RoF Beamforming Phase Compensation for Fiber Dispersion
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Solution Overview
Problem
In high-frequency-band RoF systems, beam collapse occurs due to phase rotation amount differences caused by wavelength dispersion in optical fiber transmission, leading to deteriorated coherency of signals and reduced gain in beamforming.
Innovation Solution
A wireless communication system and method that includes an accommodation station device and a base station device connected via an optical transmission path, utilizing a prior information acquisition unit to acquire dispersion phase difference information and a compensation phase shift unit to reduce phase rotation amount differences through compensation phase shift processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If remote beamforming is applied in RoF system with wavelength assignment to antenna elements, then beam direction control is achieved, but phase rotation amount differences due to wavelength dispersion cause beam collapse and signal coherency deterioration
Solution Approach 1:
The patent applies preliminary action by performing dispersion compensation processing before beamforming operations. The aggregation station calculates compensation phase shifts based on wavelength dispersion characteristics of the optical fiber and applies these phases to the optical signals before they reach the antenna elements. This preliminary compensation prevents beam collapse and maintains signal coherency throughout the beamforming process, ensuring reliable operation without requiring complex real-time adjustments.
2Adaptability or versatility
If multiple wavelengths are assigned to antenna elements for beamforming, then beam direction can be controlled, but phase rotation differences due to optical fiber transmission cause beam collapse
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the phase parameters of optical signals based on wavelength dispersion characteristics. The aggregation station calculates compensation phases as a function of wavelength, optical fiber length, and dispersion parameters, then applies these phase adjustments to maintain stable beam formation. This allows the system to adapt to different wavelength assignments while maintaining beam stability through parameter optimization.
3Device complexity
If wavelength dispersion compensation is not applied, then system complexity is reduced, but beam collapse occurs and gain in beamforming deteriorates
Solution Approach 1:
The patent applies mechanics substitution by replacing complex hardware-based dispersion compensation mechanisms with signal processing-based compensation. Instead of using dispersion compensating fibers or optical filters, the system uses electronic calculation and phase adjustment of optical signals at the aggregation station. This substitution maintains beamforming gain while avoiding the complexity and cost of additional optical components, achieving a balance between performance and simplicity.
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 solution effectively reduces beam collapse and maintains signal coherency by compensating for phase rotation errors, ensuring stable beamforming and optimal gain in wireless communication systems.
Implementation Method 1
phase rotation amount differences caused by wavelength dispersion in optical fiber transmission
Implementation Method 2
a radio frequency (RF) signal is subjected to electrical-optical (E/O) conversion and transmitted through an optical fiber
Implementation Method 3
the signal is returned to the original RF signal by performing optical-electrical (O/E) conversion at a transmission destination
Data Source
AI summary
An aspect of the present invention is a wireless communication system including an accommodation station device and a base station device connected to the accommodation station device through an optical transmission path and having n (n is an integer of 2 or more) antenna elements, wherein a plurality of optical signals having different wavelengths propagate through the optical transmission path, the wireless communication system including a prior information acquisition unit configured to execute prior information acquisition processing for acquiring, as prior information, dispersion phase difference information that is information including a dispersion phase difference that is a phase rotation amount difference generated between adjacent optical signals on a wavelength axis due to propagation of the optical signals through the optical transmission path, and a compensation phase shift unit configured to execute compensation phase shift processing for reducing a difference from a phase difference reference that is a predetermined reference on the basis of the prior information with respect to the phase rotation amount difference generated between adjacent optical signals on the wavelength axis caused by wavelength dispersion in the optical transmission line.