Evaluating radio frequency (RF) exposure in real time

Patent metadata

Field	Value
Publication number	US-11457416-B2
Application number	US-202117141150-A
Country	US
Kind code	B2
Filing date	Jan 4, 2021
Priority date	Jul 5, 2018
Publication date	Sep 27, 2022
Grant date	Sep 27, 2022

Abstract

In certain aspects, a method implemented in a wireless device includes determining a specific absorption rate (SAR) distribution for a first wireless communication technology, determining a power density (PD) distribution for a second wireless communication technology, and combining the SAR distribution and the PD distribution to generate a combined RF exposure distribution. The method also includes determining at least one first maximum allowable power level and at least one second maximum allowable power level for a future time slot based on the combined RF exposure distribution, setting at least one transmission power limit for a first transmitter in the future time slot based on the at least one first maximum allowable power level, and setting at least one transmission power limit for a second transmitter in the future time slot based on the at least one second maximum allowable power level.

First claim

What is claimed is:

1. A wireless device, comprising:
a transmitter; and
a processor coupled to the transmitter, wherein the processor is configured to:
receive a power density (PD) limit for a time slot, the time slot comprising sub-time slots;
determine a PD allocation for the time slot based on the PD limit;
determine a maximum allowable power level for one of the sub-time slots based on a portion of the PD allocation used up by one or more of the sub-time slots preceding the one of the sub-time slots; and
set a transmission power limit for the transmitter based on the maximum allowable power level.

2. The wireless device of claim 1 , wherein, during the one of the sub-time slots, the transmitter is configured to transmit a signal at a transmission power level equal to or less than the transmission power limit.

3. The wireless device of claim 1 , wherein the determination by the processor of the PD allocation for the time slot comprises multiplying the PD limit by a number of the sub-time slots.

4. The wireless device of claim 1 , wherein the processor is configured to determine the PD allocation used up by the one or more of the sub-time slots preceding the one of the sub-time slots.

5. The wireless device of claim 4 , wherein the determination by the processor of the PD allocation used up by the one or more of the sub-time slots preceding the one of the sub-time slots comprises summing PDs of the one or more of the sub-time slots preceding the one of the sub-time slots.

6. The wireless device of claim 1 , wherein the processor is further configured to:
determine a portion of the PD allocation reserved for one or more of the sub-time slots succeeding the one of the sub-time slots; and
determine the maximum allowable power level for the one of the sub-time slots based also on the portion of the PD allocation reserved for the one or more of the sub-time slots succeeding the one of the sub-time slots.

7. The wireless device of claim 6 , wherein the determination by the processor of the portion of the PD allocation reserved for the one or more of the sub-time slots succeeding the one of the sub-time slots comprises multiplying a reserved PD by a number of the one or more of the sub-time slots succeeding the one of the sub-time slots.

8. The wireless device of claim 7 , wherein the processor is configured to determine the reserved PD based on the PD limit and a reserve ratio.

9. The wireless device of claim 8 , wherein the determination by the processor of the reserved PD comprises multiplying the PD limit by the reserve ratio.

10. The wireless device of claim 8 , wherein the processor is configured to set the reserve ratio based on at least one of a channel condition between the wireless device and another wireless device, or a scheduled data transmission for the wireless device.

11. The wireless device of claim 1 , wherein the determination by the processor of the maximum allowable power level for the one of the sub-time slots comprises:
determining an allowed PD for the one of the sub-time slots based on the portion of the PD allocation used up by the one or more of the sub-time slots preceding the one of the sub-time slots;
retrieving a transmission power level from a memory, the transmission power level corresponding to a reference PD; and
determining the maximum allowable power level for the one of the sub-time slots based on the retrieved transmission power level, the allowed PD, and the reference PD.

12. The wireless device of claim 11 , wherein the determination by the processor of the maximum allowable power level for the one of the sub-time slots based on the retrieved transmission power level, the allowed PD, and the reference PD comprises scaling the retrieved transmission power level by a ratio of the allowed PD to the reference PD.

13. The wireless device of claim 1 , wherein the processor is configured to:
determine a time-averaged radio frequency (RF) exposure distribution; and
determine the PD limit for the time slot based on the time-averaged RF exposure distribution.

14. The wireless device of claim 13 , wherein the determination of the time-averaged RF exposure distribution by the processor comprises:
determining a time-averaged specific absorption (SAR) distribution over a first time window;
determining a time-averaged power density (PD) distribution over a second time window; and
combining the time-averaged SAR distribution and the time-averaged PD distribution to generate the time-averaged RF exposure distribution.

15. The wireless device of claim 14 , wherein the first time window and the second time window have different lengths.

16. The wireless device of claim 13 , wherein the time-averaged RF exposure distribution comprises a time-averaged power density (PD) distribution.

17. A method implemented in a wireless device, comprising:
receiving a power density (PD) limit for a time slot, the time slot comprising sub-time slots;
determining a PD allocation for the time slot based on the PD limit;
determining a maximum allowable power level for one of the sub-time slots based on a portion of the PD allocation used up by one or more of the sub-time slots preceding the one of the sub-time slots; and
setting a transmission power limit for a transmitter based on the maximum allowable power level.

18. The method of claim 17 , further comprising:
determining a time-averaged radio frequency (RF) exposure distribution; and
determining the PD limit for the time slot based on the time-averaged RF exposure distribution.

19. The method of claim 18 , wherein determining the time-averaged RF exposure distribution comprises:
determining a time-averaged specific absorption (SAR) distribution over a first time window;
determining a time-averaged power density (PD) distribution over a second time window; and
combining the time-averaged SAR distribution and the time-averaged PD distribution to generate the time-averaged RF exposure distribution.

20. A wireless device, comprising:
a transmitter; and
a processor coupled to the transmitter, wherein the processor is configured to:
determine a time-averaged radio frequency (RF) exposure distribution over time slots;
determine an RF exposure limit for one of the time slots based on the time-averaged RF exposure distribution over the time slots, the one of the time slots comprising sub-time slots;
determine a time-averaged RF exposure distribution within the one of the time slots;
determine a maximum allowable power level for one of the sub-time slots based on the RF exposure limit and the time-averaged RF exposure distribution within the one of the time slots; and
set a transmission power limit for the transmitter based on the maximum allowable power level.

21. The wireless device of claim 20 , wherein the determination of the time-averaged RF exposure distribution over the time slots by the processor comprises:
determining a time-averaged specific absorption (SAR) distribution over a first time window;
determining a time-averaged power density (PD) distribution over a second time window; and
combining the time-averaged SAR distribution and the time-averaged PD distribution to generate the time-averaged RF exposure distribution over the time slots.

22. The wireless device of claim 21 , wherein the first time window and the second time window have different lengths.

23. The wireless device of claim 21 , wherein the time-averaged SAR distribution corresponds

Assignees

• Qualcomm Inc

Inventors

• Nadakuduti Jagadish
• Lu Lin
• Guckian Paul
• Cai Mingming
• Han Junsheng
• Fernando Udara
• Challa Raghu

Classifications

• H04B1/3838

  Arrangements for reducing RF exposure to the user, e.g. by changing the shape of the transceiver while in use · CPC title

• H04W52/38

  TPC being performed in particular situations · CPC title

• H04W52/225 Primary

  Calculation of statistics, e.g. average or variance · CPC title

• H04W88/06

  adapted for operation in multiple networks {or having at least two operational modes}, e.g. multi-mode terminals · CPC title

• H04W52/12

  Outer and inner loops · CPC title