Power-saving mechanisms for 802.11 clients
The station does not wake up for the beacon TIM if there is periodic uplink data with period less than or equal to the tolerance for downlink delay. If the station has no uplink data for at least a service interval (period of the stream), it wakes up to listen to the TIM. It continues to do so until either uplink or downlink data arrives. If the TIM indicates downlink data buffered, and if the station continues to have no uplink data, it starts waking tip at the service interval and sends null frames uplink, in order to signal that it is awake and ready to receive downlink data. If uplink data is generated, the station will send the uplink frame instead of the null frame.
1. A method comprising:
receiving, at a station, a downlink frame from an Access Point (AP), said downlink frame indicating that no more frames will be sent from said AP to said station;
indicating, by said station, that said station is going into power-save mode upon receipt of said downlink frame indicating that no more frames will be sent from said AP;
said station remaining active while said station waits to receive another transmission intended for said station from said AP within a predetermined time period; and
wherein said station enters power-save mode when said another transmission is not received at said station and wherein said station remains active when said another transmission is received by said station;
wherein said predetermined time period comprises a Point coordination function Inter-Frame Space (PIFS) following an acknowledgement.
2. The method of claim 1 further comprising sending an acknowledgement (ACK) upon receipt of said another transmission.
3. The method of claim 2 further comprising remaining active until an additional transmission is received within said predetermined time frame.
4. The method of claim 1 wherein a downlink service interval is less than a Traffic Indication Map (TIM) beacon interval.
5. The method of claim 1 wherein said indicating, by said station, that said station is going into power-save mode comprises sending an acknowledgement to said AP.
6. A computer system comprising:
a memory;
a processor;
a communications interface;
an interconnection mechanism coupling the memory, the processor and the communications interface; and
wherein the memory is encoded with an application that when performed on the processor, provides a process for processing information, the process causing the computer system to perform the operations of:
receiving, at a station, a downlink frame from an Access Point (AP), said downlink frame indicating that no more frames will be sent from said AP to said station;
indicating, by said station, that said station is going into power-save mode upon receipt of said downlink frame indicating that no more frames will be sent from said AP;
said station remaining active while said station waits to receive another transmission intended for said station from said AP within a predetermined time period; and
wherein said station enters power-save mode when said another transmission is not received at said station and wherein said station remains active when said another transmission is received by said station;
wherein said predetermined time period comprises a Point coordination function Inter-Frame Space (PIFS) following an acknowledgement.
7. The computer system of claim 6 further comprising sending an acknowledgement (ACK) upon receipt of said another transmission.
8. The computer system of claim 7 further comprising remaining active until an additional transmission is received within said predetermined time frame.
9. The computer system of claim 6 wherein a downlink service interval is less than a Traffic Indication Map (TIM) beacon interval.
10. The computer system of claim 6 wherein said indicating, by said station, that said station is going into power-save mode comprises sending an acknowledgement to said AP.