Optical Radio Link Segmentation for High-Frequency Polymer Fiber Transmission
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Solution Overview
Problem
Existing methods for transmitting data via radio antennas using optical fibers are limited by high costs and difficulties in implementing carrier frequencies above 20 gigahertz, especially with inexpensive polymer fibers, due to attenuation and dispersion, which restricts transmission paths and requires expensive, noise-prone frequency generators.
Innovation Solution
A method involving demodulation of the transmitted carrier signal to regenerate a subcarrier signal, which is then modulated and sent via a radio antenna, using techniques like amplitude modulation and phase locked loops, enabling low-error transmission even with distorted signals, and suitable for use with polymer fibers and high carrier frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If phase modulation (PSK or QAM) is used for high-frequency carrier signals (>20 GHz), then data transmission capability is improved, but transmission path length is limited due to attenuation and dispersion in optical fiber
Solution Approach 1:
The transmission system is segmented into two independent parts: data transmission over optical fiber and carrier frequency transmission via radio link. The data is modulated onto an optical carrier, transmitted through the fiber, converted to electrical signal, and then modulated onto a radio frequency carrier for wireless transmission. This segmentation allows each part to operate in its optimal domain, overcoming the limitation of direct high-frequency optical transmission over long distances.
Solution Approach 2:
An intermediate electrical signal is introduced as a mediator between the optical domain and radio frequency domain. The optical signal carrying data is converted to an electrical intermediate signal at the receiver, which then modulates the radio frequency carrier. This intermediary enables the separation of data transmission (over fiber) from final radio transmission, allowing extended transmission paths.
2Productivity
If carrier frequencies above 20 gigahertz are used, then transmission bandwidth is improved, but implementation difficulty and noise increase significantly
Solution Approach 1:
The patent uses commercially available, cost-effective components for generating and processing radio frequency carriers above 20 GHz, rather than requiring expensive, highly stable frequency generators. The system accepts that phase noise increases at these frequencies but compensates through robust modulation and detection schemes, effectively using affordable, readily available components.
Solution Approach 2:
The system changes the operating parameters by using amplitude modulation instead of phase modulation for the radio frequency carrier. This parameter change simplifies the receiver design and reduces sensitivity to phase noise, making implementation at high frequencies more feasible despite the inherent noise challenges.
3Reliability
If expensive single-mode glass fibers are used, then transmission quality is improved, but system cost increases significantly
Solution Approach 1:
The patent extracts the requirement for high transmission quality from the optical fiber domain and relocates it to the radio frequency domain. By using robust radio frequency transmission with proper modulation and detection, the system achieves reliable data transmission without requiring expensive single-mode glass fibers, thereby reducing overall system cost while maintaining transmission quality.
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 method allows for reliable, low-error data transmission over long distances and high frequencies using inexpensive polymer fibers, supporting applications like MIMO and pico cells, and enables bidirectional data transmission with passive antenna heads.
Implementation Method 1
due to the attenuation and dispersion in the optical fiber line
Implementation Method 2
due to the attenuation and dispersion in the optical fiber line
Implementation Method 3
Demodulating the transmitted modulated carrier signal while generating received data or a received data signal
Implementation Method 4
modulating the subcarrier signal as a function of the received data or the received data signal
Data Source
Figure 1~2
Figure 3~4
AI summary
The invention inter alia refers to a method whereby a carrier signal is modulated depending on data to be transmitted. The modulated carrier signal is transmitted via an optical fiber line. The transmitted modulated carrier signal is demodulated, thereby producing received data. The transmitted modulated carrier signal is used to produce an auxiliary carrier signal. Said auxiliary carrier signal (HT) is modulated depending on the received data and is then transmitted via a radio antenna (29).