Interference Cancellation Circuit With Adaptive Filtering for Signal Leakage
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Solution Overview
Problem
Wireless communication systems face challenges in processing signals with high complexity due to interference signals, including inter-cell interference, intra-cell interference, channel interference, and self-interference caused by transmission signal leakage, which are exacerbated by techniques like Carrier Aggregation and MIMO, leading to signal deterioration and reduced reception sensitivity.
Innovation Solution
An interference cancellation circuit is implemented, utilizing a reference generation circuit and an adaptive filter to model and cancel interference signals, including a transmission/reception delay removal circuit to handle real-time delays and a relative delay removal circuit to mitigate intermodulation interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If techniques like Carrier Aggregation and MIMO are employed to increase throughput, then communication capacity is improved, but signal processing complexity increases and interference signals are exacerbated
Solution Approach 1:
The interference cancellation process is segmented into distinct stages: self-interference cancellation (SIC) handles transmission signal leakage, while inter-cell interference cancellation (ICIC) handles external interference. This segmentation allows each stage to be optimized independently, managing the overall complexity of processing high-capacity signals from CA and MIMO techniques.
Solution Approach 2:
Self-interference cancellation is performed as a preliminary action before inter-cell interference cancellation. By removing the dominant self-interference component first (caused by transmission signal leakage), the subsequent ICIC stage can more effectively process the remaining interference, reducing the overall computational burden while maintaining high communication capacity.
2Productivity
If transmission signals are independently transmitted according to CA, EN-DC, and MIMO, then communication throughput is improved, but passive interference due to intermodulation between transmission signals is generated
Solution Approach 1:
The patent converts the harmful intermodulation interference into a beneficial process by using the known transmission signals to generate reference interference signals. These reference signals, which replicate the harmful intermodulation products, are then subtracted from the received signal, effectively canceling the interference while preserving the desired communication throughput from CA and MIMO techniques.
Solution Approach 2:
Reference interference signals serve as intermediaries between the transmitted signals and the received signal. These reference signals model the intermodulation interference and enable its cancellation without requiring direct modification of the transmission process, thus maintaining high throughput while eliminating the harmful effects.
3Power
If power-amplified transmission signal is fed back as interference signal, then self-interference is generated, but reception sensitivity deteriorates greatly
Solution Approach 1:
The patent applies preliminary anti-action by generating a reference self-interference signal that anticipates and counteracts the power-amplified transmission signal leakage. This reference signal is subtracted from the received signal before the harmful self-interference can significantly degrade reception sensitivity, allowing high transmission power to be maintained while protecting receiver performance.
Solution Approach 2:
The system uses feedback by monitoring the transmission signals and generating corresponding reference interference signals that replicate the self-interference. This feedback mechanism enables real-time cancellation of self-interference, allowing the system to maintain high transmission power without sacrificing reception sensitivity.
Data Source
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AI summary
Provided is an interference cancellation circuit including a relative delay control circuit receiving a first transmission signal of a first frequency, and a second transmission signal of a second frequency different from the first frequency and including a first delay buffer delaying the second transmission signal by a first delay time and a second delay buffer delaying the second transmission signal by a second delay time, a delay reference generation circuit generating respective reference signals by receiving the first transmission signal and the delayed second transmission signal from the relative delay control circuit, a weight control circuit updating a weight vector, a relative delay estimation circuit estimating a relative delay based on the reference signals, and an adaptive filter generating an interference model signal based on the weight vector and a first reference signal of the reference signals and filter the interference model signal from a received signal.