Optical Transceiver Time Alignment for Multi-OFE Signal Synchronization
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Solution Overview
Problem
In optical wireless communication systems with multiple optical front ends connected via cables to a shared baseband module, differing cable lengths cause phase shifts leading to destructive interference and signal degradation, especially in systems requiring wide coverage areas like offices or classrooms.
Innovation Solution
A time-alignment subsystem with signal detectors and a delay network that measures and compensates for phase differences by selectively adding delays to individual signal paths using controllers and delay elements like lumped-element delay lines or printed circuit board traces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If multiple Optical Front Ends are connected via cables of different lengths to a shared baseband module, then the coverage area can be extended, but destructive interference occurs due to phase shifts
Solution Approach 1:
The patent introduces a time-alignment subsystem that dynamically adjusts the delay parameters of individual signal paths. By measuring the time of arrival of signals from different OFEs and calculating appropriate delay values, the system compensates for cable length differences. This parameter adjustment ensures that signals arrive at the baseband module in synchronization, eliminating destructive interference while maintaining extended coverage through multiple OFEs.
2Reliability
If cables of the same length are used to connect multiple OFEs, then destructive interference is avoided, but device complexity and installation difficulty increase
Solution Approach 1:
The time-alignment subsystem operates autonomously to compensate for cable length variations. It automatically performs signal detection, time of arrival measurement, delay calculation, and compensation without requiring manual intervention. This self-service mechanism eliminates the need for precise cable length matching during installation, reducing system complexity while maintaining signal quality.
3Reliability
If manual cable length matching is required, then installation time and cost increase, but signal synchronization is achieved
Solution Approach 1:
The time-alignment subsystem performs preliminary automatic calibration of signal path delays during system initialization or setup phase. By pre-measuring the time of arrival of test signals and pre-calculating the required delay compensations, the system establishes synchronized signal paths before normal operation begins. This preliminary action eliminates the need for time-consuming manual cable length matching during installation.
Data Source
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AI summary
This invention discloses a time-alignment subsystem (100) for use with an optical transceiver (200) that comprises a plurality of Optical Front Ends, OFEs (210), connected to a common baseband module (220) via a plurality of cables (211). The time-alignment subsystem comprises a controller (110), a plurality of signal detectors (111) with each connected to an individual cable (211) out of the plurality of cables (211), and a delay network (120). Each of the plurality of signal detectors (111) is configured to detect, on the individual cable (211), an individual copy of an incoming signal received by a corresponding OFE (210); and to provide the controller (110) with detection information. The delay network (120) is configured to selectively add an individual delay to an individual signal path of each individual cable (211) to improve time-alignment among the plurality of signal paths. The controller (110) is configured to determine the individual delay for the individual signal path based on the detection information provided by each signal detector (111).