FIR Filter Tuning for In-Band Full Duplex Self-Interference Cancellation
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Solution Overview
Problem
In-band full duplex transceivers face challenges in maintaining high self-interference cancellation (SIC) gain, especially when quickly adapting to changes in a wideband environment, due to limitations in existing active SIC technologies.
Innovation Solution
A method and apparatus for tuning a finite impulse response (FIR) filter that converts input signals into baseband equivalent signals, calculates attenuation using delta time or frequency responses, and applies this attenuation to the FIR filter to continuously maintain high SIC gain.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing active SIC technology uses an adaptive analog FIR filter circuit, then SIC gain is higher than passive SIC technology, but the system cannot continuously maintain high SIC gain while quickly adapting to environmental changes over a wideband
Solution Approach 1:
The patent implements dynamic adaptation by continuously updating FIR filter coefficients based on real-time channel estimates. The system adjusts filter parameters dynamically to track environmental changes, enabling the transceiver to maintain high SIC gain across varying conditions and wideband frequencies without requiring manual reconfiguration.
Solution Approach 2:
The patent employs feedback mechanisms where the system continuously monitors the self-interference cancellation performance and uses this information to adjust FIR filter coefficients. By feeding back channel state information and interference levels, the system optimizes filter parameters in real-time, ensuring continuous high SIC gain while adapting to environmental changes.
2Reliability
If antenna region SIC technology significantly spaces transmitting and receiving antennas apart, then self-interference cancellation is achieved, but the technology cannot be applied to small apparatus due to physical space requirements
Solution Approach 1:
The patent replaces the mechanical/physical solution (spatial separation of antennas) with an electronic/digital solution (FIR filter-based signal processing). By substituting physical distance with digital signal processing, the system achieves effective self-interference cancellation without requiring significant physical space, making it suitable for compact devices.
Solution Approach 2:
The patent changes the approach from modifying physical parameters (antenna spacing) to modifying signal parameters (filter coefficients, frequency response). By adjusting digital signal processing parameters rather than physical dimensions, the system achieves interference cancellation in compact form factors while maintaining effectiveness.
Data Source
AI summary
A method and an apparatus for tuning an FIR filter in an in-band full duplex transceiver. The method for tuning an FIR filter includes: converting an input signal of the FIR filter into a first signal that is a baseband signal; converting a signal obtained by subtracting an output signal of the FIR filter from the self-transmitted interference signal into a second signal that is the baseband signal; and calculating attenuation of the FIR filter using the first signal and the second signal.