Beamforming Beam-Pair Selection for Human RF Exposure Control
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Solution Overview
Problem
Existing beamforming technologies in emerging communication systems like 5G New Radio and WiGig increase RF exposure to humans, and traditional methods to reduce radiation, such as power reduction and duty cycle adjustment, fail to maintain link quality and are not suitable for bi-directional beamforming systems.
Innovation Solution
Implement a beam recovery procedure that involves detecting nearby human presence using mobile device sensors to adjust both the mobile device's and its communication partner's beamforms, ensuring compliance with EMR exposure regulations while maintaining link quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If beamforming is used to focus transmissions in a narrow direction, then link sensitivity is improved, but RF exposure power to humans increases
Solution Approach 1:
The patent implements dynamic beam management where the system continuously monitors RF exposure levels and link quality, then adapts beamforming parameters in real-time. When RF exposure thresholds are approached, the system dynamically adjusts beam direction, width, or power allocation while maintaining acceptable link sensitivity through coordinated changes in transmit and receive beamforming.
Solution Approach 2:
The system changes key parameters including beam direction angles, beamwidth, transmit power levels, and beamforming weights based on detected RF exposure conditions. By modifying these parameters dynamically, the system can reduce RF exposure to compliant levels while attempting to preserve link sensitivity through compensatory adjustments in other parameters.
2Object-affected harmful factors
If traditional power reduction methods are used to reduce radiation, then RF exposure is reduced, but link quality deteriorates
Solution Approach 1:
The patent segments the total transmit power across multiple beams and time slots rather than uniformly reducing power. By distributing power across spatial and temporal domains, the system can reduce peak exposure levels while maintaining adequate total power for reliable communication through multi-beam diversity and time-division multiplexing.
Solution Approach 2:
The system employs feedback mechanisms where RF exposure measurements and link quality metrics are continuously monitored and used to adjust beamforming parameters. This closed-loop control enables the system to find optimal operating points that satisfy both RF exposure constraints and link quality requirements through iterative parameter optimization.
3Object-affected harmful factors
If duty cycle adjustment is used to reduce radiation, then RF exposure is reduced, but data rate decreases
Solution Approach 1:
The patent implements periodic beam sweeping and exposure monitoring cycles where the system systematically varies beam directions and measures RF exposure levels. During these periodic assessments, the system identifies safe transmission opportunities and schedules data transmissions during low-exposure periods, thereby maintaining data throughput while ensuring compliance.
Solution Approach 2:
Instead of reducing data rate through duty cycle adjustment in the time domain, the system exploits the spatial dimension by using multiple beams with different directions. This allows parallel transmissions across multiple spatial channels during periods when individual beams may be constrained by RF exposure limits, thereby maintaining aggregate data rate while achieving compliance.
Data Source
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Figure 3A~3B
AI summary
A communication device includes an evaluator configured to evaluate one or more criteria, wherein a first criterion of the one or more criteria includes detecting an object, a determiner configured to determine one or more beam pairs from a plurality of potential beam pairs to use in communications with a second device based on the evaluation of the one or more criteria and transmit an indication of one or more partner-side beams of a selected beam pair of the one or more beam pairs to the second device, and a beam controller configured to adjust an antenna to communicate with the second device via a device-side beam of the selected beam pair.