OAM System Using Wavelength Division Multiplexing for Interference Resistance
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Solution Overview
Problem
Conventional systems for generating orbital angular momentum (OAM) RF signals are limited in their ability to create multiple orthogonal signals simultaneously and efficiently, particularly in terms of interference resistance and flexibility in carrier frequencies and data channel management.
Innovation Solution
An OAM system that uses optical and electrical domains to generate arbitrary OAM states by modulating data streams onto multiple wavelengths, splitting them into copies, delaying each copy to produce distinct OAM RF modes, and combining them using wavelength division multiplexing, allowing for flexible carrier frequencies and precise delay control to optimize beam shape and interference resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional systems use triaxial or vivaldi antennas to generate OAM RF signals, then the system structure is relatively simple, but the ability to create multiple orthogonal signals simultaneously is limited and interference resistance is poor
Solution Approach 1:
The system divides the signal generation process into multiple independent laser wavelengths (m wavelengths), each carrying separate data streams. Each wavelength is processed through independent modulators and delay elements, creating segmented orthogonal OAM modes that resist interference while maintaining manageable complexity through modular architecture
Solution Approach 2:
The patent transitions from conventional single-frequency RF signal generation to multi-wavelength optical domain processing. By adding the optical frequency dimension and utilizing multiple laser wavelengths simultaneously, the system generates multiple orthogonal OAM modes with improved interference resistance while the optical domain provides a new dimension for signal manipulation
2Productivity
If multiple data channels are multiplexed onto the same RF carrier frequency, then data capacity increases, but signal interference and orthogonality maintenance become difficult
Solution Approach 1:
The patent introduces multiple laser wavelengths as intermediary carriers between data streams and the final RF signal. Each data channel is modulated onto a distinct optical wavelength, which serves as an intermediary that preserves signal orthogonality during multiplexing. The optical domain acts as a mediator that maintains channel separation until the final combination stage
Solution Approach 2:
The system changes the frequency parameter by utilizing multiple laser wavelengths instead of a single RF carrier. This parameter change allows multiple data channels to be transmitted simultaneously with orthogonal characteristics. The optical frequency domain provides sufficient separation to maintain orthogonality while maximizing data capacity through wavelength division multiplexing
3Adaptability or versatility
If static delay elements are used to encode wavelengths onto OAM RF modes, then the system is simpler to implement, but flexibility in dynamically re-assigning data to different modes is lost
Solution Approach 1:
The patent implements variable delay elements that can dynamically adjust the time delay applied to each optical wavelength. This dynamic capability allows the system to re-assign data channels to different OAM modes in real-time, adapting to changing transmission requirements. The delay elements transition from static fixed values to dynamically controllable parameters, enabling flexible mode assignment while maintaining system functionality
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
The system enables the generation of multiple orthogonal OAM RF modes with low interference and high data capacity, supporting a large number of channels on the same RF carrier frequency, with precise optical delay control and flexibility in beam divergence, enhancing transmission efficiency and adaptability.
Implementation Method 1
modulating data streams onto multiple wavelengths
Implementation Method 2
Each WDM element feeds the fiber to a distinct photodiode (PD), which performs an optical to electrical conversion process
Data Source
AI summary
Methods and apparatus for an OAM system having simultaneous OAM states. In embodiments, m data streams are encoded and split into n copies each of which is delayed to produce a distinct RF orbital angular momentum (OAM) mode. The delayed copies are combined using wave division multiplexing. The combined m data streams are transmitted using n antenna elements.