TDM Control Channel Multiplexing for Open Fiber and Loss of Light Propagation
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Solution Overview
Problem
Current fiber optic networks using time and wavelength division multiplexing struggle to effectively propagate loss of light (LOL) and open fiber control (OFC) conditions across the network, especially when time multiplexing multiple ISC channels, as existing methods cannot disable lasers in case of equipment failures and require complex handshaking protocols.
Innovation Solution
The solution involves time multiplexing control channels with data channels in a TDM/WDM network, allowing each input channel to have a dedicated overhead control channel for LOL and OFC propagation, and implementing peer-to-peer or master-slave protocols for OFC initialization and propagation, enabling efficient recognition and management of link failures without disrupting other channels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If time multiplexing is used to scale WDM network capacity, then cost-effectiveness and bandwidth efficiency are improved, but propagation of link state conditions (LOL and OFC) becomes complex and unreliable
Solution Approach 1:
The patent segments the control channel into multiple time slots, with each slot dedicated to carrying control information for a specific input channel. This allows multiple control channels to be time-multiplexed while maintaining clear separation and reliable propagation of link state conditions for each channel independently
Solution Approach 2:
The patent introduces a control character as an intermediary signal that is inserted into the multiplexed control channel. This control character allows receiving equipment to identify and extract control information for specific input channels from the time-multiplexed stream, enabling reliable propagation through the TDM/WDM network
2Reliability
If dedicated control channels are used for each input channel, then link state propagation is simplified, but device complexity and overhead increase
Solution Approach 1:
The patent merges multiple dedicated control channels into a single time-multiplexed control channel. Instead of having separate physical control channels for each input channel, the system combines them temporally, reducing the number of simultaneous channels while maintaining the ability to propagate link state conditions reliably through the control character mechanism
3Object-affected harmful factors
If laser disablement is implemented for safety, then laser eye safety is improved, but network availability decreases due to automatic link deactivation on any failure
Solution Approach 1:
The patent segments the laser control so that each input channel has independent laser disablement capability. When a failure is detected in one channel, only the lasers for that specific channel are deactivated, while lasers for other channels remain operational. This maintains laser safety while preserving network availability for unaffected channels
Data Source
AI summary
A method and apparatus for transmitting signals from a plurality of input channels over a TDM optical network, where each of the input channels contains an optical data signal and an electrical control signal containing control information relating to the optical data signal. In accordance with the invention, respective optical receivers convert the optical data signals to respective electrical data signals, which a TDM data multiplexer time-multiplexes to generate a multiplexed data signal. A TDM control signal multiplexer time-multiplexes the electrical control signals to generate a multiplexed control signal that is combined with said multiplexed data signal to generate a composite electrical signal. An optical transmitter generates a composite optical signal from the composite electrical signal that is transmitted over the network, optionally after WDM multiplexing it with other composite optical signals. The corresponding reverse operations are performed at the receiving end to regenerate the original data and control signals.