OTN Client Signal Mapping With Cbyte Verification and 3-Frame Filtering
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Solution Overview
Problem
Existing optical transport network (OTN) technologies face challenges in reliably transporting client signals due to insufficient space for indicating client signal byte numbers, leading to errors and excessive overhead bytes, and lack of a uniform frame structure for virtually-concatenated OPUks, affecting reliability and scalability.
Innovation Solution
A method and apparatus that utilize a client signal byte number change identifier in the Cbyte field to verify and adjust client signal byte numbers, enhancing reliability by compressing overhead space and providing a uniform format for OPUk-Xv containers, using a Cbyte field divided into areas for indicating new signals and adjusting byte numbers, and implementing a 3-frame filtering mode to stabilize byte number changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If the Cbyte field uses 2 bytes to indicate client signal byte number, then the overhead space is saved, but the reliability is insufficient due to error filtering requirements
Solution Approach 1:
The Cbyte field is segmented into two distinct areas: a first area (2 bits) for indicating whether the client signal byte number has changed, and a second area (14 bits) for storing the actual byte number value. This segmentation allows the system to use minimal overhead (2 bytes) while maintaining reliability through the change indication mechanism that enables error detection and filtering.
Solution Approach 2:
The patent changes the parameter representation method by using a change indication flag (first area) combined with a value field (second area) instead of directly transmitting the full byte number in every frame. This parameter change approach reduces overhead while improving reliability through the ability to detect and filter erroneous changes.
2Reliability
If 3 same Cbyte values are transported in each frame with majority vote manner, then the reliability is improved, but the overhead bytes become excessive
Solution Approach 1:
Instead of transmitting 3 complete Cbyte values (6 bytes total), the patent segments the information into a change indication flag (2 bits) and a value field (14 bits), transmitted once per frame. This segmentation achieves error filtering through the change indication mechanism while reducing overhead from 6 bytes to 2 bytes.
Solution Approach 2:
The patent applies partial action by transmitting only the necessary information (change indication + value) rather than the full 3 redundant values. The change indication flag provides just enough information to enable error filtering without requiring excessive overhead bytes.
3Ease of manufacture
If virtual concatenation overhead and PSI occupy 4 bytes in each OPUk overhead, then the frame structure is established, but the space for Cbyte indication becomes insufficient
Solution Approach 1:
The patent segments the Cbyte field into two functional areas within the available overhead space: a first area (2 bits) for change indication and a second area (14 bits) for the byte number value. This segmentation efficiently utilizes the limited overhead space after accounting for virtual concatenation overhead and PSI, providing sufficient indication capability without requiring additional overhead bytes.
Data Source
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AI summary
A method for transporting a client signal in an optical transport network (OTN) includes steps as follows. A client signal is acquired, and a client signal clock is extracted. A byte number Cn of the client signal transported in a current OTN frame period is generated according to the client signal clock and a system clock. If the Cn of the current OTN frame falls in a certain range, a predetermined area in an optical channel payload unit-k (OPUk) overhead field is identified as normal, and the Cn is filled in the OPUk overhead field of the current OTN frame. Meanwhile, Cn client signal bytes are mapped to an OPUk payload area of a next OTN frame, and an optical channel transport unit (OTU) including the OPUk is transmitted to the OTN network. Otherwise, the predetermined area in the OPUk overhead field of the current OTN frame is identified as abnormal, and an exception handling is executed. A corresponding apparatus is also provided. Therefore, the reliability for transporting the client byte number can be improved and an OPUk overhead byte space needed for transporting the client signal byte number can be saved.