Hybrid RF-over-Fiber and Ethernet Return Data Path
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Solution Overview
Problem
Current HFC networks face challenges in cost-effectively transmitting upstream RF signals to the head-end in FTTP architectures, as deploying return-path lasers at each subscriber is expensive, and combining analog optical signals from multiple lasers leads to carrier-to-noise degradation, making reliable data transmission difficult.
Innovation Solution
A device and method that utilize an optical network terminal (ONT) to demodulate RF signals into baseband digital signals, which are then converted into optical signals for transmission over fiber, reducing bandwidth requirements and avoiding carrier-to-noise issues, while maintaining compatibility with DOCSIS-compliant networks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If return-path lasers are deployed at each subscriber to transmit upstream RF signals over fiber, then upstream data transmission capability is improved, but system cost increases significantly
Solution Approach 1:
The patent extracts the RF carrier signal from the upstream transmission path by using hybrid RF-over-fiber and Ethernet coexistence technology. Instead of transmitting modulated RF signals with lasers at each subscriber, the system separates the RF signal component and transmits only necessary data over fiber, reducing the need for expensive return-path lasers at every subscriber premise.
Solution Approach 2:
The patent introduces an intermediary approach by using existing coaxial cable infrastructure combined with selective fiber deployment. The system uses a hybrid architecture where RF signals travel over coaxial cable and Ethernet handles data transmission over fiber, acting as an intermediary solution between full RF-over-fiber and traditional HFC, thereby reducing costs while maintaining upstream capability.
2Quantity of substance
If analog optical signals from multiple lasers are combined for upstream transmission, then signal aggregation is achieved, but carrier-to-noise degradation occurs
Solution Approach 1:
The patent segments the upstream transmission into separate RF and data paths. Instead of combining multiple analog optical signals from multiple lasers which causes carrier-to-noise degradation, the system separates RF signal transmission from data transmission, allowing independent optimization of each path and avoiding the interference issues inherent in analog signal combining.
Solution Approach 2:
The patent substitutes the mechanical/analog approach of combining multiple laser outputs with a digital/Ethernet-based data transmission system. By replacing the analog optical signal combining mechanism with digital packet switching over Ethernet, the system eliminates the carrier-to-noise degradation problem while maintaining the ability to aggregate multiple subscriber signals.
3Productivity
If RF signals are transmitted directly over fiber to head-end, then bandwidth utilization is improved, but compatibility with existing DOCSIS equipment is lost
Solution Approach 1:
The patent implements multi-functionality by designing a hybrid system that can handle both traditional RF-over-coaxial cable transmissions and modern Ethernet-over-fiber transmissions simultaneously. The head-end equipment is configured to process both DOCSIS-compliant RF signals and Ethernet data packets, making the system universal and compatible with existing infrastructure while enabling new capabilities.
Solution Approach 2:
The patent introduces dynamic operation modes that allow the system to switch between different transmission protocols and paths based on traffic type and network conditions. The hybrid architecture dynamically routes RF signals through coaxial cable segments and data signals through fiber segments, optimizing bandwidth utilization while maintaining compatibility with existing DOCSIS equipment through adaptive protocol handling.
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 approach enables efficient and reliable upstream data signal transmission in HFC networks, reducing costs and preventing data loss due to carrier interference, while leveraging existing DOCSIS equipment and protocols.
Implementation Method 1
an optical transducer coupled to the diplexer and operable to convert the upstream data signal to an optical signal for transmission over the fiber optic link
Implementation Method 2
a fiber optic cable link in communication with the optical network terminal and operable to carry the optical signal from the optical network terminal to the head-end
Data Source
AI summary
Described herein are devices and methods for facilitating the transmission of an upstream data signal from at least one subscriber in a communications network. The device is operable to receive a radio frequency (RF) signal from one or more subscribers. The RF signal includes at least one upstream data signal. The RF signal is demodulated into the upstream data signal by a RF demodulator in the device, which is then converted into an optical signal by an optical transducer in the device for transmission over a fiber optic link in the network.