Interference Cancellation in Multi-Mode Wireless Modems
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Solution Overview
Problem
Multi-mode modems face interference issues due to spur frequency components from local oscillators, which desensitize receiving signals, and existing solutions like hardware design improvements or frequency changes are impractical or insufficient.
Innovation Solution
A method and apparatus for receiving signals with interference, translating the interference into a narrower frequency band, and filtering it to remove the interference, using techniques such as notch filters or adaptive filtering to recover the signal without interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If hardware components are carefully designed to prevent coupling and improve isolation, then interference cancellation is improved, but device complexity and difficulty of simulation/testing increase
Solution Approach 1:
The patent creates a digital copy of the interfering signal by capturing the aggressor signal through a known path (e.g., using the transmitted signal as a reference) and then uses this copy to generate a cancellation signal. This digital copying approach replaces complex hardware isolation design with signal processing, making the system easier to simulate and test while achieving effective interference cancellation.
Solution Approach 2:
The patent replaces physical hardware isolation mechanisms (coupling prevention, shielding, filtering) with digital signal processing techniques. Instead of designing complex hardware to physically block or isolate interference paths, the system uses software algorithms to identify and cancel interference signals digitally, simplifying hardware design while maintaining or improving cancellation effectiveness.
2Object-affected harmful factors
If frequency of transmission signal is changed to cancel interference, then interference cancellation is improved, but adaptability to assigned frequency bands deteriorates
Solution Approach 1:
Instead of changing the fundamental frequency of the transmission signal (which would violate assigned frequency bands), the patent changes the parameters of the cancellation signal by adjusting the phase and frequency of the copied aggressor signal. This allows the system to maintain compliance with assigned frequency bands while effectively canceling interference through dynamic parameter adjustment of the cancellation mechanism rather than the transmission signal itself.
3Object-affected harmful factors
If frequencies of spur sources are changed to move interference outside received signal band, then interference cancellation is improved, but system complexity increases due to multiple spur sources
Solution Approach 1:
The patent creates a universal interference cancellation mechanism that can handle multiple spur sources and interference types through a single digital signal processing framework. The system captures the aggressor signal and generates cancellation signals that can address various interference sources (LO spurs, ADC clocks, FM modulators) without requiring separate dedicated cancellation circuits for each source, thereby reducing overall system complexity despite the presence of multiple potential interference generators.
Data Source
AI summary
Certain embodiments of the present disclosure support techniques for interference cancellation in a multi-mode wireless modem that supports coexistence of different radio technologies.