Staircase FEC Block Coding for High-Gain Low-Latency Links
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current Forward Error Correction (FEC) coding schemes in optical communication systems, such as those defined in ITU-T Recommendations G.709 and G.975.1, face challenges in achieving higher coding gains without requiring impractical additional processing resources, particularly in maintaining reliable communication and error correction capabilities at lower power levels.
Innovation Solution
The implementation of a staircase Forward Error Correction (FEC) coding scheme, which involves a blockwise recursively encoded method where symbol blocks are mapped to two-dimensional matrices, allowing for the computation of coding symbols across multiple blocks to form valid codewords, achieving a coding gain approaching the Shannon limit with low latency and high burst error correction capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional FEC coding schemes (G.709, G.975.1) are used, then processing resources remain practical, but coding gain is limited and cannot approach the Shannon limit
Solution Approach 1:
The patent segments the data stream into multiple symbol blocks that are processed in a staged manner through the staircase encoding structure. Each block is encoded independently to a certain degree, allowing parallel processing while maintaining overall coding gain. This segmentation enables practical implementation by breaking down the complex encoding task into manageable units that can be processed with reasonable computational resources.
Solution Approach 2:
The patent introduces a two-dimensional staircase structure to the traditional one-dimensional FEC encoding. Data symbols are arranged in a two-dimensional array where encoding proceeds along both rows and columns, creating a staircase pattern of dependency. This dimensional transformation allows the system to achieve higher coding gain by exploiting redundancy in multiple directions while maintaining processing complexity at practical levels through the structured progression of the staircase approach.
2Reliability
If higher coding gain is achieved through enhanced FEC schemes, then error correction capability improves, but latency increases
Solution Approach 1:
The staircase encoding structure performs preliminary encoding actions on early symbol blocks before all input data is available. Each block is encoded to the extent possible with currently available data, rather than waiting for the complete data set. This preliminary action reduces latency by producing encoded output progressively while still achieving high coding gain through the eventual completion of the full staircase structure.
Solution Approach 2:
The patent implements dynamic encoding where the degree of encoding completion varies across different symbol blocks in the staircase structure. Earlier blocks are encoded to a lesser degree initially and refined as more data becomes available, while later blocks benefit from the full staircase structure. This dynamic approach allows the system to balance latency and coding gain by adjusting encoding completeness based on available data and timing requirements.
3Reliability
If more processing resources are allocated to FEC encoding, then coding gain increases, but system complexity becomes impractical
Solution Approach 1:
The patent segments the encoding process into discrete staircase steps where each step processes a specific symbol block. This segmentation allows the system to distribute processing resources across multiple time steps and parallel processing units, avoiding the need for excessive resources concentrated at any single point. Each segment requires moderate processing power, making the overall high-gain encoding practical to implement.
Solution Approach 2:
By transforming the encoding problem into a two-dimensional staircase structure, the patent distributes the computational burden across spatial and temporal dimensions. Rather than requiring all processing power simultaneously, the staircase approach spreads computations across multiple blocks and processing stages, reducing peak resource requirements while achieving the same or better coding gain through the structured redundancy of the two-dimensional approach.
Data Source
AI summary
In staircase forward error correction coding, a stream of data symbols are mapped to data symbol positions in a sequence of two-dimensional symbol blocks Bi, i a positive integer. Each of the symbol blocks has data symbol positions and coding symbol positions. Coding symbols for the coding symbol positions in each symbol block Bi in the sequence are computed. The coding symbols are computed such that, for each symbol block Bi that has a preceding symbol block Bi−1 and a subsequent symbol block Bi+1 in the sequence, symbols at symbol positions along one dimension of the preceding symbol block Bi−1, concatenated with the data symbols and the coding symbols along the other dimension in the symbol block Bi, form a codeword of a FEC component code, and symbols at symbol positions along the one dimension of the symbol block Bi, concatenated with the data symbols and the coding symbols along the other dimension in the subsequent symbol block Bi+1, form a codeword of the FEC component code. Thus, each row in [Bi−1TBi] and each column in [BiBi+1T]for example, is a valid codeword.