Optical Subcarrier Frequency Division Multiplexing for Hub-Leaf Networks
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Solution Overview
Problem
Conventional optical communication systems face increased costs and complexity due to the need for multiple lasers, modulators, and high-speed circuitry, especially when transmitting high-capacity signals to lower capacity nodes, and are limited by the amount of customer data that can be transmitted due to excessive operation, administration, and maintenance (OAM) information.
Innovation Solution
A network architecture where a primary hub node communicates with multiple remote leaf nodes using optical subcarriers generated by a combination of a laser and modulator, employing frequency division multiplexing access, and dynamically adjusting the number of subcarriers and data allocation based on changing bandwidth requirements, with dedicated subcarriers carrying OAM information to configure leaf nodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple lasers and modulators are employed to increase system capacity, then the data transmission capacity is improved, but the system cost increases
Solution Approach 1:
Multiple optical signals with different wavelengths are multiplexed onto a single optical fiber using wavelength division multiplexing (WDM). This combines multiple data streams into one physical medium, increasing transmission capacity without requiring separate fibers for each signal, thereby reducing overall system cost while maintaining high productivity
Solution Approach 2:
A single optical fiber infrastructure is designed to carry multiple wavelength channels simultaneously, each capable of carrying independent data streams. This multi-functional use of the same physical infrastructure allows the system to handle multiple data streams efficiently, increasing capacity without proportionally increasing the number of physical components
2Productivity
If high-speed circuitry is provided at receive end to detect and forward data, then the data detection capability is improved, but the cost of lower capacity nodes increases
Solution Approach 1:
The optical signal is segmented into multiple wavelength channels, each carrying a portion of the total data capacity. Lower capacity nodes can selectively receive and process only the specific wavelength channel(s) they need, rather than requiring full high-speed circuitry to handle the entire aggregated capacity. This segmentation allows cost-effective deployment of nodes with varying capacity requirements
Solution Approach 2:
Each receive node is equipped with filtering or selection capability to process only its designated wavelength channel locally. This means each node has the appropriate detection capability for its specific need without requiring the full high-speed processing power needed for the entire system capacity, reducing costs for lower capacity nodes while maintaining adequate detection capability for their specific function
3Ease of operation
If OAM information is included in each data frame, then the system control capability is improved, but the amount of customer data that can be transmitted decreases
Solution Approach 1:
Control and management information is extracted from the customer data stream and transmitted separately using dedicated overhead channels or out-of-band communication mechanisms. This separation allows OAM information to be carried without consuming customer data bandwidth, maintaining full control capability while preserving maximum customer data transmission capacity
Solution Approach 2:
The system uses wavelength division to separate control traffic from customer data traffic into different dimensional spaces (different wavelength channels). Management and control information can be transmitted on dedicated wavelengths while customer data occupies other wavelengths, allowing both functions to operate simultaneously without competing for the same bandwidth resources
Data Source
AI summary
A network or system in which a hub or primary node may communicate with a plurality of leaf or secondary nodes. The hub node may operate or have a capacity greater than that of the leaf nodes. Accordingly, relatively inexpensive leaf nodes may be deployed to receive data carrying optical signals from, and supply data carrying optical signals to, the hub node. One or more connections may couple each leaf node to the hub node, whereby each connection may include one or more spans or segments of optical fibers, optical amplifiers, optical splitters/combiners, and optical add/drop multiplexer, for example. Optical subcarriers may be transmitted over such connections, each carrying a data stream. The subcarriers may be generated by a combination of a laser and a modulator, such that multiple lasers and modulators are not required, and costs may be reduced. As the bandwidth or capacity requirements of the leaf nodes change, the number of subcarriers, and thus the amount of data provided to each node, may be changed accordingly. Each subcarrier within a dedicated group of subcarriers may carry OAM or control channel information to a corresponding leaf node, and such information may be used by the leaf node to configure the leaf node to have a desired bandwidth or capacity.