Digital Self-Interference Cancellation in Full-Duplex Radio
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Solution Overview
Problem
Full-duplex radio communications face significant self-interference challenges due to simultaneous transmission and reception on the same channel, requiring complex multiple cancellation stages to achieve acceptable interference reduction.
Innovation Solution
A method and system that incorporate both passive analog and digital cancellation stages in full-duplex communications devices, where channel distortion is estimated using sampled transmitted and received signals to digitally cancel self-interference, with the digital stage buffering signals to avoid time constraints and correct linear distortions introduced by analog stages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple cancellation stages (analog and digital) are used to reduce self-interference, then self-interference reduction effectiveness is improved, but device complexity increases
Solution Approach 1:
The cancellation system is segmented into distinct functional stages: passive analog cancellation stage and active digital cancellation stage. Each stage handles specific aspects of interference reduction, with the passive stage providing initial rejection and the active stage providing precise digital cancellation based on channel estimation, thereby achieving effective interference reduction while maintaining manageable system complexity through modular design
Solution Approach 2:
A passive analog cancellation circuit is introduced as an intermediary component between the transmitter and receiver. This circuit provides initial signal isolation and rejection before the signals reach the digital processing stage, reducing the burden on the digital cancellation algorithm and enabling effective interference reduction with reduced computational complexity
2Measurement precision
If accurate channel estimation is performed to cancel self-interference, then signal accuracy is improved, but processing time increases
Solution Approach 1:
Channel estimation is performed in advance using the known transmitted signal and received signal relationship. The system pre-computes the channel characteristics and cancellation coefficients before they are needed for actual signal cancellation, allowing the digital cancellation stage to operate with pre-prepared parameters and reducing real-time processing latency while maintaining accurate signal cancellation
Data Source
AI summary
Embodiments are provided for cancelling self-interference in a full-duplex communications system. The cancellation includes using a digital cancellation stage in additional to analog cancellation. In an embodiment, a method by a full-duplex communications device includes sampling a received signal, wherein the sampling provides a received digital signal corresponding to the received signal. The method further includes sampling a transmitted signal, wherein the sampling provides a transmitted digital signal corresponding to the transmitted signal. A channel distortion introducing self-interference in the received signal is then estimated according to the transmitted digital signal and the received digital signal. The method further includes estimating the self-interference in the received digital signal according to the estimated channel distortion.