Dynamic energy saving mechanism for access points

• US 8,542,620 B2
• Filed: 06/26/2009
• Issued: 09/24/2013
• Est. Priority Date: 05/05/2009
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Sampathkumar, Badri Srinivasan
• Primary Examiner(s): MEW, KEVIN D
• Application Number:
  US12/492,405
• Publication Number:
  US 20100284316A1
• Time in Patent Office: 1,551 Days
• Field of Search: 370/311, 370328-329, 370335-336, 370/338, 370341-343, 370/345, 370/432, 370/437, 370441-442, 370449-450, 370458-459
• US Class Current: 370/311
• CPC Class Codes: H04W 52/0206 in access points, e.g. base stations access point devices per se H04W88/08
• CPC Class Codes: H04W 52/0216 using a pre-established activity schedule, e.g. traffic indication frame
• CPC Class Codes: H04W 88/08 Access point devices
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

Mobile access points typically run on batteries, and therefore, can operate for a limited amount of time without an external power source. However, because the access point service model requiring the access point to always be available and the access point'"'"'s limited battery capacity reduces the time that the mobile access point can be used. Functionality can be incorporated in mobile access points to implement power saving mechanisms by altering the service model that requires the access point to always be available. Configuring the access point to enter into a low powered state for a predefined period of time can conserve mobile access point power and prolong battery life. Functionality for implementing power saving mechanisms can also be incorporated on fixed access points for efficient utilization of computing resources.

Claims

1. A method for reducing power consumption in an access point, the method comprising:

receiving a message at the access point from a first station, via a wireless communication channel, indicating a first station sleep interval associated with the first station, wherein the first station sleep interval indicates a time interval in which the first station will enter a sleep mode;

calculating a first access point quiet information comprising a first access point sleep interval based, at least in part, on the first station sleep interval, wherein the first access point sleep interval indicates a time interval in which the access point will enter a sleep mode;

transmitting to the first station, via the wireless communication channel, a beacon indicating the first access point quiet information to prevent the first station from initiating transmissions to the access point during the first access point sleep interval;

determining, based on the first access point quiet information, a start of the first access point sleep interval; and

initiating the sleep mode in the access point at the start of the first access point sleep interval.

2. The method of claim 1, wherein the first access point quiet information further comprises one or more of a time instant at which the access point enters the sleep mode, a time instant at which the access point wakes up from the sleep mode, and an indication of how often the access point enters the sleep mode.

3. The method of claim 1, further comprising:

detecting, at the access point, a pending transmission associated with the first station, wherein the pending transmission comprises one of a data frame transmission and a management frame transmission;

calculating a transmission time associated with the pending transmission;

comparing the transmission time with an amount of time remaining before the first access point sleep interval begins;

determining that the transmission time is greater than the amount of time remaining before the first access point sleep interval begins; and

preventing execution of the pending transmission associated with the first station.

4. The method of claim 1, wherein the access point is a mobile phone access point.

5. The method of claim 1, wherein said calculating the first access point quiet information comprises calculating the first access point sleep interval that initiates the sleep mode in the access point during the first station sleep interval.

6. The method of claim 1, further comprising:

determining that no stations are connected to the access point, via the wireless communication channel;

calculating a second access point quiet information comprising a second access point sleep interval based, at least in part, on a beacon interval and on said determining that no stations are connected to the access point, wherein the beacon interval indicates a time interval in which a beacon is transmitted, and wherein the second access point sleep interval indicates a time interval in which the access point will enter a sleep mode;

transmitting, via the wireless communication channel, a second beacon indicating the second access point quiet information to prevent one or more stations from initiating transmissions to the access point during the second access point sleep interval;

determining, based on the second access point quiet information, a start of the second access point sleep interval;

initiating the sleep mode in the access point at the start of the second access point sleep interval;

determining, based on the second access point quiet information, an end of the second access point sleep interval; and

initiating a normal operational mode, at the access point, in response to determining the end of the second access point sleep interval.

7. The method of claim 1, further comprising:

receiving a second message at the access point from a second station, via the wireless communication channel, indicating a second station sleep interval associated with the second station, wherein the second station sleep interval indicates a time interval in which the second station will enter a sleep mode;

calculating a second access point quiet information comprising a second access point sleep interval based, at least in part, on the first station sleep interval and the second station sleep interval, wherein the second access point sleep interval indicates a time interval for which the access point will enter a sleep mode; and

transmitting to the first and the second stations, via the wireless communication channel, a second beacon indicating the second access point quiet information to prevent the first and the second stations from initiating transmissions to the access point during the second access point sleep interval.

