Frequency-Domain Self-Interference Cancellation for 5G Transceivers
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Solution Overview
Problem
Conventional time-domain Self-Interference Cancellation (SIC) techniques face challenges such as high current consumption, redundancy in signals, and instability in adaptive filter coefficients, which affect the suppression of self-interference in multicarrier transceivers, particularly in 5G NR systems with complex modulation schemes and multiple frequency bands.
Innovation Solution
Implementing Self-Interference Cancellation (SIC) purely in the frequency-domain, using transformation circuitry to convert signals between frequency and time domains, and employing frequency-domain SIC circuitry to modify frequency-domain RX symbols based on frequency-domain TX symbols and crosstalk channel estimates, thereby reducing noise and improving signal processing efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If time-domain SIC techniques are used, then self-interference suppression is achieved, but current consumption increases and signal redundancy occurs
Solution Approach 1:
The patent transitions the SIC process from the time domain to the frequency domain by applying FFT transformation. This dimensional change allows interference cancellation to occur in the frequency domain where redundant time-domain signals are eliminated, reducing current consumption while maintaining self-interference suppression effectiveness.
Solution Approach 2:
The patent extracts and removes redundant signal components that exist in the time domain but are eliminated through frequency-domain transformation. By working in the frequency domain, the system extracts only the necessary information for interference cancellation without processing redundant time-domain samples, thereby reducing energy consumption.
2Object-affected harmful factors
If time-domain SIC techniques are used, then self-interference cancellation is achieved, but adaptive filter coefficient stability deteriorates
Solution Approach 1:
The patent applies FFT transformation to move the adaptive filtering operation from the time domain to the frequency domain. This dimensional change fundamentally improves the stability of adaptive filter coefficients by operating on frequency-domain representations where the statistical properties of the signals lead to more stable convergence behavior during adaptation.
3Object-affected harmful factors
If high-performance analog filters are used to separate TX and RX bands, then frequency band separation is improved, but hardware cost increases
Solution Approach 1:
The patent replaces the mechanical/analog filter system with a digital signal processing system. Instead of using expensive high-performance analog filters for frequency band separation, the invention uses digital FFT-based processing to achieve the same separation function, thereby reducing hardware costs while maintaining effective frequency band separation.
Solution Approach 2:
The patent changes the operating domain from analog time-domain signals to digital frequency-domain representations. This parameter change allows the system to achieve frequency band separation through digital processing rather than analog filtering, reducing hardware requirements and cost while maintaining separation performance.
Data Source
AI summary
The present disclosure relates to a transceiver comprising a transmitter with transformation circuitry configured to transform a frequency-domain transmit symbol from frequency domain to time domain to generate a time-domain transmit signal, a receiver with inverse transformation circuitry configured to transform a time-domain receive signal from time domain to frequency domain to generate a frequency-domain receive symbol, and self-interference cancellation circuitry configured to modify the frequency-domain receive symbol based on at least one frequency-domain transmit symbol and a frequency-domain crosstalk channel estimate of a crosstalk channel between the transmitter and the receiver.