10G-PON Downstream Frame Synchronization with HEC Protection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing PON systems face challenges in maintaining transmission synchronization and error detection/correction, particularly in high-bandwidth applications like 10 Gigabit PONs, where additional synchronization information is needed but not protected by FEC schemes.
Innovation Solution
Implementing a framing mechanism that includes FEC codewords for error correction and additional non-FEC encoded bytes with HEC encoding for synchronization information, ensuring robust error detection and correction within a 125 microsecond window.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If additional non-FEC encoded bytes with HEC encoding are added for synchronization information, then synchronization reliability is improved, but frame structure complexity increases
Solution Approach 1:
The frame structure is segmented into distinct functional areas: FEC-encoded data payload and separate non-FEC encoded synchronization bytes with HEC protection. This segmentation allows independent optimization of each section - the data portion uses robust FEC while the synchronization portion uses simpler HEC encoding, resolving the contradiction between reliability and complexity.
Solution Approach 2:
Different error protection mechanisms are applied to different parts of the frame based on their specific requirements. The synchronization information bytes use HEC encoding which is simpler and more suitable for frequent synchronization patterns, while the main data payload uses comprehensive FEC. This local differentiation improves overall system reliability without uniformly increasing complexity.
2Reliability
If HEC encoding is used for synchronization information, then error detection capability is improved, but processing overhead increases
Solution Approach 1:
HEC encoding is applied selectively only to the synchronization information bytes rather than the entire frame. This partial application provides sufficient error detection capability for synchronization purposes without the excessive processing overhead of applying full FEC encoding to all data, resolving the contradiction between error detection capability and processing overhead.
3Productivity
If synchronization information is not protected by FEC, then bandwidth efficiency is improved, but transmission reliability deteriorates
Solution Approach 1:
The error protection parameter is changed from full FEC encoding to HEC encoding specifically for synchronization information. This parameter change maintains bandwidth efficiency by using less redundant encoding while still providing adequate transmission reliability for synchronization data through the HEC error detection and correction capabilities.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
An apparatus comprising an optical line terminal (OLT) configured to couple to a plurality of optical network units (ONUs) and transmit a plurality of downstream frames to the ONUs, wherein each of the downstream frames comprises a plurality of forward error correction (FEC) codewords and a plurality of additional non-FEC encoded bytes that comprise synchronization information that is protected by Header Error Control (HEC) code. An apparatus comprising a processing unit configured to arrange control data, user data, or both into a plurality of FEC codewords in a downstream frame and arrange a physical synchronization sequence (PSync), a superframe structure, and a Passive Optical Network-identifier (PON-ID) structure in a plurality of additional non-FEC encoded bytes in the downstream frame, and a transmission unit configured to transmit the FEC codewords and the additional non-FEC encoded bytes in the downstream frame within a 125 microsecond window.