CCFD Signal Receiver Self-Interference Cancellation
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Solution Overview
Problem
Current CCFD technologies face significant challenges in achieving effective self-interference cancellation, leading to poor receiver sensitivity and impaired timing synchronization due to residual self-interference and noise interference, which restricts spectrum efficiency and wireless transmission performance.
Innovation Solution
A CCFD signal receiving method that divides self-interference cancellation into two stages: primary self-interference cancellation and joint self-interference cancellation and equalization, using adaptive algorithms like LMS, RLS, or FBLMS, and incorporates a timing synchronization loop with low-pass filtering to recover optimal sampling points, ensuring the useful signal dominates and minimizing noise impact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If self-interference cancellation is performed using existing methods, then the self-interference can be reduced to some extent, but the receiver sensitivity deteriorates significantly and residual self-interference remains
Solution Approach 1:
The patent segments the self-interference cancellation process into two distinct stages: primary self-interference cancellation (using sent baseband signal as reference) and joint self-interference cancellation and equalization (using demodulation error as reference). This segmentation allows each stage to focus on specific aspects of interference cancellation without the useful signal degrading the cancellation performance, thereby maintaining receiver sensitivity while effectively reducing self-interference.
Solution Approach 2:
The patent introduces a feedback mechanism where the demodulation error is used as the reference signal for joint self-interference cancellation and equalization. This feedback approach allows the system to continuously adjust and improve cancellation performance based on actual reception quality, preventing the useful signal from degrading the cancellation process while maintaining high receiver sensitivity.
2Object-generated harmful factors
If the useful signal is included in the driving signal for self-adaptive self-interference reconstruction, then the reconstruction can be performed, but the self-interference cancellation capability is restricted
Solution Approach 1:
The patent extracts and removes the useful signal from the driving signal used for self-interference reconstruction. By using only the demodulation error (which contains residual self-interference and noise but excludes the useful signal) as the reference, the system prevents the useful signal from degrading the self-interference cancellation capability while maintaining effective spectrum utilization.
3Measurement precision
If timing synchronization is performed on the signal after self-interference cancellation, then the optimal sampling point can be recovered, but residual self-interference and noise interfere with the synchronization
Solution Approach 1:
The patent performs preliminary self-interference cancellation before timing synchronization. By removing the majority of self-interference in the primary cancellation stage and then performing joint cancellation in the equalization stage, the system prepares a cleaner signal for timing synchronization, significantly reducing the interference and noise that would otherwise degrade synchronization accuracy.
Data Source
AI summary
A co-frequency co-time full duplex (CCFD) signal receiving method includes: taking the sent baseband signal as the self-interference reference signal, reconstructing self-interference, and then performing primary self-interference cancellation on the received signal; processing, by using a timing synchronization loop, the signal after the primary self-interference cancellation, realizing timing recovery at the optimal sampling point of the useful signal through resampling a, and controlling resampling b1 and resampling b2 after performing low-pass filtering on the timing error signal in the timing synchronization loop, to recover the optimal sampling points of the self-interference reference signal and the received signal respectively; and performing joint self-interference cancellation and equalization on the resampled self-interference reference signal and the resampled received signal, and receiving the useful signal through signal demodulation. The above method can significantly enhance the self-interference cancellation capability of CCFD technology and improve the receiving performance of the useful signal.