System and method for adaptive beamforming for specific absorption rate control

• US 8,630,596 B2
• Filed: 05/08/2013
• Issued: 01/14/2014
• Est. Priority Date: 09/08/2009
• Status: Active Grant

• Current Assignee: Google LLC (Alphabet Inc.)
• Original Assignee: Google Inc. (Alphabet Inc.)
• Inventors: Harel, Haim, Kludt, Kenneth, Chen, Phil F.
• Primary Examiner(s): VO, NGUYEN THANH
• Application Number:
  US13/889,918
• Publication Number:
  US 20130271322A1
• Time in Patent Office: 251 Days
• Field of Search: 455/63.4, 455/562.1, 455/575.7, 455/103, 455/117, 455/126, 455/101, 455/129, 455/115.1, 455/115.3, 342/360, 342/368
• US Class Current: 455/117
• CPC Class Codes: H01Q 3/00 Arrangements for changing or varying the orientation or the shape of the directional pattern of the waves radiated from an antenna or antenna system means for positioning H01Q1/125
• CPC Class Codes: H01Q 3/2605 Array of radiating elements provided with a feedback control over the element weights, e.g. adaptive arrays
• CPC Class Codes: H04B 1/3838 Arrangements for reducing RF exposure to the user, e.g. by changing the shape of the transceiver while in use
• CPC Class Codes: H04B 17/103 Reflected power, e.g. return loss
• CPC Class Codes: H04B 7/0404 the mobile station comprising multiple antennas, e.g. to provide uplink diversity
• CPC Class Codes: H04B 7/0617 for beam forming
• CPC Class Codes: H04B 7/0689 using different transmission schemes, at least one of them being a diversity transmission scheme
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

A system may include a modifiable mobile device having at least two antennas coupled to fractional amplifiers, with returned power detectors. A beamformer unit provides adaptive beam shaping pattern, and a baseband processor provides beam pattern requirements, wherein the beamformer unit modifies the beam pattern requirements with return loss sampling information to shape the adaptive beam pattern so that a transmitted beam pattern minimizes transmitted power reflected back to the mobile device. A method may include regularly measuring a return power level, if output power is greater than a specific absorption rate level, comparing the return power level to a first threshold, else implementing mobile transmit diversity (MTD), and repeating. If the return power level is greater than the first threshold, implementing a MTD combined with reflection-based beamforming that modifies beam pattern requirements of the mobile device with return loss sampling information to create an adaptive beam pattern.

Claims

1. A system comprising:

a modifiable mobile communication device including;

a first antenna coupled by a first transmission path to a first fractional power amplifier;

a second antenna coupled by a second transmission path to a second fractional power amplifier;

a first returned power detector coupled to the first transmission path, and a second returned power detector coupled the second transmission path;

a beamformer unit configured to provide an adaptive beam shaping pattern to the first and second fractional power amplifiers, the adaptive beam shaping pattern configured to shape a transmitted beam pattern to minimize an amount of transmitted power reflected back to at least one of the first and second antennas; and

a baseband processor configured to provide beam pattern requirements to the beamformer unit;

wherein the first and second returned power detectors provide return loss sampling information to the beamformer unit.

2. The system of claim 1, wherein the beamformer unit is configured to modify the beam pattern requirements with the return loss sampling information to determine the adaptive beam shaping pattern.

3. The system of claim 1, wherein the at least two antennas are each one of a single radiating element and an array of radiating elements.

4. The system of claim 1, further including a radio frequency transmitter disposed between the beamformer unit and the baseband processor.

5. The system of claim 1, further including at least two radio frequency transmitters disposed between the beamformer unit and first and second fractional power amplifiers.

6. The system of claim 1, wherein a radiated beam pattern of the modifiable communication device is modified by the adaptive beam shaping pattern so as to reduce a user'"'"'s exposure to radiated energy from the first and second antennas.

7. The system of claim 1, wherein the beamformer unit is configured to provide an adaptive beam pattern at regular timing intervals based on updated return loss sampling information.

8. The system of claim 1, wherein the amount of transmitted power reflected to at least one of the first and second antennas is less than a predefined specific absorption rate.

9. The system of claim 1, wherein the beamformer unit comprises a processor.

10. The system of claim 1, wherein the beamformer unit comprises a field programmable array.

11. The system of claim 1, wherein the first returned power detector comprises a solid state device.

12. The system of claim 11, wherein the solid state device is selected from the group consisting of:

a circulator, a diode, and a crystal.

13. The system of claim 1, wherein the first returned power detector is adapted to provide sampling information to the beamformer unit.

14. The system of claim 13, wherein the sampling information includes information from the group consisting of:

amplitude of return loss signals and phase of return loss signals.

15. The system of claim 1, wherein the first antenna is an antenna selected from the group consisting of:

a monopole antenna, a dipole antenna, a loop antenna, a patch antenna, a microstrip antenna, and a dielectric antenna.