Transmit Chain Phase Amplitude Control for SAR Compliance
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Solution Overview
Problem
Portable devices with multiple transmit chains face challenges in meeting electromagnetic radiation thresholds while maintaining good reception quality, as the additive radiation from multiple radios increases exposure, necessitating methods to control and reduce user exposure without sacrificing output power.
Innovation Solution
A method utilizing multiple transmit chains that adjust phase or amplitude based on a cost function balancing electromagnetic radiation thresholds with reception quality criteria, such as signal-to-noise ratio or data-rate, to optimize transmission and minimize radiation exposure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple transmit chains operate simultaneously to provide multiple radio functions, then device functionality and power are improved, but electromagnetic radiation exposure increases
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the phase and amplitude parameters of transmit chains based on a cost function. The cost function includes a radiation component that penalizes high SAR values and a reception component that rewards good signal quality. By continuously optimizing these parameters, the system achieves low radiation exposure while maintaining multiple radio functions simultaneously.
2Reliability
If transmit power is increased to maintain reception quality, then signal strength is improved, but electromagnetic radiation exposure increases
Solution Approach 1:
Instead of increasing transmit power, the patent changes phase and amplitude parameters to optimize the beamforming pattern. The cost function guides the optimization to concentrate energy in the direction of the intended receiver while minimizing radiation in other directions, particularly toward the user's body, thus maintaining reception quality without increasing overall radiation exposure.
Solution Approach 2:
The patent applies local quality by creating directional beamforming patterns that concentrate electromagnetic energy in specific spatial locations where it is needed (toward the receiver) while minimizing energy in other locations (away from the user). This spatial differentiation of energy distribution allows high reception quality in the target direction while keeping radiation exposure low in the user's vicinity.
3Object-affected harmful factors
If radiation thresholds are strictly enforced, then user safety is improved, but transmission power and output are reduced
Solution Approach 1:
The patent changes the optimization approach from maximizing transmit power to optimizing phase and amplitude parameters subject to a radiation constraint. The cost function incorporates a radiation penalty term that enforces SAR thresholds while allowing the system to achieve sufficient reception quality through intelligent beamforming, thus maintaining transmission effectiveness without exceeding radiation limits.
Data Source
AI summary
Embodiments of methods and apparatuses for transmission using a plurality of transmit chains based on a cost function for electromagnetic radiation are disclosed. One method is utilizing a plurality of chains, adjusting at least one of a phase or an amplitude of at least one of the transmit chains based on a cost function, wherein the cost function comprises a criterion for quality of reception at an intended receiver and a threshold for electromagnetic radiation.