Power saving mechanism for wireless LANs via schedule information vector

• US 20040190467A1
• Filed: 03/25/2003
• Published: 09/30/2004
• Est. Priority Date: 03/25/2003
• Status: Active Grant

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Shoemake, Matthew B., Ho, Jin-Meng, Liu, Yonghe
• Granted Patent: US 7,508,781 B2
• Time in Patent Office: Days
• US Class Current: 370/311
• CPC Class Codes: H04W 52/0216 using a pre-established activity schedule, e.g. traffic indication frame
• CPC Class Codes: H04W 72/12 Wireless traffic scheduling
• CPC Class Codes: H04W 74/06 using polling
• CPC Class Codes: H04W 84/12 WLAN [Wireless Local Area Networks]
• CPC Class Codes: H04W 88/08 Access point devices
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

A new protocol system and method is described implemented in the MAC sublayer, utilizing a Schedule Information Vector (SIV) protocol for saving power in wireless local area networks. The protocol comprises an access point, one or more stations, and an SIV frame comprising an association ID for identifying one of the stations and a scheduled wake-up time for the identified station. The access point originates and transmits the SIV frame protocol of the scheduled wake-up time to the stations. When the identified station awakes at the scheduled time, the AP directs the station to uplink or downlink CF data according to another suitable protocol (e.g., a CC/RR protocol). The AP may then be used to direct the identified station to send a request for uplink data, to receive a poll for uplink CF transmission, or to receive downlink CF data, thereby minimizing time the station must remain awake, thus saving power by minimizing time in channel contention. The SIV frame protocol of the wireless network is further operable to dynamically adjust the scheduled wake-up times of the stations, a sequence of the wake-up times, a periodic wake-up time, a plurality of wake-up times, and a duration of the wake-up times of the stations. These adjustments may be made based on network traffic, traffic buffering times, data priorities, data length, and data rates.

Claims

1. A system for saving power in a wireless network, comprising:

an access point;

one or more stations; and

an SIV frame comprising;

one or more schedules of wake-up times, corresponding to the one or more stations;

wherein the access point originates and transmits the SIV frame of the scheduled wake-up time to the one or more stations, and wherein the one or more stations selectively awake from a sleep mode for data transmission therewith based on the schedule.

2. The SIV frame of claim 1, wherein the SIV frame comprises:

a schedule field comprising one or more schedules for scheduling the next wake-up time of one or more stations, based on one of an offset relative to a last beacon or a next beacon, and an offset relative to the current SIV frame; and

wherein the one or more stations are directed to uplink or downlink CF data, thereby minimizing time the station must remain awake, saving power while minimizing channel contention.

3. The SIV frame of claim 2, wherein the SIV frame further comprises an AID field to numerate the one or more association IDs of the one or more stations for identifying one or more of the stations.

4. The SIV frame of claim 3, wherein the SIV frame further comprises an N_SIV field to denote the number of stations scheduled in the current frame, wherein the number of association IDs contained in the AID field.

5. The SIV frame of claim 4, wherein the SIV frame further comprises a listening window field to denote the time period following the scheduled wake-up time, during which the AP should send network traffic.

6. The SIV frame of claim 2, wherein the SIV frame is further operable to schedule one of a next CC frame and a next SIV frame for the one or more stations.

7. The SIV frame of claim 2, wherein the SIV frame is further operable to schedule one or a combination of wake-up times, a sequence of wake-up times, a periodic wake-up time, a plurality of wake-up times, and a duration of the wake-up times for the stations as identified by the SIV frame.

8. The wireless network of claim 2, wherein the uplink data is sent via a protocol that provides a method of collecting requests for delay sensitive signaling or bursty traffic.

9. The wireless network of claim 8, wherein the protocol comprises a CC/RR protocol, thereby providing a method of determining with little overhead, which stations have traffic to send on a heavily loaded network.

10. The SIV frame of claim 2, wherein the SIV frame occurs after the last beacon.

11. The SIV frame of claim 2, wherein the SIV frame occurs before the next beacon.

12. The wireless network of claim 1, wherein the SIV frame is transmitted to the stations within a TIM frame of a beacon.

13. The wireless network of claim 1, wherein the access point is configured to generate a TSPEC element comprising a PS interval for specifying a timing offset relative to the current transmission.

14. The wireless network of claim 1, wherein the access point is further operable to dynamically adjust one or more of the scheduled wake-up times of the stations, a sequence of wake-up times, a periodic wake-up time, a plurality of wake-up times, and a duration of the wake-up times of the stations, based on one or more of network traffic, traffic buffering time, data priorities, data length, and data rates.

15. The wireless network of claim 14, wherein the dynamic adjustments are made by the access point in the fields of the SIV frame.

16. The wireless network of claim 14, wherein the access point has a higher channel access priority than that of any station of the network.

17. The wireless network of claim 1, wherein the access point is further operable to unicast the SIV to one station, thereby providing self correction or retransmission of a schedule for an individual station.

18. The wireless network of claim 1, wherein the access point is further operable unicast an SIV frame to a station to alter one or more of the scheduled wake-up times of the station in response to errors on the network and to the arrival of higher priority data.

19. The wireless network of claim 1, further providing an SIV protocol configurable to allow the access point to ignore current scheduling activities and perform scheduling in response to errors on the network and to the arrival of higher priority data.

20. A method of saving power in a wireless network comprising an access point, a station, and an SIV frame, the method comprising:

awaking the station from a sleep mode to monitor a beacon from the access point;

determining whether a station'"'"'s association ID is indicated in the beacon;

returning the station to the sleep mode if the station'"'"'s association ID is not indicated;

transferring the SIV frame containing schedule data to the station; and

returning the station to the sleep mode and awakening the station for data transmission therewith based on the schedule data.

21. The method of claim 20, further comprising:

determining whether uplink data is to be transmitted from the station to the access point if the station'"'"'s association ID is indicated in the beacon; and

keeping the station awake; and

sending a CC from the access point to the station and sending an RR back from the station to the access point prior to receiving the SIV.

22. The method of claim 21, wherein returning the station to sleep mode comprising returning the station to sleep mode after receipt of the SIV, and maintaining the station in sleep mode until the schedule data dictates that the station awaken.

23. The method of claim 20, further comprising:

determining whether downlink data is to be transmitted from the access point to the station if the station'"'"'s association ID is indicated in the beacon; and

keeping the station awake until SIV frame containing schedule data is received.

24. The method of claim 23, further comprising returning the station to sleep mode after receipt of the SIV frame, and maintaining the station in sleep mode until the schedule data dictates that the station awaken.

25. The method of claim 20, wherein awaking the station to monitor a beacon from the access point, comprises awaking the station at a periodic time to monitor a beacon from the access point.

26. The method of claim 20, wherein determining whether a station'"'"'s association ID is indicated, comprises determining whether a stations association ID is indicated within a TIM of the beacon.

27. The method of claim 20, further comprising modifying the schedule data within a subsequent SIV frame based on one or more of network traffic, traffic buffering time, data priorities, data lengths and data rates.