RFoG CPE Wavelength Separator Up-Conversion
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Solution Overview
Problem
The conventional RFoG architecture is cost-inefficient due to the high cost of 1590 nm lasers required for transporting traditional cable return signals, which are significantly more expensive than 1310 nm lasers used for PON signals, despite offering lower bandwidth and capacity.
Innovation Solution
Implementing a novel RFoG architecture that uses HI PHY modems and frequency-division-multiplexing to up-convert upstream high-speed data signals, allowing a single laser to transport both cable return and PON signals, thereby eliminating the need for expensive 1590 nm lasers and simplifying optical filtering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single laser wavelength is used for both cable return and PON upstream signals, then device complexity is reduced and cost is lowered, but wavelength collision occurs making signal separation difficult
Solution Approach 1:
The patent changes the frequency parameter of the cable return signal by up-converting it to a higher frequency band that does not collide with the PON upstream signal wavelength, enabling both signals to coexist on the same optical carrier without interference
Solution Approach 2:
The patent introduces frequency up-conversion as an intermediary process that transforms the cable return signal from its original frequency band to a higher frequency band, allowing it to share the optical fiber infrastructure with PON signals without wavelength collision
2Reliability
If 1590 nm laser is used to transport cable return signals, then traditional cable services are maintained, but the cost of CPE devices increases significantly
Solution Approach 1:
The patent merges the transport of cable return signals and PON upstream signals onto a single optical wavelength (1310 nm), eliminating the need for separate 1590 nm laser infrastructure and reducing CPE device costs while maintaining both service types
Solution Approach 2:
The patent makes the 1310 nm laser perform multiple functions by using it to transport both cable return signals (after up-conversion) and PON upstream signals, replacing the need for specialized 1590 nm lasers and reducing overall system cost
3Adaptability or versatility
If frequency up-conversion is implemented for cable return signals, then wavelength collision is avoided, but additional signal processing complexity is introduced
Solution Approach 1:
The patent moves the cable return signal to a higher frequency dimension (above 120 MHz) that does not overlap with the PON signal band, allowing both signals to coexist on the same wavelength without interference while using standard RF up-conversion techniques
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 reduces the cost of customer-premise-equipment (CPE) devices by eliminating expensive lasers and optical receivers, achieving cost savings while maintaining high-speed Ethernet and traditional cable return services.
Implementation Method 1
transmitting an upstream signal having a wavelength of about 1310 nm over an optical fiber
Implementation Method 2
optical receivers for the downstream signals
Data Source
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AI summary
In fiber-to-the-home (FTTH) RF over Glass (RFoG) Architecture a customer-premise-equipment (CPE) includes a wavelength separator. A method includes up-converting a baseband upstream data signal to a frequency band above a frequency band of a baseband downstream data signal; combining the up-converted upstream data signal with an upstream cable return signal; transmitting the up-converted upstream data signal and the upstream cable return signal using a single upstream laser; and separating, with a wavelength separator, A) a downstream data signal and a downstream cable feed signal from B) the combined up-converted upstream data signal and upstream cable return signal.