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Sleep Mode Considerations for a Device-Based Power Saving
Document Number: S80216m-08_580Date Submitted: 2008-07-07Source: Mamadou Kone E-mail: [email protected], [email protected]
Ming-Hung TaoYing-Chuan Hsiao Richard Li E-mail: [email protected].
Venue: Session #56 Denver, USABase Contribution: IEEE C80216m-08_580r1Purpose: For discussion and adoption by IEEE 802.16m group Notice:
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Approach Actual design of power saving mode has lots of complexities and signaling
overheads making inefficient the power saving for a device. Two important performance factors have to be considered for MS operating in
sleep mode:1. MS power consumption
Depend on the number of Power Saving Class (PSC) and their design2. Signaling load generated by MS in sleep mode
Traffic indications, deactivation and handoffs signals from the network
Unavailability intervalAvailability interval
Positive Traffic indication
The PSC type 2 could be still running, but the device power saving is interrupted.
DL/ UL data burst
Receive signal from BS to reactivate PSC1
PSC type 1 – listening window of constant size and doubling sleep windowPSC type 2 – listening window of constant size and sleep window of constant size
Traffic indication
Type 1 connections : BE, NRT-VR; Type 2 connections : RTVR, UGS, ERTVR
Type 3 connections : Multicast, Periodic ranging, Management messages
Deactivation of PSC type 3
Device mode – Unavailability interval - period of inactivity of the device
Sleep mode issues
Common issues from 802.16e: Three kinds of PSC: Overlapping of listening and sleep windows may extend
power consumption. Possibly several PSCs within same type of connection: Overlapping issue to
get the device sleep interval. PSC type 2 issues
Fix listening window : May be too long or too short to cover different cases of traffic behaviors (HARQ operations, etc).
PSC type 1 issues: Signaling load: MOB_TRF_IND (traffic indication) at every listen window a
nd signals for deactivation / reactivation of the power saving. Reactivation of the power saving with Initial sleep window no matter the len
gth of the sleep window before deactivation. No influence of the doubling sleep window on device sleep interval when co
upled with PSC type 2. PSC type 3 issues
Lack of listen window: signaling for reactivation of the power saving No influence of long sleep window on device sleep interval when coupled wi
th PSC type 2 or type 1.
Enhancement within same type of connections
Use of traffic timer to monitor data burst or positive traffic indication
Use of data burst timer to monitor data burst ending
Match the start of every listening window with a super frame header
Use a HARQ timer for data recovery After incoming data, new Initsleep=
multiple of Initial sleep < last sleep.
Data burst timer reached, MS sleeps
Data/positive traffic indication received before timer ends
Type 3 operations
Signal to sleep and/or for next wakeup time
The listening window is extended to recover the data
HARQ traffic timer expires for each reception
HARQ traffic timer stopped because of erroneous data
Default listen window Sleep window
HARQ traffic timer expires for each reception
Traffic timer ends, no data burst received
Only type 2 connections
Only type 3 connections
Only type 1 connections
Super frame header
For same type of connections: Integrate all the connections into a unique power saving class to represent their traffics pattern.
Timer not expired, incoming data
Timers not expired still data
Initial sleep longer
Default listen window to carry out normal operations of DL and UL based on no error of transmission
Use HARQ traffic timer or data recovery and listening window may cover the next sleep length
Define default listen and timers(multicast, periodic ranging) are used to increase its length when needed.
The default listen window size could be a multiple of the longest timer used.
Signaling to trigger MS sleep and/or decide for the next data time otherwise default length of inactivity used after timers expire.
Merging connections into a unique PSC Combine in each case two different types of connection in a unique Power saving
class
predicted type 3 inactive time matches with listen
Listen matches with type 3 connections data reception
timers expire or signal for next wakeup time
Data burst timer expiresData burst / positive traffic indication for type 1 trafficsWork as PSC type 2 connections
only, because no data burst
Traffic timer starts and ends no data burst received
Receiving type 3 dataPositive traffic indication for type 1 traffics
Data burst timer expires Predicted type 3 inactive time is ok for type 1 traffics buffering
Use type 2 connections to design the unique PSC
With type 1 connection use: all timers from different types as previously defined.
With type 3 connections use the predictive sleep period to define the scenarios of listen and sleep
Listen window extensible with timers to support operations
Signal for next wake up time
Remaining Sleep windowType 2 and type 3 connections
Type 2 and type 1 connections
Type 1 and type 3 connections
Traffic timer didnt expire
Use the length of the type 3 connection inactive time as the default sleep window (matching with BS buffer for type 1 data)
Integrate the timers/signals from type 1 and type 3 connections during listening window to either continue to receive data or sleep
Toward the design of a unique PSC
Integrate type 1 connection to the merging of type 2 and type 3 to define only a unique Power Saving Class
Type 1 connections data burst opportunity can be offered during every n default listening period.
Apply all the timers and signals already define from all types of connections and also the possible listening window flexibility.
Predicted type 3 inactive time matches with default listen sleep window reduced by listening extension length
Listening matches with type 3 connections data reception
Signal to stop data sending for type 3 and define next wake up time
2nd opportunity: traffic indication positive for type 1 traffics
1st opportunity for type 1 traffic, but no burst, so works as PSC 2
Listening extended Data burst timer ends
Inactive
Active
Illustration of the device power saving from the unique PSC
A unique power saving class representing all traffic patterns
Power saving periods
Here n= every 2 listening window
Dynamic Update of the unique PSC In case of update within the same type of connection, apply the update to listening and
sleep windows definition. Applied the change to the next sleep when decreasing the sleep length Can apply the change to a later sleep period when increasing the sleep length
In case of update or complete deletion of one type of connection included in the unique PSC design. Update the unique Power saving class based on the remaining types of connection. Signaling to decide for the effective start of the new definition if needed.
predicted type 3 inactive time
type 3 connections data reception
traffic indication for type 1 traffics
1st opportunity for data burst, but traffic timer expires, works as PSC 2
type 3 connections data reception
Signal for next wakeup
type 3 connections data reception
No traffic indication/data burst
1st new opportunity: traffic indication positive
type 3 connections data reception
Signal for next wakeup time
……
Type 2 connection deletion indication
Exchange new windows definition for 2nd sleep
…
Next predicted inactive time
New parameters applied
Type 1 connection deletion indication
…
type 3 connections data receptionSignal for next
wakeup time
Signal for next wakeup time
No more traffic timer, works with type 3 connections only
Define or not new windows size for next sleep New parameters are applied
No traffic indication/ data burst
Signal for next wakeup time
3. Proposed text for SDD
[Insert the following into sleep section of [2]]--------------------------------------- Text start ---------------------------------------------
X.x.x Sleep mode
Sleep mode operation uses connection behaviors to design a unique device-based power saving framework.
A mechanism for adaptively adjusting sleep patterns (i.e. duration of sleep and listening windows) based on traffic pattern without deactivating the sleep mode should be provided.
This unique power saving framework uses efficient timers with less signaling that enables maximum MS power saving and reduces the air-link resource usage associated with sleep mode signaling.
--------------------------------------- Text end -----------------------------------------------
References[1] IEEE Std. 802.16e-2005, IEEE Standard for Local and metropolitan area networks, Part 16: Air Interface for Fixed and Mobile Broadband Wireless Access Systems, Amendment 2: Physical and Medium Access Control Layers for Combined Fixed and Mobile Operation in Licensed Bands, and P802.16Rev2/D3 (February 2008). [2] IEEE 802.16m-08/003r1, “The Draft IEEE 802.16m System Description Document”
