman Kodak
August 2001
doc.: IEEE 802.15-01/315r3
EPS Notification via CTA
EPS Information
Element
“No-OP” CTA
Information
Element
Information bearing
CTA Information
Element
Submission
1 Octet
Dest. DEV ID
1 Octet
1 Octet 1 Octet
2 Octet
SRC DEV DST DEV
Address Address
Slot Start Time
Zero Value
1 Octet 1 Octet
2 Octet
2 Octet
SRC DEV DST DEV
Address Address
Slot Start Time
Slide 10
2 Octet
Time slot duration
Jay Bain Time Domain, Mark Schrader Eastman Kodak
August 2001
doc.: IEEE 802.15-01/315r3
Channel Time Request Additions
Existing Channel
Time Request
EPS Support
Octet Added
Currently defined operation
Of Channel Time Request
0
Persistent at EPSTime
- New operation
1
Multi-slot staged operation –
New operation
2
Submission
Slide 11
Jay Bain Time Domain, Mark Schrader Eastman Kodak
August 2001
doc.: IEEE 802.15-01/315r3
Power Save – Control Mechanisms (TBD)
• Snd Dev to Rcv Dev
– Request/Confirm of EPSTime
– Coordination of EPS beacon location
• Snd Dev to PNC
– Parms for EPSTime
– Coordination of EPS beacon location
– Channel time request blocks
• Add field to indicate EPS operation
– Sequence to specific channel time operation
Submission
Slide 12
Jay Bain Time Domain, Mark Schrader Eastman Kodak
August 2001
doc.: IEEE 802.15-01/315r3
Changes to PNC and CTA - Benefits
• Gives PNC the knowledge to communicate with EPS
dev
• Provides sanity check for EPS receiving dev that it is
still in sync
• Facilitates different models of QoS for EPS devices
Submission
Slide 13
Jay Bain Time Domain, Mark Schrader Eastman Kodak
August 2001
doc.: IEEE 802.15-01/315r3
EPS Information Element Disposition
• Remove EPS gauge level bits. Average power decrease didn’t
weigh well against the increased complexity
• Remove the more bit. Message Header in assigned slot carries
the intent that EPS receiver remains awake after that
superframe
• Remove Current sequence value. Use zero duration CTA
element to reflect the presence or absence of information for the
EPS receive device. Zero duration CTA only present during
superframe for EPS wake.
• Remove the Acknowledged sequence value. The desired effect
is proved by exception handling
• Remove the Active update bit. Define the sending QoS to be
single message or multimessage. (assurance that an errant
sending device doesn’t impact a receiving EPS device)
Submission
Slide 14
Jay Bain Time Domain, Mark Schrader Eastman Kodak
August 2001
doc.: IEEE 802.15-01/315r3
Sender-PNC-EPS device diagram (needs updating)
Source
PNC
EPS Destination
EPS
Traffic Command
Update Beacon
Traffic Ack
Beacon is
Second chance
B
B
Message in
Assigned slot
(short retry timer)
Missed Beacon
Missed traffic
B
Missed Beacon
Missed traffic
Message
Repeat
B
Message
Repeat
Receive Beacon
Receive traffic
Wake
Ack traffic
Traffic Command
Update Beacon
Traffic Ack
EPS
Submission
Slide 15
Jay Bain Time Domain, Mark Schrader Eastman Kodak
August 2001
doc.: IEEE 802.15-01/315r3
QoS Aspects for EPS
• Higher order protocols dictate the
latency of the EPS device waking for a
beacon
• Higher layers should not ask for more
than needed
• Two profile operation
– Low duty cycle
– High rate operation
Submission
Slide 16
Jay Bain Time Domain, Mark Schrader Eastman Kodak
August 2001
doc.: IEEE 802.15-01/315r3
Repeater Considerations
• Use repeater in normal manner as piconet
coverage enhancer.
Submission
Slide 17
Jay Bain Time Domain, Mark Schrader Eastman Kodak
August 2001
doc.: IEEE 802.15-01/315r3
Where is the Beacon?
• Consideration of Beacon change (new superframe length) –
– PNC should not change the superframe length if not truly
beneficial to traffic requirements
– If it does change, the EPS device shall stay on to find the
beacon – if once in a long while event, not a problem.
• Clock drift calculation and leading of nominal beacon time is
EPS device responsibility.
Submission
Slide 18
Jay Bain Time Domain, Mark Schrader Eastman Kodak
August 2001
doc.: IEEE 802.15-01/315r3
MAC to PHY communications
• Taking James Gilb suggestion
• Table of power save options in PHY sent to
MAC. Content is time to return to normal
operation.
• MAC chooses the appropriate table index for
each power down command to PHY.
• MAC sends power on command to return the
PHY to normal mode.
Submission
Slide 19
Jay Bain Time Domain, Mark Schrader Eastman Kodak
August 2001
doc.: IEEE 802.15-01/315r3
Performance modeling
• Note: these will be updated in the next
rev
Submission
Slide 20
Jay Bain Time Domain, Mark Schrader Eastman Kodak
August 2001
doc.: IEEE 802.15-01/315r3
No-Op Wake Cycle Average Amp Chart
1.00E+00
0.01
0.1
1
1.00E-01
10
no return assumption
1 mS return assumed
1.00E-02
multi superframe return
assumed
always active
1.00E-03
always inactive
1.00E-04
1.00E-05
Submission
Slide 21
Jay Bain Time Domain, Mark Schrader Eastman Kodak
August 2001
doc.: IEEE 802.15-01/315r3
Tri-shake approach
Active State Indication
ACK at end of SIFS
Sleep State Request
ACK at end of SIFS
CAP
Opportunity to
reenter EPS
CFP
EPS Ret
Beacon
CAP
Opportunity to
reenter EPS
CFP
EPS Ret
Beacon
CAP
EPS Ret
Beacon
CFP
Opportunity to
reenter EPS
Sleep State Permit
ACK at end of SIFS
Assume 1 mS EPS Return required
Assume CAP of 1 mS
Submission
Slide 22
Jay Bain Time Domain, Mark Schrader Eastman Kodak
August 2001
doc.: IEEE 802.15-01/315r3
EPS approaches - Comparison
• Emphasis on lowest power use for “no op” wake cycles.
• Beacon provides
– Association timeout gauge
– Ack + indications
• PNC does not responsible for ack/indications during active
mode
• Dev-to-dev and repeater service available
• PNC not required to support repeater service for basic EPS
• PNC provides repeater service for EPS-EPS devs (if PNC
supports repeater service). Ceases when devs go active.
Submission
Slide 23
Jay Bain Time Domain, Mark Schrader Eastman Kodak