System and method for adaptive beamforming for specific absorption rate control
View Patent ↗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.
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.