POWER EFFICIENT PS-POLL
A IEEE 802.11 Wireless Local Area Network (WLAN) system of an access point (AP) and one or more stations (STAB) reduces power consumption and increases battery life of power efficient low power STAB by decreasing the amount of time that a power efficient low power STA remains in an awake state. After indicating power efficient low power operation during association with an AP supporting such operation, the power efficient low power STA may enter the doze state from the time that the power efficient low power STA sends a PS-Poll until the power efficient low power STA receives the buffered DATA frame from the AP. While implementing the power efficient PS-Poll method, the AP can send the buffered DATA frame to the STA SIFS after the AP sends an ACK to the received PS-Poll from the STA.
1 . A method, comprising:
waking a wireless station (STA) from a doze state to send a PS-Poll frame from the STA to an access point (AP);
in response to the PS-Poll frame, receiving at the STA from the AP one of an acknowledgement (ACK) frame containing a traffic buffering (BU) bit and a data frame containing buffered data for the STA and a delaying transmission indication of a buffered data frame;
when the BU bit of a received ACK frame has a bit value of logical one, receiving at the STA from the AP a data frame containing data for the STA after a specific time period following the received ACK frame; and
when the BU bit of the received ACK frame has a bit value of logical zero, causing the STA to re-enter the doze state.
2 . The method of claim 1 , further comprising:
causing the STA to enter the doze state after receiving the ACK of the PS-Poll with a delaying transmission indication of the buffered frame and before receiving the buffered data frame from the AP.
3 . The method of claim 2 , wherein the STA enters the doze state during a transmission opportunity (TXOP) in which a receiver of the frame in the TXOP is not the STA.
4 . The method of claim 3 , wherein the STA does not receive the data frame from the AP in a TXOP where there is at least one data frame whose receiver is not the STA.
5 . The method of claim 1 , wherein the STA receives an indication from the AP that the AP supports power efficient low power STAB in the basic service set (BSS).
6 . The method of claim 1 , wherein during association, the STA indicates to the AP that the STA is a power efficient low power STA.
7 . An apparatus, comprising:
a controller configured to
wake a wireless station (STA) from a doze state and to send a PS-Poll frame to an access point (AP),
in response to the PS-Poll frame, receive from the AP one of an acknowledgement (ACK) frame containing a traffic buffering (BU) bit and a data frame containing buffered data for the STA and a delaying transmission indication of a buffered data frame,
when the BU bit of a received ACK frame has a bit value of logical one, receive from the AP a data frame containing data for the STA after a specific time period following the received ACK frame, and
when the BU bit of the received ACK frame has a bit value of logical zero, cause the STA to re-enter the doze state.
8 . The apparatus of claim 7 , wherein the controller is configured to cause the STA to enter the doze state after receiving the ACK of the PS-Poll with a delaying transmission indication of the buffered frame and before receiving the buffered data frame from the AP.
9 . The apparatus of claim 8 , wherein the STA enters the doze state during a transmission opportunity (TXOP) in which a receiver of the frame in the TXOP is not the STA.
10 . The apparatus of claim 8 , wherein the STA does not receive the data frame from the AP in a TXOP where there is at least one data frame whose receiver is not the STA.
11 . The apparatus of claim 7 , wherein the STA receives an indication from the AP that the AP supports power efficient low power STAB in the basic service set (BSS).
12 . The apparatus of claim 7 , wherein the controller is configured, during association, to indicate to the AP that the STA is a power efficient low power STA.
13 . A method, comprising:
responsive to receiving an indication that an associated station (STA) is a power efficient low power STA, receiving a PS-Poll frame from the STA at an access point (AP);
transmitting to the STA from the AP one of an acknowledgement (ACK) frame containing a traffic buffering (BU) bit and an immediate transmission indication of a buffered data frame; and
when the BU bit of a transmitted ACK frame has a bit value of logical one and the immediate transmission indication of the buffered data frame, transmitting to the STA from the AP a data frame containing data for the STA after a specific time period following the received ACK frame.
14 . The method of claim 13 , wherein the STA remains active after receiving the ACK frame with the BU bit having the bit value of logical one and the immediate transmission indication of the buffered data frame.
15 . The method of claim 14 , wherein the STA enters a doze state after transmitting an ACK frame from the STA to the AP that acknowledges the received buffered data frame.
16 . The method of claim 13 , wherein the specific time period is one of a SIFS and a Point Coordination Function Inter-Frame Space (PIFS).
17 . The method of claim 13 , wherein, during association, the AP indicates that the AP supports power efficient low power STAs in the basic service set (BSS).
18 . The method of claim 13 , during association, the AP receives an indication that the STA is a power efficient low power STA.
19 . An apparatus, comprising:
a controller configured to
responsive to receiving an indication that an associated station (STA) is a power efficient low power STA, receive a PS-Poll frame from the STA at an access point (AP),
transmit to the STA one of an acknowledgement (ACK) frame containing a traffic buffering (BU) bit and an immediate transmission indication of a buffered data frame, and
when the BU bit of a transmitted ACK frame has a bit value of logical one and the immediate transmission indication of the buffered data frame, transmit to the STA a data frame containing data for the STA after a specific time period following the received ACK frame.
20 . The apparatus of claim 19 , wherein the STA remains active after receiving the ACK frame with the BU bit having the bit value of logical one and the immediate transmission indication of the buffered data frame.
21 . The apparatus of claim 20 , wherein the STA enters a doze state after transmitting an ACK frame from the STA to the AP that acknowledges the received buffered data frame.
22 . The apparatus of claim 19 , wherein the specific time period is one of a SIFS and a Point Coordination Function Inter-Frame Space (PIFS).
23 . The apparatus of claim 19 , wherein, during association, the AP indicates that the AP supports power efficient low power STAB in the basic service set (ESS).
24 . The apparatus of claim 19 , wherein the controller is configured, during association, to receive an indication that the STA is a power efficient low power STA.