Adaptive power management methods and systems for wireless networks

• US 20070275748A1
• Filed: 12/18/2006
• Published: 11/29/2007
• Est. Priority Date: 05/29/2006
• Status: Active Grant

• Current Assignee: Institute For Information Industry
• Original Assignee: Institute For Information Industry
• Inventors: Chou, Zi-Tsan
• Granted Patent: US 8,014,369 B2
• Time in Patent Office: Days
• US Class Current: 455/522
• CPC Class Codes: H04W 52/265 taking into account the quality of service QoS
• CPC Class Codes: H04W 52/343 taking into account loading or congestion level

Abstract

Adaptive power management methods and systems for a first station and a second station in a wireless network. Each station operating in the power-saving (PS) mode adaptively determines a “listen interval” (LI) according to residual power state, quality-of-service requirements, or other considerations. The LI is composed of a “normal beacon interval” (NBI) followed by the combination of “beacon-window-only beacon intervals” (BBIs) and “sleep beacon intervals” (SBIs). The LI value is one or a prime number which is larger than two, and the positions of the NBI and BBIs in an LI form a cyclic difference set. Each station broadcasts a beacon frame comprising at least information about “the remaining number of BIs (RBI)” within a beacon window. Once the first station correctly receives the beacon frame from the second station, the first station predicts the awake/sleep schedule of the second station, and transmits data frames to the second station at the NBI of the second station.

Claims

1. An adaptive power management method for use in a first station and a second station in a wireless network, in which the second station enters a NBI (Normal Beacon Interval) every certain number of BIs (Beacon Intervals) for data reception and transmission, where the certain number is a LI (Listen Interval) value, comprising:

setting the 0th BI in the LI is the NBI, in which the BIs in the LI are notated as 0th, 1st, 2nd, . . . , and n−

1th BIs, respectively, where n is the LI value;

determining a number of BBIs (Beacon-Window-Only Beacon Intervals) and positions thereof within the LI, in which the LI value is one or a prime number is larger than two, and the positions of the NBI and BBIs in the LI form a cyclic difference set;

the second station broadcasting a beacon frame within at least one BW, the beacon frame comprises a station identification and a RBI representing the remaining number of BIs between the BBI where the beacon frame is transmitted and the NBI; and

the first station receiving the beacon frame from the second station, predicting the NBI of the second station according to the RBI, and transmitting a data frame to the second station at the NBI of the second station.

2. The method of claim 1 further comprising the second station resetting the LI value according to residual power state after the LI ends.

3. The method of claim 1 further comprising the second station transmitting the beacon frame comprising the LI value to the first station.

4. The method of claim 1 further comprising:

the first station reducing the RBI corresponding to the second station in a neighbor station table by 1 if one of the BI passes; and

setting the RBI as the LI value minus 1 if the RBI equals −

1.

5. The method of claim 1 further comprising the first station deleting data corresponding to the second station if no other beacon frame is received from the second station in a predetermined interval.

6. The method of claim 1 further comprising the second station determining the number of SBIs (Sleep Beacon Intervals), in which the second station enters a doze state in the SBIs.

7. The method of claim 6 wherein the number of the BBIs and the SBIs equals the LI value minus 1.

8. The method of claim 1 wherein each BBI comprises a BW (Beacon Window), the second station transmits the beacon frame within the BW, and enters a doze state in the BBI except during the interval of the BW.

9. The method of claim 1 wherein the NBI comprises an AW (ATIM Window) comprising a BW (Beacon Window), and the second station transmits the beacon frame within the BW of the NBI.

10. The method of claim 9 further comprising:

the first station transmitting an ATIM frame to the second station within the AW of the NBI of the second station;

the second station transmitting an ATIM ACK to the first station in response to the ATIM frame;

the first station transmitting the data frame to the second station within the NBI after the AW ends; and

the second station transmitting a data ACK to the first station after receiving the data frame.

