Self-Interference Cancellation in Full-Duplex Radio Systems
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Solution Overview
Problem
In Full-Duplex Radio (FDR) systems, intra-device self-interference significantly deteriorates performance due to the simultaneous transmission and reception of signals at the same time and frequency, making it challenging to achieve effective self-interference cancellation, especially in frequency asynchronous environments where oscillator errors and Doppler effects cause frequency synchronization mismatches.
Innovation Solution
A method for canceling self-interference signals in FDR mode involves estimating frequency synchronization between a reception signal and a self-interference signal, transforming the self-interference signal into the frequency domain, estimating the self-interference channel, generating a self-interference signal in the frequency domain, and subtracting it from the reception signal in the time domain, while also compensating for frequency offsets to improve signal detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If full-duplex radio transmission is implemented to double system capacity, then transmission efficiency is improved, but self-interference signal significantly deteriorates system performance
Solution Approach 1:
The self-interference cancellation process is divided into multiple stages: analog cancellation in the RF domain, digital cancellation in the baseband domain, and iterative refinement. This segmentation allows each stage to address specific aspects of interference without being overwhelmed by the full complexity of the problem.
Solution Approach 2:
A self-interference cancellation module is introduced as an intermediary component between the transmitter and receiver. This module includes analog cancellation circuits and digital signal processing units that actively subtract the transmitted signal from the received signal, preventing it from interfering with the desired reception.
2Measurement precision
If self-interference cancellation is performed in frequency asynchronous environment, then signal detection accuracy is improved, but frequency synchronization estimation complexity increases
Solution Approach 1:
Frequency synchronization estimation is performed as a preliminary step before self-interference cancellation. The system estimates the frequency offset between transmitted and received signals in advance, allowing the cancellation process to operate with accurate frequency alignment even in asynchronous environments.
Solution Approach 2:
The system employs feedback mechanisms where the estimated frequency synchronization information is continuously refined based on the residual signal after cancellation. This iterative feedback process improves accuracy while managing complexity through adaptive adjustment.
Data Source
AI summary
A method by which a first network node cancels a self-interference signal when operating in a full duplex radio (FDR) mode in a wireless network can comprise the steps of: cancelling a self-interference signal on the basis of frequency synchronization estimation of the self-interference signal when frequencies of a reception signal received from a second network node and the self-interference signal are asynchronous; and estimating frequency synchronization of the reception signal by using a residual signal according to the cancellation of the self-interference signal, and detecting the reception signal on the basis of the frequency synchronization estimation of the reception signal.