Method and apparatus for transmission power control

• US 7,245,935 B2
• Filed: 11/10/2003
• Issued: 07/17/2007
• Est. Priority Date: 12/17/2002
• Status: Active Grant

• Current Assignee: Google Technology Holdings LLC (Alphabet Inc.)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Lin, Jie
• Primary Examiner(s): Maung; Nay
• Assistant Examiner(s): NGUYEN, TUAN HOANG
• Application Number:
  US10/533,280
• Publication Number:
  US 20060040696A1
• Time in Patent Office: 1,345 Days
• Field of Search: 455/13.4, 455/522, 455/68, 455/69, 455/127.1
• US Class Current: 455/522
• CPC Class Codes: H04W 52/24 using SIR [Signal to Interference Ratio] or other wireless path parameters
• CPC Class Codes: H04W 52/26 using transmission rate or quality of service QoS [Quality of Service]
• CPC Class Codes: H04W 52/34 TPC management, i.e. sharing limited amount of power among users or channels or data types, e.g. cell loading
• CPC Class Codes: H04W 52/367 Power values between minimum and maximum limits, e.g. dynamic range
• CPC Class Codes: H04W 52/44 in connection with interruption of transmission

Abstract

The invention relates to a system for power control in a cellular communication system. The power control may be operated (201) in a first mode of operation wherein power control data are determined in response to a quality parameter, such as a desired signal to noise ratio. The method further comprises entering (205) a reduced power mode of operation by communicating power down power control data between a base station and a communication unit. The base station and/or communication unit then proceeds to operate (207) in the reduced power mode by communicating power control data corresponding to a reduced transmit power level. The reduced transmit power level may specifically be zero. After a given duration, the base station and/or communication unit proceeds to exit (211) the reduced power mode by communicating power up power control data between the base station and the communication unit.

Claims

1. A method of power control for a transmitter in a cellular communication system comprising the steps of:

determining power control data in response to a quality parameter of a communication between a base station and a communication unit;

communicating the power control data between the base station and the communication unit;

determining that a transmit power of the transmitter exceeds a threshold;

determining that a quality level of the communication between the communication unit and the base station cannot be achieved when the transmit power of the transmitter exceeds the threshold;

in response to determining that a quality level of the communication between the communication unit and the base station cannot be achieved when the transmit power of the transmitter exceeds the threshold, entering a reduced power mode of operation by communicating power down power control data between the base station and the communication unit;

operating in the reduced power mode by communicating power control data corresponding to a reduced transmit power level that allows communication at a reduced data rate between the communication unit and the base station; and

exiting the reduced power mode when a quality characteristic of a data communication between the communication unit and the base station is improving by communicating power up power control data between the base station and the communication unit.

2. A method as claimed in claim 1 wherein the power control is an uplinik power control and the power control data is transmitted from the base station to the communication unit.

3. A method as claimed in claim 1 wherein the power control is a downlink power control and the power control data is transmitted from the communication unit to the base station.

4. A method as claimed in claim 1 wherein the reduced transmit power level is substantially zero.

5. A method as claimed in claim 1 wherein the power control data communicated in the reduced power mode is power down control values.

6. A method as claimed in claim 1 wherein the step of exiting comprises transmitting power up power control data until the transmit power corresponds to a power level determined in response to the quality parameter.

7. A method as claimed in claim 1 wherein the step of exiting comprises transmitting power up power control data until the transmit power corresponds to a power level corresponding to the power level prior to entering the reduced power mode.

8. A method as claimed in claim 1 wherein a duration of the reduced power mode is less than a data re-transmission interval associated with the communication between the communication unit and the base station.

9. A method as claimed in claim 1 further comprising the step of determining that an interference level exceeds a threshold and in response entering the reduced power mode.

10. A method as claimed in claim 1 further comprising the step of determining that a propagation characteristic exceeds a threshold and in response entering the reduced power mode.

11. A method as claimed in claim 10 wherein the propagation characteristic is a path loss of a communication link supporting the communication between the communication unit and the base station.

12. A method as claimed in claim 1 further comprising the step of determining that a duration of the reduced power mode exceeds a threshold and in response exiting the reduced power mode.

13. A method as claimed in claim 1 further comprising the step of determining that an interference level is below a threshold and in response exiting the reduced power mode.

14. A method as claimed in claim 1 further comprising the step of determining that a propagation characteristic is below a threshold and in response exiting the reduced power mode.

15. A method as claimed in claim 14 wherein the propagation characteristic is a path loss of a communication link supporting the communication between the communication unit and the base station.

16. A method as claimed in claim 1 further comprising the steps of:

determining an expected interference level for a plurality of communication units including the communication unit;

determining a total expected interference level; and

entering the communication unit into the reduced power mode if the total expected interference level exceeds a threshold.

17. An apparatus for power control for a transmitter in a cellular communication system, the apparatus comprising:

means for determining power control data in response to a quality parameter of a communication between a base station and a communication unit;

means for communicating the power control data between the base station and the communication unit;

means for determining that a transmit power of the transmitter exceeds a threshold;

means for determining that a quality level of the communication between the communication unit and the base station cannot be achieved when the transmit power of the transmitter exceeds the threshold;

means for entering a reduced power mode of operation by communicating power down power control data between the base station and the communication unit, in response to the determining that a quality level of the communication between the communication unit and the base station cannot be achieved when the transmit power of the transmitter exceeds the threshold;

means for operating in the reduced power mode by communicating power control data corresponding to a reduced transmit power level that allows communication at a reduced data rate between the communication unit and the base station; and

means for exiting the reduced power mode when a quality characteristic of a data communication between the communication unit and the base station is improving by communicating power up power control data between the base station and the communication unit.