Joint Analog Digital Interference Cancellation
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Solution Overview
Problem
Existing wireless communication systems face challenges in effectively canceling interfering signals, particularly due to mismatched phase noises and non-linearities between analog and digital interference cancellation stages, which degrades interference cancellation performance.
Innovation Solution
The system employs joint analog and digital interference cancellation using an analog reference interfering signal for both stages, preserving phase noise characteristics through coherent downconversion and digitization, allowing for better matching of transmit non-linearities and improved cancellation performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate analog and digital interference cancellation stages are used, then interference cancellation capability is provided, but phase noise mismatch and non-linearity mismatch occur between stages degrading performance
Solution Approach 1:
The patent merges the analog and digital interference cancellation stages by using the same reference interfering signal for both stages. The analog reference signal is used directly in the analog cancellation stage and also digitized for the digital cancellation stage, ensuring consistency and eliminating mismatch between stages.
Solution Approach 2:
The reference interfering signal serves multiple functions: it is used as the cancellation reference in the analog stage and also as the cancellation reference in the digital stage after digitization. This multi-functional use of a single reference signal eliminates the need for separate references and ensures phase noise and non-linearity matching across both stages.
2Reliability
If analog reference interfering signal is used for both analog and digital cancellation stages, then phase noise characteristics are preserved and non-linearities are matched, but additional signal processing steps are required
Solution Approach 1:
The analog reference interfering signal is prepared in advance and used for analog interference cancellation before digitization. This preliminary analog processing reduces the complexity of subsequent digital processing by removing the bulk of the interference in the analog domain, where phase noise and non-linearities can be directly matched.
Solution Approach 2:
The analog reference interfering signal is copied and used for both analog and digital cancellation stages. By copying the same reference signal to both stages, the system ensures that phase noise characteristics and non-linearity effects are consistent across both analog and digital processing, eliminating mismatch.
3Reliability
If coherent downconversion and digitization are performed to preserve phase noise characteristics, then interference cancellation is improved by up to 10 dB, but processing time and computational resources are increased
Solution Approach 1:
The interference cancellation process is segmented into two distinct stages: an analog stage that handles the bulk of the interference cancellation using coherent downconversion, and a digital stage that completes the cancellation and processes the signal. This segmentation allows each stage to operate optimally while reducing overall processing time compared to purely digital processing.
Data Source
AI summary
An apparatus for joint analog and digital interference cancellation includes a receiver configured to receive an analog reference interfering signal on a reference path, and a sum of an analog interference signal and an analog signal of interest on an antenna path. An analog interference canceller may be configured to produce an analog partially interference-cancelled signal using the analog reference interfering signal and the sum of the analog interference signal and the analog signal of interest. A first analog-to-digital converter may be configured to digitize the analog reference interfering signal to produce a digital reference interfering signal. A second analog-to-digital converter may be configured to digitize the analog partially interference-cancelled signal to produce a digital partially interference-cancelled signal. A digital interference canceller may be configured to produce an interference-cancelled signal using the digital reference interfering signal and the digital partially interference-cancelled signal.