8. The method of claim 7, wherein said calculating the second access point quiet information comprises:

determining a least common factor between the first station sleep interval associated with the first station and the second station sleep interval associated with the second station; and

determining when to initiate the second access point sleep interval based, at least in part, on said determining the least common factor between the first station sleep interval associated with the first station and the second station sleep interval associated with the second station.

9. A method comprising:

receiving access point quiet information at a station from an access point, via a wireless communication channel, wherein the access point quiet information comprises an access point sleep interval indicating a time interval for which the access point will enter a sleep mode;

determining that the wireless communication channel is available for transmission of information to the access point, wherein the transmission of information comprises one of a data frame transmission and a management frame transmission;

calculating a transmission time associated with the transmission of information to the access point;

comparing the transmission time with an amount of time remaining before a station sleep interval associated with the station begins, wherein the station sleep interval indicates a time interval in which the station will enter a sleep mode;

determining that the transmission time is less than the amount of time that remains before the station sleep interval begins; and

transmitting the information to the access point.

10. The method of claim 9, further comprising:

transmitting, to the access point, the station sleep interval associated with the station, wherein the access point sleep interval is determined based, in part, on the station sleep interval.

11. The method of claim 9, further comprising:

determining, based on the station sleep interval, a start of the station sleep interval; and

initiating the sleep mode in the station at the start of the station sleep interval.

12. The method of claim 11, wherein said determining, based on the station sleep interval, the start of the station sleep interval further comprises:

determining that a station sleep timer associated with the station is expired, wherein the station sleep timer indicates an amount of time that remains before the station enters the sleep mode.

13. The method of claim 12, further comprising:

storing, in a network allocation vector timer, associated with the station, the access point sleep interval, wherein the network allocation vector timer indicates an amount of time that remains before the station wakes up from the sleep mode;

determining that the network allocation vector timer associated with the station has expired; and

initiating a normal operational mode, at the station, in response to determining that the network allocation vector timer associated with the station has expired.

14. An access point device comprising:

a processor unit;

a transceiver unit coupled with the processor unit, the transceiver unit configured to receive a message from a first station, via a wireless communication channel, indicating a first station sleep interval associated with the first station, wherein the first station sleep interval indicates a time interval in which the first station will enter a sleep mode; and

a power saving unit coupled with the processor unit, the power saving unit configured to;

calculate a first access point quiet information comprising a first access point sleep interval based, at least in part, on the first station sleep interval, wherein the access point sleep interval indicates a time interval in which the access point device will enter a sleep mode;

transmit to the first station, via the wireless communication channel, a beacon indicating the first access point quiet information to prevent the first station from initiating transmissions to the access point device during the first access point sleep interval;

determine, based on the first access point quiet information, a start of the first access point sleep interval; and

initiate the sleep mode in the access point device at the start of the first access point sleep interval.

15. The access point device of claim 14, wherein the first access point quiet information further comprises one or more of a time instant at which the access point device enters the sleep mode, a time instant at which the access point device wakes up from the sleep mode, and an indication of how often the access point device enters the sleep mode.

16. The access point device of claim 14, further comprising:

the transceiver unit configured to;

detect a pending transmission associated with the first station, wherein the pending transmission comprises one of a data frame transmission and a management frame transmission;

the power saving unit configured to;

calculate a transmission time associated with the pending transmission;

compare the transmission time with an amount of time remaining before the first access point sleep interval begins;

determine that the transmission time is greater than the amount of time remaining before the first access point sleep interval begins; and

prevent execution of the pending transmission associated with the first station.

17. The access point device of claim 14, wherein the power saving unit configured to calculate the first access point quiet information further comprises the power saving unit configured to calculate the first access point sleep interval that initiates the sleep mode in the access point device during the first station sleep interval.

