Time-Wavelength Shifted Bidirectional Optical Network
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Solution Overview
Problem
Current metro-access optical networks lack efficient bidirectional communication capabilities, particularly in terms of time- and wavelength-shifted dynamic optical networks, which are essential for reliable and flexible data and service transmission between headends and subscribers.
Innovation Solution
A time- and wavelength-shifted bidirectional optical network is implemented, where optical signals are propagated with dynamic or statistical wavelength assignment, allowing for time-shifted downstream signals to be reflected as upstream signals with slight wavelength shifts, utilizing fast switching tunable lasers, modulators, optical amplifiers, and arrayed waveguide grating routers to establish a flexible and secure communication system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If bidirectional communication is implemented in optical networks, then communication flexibility is improved, but signal interference and collision between upstream and downstream signals occur
Solution Approach 1:
The patent applies wavelength division by introducing a wavelength shift dimension to separate upstream and downstream signals. The wavelength shifter converts the downstream signal wavelength from λ1 to λ2, creating spectral separation that prevents signal interference while enabling full-duplex bidirectional communication over the same optical fiber.
Solution Approach 2:
The patent implements time-division multiplexing where downstream transmission occurs during a first time period and upstream transmission occurs during a second time period. This periodic time-slot allocation prevents signal collision by ensuring that opposite-direction transmissions do not occur simultaneously.
2Adaptability or versatility
If dynamic wavelength assignment is implemented, then network flexibility and resource utilization are improved, but system complexity increases
Solution Approach 1:
The wavelength shifter operates autonomously at each subscriber premises equipment, automatically converting the downstream wavelength to an upstream wavelength without requiring centralized wavelength management or complex control systems. This self-service approach simplifies overall network complexity while enabling dynamic wavelength assignment.
Solution Approach 2:
The system dynamically changes the wavelength parameter of optical signals based on communication direction. The wavelength shifter modifies the wavelength from λ1 (downstream) to λ2 (upstream), enabling flexible wavelength assignment that adapts to different communication needs without increasing system complexity.
3Object-affected harmful factors
If time-shifting is used to separate upstream and downstream signals, then signal collision is prevented, but time synchronization requirements increase
Solution Approach 1:
The system uses periodic time-division multiplexing with clearly defined time slots for downstream and upstream transmissions. This periodic structure provides inherent time synchronization references that simplify the timing coordination between headend and subscriber equipment while effectively preventing signal collision.
Data Source
AI summary
A bidirectional optical network, in which an incoming/downstream modulated optical signal(s) of a particular wavelength may carry content from a headend to a subscriber. An incoming/downstream unmodulated continuous wave optical signal(s) from the headend is time-shifted (i.e., time delayed with respect to just received incoming/downstream optical signal(s)), collected, modulated and sent back as return/upstream optical signal(s) from the subscriber to the headend. The return/upstream optical signal(s) may have the same wavelength or a slightly shifted wavelength relative to incoming/downstream optical signal(s). Wavelength, bandwidth, subscriber priority and service (content) provider may be fixed, dynamically, or statistically assigned. A modulated marker optical signal(s) is sent along with a modulated data optical signal simultaneously in a different plane. The modulated data optical signal(s) can therefore be securely delivered to a subscriber(s) according to the marker identification. Furthermore a device can be constructed from a group of components comprising an integrated tunable laser-modulator, a wavelength converter, a cyclic arrayed waveguide grating router, a photonic bandgap cyclic arrayed waveguide grating router, a burst enabled detector in order to electro-optically connect network elements, processors and chipsets on a printed circuit board.