Active Interference Cancellation Using Adaptive Filter Coefficients
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Solution Overview
Problem
Current duplexing solutions, such as hybrid junctions and diplexing filters, face challenges in achieving effective signal isolation across multiple frequency bands due to varying antenna impedance and signal leakage, limiting their ability to support multiple frequency bands and increasing complexity and cost.
Innovation Solution
An active interference cancellation apparatus with an auxiliary transmitter chain and adaptive filter unit generates a cancellation signal to isolate the receive signal from the transmit signal, using an interpolation processor to estimate coefficients for the adaptive filter, allowing for simultaneous transmission and reception in a common frequency band without requiring spectrally contiguous waveforms or ceasing data transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If diplexing filters are used to achieve signal isolation, then isolation between transmit and receive signals is improved, but device complexity and cost increase when supporting multiple frequency bands
Solution Approach 1:
The patent implements a universal active interference cancellation system that can operate across multiple frequency bands without requiring separate diplexing filters for each band. The adaptive filter dynamically adjusts its coefficients to provide signal isolation functionality across the entire operating spectrum, making the system multi-functional and eliminating the need for multiple band-specific filters.
Solution Approach 2:
The system changes the parameters of the adaptive filter coefficients dynamically based on the operating frequency band. By adjusting the filter coefficients in response to frequency changes, the system maintains effective signal isolation across multiple bands without requiring physical filter changes or additional hardware for each band.
2Productivity
If hybrid junctions are used for duplexing, then simultaneous transmission and reception is enabled, but signal leakage and impedance variation reduce isolation effectiveness
Solution Approach 1:
The patent employs an adaptive filter that continuously monitors the received signal and adjusts its coefficients in real-time to cancel out leakage from the transmit signal. This feedback mechanism compensates for impedance variations and signal leakage dynamically, maintaining effective isolation while enabling simultaneous transmission and reception.
Solution Approach 2:
The system transitions from static filter-based isolation to dynamic adaptive filtering. The adaptive filter coefficients are continuously updated based on the current operating conditions, allowing the system to adapt to impedance variations and maintain optimal signal isolation performance while supporting simultaneous transmit and receive operations.
3Measurement precision
If separate waveform transmission is used to calculate filter coefficients, then coefficient accuracy is improved, but operational time and data transmission interruption increase
Solution Approach 1:
The patent enables continuous operation by calculating adaptive filter coefficients without interrupting data transmission. The system uses the ongoing data signals themselves for coefficient estimation, eliminating the need for separate waveform transmission phases. This maintains coefficient accuracy while ensuring uninterrupted operational time and continuous data flow.
Data Source
AI summary
An apparatus includes a receiver chain includes an input node and a transmitter chain comprising a tap and output nodes. An auxiliary transmitter chain comprises an auxiliary input node coupled to the tap node, an adaptive filter unit and a signal output coupled to the input node. The filter unit includes an interpolation processor, and an adaptive filter and a coefficient processor coupled to the receiver chain and the adaptive filter. The transmitter chain generates a first waveform comprising a plurality of frequency-separated signals. Contemporaneously, the auxiliary chain applies a second waveform comprising another plurality of frequency-separated signals at the input node. The receiver chain receives a composite waveform comprising a waveform coupled from the output node and the second waveform. The first waveform lacks signals required for determination of coefficients of the filter whose frequencies coincide with the another plurality of signals of the second waveform.