Low power receiving
View Patent ↗The disclosed methods of low power communications facilitate high speed reception of data from an access point (AP) with low transmission latencies while remaining in power save mode as long as possible. The disclosed methods allow the client to remain in a power save state and involve creating a synchronous client frame exchange with the AP that is independent of a digital traffic indication map and the AP's beacon interval. Two methods to accomplish this goal are disclosed: one which involves sending PS Poll Frames; and one that includes fast CAM switching, both at a self tuning frequency.
1. A method implemented in a station, the method comprising:
receiving a data frame at a station from an access point;
polling synchronously, at the station, to determine if more data frames for the station are buffered at the access point, wherein polling synchronously comprises polling with a power save poll message;
if more data frames for the station are not buffered at the access point, determining if a poll timer value is less than a target beacon transmission time;
if the poll timer value is less than the target beacon transmission time, adjusting a poll interval value;
entering sleep mode; and
delaying for a time substantially equal to the poll interval value before waking up from the sleep mode;
if the poll timer value is not less than the target beacon transmission time,
resetting the wakeup delay; and
returning to sleep mode.
2. The method of claim 1 , wherein polling synchronously comprises:
constantly awake mode polling by sending a null data packet to the access point to indicate that the station is ready to receive a data frame.
3. The method of claim 2 , further comprising:
if more data frames for the station are buffered at the access point, receiving the data frames;
determining whether a receive timeout occurred;
if the receive timeout has occurred, then determining if the poll timer value is less than the target beacon transmission time; and
if the receive timeout has not occurred, then delaying for a delay period and repeating the step of determining if the receive timeout has occurred.
4. The method of claim 2 , wherein if the poll timer value is less than the target beacon transmission time, adjusting the poll interval value further comprises:
determining if a number of received data frames is greater than a target number;
decreasing the poll interval value if the number of received data frames is greater than the target number;
increasing the poll interval value if the number of received data frames is not greater than the target number; and
setting a wakeup delay to the poll interval value.
5. The method of claim 2 , wherein if the poll timer value is not less than the target beacon transmission time, resetting the wakeup delay; and
returning to sleep mode.
6. The method of claim 1 , wherein the determining if more data for the station is buffered at the access point comprises checking the MORE bit of the data frame.
7. The method of claim 1 , further comprising:
if more data frames for the station are buffered at the access point, receiving the data frames;
transmitting a power save poll message;
receiving a data frame; and
transmitting an acknowledgement frame in response to receiving the data frame.
8. The method of claim 1 , wherein if the poll timer value is less than the target beacon transmission time, adjusting a poll interval value further comprises:
determining if a number of received data frames is greater than a target number;
decreasing the poll interval value if the number of received data frames is greater than the target number;
increasing the poll interval value if the number of received data frames is not greater than the target number; and
setting a wakeup delay to the poll interval value.
9. A system comprising:
a processor in a station configured to:
receive a data frame from an access point;
poll synchronously to determine if more data frames for the station are buffered at the access point;
if more data frames for the station are not buffered at the access point, determine if a poll timer value is less than a target beacon transmission time;
if the poll timer value is less than the target beacon transmission time, adjust a poll interval value;
cause the station to enter sleep mode;
delay for a time substantially equal to the poll interval value before waking up from the sleep mode;
send a null data frame to the access point to indicate that the station is ready to receive data;
if more data frames for the station are buffered at the access point, receive the data frames;
determine whether a receive timeout occurred;
if the receive timeout has occurred, then determine if the poll timer value is less than the target beacon transmission time; and
if the receive timeout has not occurred, then delay for a delay period and repeat the determination of whether the receive timeout has occurred.
10. The system of claim 9 , wherein the processor is further configured to:
synchronously poll for a data frame residing in a buffer by sending a power save poll message.
11. The system of claim 10 , wherein the processor is further configured to:
if more data frames for the station are buffered at the access point, receive the data;
transmit a power save poll message;
receive a data frame; and
transmit an acknowledgement frame in response to receiving the data frame.
12. A system comprising:
means for receiving a data frame from an access point;
means for polling synchronously to determine if more data frames for a station are buffered at the access point, wherein means for polling synchronously comprises means for polling with a power save poll message;
means for, if more data frames for the station are not buffered at the access point, determining if a poll timer value is less than a target beacon transmission time;
means for, if the poll timer value is less than the target beacon transmission time, adjusting a poll interval value;
means for causing the station to enter sleep mode; and
means for delaying for a time substantially equal to the poll interval value before waking up from the sleep mode;
means for, if the poll timer value is not less than the target beacon transmission time, resetting the wakeup delay; and
means for returning to sleep mode.
13. The system of claim 12 , further comprising:
means for sending a null data frame to the access point to indicate that the station is ready to receive a data frame.
14. The system of claim 13 , further comprising:
means for, if more data frames for the station are buffered at the access point, receiving the data;
means for determining whether a receive timeout occurred;
means for, if the receive timeout has occurred, then determining if the poll timer value is less than the target beacon transmission time; and
means for, if the receive timeout has not occurred, then delaying for a delay period and repeating the determination of whether the receive timeout has occurred.
15. The system of claim 12 , further comprising means for synchronously polling for buffered data packets with a power save poll message.
16. The system of claim 15 , further comprising:
means for, if more data frames for the station are buffered at the access point, receiving the data;
means for transmitting a power save poll message;
means for receiving a data frame; and
means for transmitting an acknowledgement frame in response to receiving the data frame.