Optical Network Carrier Frequency Control via Automatic Feedback
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Solution Overview
Problem
Carrier frequency drift in optical networks reduces effective channel bandwidth, especially in high-speed systems like 400G, due to the need for large channel bandwidth guard bands, which limits spectral efficiency and increases costs.
Innovation Solution
Implementing end-to-end automatic frequency control (AFC) using a feedback loop that continuously monitors performance information to adjust the transmitter laser frequency and align it to the center of the signal channel bandwidth, reducing the need for guard bands and improving channel utilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If large channel bandwidth guard bands are used to accommodate carrier frequency drift, then frequency stability is improved, but spectral efficiency deteriorates
Solution Approach 1:
The patent implements an automatic frequency control (AFC) system that continuously monitors the carrier frequency at the receiver and feeds back frequency offset information to the transmitter. The transmitter uses this feedback to adjust its laser frequency in real-time, eliminating the need for large guard bands while maintaining frequency stability.
Solution Approach 2:
The system dynamically changes the transmitter laser frequency parameter based on feedback from the receiver. By continuously adjusting the frequency parameter to track the center of the signal channel bandwidth, the system maintains optimal performance without requiring fixed large guard bands.
2Device complexity
If carrier frequency drift is allowed, then device complexity is reduced, but channel bandwidth utilization deteriorates
Solution Approach 1:
The AFC system enables the optical network to self-correct frequency drift automatically. The receiver monitors frequency offset and the transmitter self-adjusts its laser frequency based on this information, eliminating the need for complex external frequency control mechanisms while maximizing channel bandwidth utilization.
3Reliability
If guard bands are increased to accommodate frequency drift, then frequency offset tolerance is improved, but bandwidth utilization deteriorates
Solution Approach 1:
The AFC system replaces static guard bands with dynamic feedback-based frequency adjustment. By continuously monitoring and correcting frequency offsets, the system achieves high frequency offset tolerance with minimal bandwidth consumption, dramatically improving bandwidth utilization compared to fixed guard band approaches.
Data Source
AI summary
A system to provide carrier frequency control in an optical network includes a first network element monitoring performance information and a second network element coupled to the first network element by the optical network. The second network element receives performance information from the first network element using an administration channel bandwidth, and modifies a carrier frequency associated with the second network element based on the performance information such that the carrier frequency is aligned to a center of a signal channel bandwidth. A method of providing carrier frequency control includes transmitting performance information by the first network element to the second network element using an administration channel bandwidth, and modifying the carrier frequency by the second network element based on the performance information such that the carrier frequency is aligned to the center of the signal channel bandwidth. The administrative channel bandwidth can be within or outside the signal channel bandwidth. A corresponding computer-readable device is disclosed.