Efficient power management in wireless local area networks
View Patent ↗A method of providing power management in a Wireless Local Area Network (WLAN) is presented. The method includes receiving a Traffic Indication Map (TIM) at a station, indicating the presence of buffered frames, associated with any AC, for the station at an Access Point (AP). The method further includes sending, by the station, one of an uplink data frame if one is buffered, and a null frame to retrieve the buffered frames from said AP. The station remains awake to receive frames from the AP until a downlink frame is received containing an indication that it is the last frame to be transmitted in the service period. The method may further include determining at the end of service period whether there are more frames remaining buffered for the station at the AP.
1. A method of providing power management in a Wireless Local Area Network (WLAN) comprising:
receiving a Traffic Indication Map (TIM) at a station, said TIM indicating the presence of buffered frames, associated with any access category (AC), for said station at an Access Point (AP), wherein said TIM indicates the presence of scheduled frames and wherein said TIM also indicates the presence of unscheduled frames such that stations with non-periodic traffic are able to use Automatic Power Save Delivery (APSD) to retrieve said unscheduled frames;
sending, by said station, one of an uplink quality-of-service (QoS) Data frame when one is buffered, and a Null frame to retrieve said buffered frames from said AP; and
said station remaining awake to receive frames from the AP, as indicated by the TIM, until a downlink frame is received containing an indication that it is the last frame to be transmitted in the service period.
2. A method of providing power management in a Wireless Local Area Network (WLAN) comprising:
receiving a Traffic Indication Map (TIM) at a station, said TIM indicating the presence of buffered frames for said station at an Access Point (AP), wherein said TIM indicates the presence of scheduled frames and wherein said TIM also indicates the presence of unscheduled frames such that stations with non-periodic traffic are able to use Automatic Power Save Delivery (APSD) to retrieve said unscheduled frames;
sending, by a station, one of an uplink data frame when one is buffered, and a null frame to retrieve said buffered frames from said AP;
said station remaining awake to receive frames from the AP, as indicated by the TIM, until a downlink frame is received containing an indication that it is the last frame to be transmitted in the service period; and
determining at the end of service period whether there are more buffered frames remaining for said station at the AP, wherein said buffered frames include scheduled frames and wherein said buffered frames further include unscheduled frames such that stations with non-periodic traffic are able to use Automatic Power Save Delivery (APSD) to retrieve said unscheduled frames.
3. The method of claim 2 further comprising said station retrieving remaining buffered frames by one of sending a null frame, sending Power Save (PS) Polls, and entering the Active mode and then transitioning back to PS mode.
4. A method of providing power management in a Wireless Local Area Network (WLAN) comprising:
receiving a Traffic Indication Map (TIM) at a station, said TIM indicating the presence of buffered frames for said station at an Access Point (AP), wherein said TIM indicates the presence of scheduled frames and wherein said TIM also indicates the presence of unscheduled frames such that stations with non-periodic traffic are able to use Automatic Power Save Delivery (APSD) to retrieve said unscheduled frames;
receiving, by said station, a periodic downlink traffic stream from an Access Point (AP) during a scheduled period;
said station remaining awake to receive frames from the AP, as indicated by the TIM, until a downlink frame is received containing an indication that it is the last frame to be transmitted in the service period; and
determining, when said station receives the indication of the end of the service period in the downlink frame, whether there are more buffered frames remaining for said station at the AP, wherein said buffered frames include scheduled frames and wherein said buffered frames further include unscheduled frames such that stations with non-periodic traffic are able to use APSD to retrieve said unscheduled frames.
5. The method of claim 4 wherein said station retrieving any remaining buffered frames by one of sending a null frame, sending Power Save (PS) Polls, and by entering the Active mode and then transitioning back to PS mode.
6. The method of claim 4 further comprising indicating, by a station, a time when said station expects to receive traffic.
7. The method of claim 4 wherein a service period schedule is produced by the AP by determining a service interval and a start time so that overlap between service periods of different stations is minimized.
8. The method of claim 7 further comprising adjusting the service start time to be later than or equal to a requested service start time and less than a service period relative to said requested start time.
9. The method of claim 4 wherein said station uses Enhanced Distributed Channel Access (EDCA) and wherein a service period schedule comprises a predetermined schedule.
10. The method of claim 9 further comprising delivering by said AP buffered frames to said station at the start of said service period.
11. The method of claim 9 wherein said schedule includes staggered service periods for different stations.
12. The method of claim 9 wherein, after said AP transmits buffered frames to a station, refraining from transmitting for a predetermined time period.
13. The method of claim 9 further comprising using backoff delays drawn from a shorter contention window by said EDCA station than other EDCA stations with a same priority traffic.