Proximity-Based Transmit Power Control for Mobile Wireless Devices
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Solution Overview
Problem
Mobile wireless communications devices face challenges in complying with SAR and HAC requirements due to the proximity of internal antennas to the user's face, which affects radio-frequency signal transmission power levels and user exposure.
Innovation Solution
A mobile wireless communications device equipped with capacitive proximity sensors and a controller that adjusts the transmitted power output based on the user's proximity, reducing RF radiation exposure when the device is near the user's head and increasing power when it is not, to ensure compliance with safety standards.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the antenna is placed in close proximity to the user's face to enable smaller device design, then device portability is improved, but SAR compliance becomes difficult to achieve
Solution Approach 1:
The patent implements dynamic transmit power adjustment based on real-time proximity detection. The system transitions from static power levels to dynamic control, where the transmitter adapts its power output according to the detected distance between the device and the user's head, thereby maintaining SAR compliance while enabling compact antenna placement
Solution Approach 2:
The patent employs a feedback mechanism where proximity sensors continuously monitor the distance to the user's head and feed this information back to the transmitter controller. This closed-loop control system automatically adjusts transmit power levels based on real-time proximity data, ensuring SAR compliance without requiring larger device dimensions
2Object-affected harmful factors
If transmit power is reduced to comply with SAR requirements when near the user's head, then RF radiation exposure is decreased, but transmission performance may deteriorate
Solution Approach 1:
The system dynamically adjusts transmit power based on real-time proximity conditions rather than using fixed power levels. When the device is detected to be close to the user's head, power is reduced to comply with SAR limits. When the device is at a normal distance, full power is restored to maintain optimal transmission performance, thus resolving the trade-off between safety and performance
Solution Approach 2:
The patent changes the transmit power parameter dynamically based on proximity detection results. By adjusting this critical parameter in response to changing operational conditions (proximity to user), the system maintains both SAR compliance and transmission performance across different usage scenarios
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
This solution effectively reduces user exposure to RF radiation, enhancing SAR compliance and maintaining RF performance by dynamically adjusting power output in response to user proximity, thereby addressing the challenges of smaller device designs.
Implementation Method 1
at least one capacitive proximity sensor carried by the portable housing and configured to sense proximity of a user's head adjacent thereto
Data Source
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AI summary
A mobile wireless communications device may include a portable housing, at least one antenna carried by the portable housing, and at least one capacitive proximity sensor carried by the portable housing and configured to sense proximity of a human user adjacent thereto. The mobile wireless communications device may also include a wireless transmitter carried by the portable housing and coupled to the at least one antenna, and a controller carried by the portable housing and coupled to the wireless transmitter and the at least one capacitive proximity sensor. The controller may be configured to cooperate with the wireless transmitter to adjust transmitted power output from the at least one antenna based upon the at least one capacitive proximity sensor.