SYSTEM AND METHODS FOR REDUCING POWER CONSUMED BY A BASE STATION

• US 20110051640A1
• Filed: 08/26/2009
• Published: 03/03/2011
• Est. Priority Date: 08/26/2009
• Status: Active Grant

• Current Assignee: Telefonaktiebolaget LM Ericsson
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Koorapaty, Havish, Balachandran, Kumar, Grant, Stephen, Ramesh, Rajaram
• Granted Patent: US 8,526,305 B2
• Time in Patent Office: Days
• US Class Current: 370/311
• CPC Class Codes: H04W 48/14 using user query or user detection
• CPC Class Codes: H04W 48/20 Selecting an access point
• CPC Class Codes: H04W 52/0206 in access points, e.g. base stations access point devices per se H04W88/08
• CPC Class Codes: H04W 52/0274 by switching on or off the equipment or parts thereof
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

The present invention provides systems and methods that enable a base station to consume less power. According to an embodiment of the invention, the base station reduces its power consumption by not continuously broadcasting control information. In such an embodiment, a mobile station that seeks access to a network to which the base station provides access does not search for broadcast control information prior to transmitting an access message to the base station, but rather simply transmits on a predetermined access channel an access request message. A base station that receives the access request message may unicast control information to the mobile station.

Claims

1. At a base station comprising a transmitter and a receiver, a method comprising:

(a) configuring the transmitter such that it transmits control information on a discontinuous basis;

(b) configuring the base station in a mode whereby the receiver is activated on a discontinuous basis; and

(c) when the receiver is activated, using the receiver to detect an access request message transmitted from a mobile station on an access frequency.

2. The method of claim 1, wherein activating the receiver on a discontinuous basis comprises activating the receiver at pre-determined time instants.

3. The method of claim 2, wherein the pre-determined time instants are referenced to a time of day value obtained by the base station from (i) an adjunct timing system or (ii) a local clock that is calibrated using a signal transmitted from an adjunct timing system.

4. The method of claim 1, further comprising, after detecting the access request message, transmitting, from the base station to the mobile station, a response message comprising control information, wherein the control information contains information that is needed by the mobile station to further communicate with the base station.

5. The method of claim 1, further comprising:

determining the load on the base station; and

if the determined load exceeds a threshold, then continuously broadcasting the control information until the load on the base station falls below a threshold.

6. The method of claim 1, further comprising:

after detecting the access request message, determining the quality of the access request message;

determining whether the determined quality of the access request message exceeds a threshold; and

in response to determining that the quality exceeds the threshold, transmitting from the base station to the mobile station, a response message comprising control information, wherein the control information contains information that is needed by the mobile station to further communicate with the base station.

7. The method of claim 1, further comprising:

after detecting the access request message, determining the quality of the access request message;

transmitting, from the base station to a radio network controller, a control message indicating the quality of the access request message;

receiving from the radio network controller a command message sent in response to the control message; and

in response to receiving the command message, transmitting from the base station to the mobile station, a response message comprising control information, wherein the control information contains information that is needed by the mobile station to further communicate with the base station.

8. The method of claim 1, wherein the access request message comprises a mobile station identifier associated with the mobile station.

9. The method of claim 1, wherein the access request message comprises information identifying the position of the mobile station.

10. A method at a mobile station, comprising

(a) generating an access request message to be sent on an access frequency;

(b) sending the access request message at a pre-determined time instant referenced to a time of day value obtained from an adjunct timing system.

11. The method of claim 10, further comprising

determining a time of day value using a signal from an adjunct timing system;

and

determining the pre-determined time instant using an elapsed time from the time of day value, wherein the elapsed time is calculated using a timer at the mobile station.

12. The method of claim 11, further comprising:

determining the location of the mobile station using a locating system; and

selecting an access frequency based on the determined location of the mobile station, wherein the step of sending the access request message comprises sending the access request message using the selected access frequency.

13. The method of claim 12, wherein the step of selecting an access frequency comprises using information indicating the determined location of the mobile station to retrieve from a database information identifying an access frequency.

14. A method at a radio network controller (RNC) in communication with a set of base stations, the method comprising:

receiving, from each one of the base stations, a control message sent by the base station in response to the base station receiving an access request message from a mobile station;

selecting a base station from the set of base stations, wherein the selection is based on, at least in part, the location of the base stations, the location of the mobile station, and/or the quality of the access request messages received by the base stations;

transmitting a command message to the selected base station, wherein the command message causes the base station to transmit to the mobile station a response message comprising control information.

