Dynamic Power Backoff for Multi-Antenna SAR Compliance
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Solution Overview
Problem
Wireless mobile terminals emit radio frequency energy that can be absorbed by the human body, leading to potential health risks, necessitating a method to limit exposure to electromagnetic waves, particularly in scenarios where the device is close to the body.
Innovation Solution
An electronic device with multiple antennas and wireless communication circuits that adjust signal power based on proximity to the body, using power backoff mechanisms to ensure compliance with specific absorption rate (SAR) regulations by dynamically controlling the output power of signals transmitted through different frequency bands and radio access technologies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the wireless mobile terminal outputs high power signals for efficient communication, then communication efficiency is improved, but the specific absorption rate (SAR) increases causing harmful effects to the human body
Solution Approach 1:
The patent implements dynamic power backoff control that adjusts the transmit power of the wireless communication terminal in real-time based on the detected proximity to the human body. When the terminal is close to the body, the system dynamically reduces power to multiple antennas coordinate, ensuring SAR compliance while maintaining optimal communication performance when away from the body
Solution Approach 2:
The system employs feedback mechanisms by detecting the distance between the wireless terminal and the human body, then using this information to adjust the transmit power levels. The feedback loop continuously monitors and adjusts power backoff values to maintain SAR compliance while optimizing communication efficiency based on actual usage conditions
2Object-affected harmful factors
If power backoff is applied to reduce electromagnetic wave exposure, then SAR compliance is improved, but communication signal strength deteriorates
Solution Approach 1:
The patent applies localized power backoff control to different antennas based on their specific proximity to the human body. Instead of uniformly reducing power across all antennas, the system selectively adjusts power backoff values for individual antennas or antenna groups that are close to the body, maintaining full power for antennas that are not near the body, thus preserving communication signal strength where possible while reducing exposure where necessary
3Adaptability or versatility
If multiple antennas operate simultaneously in different frequency bands, then communication versatility is improved, but cumulative electromagnetic exposure increases
Solution Approach 1:
The system dynamically changes power parameters for multiple antennas operating in different frequency bands based on their proximity to the human body. The patent calculates separate power backoff values for each antenna or antenna group operating in different frequency bands (e.g., LTE, 5G NR), adjusting the transmit power of each band independently to control cumulative electromagnetic exposure while maintaining communication versatility across multiple bands when appropriate
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Effectively reduces the exposure of the human body to electromagnetic waves by dynamically adjusting signal power, ensuring compliance with SAR standards and enhancing safety during wireless communication.
Implementation Method 1
a first antenna (542) that transmits/receives a signal in a first frequency band based on a first radio access technology (RAT), a second antenna (544) that transmits/receives a signal in a second frequency band based on a second RAT
Implementation Method 2
a power backoff operation may be performed in a way to reduce a power to be input or fed to an antenna module in consideration of a reference for electromagnetic waves emitted from an electronic device
Data Source
AI summary
An electronic device includes a first antenna that transmits/receives a signal in a first frequency band, a second antenna that transmits/receives a signal in a second frequency band, a first wireless communication circuit connected with the first antenna, a second wireless communication circuit connected with the second antenna, at least one processor connected with the first and second wireless communication circuits, and a memory. The memory stores instructions that cause the processor to output a first signal with a first power to control the first wireless communication circuit to output the first signal through the first antenna, and output the first signal with a power, which is obtained by backing off from the first power as much as a first backoff value, to control the second wireless communication circuit to output a second signal through the second antenna while controlling the first wireless communication circuit to output the first signal.