Digital RF Self-Interference Cancellation for Full-Duplex Radio
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Solution Overview
Problem
Full-duplex RF communication systems face interference challenges due to simultaneous transmission and reception on the same frequency, which existing hardware-based cancellation methods fail to adequately address, leading to inefficient bandwidth usage and complex systems.
Innovation Solution
A software-based method using high-speed analog-to-digital converters and digital adaptive filters to time- and phase-align the transmitted and received signals, allowing for effective cancellation of interference without the need for frequency-, time-, or code-division multiplexing and hardware RF cancellers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If hardware RF cancellers are used to cancel interference between transmitted and received signals, then signal cancellation capability is improved, but device complexity increases due to multiple cancellation filters
Solution Approach 1:
The patent replaces hardware RF cancellers with a software-based digital signal processing approach. The system uses a digital adaptive filter implemented in software to cancel the transmitted signal from the received signal, eliminating the need for complex hardware cancellation filters while achieving effective interference removal
Solution Approach 2:
The patent employs an adaptive filter that dynamically adjusts its parameters (filter coefficients) based on the input signals. The filter weights are continuously optimized to match the characteristics of the transmitted signal, enabling effective cancellation across varying signal conditions without requiring multiple fixed hardware filters
2Object-affected harmful factors
If frequency-division multiplexing is used to separate transmitted and received signals, then signal interference is reduced, but bandwidth utilization decreases due to frequency separation requirements
Solution Approach 1:
The patent extracts the transmitted signal component from the received signal using digital signal processing. By identifying and removing the specific transmitted signal characteristics from the composite received signal, the system eliminates interference without requiring frequency separation, thereby maintaining full bandwidth utilization
Solution Approach 2:
The system creates a digital copy of the transmitted signal and uses it as a reference for cancellation. This digital replica is processed through the adaptive filter to generate an accurate model of the transmitted signal present in the received signal, enabling precise interference removal without frequency division
3Object-affected harmful factors
If time-division multiplexing is used to avoid signal interference, then interference cancellation is improved, but productivity decreases due to loss of transmitting time
Solution Approach 1:
The patent enables continuous full-duplex operation by canceling the transmitted signal from the received signal in real-time. Both transmission and reception occur simultaneously without time division, maintaining continuous useful action in both directions and maximizing communication efficiency while eliminating self-interference
Data Source
AI summary
A full-duplex RF communication system and corresponding methods use digital adaptive filters for interference cancellation. As provided, the techniques allow full-duplex radio frequency communication without frequency-, time-, or code-division multiplexing and without the use of hardware RF cancellers. Such techniques may be useful for wireless communication, such a cellular communication, radio communication, broadcasting, short-range point-to-point communication, wireless sensor networks, and wireless computer networks.