Power Efficient PS Poll February 2008 doc.: IEEE 802.11-07/2376r0 Date: March, 2012 Power Efficient PS Poll Date: 2012-03-02 Authors: Liwen Chu Etc. Liwen Chu, STMicroelectronics

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

Date: March, 2012 TXOP Power Save in 802.11ac 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

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

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

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