1. Power Efficient PS Poll
February 2008
doc.: IEEE /2376r0
Date: March, 2012
Power Efficient PS Poll
Date:
Authors:
Liwen Chu Etc.
Liwen Chu, STMicroelectronics

2. Date: March, 2012
PS Poll Procedure
Once a power save STA sends PS Poll, it needs to keep awake until the next beacon or data frame from the AP.
This increases power consumption of a low power STA.
Beacon
ACK
BU=1
Data
Beacon PS
Poll
Awake Time
Doze
Doze
Beacon
ACK
BU=1
Data
Beacon PS
Poll
Doze
Awake Time
Doze 2

3. Date: March, 2012
TXOP Power Save in ac
An AP may indicate support TXOP power save and if it allows to use TXOP power save in a specific TXOP.
A TXOP Power Save STA may go to doze state if the AP allows to use TXOP power save in a specific TXOP and a PPDU is not for it. 3

4. Date: March, 2012
Power Save PS Poll 1
A Low Power STA is introduced.
An AP can indicate if it supports low power STA. If it support low power STA, it shall allow TXOP power save in all TXOPs during a period after at least a PS Poll is received and before it sends buffered data frame to all Low Power STAs from which it receives Ps Poll from.
After a STA sends PS Poll, if the first PPDU does not include MPDU for it in a TXOP, a STA that announces being a Low Power STA can go to doze in the TXOP. AP
Beacon
BLKACK
ACK
BU=1
BLKACK
Data
STA
A-MPDU
A-MPDU PS
Poll
ACK
Low Power STA
Doze
Awake
Doze
Doze
Awake
Awake
Doze 4

5. Power Save PS Poll 2 A Low Power STA is introduced.
Date: March, 2012
Power Save PS Poll 2
A Low Power STA is introduced.
An AP can indicate if it supports low power STA. If it support low power STA and receives a PS-Poll from a low power STA, it shall do one of the following:
sending data frame SIFS after it receives the PS-Poll from a low power STA, or
sending data frame SIFS /PIFS after it finish transmission the ACK to acknowledge the PS-Poll from a low power STA. AP
Beacon
BLKACK
ACK
BU=1
Data
STA
A-MPDU PS
Poll
ACK
Low Power STA
Doze
Awake
Doze
Awake
Doze AP
Beacon
ACK
BU=1
Data PS
Poll
ACK
Low Power STA
Doze
Awake
Doze 5

6. Date: March, 2012
Reference
[1] IEEE P802.11ac™/D2.0 Draft STANDARD for Information Technology— Telecommunications and information exchange between systems— Local and metropolitan area networks— Specific requirements Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) specifications Amendment 4: Enhancements for Very High Throughput for Operation in Bands below 6 GHz 6