WDM-PON Architecture Eliminates ONU Laser for Cost Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The high cost, large volume, and high power consumption of lasers with stable wavelengths in WDM-PON systems pose a challenge for widespread adoption, particularly due to the need for independent wavelength operation in optical network units (ONUs), which increases operational, management, and maintenance costs.
Innovation Solution
A wavelength division multiplexing passive optical network architecture that splits a continuous light from a shared optical source into two signals, where one signal is modulated for downlink transmission and the other, unchanged, is used as an uplink carrier signal, eliminating the need for an additional optical source generator in the ONU and allowing for cost reduction and simplified architecture.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a stable wavelength laser is used in the transmitting module of ONU or OLT, then the wavelength stability is improved, but the cost, volume, and power consumption increase
Solution Approach 1:
The patent applies universality by enabling the ONU to operate independently of specific wavelength assignments. The optical demultiplexer is designed to handle multiple wavelength channels, allowing the same ONU hardware to work with different wavelength configurations without requiring wavelength-specific components or refrigeration systems, thus reducing cost and complexity while maintaining wavelength stability through the shared optical source.
Solution Approach 2:
The patent uses copying by implementing wavelength conversion functionality where an optical demultiplexer receives signals at one wavelength and outputs them at a different wavelength. This allows the ONU to receive downlink signals at a first wavelength and transmit uplink signals at a second wavelength without requiring its own stable wavelength laser, effectively copying the wavelength stability function from the OLT side to the network infrastructure.
2Adaptability or versatility
If an optical demultiplexer is adopted in the optical path, then the wavelength division multiplexing capability is improved, but the cost increases due to the need for stable wavelength lasers
Solution Approach 1:
The patent applies merging by combining the wavelength division multiplexing functionality with a shared optical source architecture. Instead of each ONU requiring its own stable wavelength laser, the system merges the wavelength stabilization function into the OLT's optical source, allowing multiple ONUs to share this resource. The optical demultiplexer at the ONU side simply separates wavelengths without needing to generate or stabilize them, reducing individual ONU complexity while maintaining overall WDM capability.
3Ease of operation
If the ONU is designed to be independent of wavelength, then the ease of operation and maintenance is improved, but the need for additional optical source generators increases cost
Solution Approach 1:
The patent applies extraction by removing the optical source generator from the ONU configuration entirely. The ONU is designed to receive optical signals from the OLT and convert them to electrical signals for processing. By extracting the optical source function from the ONU and placing it only in the OLT, the system achieves wavelength independence for ONUs, simplifying operation and maintenance while avoiding the cost of additional optical source generators at each ONU location.
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 solution reduces system costs and maintenance by eliminating the need for an additional optical source generator in the ONU, while avoiding mutual interference between uplink and downlink signals through subcarrier modulation with different central wavelengths, and simplifies the system architecture with all-optical detection demodulation.
Implementation Method 1
the optical splitter is adapted to split a continuous light with a wavelength of λ from the optical source into the two optical signals
Implementation Method 2
the modulator is adapted to modulate a downlink signal to the first optical signal and then input a modulated downlink signal to the optical multiplexer, where a central wavelength of the modulated downlink signal has an offset of a preset value Δλ compared with a central wavelength of the second optical signal
Implementation Method 3
the optical multiplexer is adapted to multiplex the modulated downlink signal with the second optical signal
Implementation Method 4
separate the multiplexed signal and use the second optical signal received as the uplink carrier signal
Data Source
Figure 1~2
Figure 3~5
Figure 6a~7b
AI summary
A wavelength division multiplexing passive optical network and its implement method, in this optical network, optical line termination includes at least one optical transmit module, each optical network unit includes an optical receive module, said optical transmit module one-to-one corresponds to optical receive module; the optical transmit module, for splitting one optical source to two bunch, one bunch optical signal served as downlink signal carrier, another loops back through the optical network unit and served as uplink signal carrier. The optical receive module in the optical network unit, receives optical signal from optical transmit module, and transmits uplink signal using the received uplink signal carrier provided by the optical transmit module. The embodiment in the present invention provides an implement method of wavelength division multiplexing passive optical network. The embodiment in the present invention doesn't need to apply other optical source generator to generate uplink signal carrier in ONU, save the optical source generator on the ONU, and the uplink optical signal and downlink optical signal use the same optical wavelength segment together, save the optical fiber bandwidth.