1. Direct transmission in PSM
November 2007
Direct transmission in PSM
Date:
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Alexander Safonov, IITP RAS

2. PSM in the current TDLS base document (1/2)
November 2007
PSM in the current TDLS base document (1/2)
TDLS Rx Path Switch Request/Response 1
Encapsulated DATA frame (TDLS Rx Path Switch Request)
Path Element (AP Path Switch) AP AP AP
Encapsulated DATA frame (TDLS Rx Path Switch Response)
Path Element (AP Path Switch) 2
QSTA1 changes to Power Saving Mode 3
QSTA2
QSTA2
QSTA1
QSTA1
QSTA1
Alexander Safonov, IITP RAS

3. PSM in the current TDLS base document (2/2)
November 2007
PSM in the current TDLS base document (2/2)
Data is sent on the AP path, but not on the direct one AP 3
TIM element
DATA frame 1
PS-poll 4
DATA frame 5
QSTA2
QSTA1 2
QSTA1 awakes
Alexander Safonov, IITP RAS

4. Motivation When a peer is in PSM, the direct link is not used
November 2007
Motivation
When a peer is in PSM, the direct link is not used
The AP path is used, thus two successful transmissions of a long data packet are needed to deliver the packet from peer to peer
No QoS differentiation is possible because the AP is legacy
Is there another way of operation in PSM?
Alexander Safonov, IITP RAS

5. November 2007
Scenarios
1. One of two peers goes to PSM, but the other peer stays always awaken
2. Both peers may go to PSM
Alexander Safonov, IITP RAS

6. Concept of Unscheduled TDLS PSM (Scenario 1)
November 2007
Concept of Unscheduled TDLS PSM (Scenario 1)
Peers may go to PSM remaining on the direct path
Data is buffered at the originator QSTA, but not at the legacy AP
QoS differentiation
Peers use Traffic Indication Map sent through the AP path to inform the peer about buffered data
Peers use the direct path instead of the AP path for sending data
Using full potential of the direct path
Alexander Safonov, IITP RAS

7. Proposal (please animate this slide)
November 2007
Proposal (please animate this slide)
Unscheduled PSM in TDLS AP
Encapsulated DATA frame (TDLS TIM) 6
Encapsulated DATA frame (TDLS TIM) 4
QSTA1 changes to Power Saving Mode 7
Null DATA frame (Power Management Field is set to 0) 3
QSTA2
QSTA1 wakes up 5
QSTA1 8
Buffered DATA frame (EOSP is set to 1) 2
Encapsulated DATA frame (TDLS PSM Switch Response)
Encapsulated DATA frame (TDLS PSM Switch Request) 1
Alexander Safonov, IITP RAS

8. Proposal Timing Diagram for Unscheduled PSM in TDLS November 2007
QSTA1 AP
QSTA2
DATA (TDLS PSM Switch Request)
DATA (TDLS PSM Switch Response)
DATA (TDLA TIM Broadcast)
QSTA 1 awakes
DATA (TDLA TIM Broadcast)
Null DATA (Power Management Field is set to 0)
Buffered DATA (EOSP is set to 0)
Buffered DATA (EOSP is set to 0)
Buffered DATA (EOSP is set to 1)
Null DATA (Power Management Field is set to 1)
Alexander Safonov, IITP RAS

9. Concept of Scheduled TDLS PSM (Scenario 2)
November 2007
Concept of Scheduled TDLS PSM (Scenario 2)
Peers may go to PSM remaining on the direct path
Data is buffered at the originator QSTA, not at the AP
QoS differentiation
Peers wake up at negotiated times
Peers use the direct path instead of the AP path for sending data
Using full potential of the direct path
Peers use normal backoff rules
Alexander Safonov, IITP RAS

10. TDLS PSM Switch Request frame
November 2007
TDLS PSM Switch Request frame
Offset field show the offset from DTIM
Periodicity field shows times in a DTIM interval when a QSTA is definitely awaken
Duration field indicates the maximum duration of service period
Channel Number and Regulatory class fields for off-channel (optional)
Normal backoff rules are used to access the channel
If DATA frame with EOSP=1 is received the QSTA may asleep
If no time for switching to Doze/Awake, just stay Awake
DATA frame
EOSP=1: asleep
Null DATA frame
EOSP=1: asleep
DATA frame EOSP=1
But no time to sleep: stay awake
Alexander Safonov, IITP RAS

11. Proposal (please animate this slide)
November 2007
Proposal (please animate this slide)
Scheduled PSM in TDLS AP
QSTA1 changes to Power Saving Mode 3
QSTA2
QSTA1
QSTA1 wakes up at scheduled time 4 5
Buffered DATA frame (EOSP is set to 1) 2
Encapsulated DATA frame (TDLS PSM Switch Response)
Offset, Periodicity, Channel 1
Encapsulated DATA frame (TDLS PSM Switch Request)
Offset, Periodicity, Channel
Alexander Safonov, IITP RAS

12. Proposal Timing Diagram for Scheduled PSM in TDLS November 2007 QSTA1AP
QSTA2
DATA (TDLS PSM Switch Request)
DATA (TDLS PSM Switch Response)
Buffered DATA (EOSP is set to 0)
Synchronized direct transmission using conventional backoff rules
Buffered DATA (EOSP is set to 1)
Null DATA (Power Management Field is set to 1)
Buffered DATA (EOSP is set to 0)
Synchronized direct transmission using conventional backoff rules
Buffered DATA (EOSP is set to 1)
Null DATA (Power Management Field is set to 1)
Alexander Safonov, IITP RAS

13. Straw polls Straw poll #1 Straw poll #2
November 2007
Straw polls
Straw poll #1
Are you in favor to enable Unscheduled TDLS PSM?
Straw poll #2
Are you in favor to enable Scheduled TDLS PSM?
Alexander Safonov, IITP RAS