Power management methods and systems

• US 20070129093A1
• Filed: 02/23/2006
• Published: 06/07/2007
• Est. Priority Date: 12/05/2005
• Status: Active Grant

• Current Assignee: Institute For Information Industry
• Original Assignee: Institute For Information Industry
• Inventors: Hsu, Ching-Chi, Chou, Zi-Tsan
• Granted Patent: US 7,848,277 B2
• Time in Patent Office: Days
• US Class Current: 455/522
• CPC Class Codes: H04W 52/0229 where the received signal is a wanted signal
• CPC Class Codes: H04W 84/18 Self-organising networks, e.g. ad-hoc networks or sensor networks
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

Power management methods and systems for a first station and a second station in an ad-hoc network. Each station enters the normal beacon interval (NBI) every certain number of beacon intervals (BIs) for data transmission, a Listen Interval (LI). When a station switches to a power-saving mode, it first determines the number of “beacon-window-only beacon intervals (BBIs)” within a LI. In addition, 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 NBI of the second station according to the RBI. At the NBI of the second station, the first station transmits data frames to the second station.

Claims

1. A power management method for use in a first station and a second station, 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:

determining a number of BBIs (Beacon-Window-Only Beacon Intervals) within the certain number of BIs, in which the second station broadcasts a beacon frame within at least one of the BBI, the beacon frame comprises 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 transmitting the beacon frame comprising the LI value to the first station;

the first station reducing the RBI by 1 if one of the BI passes; and

setting the RBI as the LI value if the RBI equals 0.

3. The method of claim 1 further comprising the first station deleting the RBI corresponding to the beacon frame if no other beacon frame is received from the second station.

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

5. The method of claim 4 wherein the number of the BBIs and the SBIs equals the LI value minus 1.

6. 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.

7. 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.

8. The method of claim 7 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.

9. A power management system, 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, determining a number of BBIs (Beacon-Window-Only Beacon Intervals) within the certain number of BIs, broadcasting a beacon frame within at least one of the BBI, in which the beacon frame comprises 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.

10. The system of claim 9 wherein the second station further transmits the beacon frame comprising the LI value to the first station, the first station reduces the RBI by 1 if one of the BI passes, and sets the RBI as the LI value if the RBI equals 0.

11. The system of claim 9 wherein the first station further deletes the RBI corresponding to the beacon frame if no other beacon frame is received from the second station.

12. The system of claim 9 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.

13. The system of claim 12 wherein the number of the BBIs and the SBIs equals the LI value minus 1.

14. The system of claim 9 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.

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

16. The system of claim 15 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.

17. A power management method for use in a second station, 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:

determining a number of BBIs (Beacon-Window-Only Beacon Intervals) within the certain number of BIs, in which the second station broadcasts a beacon frame within at least one of the BBI, the beacon frame comprises 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.

18. The method of claim 17 further comprising:

the first station receiving the beacon frame from the second station;

predicting the NBI of the second station according to the RBI; and

transmitting the data frame to the second station at the NBI of the second station.

19. The method of claim 17 further comprising determining the number of SBIs (Sleep Beacon Intervals), in which the second station enters a doze state in the SBIs.

20. The method of claim 19 wherein the number of the BBIs and the SBIs equals the LI value minus 1.

21. The method of claim 17 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.

22. The method of claim 17 wherein the NBI comprises an AW (ATIM Window) comprising a BW (Beacon Window), the second station transmits the beacon frame within the BW of the NBI.

23. The method of claim 22 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.