Two-Stage Digital Interference Cancellation for Full Duplex
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Solution Overview
Problem
In wireless full duplex systems, strong self-interference from transmitting signals to receiving signals in the same wireless channel affects the correct reception of useful signals, as existing technologies like intelligent backhaul radios rely on isolation loops and FIR digital filters, which are insufficient for effective interference cancellation.
Innovation Solution
A two-stage digital interference cancellation apparatus is introduced, which reconstructs and subtracts near field and far field self-interference signals using digital baseband reference signals, with the first stage eliminating near field interference and the second stage addressing far field interference, improving signal reception.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a same transceiver is used to perform signal receiving and sending operations simultaneously on the same wireless channel, then the frequency spectrum efficiency is doubled, but strong self-interference from transmitting signals to receiving signals occurs
Solution Approach 1:
The interference cancellation is divided into two distinct stages: first stage cancellation handling dominant interference components, and second stage cancellation handling residual interference. This segmentation allows each stage to be optimized for its specific function, improving overall cancellation effectiveness while maintaining full-duplex operation
Solution Approach 2:
The first stage interference cancellation is performed preliminarily before the second stage cancellation. By removing the dominant interference components first, the subsequent second stage cancellation can focus on residual interference, making the overall process more efficient and effective
2Object-affected harmful factors
If isolation loops or FIR digital filters are used for interference cancellation, then some isolation is achieved, but the cancellation effectiveness is insufficient for complex communication environments
Solution Approach 1:
A digital baseband reference signal is introduced as an intermediary to model and reconstruct the self-interference signal. This reference signal serves as a mediator between the transmitted signal and the received signal, enabling accurate interference reconstruction and cancellation in complex communication environments
Solution Approach 2:
The system changes the parameters of interference cancellation by using a two-stage approach with different processing methods for each stage. The first stage uses one set of processing parameters while the second stage uses different parameters optimized for residual interference, thereby improving overall cancellation effectiveness
Data Source
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AI summary
The present invention discloses a digital interference cancellation apparatus, including: a first interference cancellation module, configured to receive a digital transmission signal output by a transceiver as a digital baseband reference signal, reconstruct a first self-interference signal by using the digital baseband reference signal, and subtract the first self-interference signal from a digital receiving signal received from the transceiver to obtain a digital receiving signal after a first stage of interference cancellation; and a second interference cancellation module, configured to receive the digital transmission signal output by the transceiver as the digital baseband reference signal, reconstruct a second self-interference signal by using the digital baseband reference signal, and subtract the second self-interference signal from the digital receiving signal after the first stage of interference cancellation to obtain a digital receiving signal after a second stage of interference cancellation. The embodiments of the present invention further disclose a digital interference cancellation method, a wireless full duplex system and a transceiver. By adopting the embodiments of the present invention, self-interference signals in a digital receiving signal can be effectively eliminated in a complex communication environment.