RF Power Adaptation for Handheld Wireless Devices
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Solution Overview
Problem
Wireless human interface devices (HIDs) face performance issues when held in hand due to negative peak gain, leading to inadequate signal transmission and user experience problems, as regulatory limits restrict maximum radiated power.
Innovation Solution
Implementing a radio frequency power adaptation system that dynamically adjusts transmit power based on the device's operating condition, such as being held in hand or not, using detection sources like hardware and software sensors to maintain compliance with regulatory requirements and ensure consistent performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the device transmits at maximum conducted power to compensate for negative peak gain when held in hand, then signal range and performance are improved, but regulatory EIRP limits are exceeded
Solution Approach 1:
The system dynamically adjusts the conducted power level based on real-time detection of the operating condition (held in hand vs. free space). When the device is detected to be held in hand with negative peak gain, the system increases conducted power from the default level to a higher level that compensates for the gain loss while keeping the resulting EIRP within regulatory limits. This dynamic adaptation resolves the contradiction by allowing higher power transmission only when necessary and permitted.
Solution Approach 2:
The system changes the conducted power parameter based on the detected operating condition. By switching between different conducted power levels (default vs. increased) depending on whether the device is held in hand or in free space, the system optimizes signal range while maintaining regulatory compliance. The parameter change allows the device to adapt its transmission characteristics to the actual operating environment.
2Object-generated harmful factors
If the device uses fixed conducted power to ensure regulatory compliance in free space, then EIRP limits are met, but signal range is inadequate when held in hand
Solution Approach 1:
Instead of using a fixed conducted power level, the system implements dynamic power adjustment based on the detected operating condition. The conducted power is set to a default level when in free space (ensuring compliance) and increased to a higher level when held in hand (maintaining signal range). This dynamic approach resolves the contradiction by adapting the power level to the actual usage scenario.
Solution Approach 2:
The system changes the conducted power parameter from a fixed value to a variable value that depends on the operating condition. By detecting whether the device is held in hand or in free space, the system adjusts the conducted power parameter accordingly, ensuring both regulatory compliance and adequate signal range for each scenario.
3Reliability
If the device increases transmit power when held in hand, then signal range and performance are maintained, but energy consumption increases
Solution Approach 1:
The system dynamically adjusts power consumption by increasing conducted power only when the device is detected to be held in hand and when the signal range would otherwise be insufficient. When in free space or when signal quality is adequate, the system uses the default lower power level. This dynamic power management resolves the contradiction by optimizing energy consumption based on actual operational needs.
Solution Approach 2:
The system changes the power consumption parameter based on the detected operating condition and signal quality feedback. By adjusting the conducted power level from default to increased only when necessary (when held in hand with inadequate signal), the system minimizes energy consumption while maintaining adequate signal range for successful communication.
Data Source
AI summary
In various examples, radio frequency conducted power of a device—such as a human interface device (HID)—may be adjusted to account for various operating conditions. For example, when a user holds the device in their hand, the radiated power level of the device may be reduced to a level that reduces transmission performance of the device. To account for this, one or more detection mechanisms may be used to determine whether the device is held in hand and, when determined to be held in hand, the radio frequency conducted power of the device may be increased—while complying with regulatory requirements governing wireless transmissions—to increase the performance of the device. When not held in hand, the radio frequency conducted power may be less, thereby resulting in consistent performance of the device under varying operating conditions.