Adaptive Analog Self-Interference Cancellation in Full Duplex Radio
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Solution Overview
Problem
Full duplex radio (FDR) systems face significant self-interference challenges due to intra-device self-interference, UE-to-UE inter-link interference, and BS-to-BS inter-link interference, which hinder efficient operation and require effective self-interference cancellation (SIC) methods.
Innovation Solution
An apparatus and method for adaptive self-interference cancellation (SIC) in FDR systems, utilizing analog SIC units with delay circuits and processors to determine successful cancellation and adjust attenuation coefficients, ensuring effective cancellation across RF transmission and reception chains.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If FDR scheme is implemented to enable simultaneous transmission and reception, then communication efficiency is improved, but self-interference increases
Solution Approach 1:
The patent segments the self-interference cancellation process into multiple stages: analog SIC at the RF end and digital SIC at the baseband end. This segmentation allows different cancellation techniques to be applied at different processing stages, effectively reducing self-interference while maintaining FDR operation
Solution Approach 2:
The patent performs analog self-interference cancellation before digital signal processing by estimating and subtracting the self-interference signal at the RF end. This preliminary action reduces the interference level before it enters the digital domain, making subsequent digital SIC more effective
2Reliability
If analog SIC is performed at RF end with multiple delay circuits, then SIC performance is improved, but device complexity increases
Solution Approach 1:
The patent divides the analog SIC function into multiple parallel delay circuits (first delay circuit, second delay circuit, etc.), each handling different self-interference signal components. This segmentation enables comprehensive interference cancellation while maintaining modular architecture
Solution Approach 2:
The patent combines multiple delayed self-interference signals through addition to reconstruct the total self-interference signal, which is then subtracted from the received signal. This merging approach efficiently cancels interference from multiple transmission paths
Data Source
AI summary
An apparatus for removing self-interference in an environment supporting an FDR method according to the present invention may comprise: an analog self-interference removal unit that is constructed to remove a first analog self-interference by subtracting a self-interference signal received through a first delay circuit connected between an RF transmission chain and an RF reception chain of the apparatus from a self-interference signal received at a first circuit of the RF reception chain of the apparatus, and that is constructed to remove a second analog self-interference by subtracting a self-interference signal received through a second delay circuit connected between the RF transmission chain and the RF reception chain of the apparatus from a self-interference signal received at a second circuit of the RF reception chain of the apparatus; and a processor that is constructed to determine whether the first and the second analog self-interference removals were respectively successful on the basis of the respective residual self-interference signals that are left after removing the first and the second analog self-interferences.