Filterless Optical Network Channel Crosstalk Reduction
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Solution Overview
Problem
In filter-free optical networks, the utilization of the spectral transmission range is limited due to crosstalk between adjacent transmission channels, which reduces the number of channels that can be used, leading to inefficient use of available bandwidth.
Innovation Solution
The method involves detuning the transmission filters by shifting their filter peak frequency (FPF) relative to the channel center frequency (CMF) for adjacent channels, allowing for the use of more transmission channels without crosstalk, thereby improving spectral range utilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If transmission filters are not detuned, then crosstalk between adjacent transmission channels occurs, but the utilization of the spectral transmission range is limited due to the need for guard channels
Solution Approach 1:
The filter peak frequency (FPF) of transmission filters is dynamically adjusted relative to the channel center frequency (CMF) based on the occupancy status of adjacent channels. When adjacent channels are occupied, the FPF is shifted away from the CMF to reduce crosstalk; when adjacent channels are unused, the FPF returns to align with the CMF to maximize spectral utilization. This parameter change resolves the contradiction by adaptively managing the filter characteristics.
Solution Approach 2:
The system transitions from static filter tuning to dynamic filter tuning where the FPF is continuously adjusted according to real-time channel occupancy information. This dynamic adaptation allows the network to optimize spectral utilization while preventing crosstalk on-demand, rather than maintaining fixed guard channels that permanently reduce spectral efficiency.
2Reliability
If guard channels are used to prevent crosstalk, then adjacent transmission channels can be protected, but the number of usable transmission channels decreases
Solution Approach 1:
The function of guard channels for crosstalk prevention is extracted from the transmission channel allocation and transferred to the transmission filter detuning mechanism. Instead of dedicating entire channels as unused guard bands, the patent extracts the protective function and implements it through selective FPF adjustment of active channels, thereby eliminating the need for sacrificed guard channels.
Solution Approach 2:
The crosstalk prevention function traditionally provided by guard channels is copied and replicated through the transmission filter detuning mechanism. Each channel's filter can be independently detuned to provide the same protective effect against adjacent channel interference that guard channels would provide, but without consuming additional spectral resources.
3Object-affected harmful factors
If transmission filters are detuned by shifting FPF relative to CMF, then crosstalk is reduced, but filter configuration complexity increases
Solution Approach 1:
The transmission filter detuning system is self-configuring based on automatically detected channel occupancy information from the network. The system monitors which adjacent channels are occupied and autonomously adjusts the FPF accordingly without requiring manual filter reconfiguration or complex external control systems, thereby limiting the increase in operational complexity.
Data Source
Figure 1a~1e
Figure 2~3
Figure 4a~4
AI summary
The invention relates to a method for data transmission in a filterless optical network (1), which consists of several network nodes (21 - 2n) with transmitters and receivers and of network edges (31 - 3n) connecting the network nodes (21 - 2n), wherein a plurality of transmission channels with channel center frequencies spaced apart from each other in a fixed channel grid are defined for the network (1) with respect to the carrier signals usable in it for the transmission of user data, and wherein protection channels not used for the transmission of user signals are provided within the channel grid between transmission channels used for the transmission of user data on a network edge (31 - 3n).According to the invention, it is proposed that when immediately adjacent transmission channels of a network edge (31 - 3n) are occupied with carrier signals transporting user data, the transmit filter for one of these transmission channels is detuned with respect to its passband in the direction of its other immediately adjacent transmission channel, which serves as a protection channel. According to a preferred embodiment, the filter peak frequency of the transmit filter is shifted relative to the channel center frequency of the associated transmission channel by Δf in the direction of the channel center frequency of the immediately adjacent protection channel.