Determining transmit power limits using a combined specific absorption measurement for multiple transmitters

Patent metadata

Field	Value
Publication number	US-2016174162-A1
Application number	US-201414572214-A
Country	US
Kind code	A1
Filing date	Dec 16, 2014
Priority date	Dec 16, 2014
Publication date	Jun 16, 2016
Grant date	—

Abstract

A method and apparatus for determining transmit power limits for multiple transmitter devices is provided. The method begins when a two-dimensional area scan and a localized three-dimensional volume scan are performed for each transmitter and antenna. These two-dimensional area scans are converted to a three-dimensional full volume data using analytical estimations to determine the peak averaged SAR value, and subsequently determining the error associated with the analytical estimation. The error associated with the analytical estimation is determined by comparison with the measured value. The combined peak averaged SAR may then be determined for simultaneous transmissions of multiple transmitters with varying transmit powers by combining the scaled and analytically determined three-dimensional full volume data for each transmitter. The value is then further scaled by the worst-case conversion error for all active transmitters. This value is compared with the SAR limit and the maximum allowable transmit power determined for the multiple transmitters.

First claim

What is claimed is:

1 . A method of determining transmit power limits for multiple transmitters, comprising:
performing a two-dimensional area scan for each transmitter; performing a localized three-dimensional volume scan for each transmitter; converting each two-dimensional area scan into a three-dimensional volume scan; determining an error for each converted scan; and determining a combined worst-case error for the multiple transmitters.

2 . The method of claim 1 , wherein the area scan is a scan of a phantom.

3 . The method of claim 1 , wherein the error for each conversion is determined by comparing peak specific absorption ratio (SAR) values for each transmitter.

4 . The method of claim 1 , wherein the converting each two-dimensional area scan into a three-dimensional volume scan uses an analytical technique.

5 . The method of claim 1 , wherein the scan performed for each transmitter is a two-dimensional area scan.

6 . The method of claim 1 , wherein three-dimensional volume scans are averaged to produce an average two-dimensional specific absorption rate (SAR) distribution for each transmitter.

7 . The method of claim 6 , further comprising:
scaling each three-dimensional scan with a varying transmit power; scaling an average two-dimensional specific absorption rate (SAR) with varying transmit power; and
determining a maximum transmit power limit for a secondary antenna based on a given primary antenna.

8 . The method of claim 7 , wherein determining the maximum transmit power is based on a combined specific absorption ratio (SAR).

9 . The method of claim 8 , wherein the combined SAR value is scaled by a worst-case two-dimensional area scan to a three-dimensional volume data conversion error.

10 . The method of claim 8 , wherein the combined SAR is determined by averaging on three-dimensional volume scans to determine a peak two-dimensional averaged SAR distribution.

11 . The method of claim 7 , wherein determining a maximum transmit power is based on a look-up table.

12 . The method of claim 7 , wherein determining a maximum transmit power is based on a look-up curve.

13 . The method of claim 11 , wherein the look-up table is generated on a wireless device.

14 . The method of claim 12 , wherein the look-up curve is generated on a wireless device.

15 . An apparatus for determining transmit limits for multiple transmitters, comprising:
a wireless device having at least two transmitters and at least one antenna; and a processor for determining transmit power limits.

16 . The apparatus of claim 15 , wherein the processor determining transmit power limits generates a look-up table or look-up curve in real time by monitoring transmit power of a primary antenna in a modem.

17 . An apparatus for determining transmit power limits for multiple transmitters, comprising:
means for performing a two-dimensional area scan for each transmitter; means for converting each two-dimensional area scan into a three dimensional volume scan; means for determining an error for each converted scan; and means for determining a combined worst-case error for the multiple transmitters.

18 . The apparatus of claim 17 , wherein the means for determining an error for each converted scan includes means for comparing peak specific absorption ratio (SAR) values for each transmitter.

19 . The apparatus of claim 17 , wherein the apparatus for determining transmit power limits further comprises:
means for scaling each three-dimensional volume scan with a varying transmit scan; and means for determining a maximum transmit power limit for a secondary antenna based on a given primary antenna.

20 . The apparatus of claim 19 , further comprising:
means for computing a combined specific absorption ratio (SAR) by scaling a difference between a SAR limit to a three-dimensional volume data conversion.

Assignees

• Qualcomm Inc

Inventors

• Nadakuduti Jagadish
• Lu Lin
• Guckian Paul

Classifications

• H04W24/02

  Arrangements for optimising operational condition · CPC title

• H04W52/18 Primary

  TPC being performed according to specific parameters · CPC title

• H04B1/3838 Primary

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

• H04B17/102

  Power radiated at antenna · CPC title

• H04W52/367

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