PON Wavelength Switching for Low Latency Transmission
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Solution Overview
Problem
Conventional Passive Optical Network (PON) systems face challenges in reducing transmission delay, particularly in mobile fronthaul, mobile backhaul, sensor networks, and in-vehicle networks, due to optical transmission delays and the need for quiet windows, which hinder efficient data transmission and ONU registration.
Innovation Solution
A wavelength switching method is introduced where an Optical Network Unit (ONU) responds to a ranging request on a first uplink wavelength, receives ranging information, and switches to a second uplink wavelength for data transmission, minimizing the path transmission time difference caused by wavelength intervals within a fault tolerance range, allowing for efficient data transfer and reduced delay.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a quiet window is opened for ONU discovery and ranging, then the OLT can discover and range the ONU, but the transmission delay increases by up to 200 microseconds
Solution Approach 1:
The patent segments the uplink wavelength resources into multiple wavelengths. Ranging operations are performed on a first uplink wavelength while data transmission occurs on a second uplink wavelength, allowing these operations to proceed simultaneously without interfering with each other, thus eliminating the need for quiet windows that cause delays
Solution Approach 2:
The patent transitions from time-division multiplexing (where ranging and data transmission compete for the same time slot) to wavelength-division multiplexing (where ranging and data transmission occur on different wavelengths simultaneously). This dimensional change from time to wavelength space allows parallel operations without mutual interference
2Adaptability or versatility
If a third wavelength is added to achieve quiet window opening, then wavelength resources are expanded, but the definition becomes difficult and wavelength resources are strained
Solution Approach 1:
The patent makes existing uplink wavelengths multi-functional by enabling them to serve both ranging and data transmission purposes simultaneously through wavelength division. The first uplink wavelength handles ranging while the second uplink wavelength handles data transmission, eliminating the need for a dedicated third wavelength and reducing overall system complexity
3Stability of the object's composition
If a TWDM-PON system uses one of the original wavelengths for quiet window opening, then the system structure is maintained, but the low delay capacity is reduced
Solution Approach 1:
The patent dynamically allocates different wavelengths for different functions based on operational needs. During ranging operations, the first uplink wavelength is used for ranging while the second remains available for data transmission. This dynamic wavelength assignment allows the system to maintain its TWDM-PON structure while achieving low-latency performance through parallel wavelength usage
Data Source
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AI summary
Provided are wavelength switching and configuration methods and devices for a Passive Optical Network (PON). The switching method includes the following operations. An Optical Network Unit (ONU) responds to a ranging request message sent by an Optical Line Terminal (OLT) on a first uplink wavelength supported by the ONU. The ONU receives ranging information sent by the OLT. The ONU uses the received ranging information as ranging information about a second uplink wavelength of the ONU, and performs data transmission on the second uplink wavelength according to a bandwidth allocation from the OLT. A path transmission time difference caused by a wavelength interval between the first uplink wavelength and the second uplink wavelength is less than a corresponding fault tolerance range when the OLT receives data. The ranging information is obtained by the OLT according to a ranging response sent by the ONU on the first uplink wavelength.