11. An adaptive power management system for wireless networks, comprising:

a second station entering a NBI (Normal Beacon Interval) every certain number of BIs (Beacon Intervals) for data transmission, where the certain number is a LI (Listen Interval) value, setting the 0th BI in the LI is the NBI, in which the BIs in the LI are notated as 0th, 1st, 2nd, . . . , and n−

1th BIs, respectively, where n is the LI value, determining a number of BBIs (Beacon-Window-Only Beacon Intervals) and positions thereof within the LI, in which the LI value is one or a prime number is larger than two, and the positions of the NBI and BBIs in the LI form a cyclic difference set, the second station broadcasting a beacon frame within at least one BW, the beacon frame comprises a station identification and a RBI representing the remaining number of BIs between the BBI where the beacon frame is transmitted and the NBI; and

a first station receiving the beacon frame from the second station, predicting the NBI of the second station according to the RBI, and transmitting a data frame to the second station at the NBI of the second station.

12. The system of claim 11 wherein the second station further resets the LI value according to residual power state after the LI ends.

13. The system of claim 11 wherein the second station further transmits the beacon frame comprising the LI value to the first station.

14. The system of claim 11 wherein first station further deletes data corresponding to the second station if no other beacon frame is received from the second station in a predetermined interval.

15. The system of claim 11 wherein the second station further determines the number of SBIs (Sleep Beacon Intervals), in which the second station enters a doze state in the SBIs.

16. The system of claim 15 wherein the number of the BBIs and the SBIs equals the LI value minus 1.

17. The system of claim 11 wherein each BBI comprises a BW (Beacon Window), the second station transmits the beacon frame within the BW, and enters a doze state in the BBI except during the interval of the BW.

18. The system of claim 11 wherein the NBI comprises an AW (ATIM Window) comprising a BW (Beacon Window), and the second station transmits the beacon frame within the BW of the NBI.

19. The system of claim 18 wherein the first station further transmits an ATIM frame to the second station within the AW of the NBI of the second station, the second station transmits an ATIM ACK to the first station in response to the ATIM frame, the first station transmits the data frame to the second station within the NBI after the AW ends, and the second station transmits a data ACK to the first station after receiving the data frame.

20. An adaptive power management method for use in a second station in a wireless network, in which the second station enters a NBI (Normal Beacon Interval) every certain number of BIs (Beacon Intervals) for data transmission, where the certain number is a LI (Listen Interval) value, comprising:

setting the 0th BI in the LI is the NBI, in which the BIs in the LI are notated as 0th, 1st, 2nd, . . . , and n−

1th BIs, respectively, where n is the LI value;

determining a number of BBIs (Beacon-Window-Only Beacon Intervals) and positions thereof within the LI, in which the LI value is one or a prime number is larger than two, and the positions of the NBI and BBIs in the LI form a cyclic difference set;

broadcasting a beacon frame within at least one BW, the beacon frame comprising a station identification and a RBI representing the remaining number of BIs between the BBI where the beacon frame is transmitted and the NBI; and

receiving a data frame from a first station at the NBI.

21. The method of claim 20 further comprising resetting the LI value according to residual power state after the LI ends.

22. The method of claim 20 further comprising transmitting the beacon frame comprising the LI value to the first station.

23. The method of claim 20 further comprising determining the number of SBIs (Sleep Beacon Intervals), in which the second station enters a doze state in the SBIs.

24. The method of claim 23 wherein the number of the BBIs and the SBIs equals the LI value minus 1.

25. The method of claim 20 wherein each BBI comprises a BW (Beacon Window), the second station transmits the beacon frame within the BW, and enters a doze state in the BBI except during the interval of the BW.

26. The method of claim 20 wherein the NBI comprises an AW (ATIM Window) comprising a BW (Beacon Window), and the second station transmits the beacon frame within the BW of the NBI.

27. The method of claim 26 further comprising:

the first station transmitting an ATIM frame to the second station within the AW of the NBI of the second station;

the second station transmitting an ATIM ACK to the first station in response to the ATIM frame;

the first station transmitting the data frame to the second station within the NBI after the AW ends; and

the second station transmitting a data ACK to the first station after receiving the data frame.