Transcript January, 2002 doc.: IEEE 802.15-02/067r1 Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs) Submission Title: [EPS Talking Points] Date Submitted: [23

January, 2002
doc.: IEEE 802.15-02/067r1
Project: IEEE P802.15 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, 14653-70223, USA]
Voice:[585-253-5241], FAX: [585-726-5658], E-Mail:[[email protected]]
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.]
[Note: Contributions that are not responsive to this section of the template, and contributions which do
not address the topic under which they are submitted, may be refused or consigned to the “General Contributions” area.]
Abstract: [Illustrations and Summary Points and PM Architecture Compromise]
Purpose: [Show functionality and PNC implementation and addition of asynchronous sleep capability.]
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
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Submission
Slide 1
Mark E. Schrader, Eastman Kodak>
January, 2002
doc.: IEEE 802.15-02/067r1
Overview
• EPS Criteria
• D09 EPS Operation
• Compromise Proposal
Submission
Slide 2
Mark E. Schrader, Eastman Kodak>
January, 2002
doc.: IEEE 802.15-02/067r1
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 802.15.3 requirements.
The following is an unofficial list of the criteria
that came out of the MAC conference calls.
Submission
Slide 3
Mark E. Schrader, Eastman Kodak>
January, 2002
doc.: IEEE 802.15-02/067r1
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.
Submission
Slide 4
Mark E. Schrader, Eastman Kodak>
January, 2002
doc.: IEEE 802.15-02/067r1
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.
Submission
Slide 5
Mark E. Schrader, Eastman Kodak>
January, 2002
doc.: IEEE 802.15-02/067r1
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.
Submission
Slide 6
Mark E. Schrader, Eastman Kodak>
January, 2002
doc.: IEEE 802.15-02/067r1
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.
Submission
Slide 7
Mark E. Schrader, Eastman Kodak>
January, 2002
doc.: IEEE 802.15-02/067r1
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.
Submission
Slide 8
Mark E. Schrader, Eastman Kodak>
January, 2002
doc.: IEEE 802.15-02/067r1
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.
Submission
Slide 9
Mark E. Schrader, Eastman Kodak>
January, 2002
doc.: IEEE 802.15-02/067r1
How It Works and Why It
Works This Way
Submission
Slide 10
Mark E. Schrader, Eastman Kodak>
January, 2002
doc.: IEEE 802.15-02/067r1
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
Submission
Slide 11
Mark E. Schrader, Eastman Kodak>
January, 2002
doc.: IEEE 802.15-02/067r1
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.
Submission
Slide 12
Mark E. Schrader, Eastman Kodak>
January, 2002
doc.: IEEE 802.15-02/067r1
Switching Between Extended Power
Save and ACTIVE Modes
ACTIVE CTAs
EPS CTAs
DEV in ACTIVE mode
DEV in EPS mode
Switch to ACTIVE CTA mode
Switch to EPS CTA mode
command
command
Action taken by the PNC
Submission
Slide 13
Mark E. Schrader, Eastman Kodak>
January, 2002
doc.: IEEE 802.15-02/067r1
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.
Submission
Slide 14
Mark E. Schrader, Eastman Kodak>
January, 2002
doc.: IEEE 802.15-02/067r1
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.
Submission
Slide 15
Mark E. Schrader, Eastman Kodak>
January, 2002
doc.: IEEE 802.15-02/067r1
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.
Submission
Slide 16
Mark E. Schrader, Eastman Kodak>
January, 2002
doc.: IEEE 802.15-02/067r1
How CTAs are Specified in ACTIVE Mode & EPS Mode
CTRB
AP
CTRB
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
Submission
Slide 17
Mark E. Schrader, Eastman Kodak>
January, 2002
doc.: IEEE 802.15-02/067r1
Yes but what about the AP in EPS mode?
CTRB
EPS Set N
slot
allocation
period
AP
?!
EPS CTA
Claim: The Allocation Period field in the
CTRB (AP) enables critical EPS
functionality with minimal PNC
overhead.
Submission
Slide 18
Mark E. Schrader, Eastman Kodak>
January, 2002
doc.: IEEE 802.15-02/067r1
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
Submission
Slide 19
Mark E. Schrader, Eastman Kodak>
January, 2002
doc.: IEEE 802.15-02/067r1
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.
Submission
Slide 20
Mark E. Schrader, Eastman Kodak>
January, 2002
doc.: IEEE 802.15-02/067r1
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 nonsynchronized network without power save.
Submission
Slide 21
Mark E. Schrader, Eastman Kodak>
January, 2002
doc.: IEEE 802.15-02/067r1
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.
Submission
Slide 22
Mark E. Schrader, Eastman Kodak>
January, 2002
doc.: IEEE 802.15-02/067r1
Controlling Complexity and Performance
Submission
Slide 23
Mark E. Schrader, Eastman Kodak>
January, 2002
doc.: IEEE 802.15-02/067r1
• 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.
Submission
Slide 24
Mark E. Schrader, Eastman Kodak>
January, 2002
doc.: IEEE 802.15-02/067r1
Power Management Architecture
Compromise
Submission
Slide 25
Mark E. Schrader, Eastman Kodak>
January, 2002
doc.: IEEE 802.15-02/067r1
Compromise
• CTA elements indicate channel time only and
are absent if no channel time in allocated
• Traffic pending indicator in the beacon.
• Beacon indication of DEV’s in EPS mode
using an EPS set. This is absent for DEVs
not in EPS mode.
• Ability of a DEV to sleep and wake up as
proposed by Raju.
• A single beacon entry for EPS Next for each
EPS Set that is in use.
Submission
Slide 26
Mark E. Schrader, Eastman Kodak>
January, 2002
doc.: IEEE 802.15-02/067r1
Compromise Continued
• For PNC capable DEV’s
– Support 1 EPS Set minimum if Des mode
bit not set
– Support 4 EPS Set minimum if AC
powered.
– Add “EPS Sets supported” to PNC
capabilities table.
Submission
Slide 27
Mark E. Schrader, Eastman Kodak>