Coherent Burst Reception With Adaptive Filter Length for Phase Noise
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Solution Overview
Problem
In point-to-multipoint PON systems, phase noise varies among optical network units due to differences in laser light source oscillation characteristics, complicating system configuration when using multi-level phase modulation, especially with digital coherent demodulation.
Innovation Solution
A communication device and method that coherently receives burst frame signals and adjusts the block length of a moving average filter in carrier phase synchronization to minimize phase noise, using one local oscillation light source for multiple ONUs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If multi-level phase modulation is used for high-speed communication, then communication speed is improved, but phase noise varies among ONUs making system configuration complicated
Solution Approach 1:
The patent changes the parameter of block length in the moving average filter to adapt to different phase noise conditions of each ONU. By dynamically adjusting this parameter, the system maintains simplified configuration while handling phase noise variations in multi-level phase modulation systems.
Solution Approach 2:
The patent introduces dynamic adjustment of the moving average filter block length based on measured phase noise characteristics. This dynamic adaptation allows the system to respond to different ONU conditions without requiring complex pre-configuration, resolving the contradiction between high-speed modulation and system complexity.
2Reliability
If OPLL technique is used to suppress phase noise, then phase noise is reduced, but system configuration becomes complicated and difficult to realize
Solution Approach 1:
The patent replaces the expensive and complex OPLL technique with a simpler, more economical approach using a moving average filter with adjustable block length. This simpler method achieves adequate phase noise handling without requiring high-precision electric and optical devices, making the system easier to realize.
Solution Approach 2:
The patent extracts only the essential function of phase noise suppression from the complex OPLL technique, implementing it through a simpler moving average filter mechanism. This extraction achieves the necessary reliability without importing the full complexity of OPLL.
3Device complexity
If one local oscillation light source is used for multiple ONUs, then device complexity is reduced, but phase noise from different laser sources cannot be compensated
Solution Approach 1:
The patent segments the phase noise compensation approach by applying individual moving average filters with customized block lengths for each ONU. This segmentation allows each filter to be optimized for its specific ONU's phase noise characteristics, achieving effective compensation despite using a single shared local oscillation light source.
Data Source
AI summary
The communication device includes: a reception unit that receives burst frame signals from a plurality of other communication devices respectively; and a control unit that changes a block length of a moving average filter in carrier phase synchronization so as to minimize a phase noise amount of the burst frame signals.