Photonic Self-Interference Cancellation for Wideband RF Links
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current RF communication systems face challenges in isolating high power co-site interference across multiple frequency bands, particularly when traditional bandpass filters are insufficient, as they cannot effectively handle simultaneous transmissions in different or overlapping bands.
Innovation Solution
The implementation of a photonic self-interference canceller system that uses wideband RF transceivers and optical cancellation techniques, including photonic interference cancellers, to simultaneously transmit and receive signals across multiple bands, employing optical time delay and variable attenuators to cancel out self-interference, and utilizing wideband antennas for efficient spectrum management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If traditional bandpass filters are used to isolate high power co-site interference, then isolation between transmitter and receiver is improved, but the system cannot handle simultaneous transmissions in multiple or overlapping frequency bands
Solution Approach 1:
The patent segments the interference cancellation process into multiple stages: analog cancellation in the RF domain, photonic processing for intermediate signals, and digital cancellation for residual interference. This multi-domain segmentation allows the system to handle multiple frequency bands simultaneously while maintaining high isolation performance.
Solution Approach 2:
The patent introduces photonic intermediaries (optical modulators, photodetectors, and optical delay lines) as mediators between the RF transmit and receive paths. These photonic components enable wideband interference cancellation across multiple frequency bands without the limitations of traditional electronic bandpass filters.
2Device complexity
If the transmitter and receiver are placed in close proximity for efficient spectrum management, then system complexity is reduced, but self-interference from the transmitter overpowers the receiver
Solution Approach 1:
The patent applies preliminary anti-action by generating canceling signals that are inverted versions of the transmitted signal before they reach the receiver. These canceling signals are created through photonic processing and combined with the received signal in advance, preventing the transmitted signal from overpowering the receiver despite close proximity placement.
Solution Approach 2:
The patent replaces traditional electronic interference cancellation mechanisms with photonic-based cancellation systems. The photonic processing provides wider bandwidth and higher isolation capability, enabling close transmitter-receiver placement without self-interference issues that would occur with conventional electronic approaches.
3Productivity
If wideband RF transceivers operating in multiple bands are used, then spectrum efficiency is improved, but self-interference cancellation becomes more difficult across overlapping bands
Solution Approach 1:
The patent transitions from single-domain RF processing to multi-domain processing by incorporating photonic intermediate representations. This dimensional change allows the system to handle wideband signals across multiple overlapping frequency bands by processing interference cancellation in the optical domain before converting back to RF, thereby managing complexity while maintaining high spectrum utilization.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution effectively reduces self-interference across multiple bands, enhancing signal reception by achieving high isolation and maintaining signal integrity even when transmit and receive signals are close or overlap, thereby improving the overall efficiency of wireless communication systems.
Implementation Method 1
The implementation of a photonic self-interference canceller system that uses wideband RF transceivers and optical cancellation techniques
Implementation Method 2
employing optical time delay and variable attenuators to cancel out self-interference
Implementation Method 3
which are converted by photodiodes to electrical and combined with the received signal
Data Source
AI summary
A method and apparatus for cancelling interference of an interfering transmit signal. The method includes the steps of (a) transmitting an RF transmit signal from a transceiver, (b) optically modulating the RF transmit signal, (c) optically modulating a RF receive signal; (d) demodulating an optical signal back to an RF signal using an optical-electrical balanced receiver and directing to the transceiver, and (e) demodulating the optical transmit signal back to RF transmit signal.