METHOD AND APPARATUS FOR CONTROLLING POWER TRANSMISSION LEVELS FOR A MOBILE STATION HAVING TRANSMIT DIVERSITY

• US 20090047998A1
• Filed: 08/16/2007
• Published: 02/19/2009
• Est. Priority Date: 08/16/2007
• Status: Abandoned Application

• Current Assignee: Motorola Mobility, Inc. (Lenovo Group Ltd.)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: ALBERTH, WILLIAM P. JR.
• Application Number:
  US11/840,128
• Publication Number:
  US 20090047998A1
• Time in Patent Office: Days
• US Class Current: 455/562.100
• CPC Class Codes: H04W 52/367 Power values between minimum and maximum limits, e.g. dynamic range
• CPC Class Codes: H04W 52/42 in systems with time, space, frequency or polarisation diversity

Abstract

A mobile communication device (100) of the embodiments will have a transmit diversity antenna system (613) that will comprise at least two antennas and processor/s (607) that will run a transmit diversity control module (609) for controlling transmit diversity output power. Using a power curve, the mobile communication device (100) determines whether a threshold, corresponding to an SAR value, is or may be exceeded. If the SAR threshold is not exceeded given various determined environmental conditions, the mobile communication device (100) continues transmit diversity operation. However, if SAR is about to be exceeded, or is exceeded, the mobile communication device (100) will take action and either reduce overall power, reduce power to one of the transmit diversity antennas, or deactivate one of the transmit diversity antennas in order to bring the SAR level back below the threshold.

Claims

1. A method of operating a mobile station, said mobile station having at least two antennas for operating in a transmit diversity mode, the method comprising:

operating said mobile station in a transmit diversity mode;

monitoring an output of said mobile station;

comparing said output to a power curve;

determining that said output will exceed a threshold based on said power curve; and

adjusting a parameter to bring said output within said threshold.

2. The method of claim 1, further comprising:

monitoring a sensor of said mobile station;

determining that said mobile station is against a user'"'"'s ear based on an output of said sensor.

3. The method of claim 1, wherein monitoring said output further comprises:

monitoring at least one of power output or phase angle.

4. The method of claim 1, wherein determining that said output will exceed a threshold based on said power curve, further comprises:

determining that said output will exceed a Specific Absorption Rate (SAR) threshold.

5. The method of claim 1, wherein adjusting a parameter to bring said output within said threshold, further comprises:

reducing overall power output of said mobile station while operating in said transmit diversity mode.

6. The method of claim 1, wherein adjusting a parameter to bring said output within said threshold, further comprises:

reducing power to one of said at least two antennas while operating in said transmit diversity mode.

7. The method of claim 1, wherein adjusting a parameter to bring said output within said threshold, further comprises:

changing the phase angle between said at least two antennas while operating in said transmit diversity mode.

8. The method of claim 1, wherein adjusting a parameter to bring said output within said threshold, further comprises:

deactivating said transmit diversity mode and operating in a single antenna mode.

9. The method of claim 1, wherein adjusting a parameter to bring said output within said threshold, further comprises:

restricting a relationship parameter, said relationship parameter defining a difference between a first input signal and a second input signal, applied respectively to a first antenna and a second antenna of said at least two antennas, said difference being limited by said restricting said relationship parameter.

10. A mobile station comprising:

a transmit diversity antenna system having at least two antennas, said transmit diversity antenna system for transmitting at least two identical signals over said at least two antennas wherein one of said at least two identical signals is phase shifted from the other of said at least two identical signals; and

a processor coupled to said transmit diversity antenna system, said processor configured to operate said mobile station in a transmit diversity mode, monitor an output of said mobile station, compare said output to a predetermined power curve, determine that said output will exceed a threshold based on said power curve; and

adjust a parameter to bring said output within said threshold.

11. The mobile station of claim 10, further comprising:

a sensor coupled to said processor, said sensor for providing an indication that said mobile station is against a user'"'"'s body.

12. The mobile station of claim 10, wherein said processor is further configured to monitor said output by monitoring at least one of power output or phase angle.

13. The mobile station of claim 10, wherein said processor is further configured to determine that said output will exceed a threshold based on said power curve by determining that said output will exceed a Specific Absorption Rate (SAR) threshold.

14. The mobile station of claim 10, wherein said processor is further configured to adjust a parameter to bring said output within said threshold by reducing overall power output of said mobile station while operating in said transmit diversity mode.

15. The mobile station of claim 10, wherein said processor is further configured to adjust a parameter to bring said output within said threshold by reducing power to one of said at least two antennas while operating in said transmit diversity mode.

16. The mobile station of claim 10, wherein said processor is further configured to adjust a parameter to bring said output within said threshold by changing the phase angle between said two identical signals while operating in said transmit diversity mode.

17. The mobile station of claim 10, wherein said processor is further configured to adjust a parameter to bring said output within said threshold by deactivating said transmit diversity mode and operating in a single antenna mode.