Multi-radio Controller IMD Detection and Power Modulation
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Solution Overview
Problem
Simultaneous transmissions from multiple radios in multi-radio devices often result in intermodulation distortion (IMD) signals that exceed FCC-regulated emissions limits, particularly in restricted frequency bands, due to asynchronous traffic and high transmit power levels, leading to unwanted emissions.
Innovation Solution
A multi-radio device with a controller that detects IMD signals generated by simultaneous transmissions and modulates information packets in real-time to adjust transmit power levels, abort or block transmissions, ensuring compliance with emissions limits, using a detection element to monitor and predict IMD signals and a decision element to dynamically manage packet transmissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If multiple radios transmit simultaneously at high power levels, then communication coverage and signal strength are improved, but intermodulation distortion signals exceed emissions limits
Solution Approach 1:
The controller predicts potential IMD signals before simultaneous transmissions occur by analyzing transmission requests from multiple radios. This preliminary detection allows the system to identify and mitigate harmful emissions before they are generated, preventing compliance violations while maintaining high transmit power levels when safe.
Solution Approach 2:
The system dynamically adjusts transmit power levels in real-time based on detected IMD conditions. When IMD signals exceed thresholds, the controller selectively reduces power for specific radios or packets; when conditions are safe, full power is maintained. This dynamic adaptation resolves the contradiction between maintaining high power for coverage and limiting power to prevent harmful emissions.
2Object-generated harmful factors
If transmit power levels are reduced to comply with emissions limits, then harmful emissions are minimized, but communication coverage and signal quality deteriorate
Solution Approach 1:
Instead of uniformly reducing power across all transmissions, the system applies localized power adjustments to specific radios, antennas, or packet types based on their contribution to IMD. This allows compliant emissions levels to be achieved while maintaining high power for transmissions that do not generate harmful intermodulation, preserving communication quality where possible.
3Object-generated harmful factors
If real-time monitoring and dynamic power adjustment are implemented, then emissions compliance is ensured, but device complexity increases
Solution Approach 1:
The controller continuously monitors actual transmissions and detected IMD signals, using this feedback to dynamically adjust power levels. This closed-loop system ensures compliance while automating the complexity of real-time decision-making, reducing the need for overly complex predetermined control logic while maintaining emissions control.
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
The solution effectively mitigates unwanted emissions by dynamically adjusting transmit power levels and managing packet transmissions, ensuring that IMD signals remain below predetermined limits, thereby adhering to FCC regulations and minimizing interference in restricted frequency bands.
Implementation Method 1
a detection element configured to detect a third signal generated in response to simultaneous transmission of the first and second signals... the third signal is an intermodulation distortion (IMD) signal... the third signal is generated in response to mixing a spectral power of the first signal with a spectral power of the second signal
Data Source
AI summary
One example discloses a multi-radio device, including: a controller configured to be coupled to a first radio that is configured to transmit a first signal, and a second radio that is configured to transmit a second signal; wherein the controller includes a detection element configured to detect a third signal generated in response to simultaneous transmission of the first and second signals; wherein the controller includes a decision element configured to modulate one or more information packets in the first and second signals in response to the third signal.