Spatially coupled codes and optical fiber communications: An ideal match?

Abstract

Abstract-In this paper, we highlight the class of spatially coupled codes and discuss their applicability to long-haul and submarine optical communication systems. We first demonstrate how to optimize irregular spatially coupled LDPC codes for their use in optical communications with limited decoding hardware complexity and then present simulation results with an FPGAbased decoder where we show that very low error rates can be achieved and that conventional block-based LDPC codes can be outperformed. In the second part of the paper, we focus on the combination of spatially coupled LDPC codes with different demodulators and detectors, important for future systems with adaptive modulation and for varying channel characteristics. We demonstrate that SC codes can be employed as universal, channel-agnostic coding schemes.

Probabilistically Shaped Rate-Adaptive Polar-Coded 256-QAM WDM Optical Transmission System

“…To overcome the error-floor of the LDPC codes, a hard-decision FEC code at the expense of extra overhead can be used, e.g., [37], [38]. Carefully designed LDPC codes can push the error floor below 10 −15 without the use of outer hard-decision codes [39].…”

Information-Bottleneck Decoding of High-Rate Irregular LDPC Codes for Optical Communication Using Message Alignment

“…However, analyzing LLRs interpretation of a particular cluster index t in density evolution allows the limiting factor of the considered decoding method to be graphically illustrated for irregular codes. Figure 5a visualizes the meanings of certain cluster indices t with respect to x before and after averaging over the degree distribution according to (4). Here, X=1|t) denote the conveyed meanings of a certain cluster t with respect to x of variable nodes with degree two and four before, that is, without averaging according to (4).…”

“…Figure 5a visualizes the meanings of certain cluster indices t with respect to x before and after averaging over the degree distribution according to (4). Here, X=1|t) denote the conveyed meanings of a certain cluster t with respect to x of variable nodes with degree two and four before, that is, without averaging according to (4). 0 1 2 3 4 5 6 7 8 9 101112131415−5 Both compression variables have the same event space T .…”

“…A very powerful and well-known class of error-correcting codes are the so-called low-density parity-check (LDPC) codes [1]. The design of LDPC codes for optical communications has been discussed in recent works [2][3][4][5][6][7]. In contrast to wireless communication, the coding schemes in optical communication use comparably high code rates R > 0.8 to keep the redundancy at a minimum.…”

“…Furthermore, bit error rates of 10 −15 are required in optical communication systems, which is often challenging to achieve with LDPC codes due to their characteristic error floor. Nevertheless, recent works [2][3][4][5][6][7] underlined the potential of LDPC codes as promising candidates in future optical communication systems. For a detailed summary of coding schemes for optical systems, we refer the interested reader to [7,8].…”