18. The access point device of claim 14, further comprising:

the power saving unit configured to

determine that no stations are connected to the access point device, via the wireless communication channel;

calculate a second access point quiet information comprising a second access point sleep interval based, at least in part, on a beacon interval and on said determining that no stations are connected to the access point device, wherein the beacon interval indicates a time interval in which a beacon is transmitted, and wherein the second access point sleep interval indicates a time interval in which the access point device will enter a sleep mode;

transmit, via the wireless communication channel, a second beacon indicating the second access point quiet information to prevent one or more stations from initiating transmissions to the access point device during the second access point sleep interval;

determine, based on the second access point quiet information, a start of the second access point sleep interval;

initiate the sleep mode in the access point device at the start of the second access point sleep interval;

determine, based on the second access point quiet information, an end of the second access point sleep interval; and

initiate a normal operational mode, at the access point device, in response to determining the end of the second access point sleep interval.

19. The access point device of claim 14, further comprising:

the transceiver unit configured to;

receive a second message from a second station, via the wireless communication channel, indicating a second station sleep interval associated with the second station, wherein the second station sleep interval indicates a time interval in which the second station will enter a sleep mode;

the power saving unit configured to;

calculate a second access point quiet information comprising a second access point sleep interval based, at least in part, on the first station sleep interval and the second station sleep interval, wherein the second access point sleep interval indicates a time interval for which the access point device will enter a sleep mode; and

transmit to the first and the second stations, via the wireless communication channel, a second beacon indicating the second access point quiet information to prevent the first and the second stations from initiating transmissions to the access point device during the second access point sleep interval.

20. The access point device of claim 19, wherein the power saving unit configured to calculate the second access point quiet information comprises the power saving unit configured to:

determine a least common factor between the first station sleep interval associated with the first station and the second station sleep interval associated with the second station; and

determine when to initiate the second access point sleep interval based, at least in part, on said determining the least common factor between the first station sleep interval associated with the first station and the second station sleep interval associated with the second station.

21. One or more non-transitory machine-readable storage media, having instructions stored therein, which when executed by one or more processors causes the one or more processors to perform operations that comprise:

receiving a message at an access point from a first station, via a wireless communication channel, indicating a first station sleep interval associated with the first station, wherein the first station sleep interval indicates a time interval in which the first station will enter a sleep mode;

calculating a first access point quiet information comprising a first access point sleep interval based, at least in part, on the first station sleep interval, wherein the first access point sleep interval indicates a time interval in which the access point will enter a sleep mode;

transmitting to the first station, via the wireless communication channel, a beacon indicating the first access point quiet information to prevent the first station from initiating transmissions to the access point during the first access point sleep interval;

determining, based on the first access point quiet information, a start of the first access point sleep interval; and

initiating the sleep mode in the access point at the start of the first access point sleep interval.

22. The machine-readable storage media of claim 21, wherein the first access point quiet information further comprises one or more of a time instant at which the access point enters the sleep mode, a time instant at which the access point wakes up from the sleep mode, and an indication of how often the access point enters the sleep mode.

23. The machine-readable storage media of claim 21, wherein the operations further comprise:

detecting, at the access point, a pending transmission associated with the first station, wherein the pending transmission comprises one of a data frame transmission and a management frame transmission;

calculating a transmission time associated with the pending transmission;

comparing the transmission time with an amount of time remaining before the first access point sleep interval begins;

determining that the transmission time is greater than the amount of time remaining before the first access point sleep interval begins; and

preventing execution of the pending transmission associated with the first station.

24. The machine-readable storage media of claim 21, wherein the operations further comprise:

receiving a second message at the access point from a second station, via the wireless communication channel, indicating a second station sleep interval associated with the second station, wherein the second station sleep interval indicates a time interval for which the second station will enter a sleep mode;

calculating a second access point quiet information comprising a second access point sleep interval based, at least in part, on the first station sleep interval and the second station sleep interval, wherein the second access point sleep interval indicates a time interval for which the access point will enter a sleep mode; and

transmitting to the first and the second stations, via the wireless communication channel, a second beacon indicating the second access point quiet information to prevent the first and the second stations from initiating transmissions to the access point during the second access point sleep interval.

25. The machine-readable storage media of claim 24, wherein said operation of calculating the second access point quiet information further comprises:

determining a least common factor between the first station sleep interval associated with the first station and the second station sleep interval associated with the second station; and

determining when to initiate the second access point sleep interval based, at least in part, on said determining the least common factor between the first station sleep interval associated with the first station and the second station sleep interval associated with the second station.