Real-time specific absorption rate implementation in wireless devices

Patent metadata

Field	Value
Publication number	US-9622187-B2
Application number	US-201615052378-A
Country	US
Kind code	B2
Filing date	Feb 24, 2016
Priority date	Aug 26, 2015
Publication date	Apr 11, 2017
Grant date	Apr 11, 2017

Abstract

Embodiments disclosed herein provide a method and apparatus for optimizing time-averaged transmitter power of a communications device. A time-averaged SAR is computed over a predefined time window using past transmitter power levels with minimum transmitter power equal to reserve transmitter power for any time interval. Based on the time-averaged SAR a maximum allowable transmitter power for a future fixed time interval is determined. The communication device then transmits at a power equal to or less than the maximum allowable transmitter power. The communication device may back off from high transmitter power to a reserve transmitter power when calculated time-averaged SAR approaches the SAR limit. When old high power transmissions expire, the communication device gains SAR margin and may then transmit at high power. The apparatus comprises: at least one antenna, a transmitter in communication with a power supply, a receiver, a timer in communication with a processor, and a memory.

First claim

What is claimed is:

1. A method for optimizing time-averaged transmitter power, comprising:
computing a time-averaged specific absorption rate (SAR) over a predefined time window;
determining a maximum allowable transmitter power level for a future fixed time interval;
transmitting at the maximum allowable transmitter power level or at a level less than the maximum allowable transmitter power level for a current fixed time interval;
reducing a transmitter power level based on the computed time-averaged SAR value; and
computing and storing a current average transmit power for the current fixed time interval.

2. The method of claim 1 , wherein the predefined time window is six minutes and the fixed time interval is five seconds.

3. The method of claim 1 , wherein reducing the transmitter power level to a reserve power level occurs when the computed time-averaged SAR value approaches a SAR limit within the predefined time window.

4. The method of claim 1 , wherein optimizing time-averaged transmitter power occurs every fixed time interval.

5. The method of claim 1 , wherein determining a maximum allowable transmitter power level for a future time interval is a based on a SAR margin.

6. The method of claim 5 , wherein the SAR margin is a difference between a SAR limit and the computed time-averaged SAR value.

7. The method of claim 5 , further comprising:
ensuring that the transmitter power level does not exceed the determined maximum allowable transmitter power.

8. The method of claim 5 , wherein the determined maximum allowable transmitter power is equal to a reserve transmit power.

9. The method of claim 5 , wherein the time-averaged SAR is calculated by treating all transmit powers below the reserve transmitter power as reserve transmitter power values.

10. The method of claim 1 , wherein the time-averaged SAR is computed every fixed time interval.

11. The method of claim 10 , wherein the time-averaged SAR is computed in at least one frequency band.

12. The method of claim 1 , wherein computing a SAR over a predefined time window incorporates subtracting a constant relative SAR margin.

13. The method of claim 12 , wherein the constant relative SAR margin corresponds to a reserve transmitter power.

14. A communication device, comprising:
at least one antenna;
a transmitter in communication with the at least one antenna; and
a processor in communication with a memory, the processor configured to:
perform a time-averaged specific absorption rate (SAR) assessment over a predetermined time window;
determine an available SAR margin;
determine a maximum allowable transmit power for a next fixed time interval based on the available SAR margin; and

limit transmission power of the transmitter to the maximum allowable transmit power during the next fixed time interval.

15. The apparatus of claim 14 , wherein the processor is further configured to:
limit the transmission power to a reserve transmit power level when the available SAR margin is zero.

16. The apparatus of claim 14 , wherein the available SAR margin comprises a difference between a SAR limit and the time-averaged SAR.

17. The apparatus of claim 14 , wherein the time-averaged SAR assessment is based on transmit power levels of transmission which occurred prior to the next fixed time interval during the predetermined time window.

18. The apparatus of claim 14 , wherein the time-averaged SAR assessment is performed every fixed time interval over the predetermined time window.

19. The apparatus of claim 14 , wherein the processor is further configured to:
determine an actual transmission power that occurred during the next fixed time interval; and
update the time-average SAR assessment based on the actual transmission power.

20. An apparatus, comprising:
means for computing a time-averaged specific absorption rate (SAR) over a predefined time window;
means for determining a maximum allowable transmitter power level for a future fixed time interval;
means for transmitting at the maximum allowable transmitter power level or at a level less than the maximum allowable transmitter power level for a current fixed time interval;
means for reducing a transmitter power level based on the computed time-averaged SAR value; and
means for computing and storing a current average transmit power for the current fixed time interval.

21. The apparatus of claim 20 , wherein the means for computing a time-averaged SAR over a predefined time window uses a predefined time window of six minutes and a fixed time interval of five seconds.

22. The apparatus of claim 20 , wherein the means for reducing a transmitter power level based on the computed time-averaged SAR value incorporates means for reducing the transmitter power to a reserve power level when the computed time-averaged SAR value approaches a SAR limit within the predefined time window.

23. The apparatus of claim 20 , wherein the means for computing a time-averaged SAR includes means for computing a time-averaged SAR value includes means for computing a SAR margin.

24. The apparatus of claim 23 , further comprising: means for ensuring that the transmitter power level does not exceed the determined maximum allowable transmitter power.

25. The apparatus of claim 20 , wherein the means for computing a time-averaged SAR includes means for subtracting a constant relative SAR margin.

26. A non-transitory computer-readable medium containing instructions, which when executed cause a processor to perform the following steps:
computing a time-averaged specific absorption rate (SAR) over a predefined time window;
determining a maximum allowable transmitter power level for a future fixed time interval;
transmitting at the maximum allowable transmitter power level or at a level less than the maximum allowable transmitter power level for a current fixed time interval;
reducing a transmitter power level based on the computed time-averaged SAR value; and
computing and storing a current average transmit power for the current fixed time interval.

27. The non-transitory computer-readable medium of claim 26 , further comprising instructions for computing a time-averaged SAR over the predetermined window of six minutes and the fixed time interval of five seconds.

28. The non-transitory computer-readable medium of claim 26 , further comprising instructions for reducing the transmitter power level to a reserve power level when the computed time-averaged SAR value approaches a SAR limit within the predefined time window.

29. The non-transitory computer-readable medium of claim 26 , further comprising instructions for optimizing the time-averaged transmitter power every fixed time interval.

30. The non-transitory computer-readable medium of claim 26 , wherein the time-averaged SAR is calculated by treating all transmit powers below a reserve transmit power as reserve transmitter power values.

Assignees

• Qualcomm Inc

Inventors

• Logan Theodore
• Nadakuduti Jagadish
• Lu Lin
• Guckian Paul

Classifications

• H04W52/36

  with a discrete range or set of values, e.g. step size, ramping or offsets · CPC title

• H04W52/18 Primary

  TPC being performed according to specific parameters · CPC title

• H04W52/226

  using past references to control power, e.g. look-up-table · CPC title

• H04W52/367 Primary

  Power values between minimum and maximum limits, e.g. dynamic range · CPC title