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 operational, administration, and maintenance (OAM) information that reduces customer data transmission.
Innovation Solution
A network architecture where a primary hub node communicates with remote leaf nodes using optical subcarriers generated by a combination of a laser and modulator, employing frequency division multiplexing and optical splitters/combiners, allowing for efficient data transmission and configuration of leaf nodes with varying bandwidth requirements without the need for intermediate high-speed circuitry.
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:
The optical signal is segmented into multiple subcarriers in the frequency domain using an IFFT operation. Each subcarrier can be independently modulated and transmitted, allowing the system to achieve high capacity through parallel subcarrier transmission rather than requiring multiple separate laser and modulator pairs. This segmentation enables cost-effective capacity expansion.
Solution Approach 2:
A single laser and modulator combination serves multiple functions by generating multiple subcarriers that can be allocated to different nodes dynamically. The same hardware infrastructure supports multiple capacity levels and multiple destination nodes, eliminating the need for dedicated hardware for each capacity level and reducing overall system cost.
2Productivity
If high-speed circuitry is provided at receive end to detect and forward data, then the data transmission capability is improved, but the cost of lower capacity nodes increases
Solution Approach 1:
Leaf nodes perform only partial signal processing by detecting and forwarding specific subcarriers assigned to them, rather than processing the entire high-speed optical signal. This partial action allows lower capacity nodes to operate with simpler, less expensive circuitry while still achieving the required data transmission capability for their specific needs.
Solution Approach 2:
The patent replaces electronic signal processing with optical signal processing in the domain of frequency. By using optical Fourier transformation and optical filtering, the system enables frequency-selective signal processing without requiring high-speed electronic circuitry at each node, thus reducing the cost and complexity of leaf nodes.
3Adaptability or versatility
If more OAM information is transmitted in each frame, then the system control capability is improved, but the amount of customer data transmission decreases
Solution Approach 1:
The patent moves OAM information transmission from the time domain (separate overhead bytes in each frame) to the frequency domain (specific subcarriers). This dimensional change allows OAM information to be multiplexed with customer data in the frequency domain, enabling both control information and customer data to coexist without reducing the overall transmission capacity for customer data.
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 approach reduces network costs by minimizing components, enhances data transmission efficiency by dynamically adjusting subcarrier allocation based on node capacity needs, and optimizes the use of bandwidth to increase customer data transmission while managing OAM information effectively.
Implementation Method 1
The subcarriers may be generated by a combination of a laser and a modulator
Implementation Method 2
optical splitters/combiners
Data Source
AI summary
A hub node may or have a capacity greater than that of associated leaf nodes. Accordingly, 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, each connection including one or more segments of optical fibers, optical amplifiers, optical splitters/combiners, and optical add/drop multiplexer. 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. As the capacity requirements of the leaf nodes change, the number of subcarriers associated with, and thus the amount of data provided to, each node, may be changed accordingly.