15. The method of claim 14, wherein, for each control message, the control message comprises information indicating the quality of the access request message received by the base station.

16. The method of claim 14, wherein, for each control message, the control message comprises information indicating the position of the mobile station.

17. The method of claim 14, wherein, for each control message, the control message comprises:

(a) information indicating the quality of the access request message received by the base station; and

(b) information indicating the position of the mobile station.

18. A base station, comprising:

a transmitter configured such that it transmits control information on a discontinuous basis; and

an access message receiver, wherein

the base station is configured such that the access message receiver is activated on a discontinuous basis, and

the access message receiver is operable to detect an access request message transmitted from a mobile station on an access frequency.

19. The base station of claim 18, wherein the base station is configured such that the access message receiver is activated at pre-determined time instants and deactivated at other predetermined time instants.

20. The base station of claim 19, further comprising:

a receiver for receiving signals from an adjunct timing system, wherein

the pre-determined time instants are referenced to a time of day value obtained by the base station from (i) the adjunct timing system, or (ii) a local clock that is calibrated using a signal transmitted from the adjunct timing system.

21. The base station of claim 18, further comprising a controller, wherein the controller is configured such that after the access message receiver detects the access request message, the controller causes the transmitter to transmit to the mobile station a response message comprising control information, wherein the control information contains information that is needed by the mobile station to further communicate with the base station.

22. The base station of claim 18, further comprising:

a controller for determining the load on the base station, wherein

the controller is configured such that, in response to the controller determining that the load exceeds a threshold, the controller causes the transmitter to frequently broadcast the control information until the load on the base station falls below a threshold.

23. The base station of claim 18, further comprising a controller, wherein

the controller is configured such that, in response to the access message receiver detecting the access request message, the controller (a) determines the quality of the access request message;

(b) determines whether the determined quality of the access request message exceeds a threshold, and (c) in response to determining that the quality exceeds the threshold, causes the transmitter to transmit to the mobile station a response message comprising control information, wherein the control information contains information that is needed by the mobile station to further communicate with the base station.

24. The base station of claim 18, further comprising a controller, wherein the controller is configured such that, in response to the access message receiver detecting the access request message, the controller (a) determines the quality of the access request message;

(b) transmits to a radio network controller a control message indicating the quality of the access request message;

(c) receives from the radio network controller a command message sent in response to the control message; and

(d) in response to receiving the command message, cause the transmitter to transmit to the mobile station a response message comprising control information, wherein the control information contains information that is needed by the mobile station to further communicate with the base station.

25. The base station of claim 18, wherein the access request message comprises a mobile station identifier associated with the mobile station.

26. The base station of claim 18, wherein the access request message comprises information identifying the position of the mobile station.

27. A mobile station, comprising:

a receiver operable to receive signals transmitted from an adjunct timing system;

a data processing system; and

a transmitter, wherein

the data processing system is operable to generate an access request message, and

the data processing system is configured to use the transmitter to send the access request message at a pre-determined time instant referenced to a time of day value obtained from the adjunct timing system.

28. The mobile station of claim 27, further comprising a local clock, and the data processing system is configured to:

determine a time of day value using a signal from the adjunct timing system; and

determine the pre-determined time instant using an elapsed time from the time of day value, wherein the elapsed time is determined using the local clock.

29. The mobile station of claim 27, wherein the data processing system is configured to:

determine the location of the mobile station using a locating system,

select an access frequency based on the determined location of the mobile station,

use the transmitter to send the access request message using the selected access frequency.

30. The mobile station of claim 29, wherein the data processing system is configured to select the access frequency by using information indicating the determined location of the mobile station to retrieve from a database information identifying an access frequency.

31. A radio network controller (RNC), comprising:

a transmit and receive circuit operable to receive, from each one of a set of base stations, a control message sent by the base station in response to the base station receiving an access request message from a mobile station; and

a data processing system configured to select a base station from the set of base stations in response to receiving the control messages, wherein the selection is based on, at least in part, the location of the base stations, the location of the mobile station, and/or the quality of the access request messages received by the base stations, wherein

the data processing system is further configured to use the transmit and receive circuit to transmit a command message to the selected base station, wherein the command message is configured to cause the base station to transmit to the mobile station a response message comprising control information.

32. The RNC of claim 31, wherein, for each control message, the control message comprises information indicating the quality of the access request message received by the base station.

33. The RNC of claim 31, wherein, for each control message, the control message comprises information indicating the position of the mobile station.

34. The RNC of claim 31, wherein, for each control message, the control message comprises:

(a) information indicating the quality of the access request message received by the base station; and

(b) information indicating the position of the mobile station.