Beyond 100 Gbit/s Pipeline Decoders for Spatially Coupled LDPC Codes

Abstract

Low-density parity-check (LDPC) codes are a well-established class of forward error correction codes that provide excellent error correction performance for large code block sizes. However, for throughputs toward 1 Tbit/s, as expected for B5G systems, state-of-the-art LDPC soft decoders are restricted to short code block sizes of several hundred to thousands of bits due to routing congestion challenges, limiting the overall communications performance of the transmission system. Spatially coupled LDPC (SC-LDPC) codes and respective sliding window decoding methods show the potential to overcome these block size restrictions. However, in contrast to conventional LDPC codes little literature exists on the efficient hardware implementation of respective high-throughput decoders. In this work, we present the first in-depth investigation on the implementation of SC-LDPC decoders for throughputs beyond 100 Gbit/s. For an $$N=51328$$ N = 51328 , $$R=0.8$$ R = 0.8 terminated SC-LDPC code with sub-block size $$c=640$$ c = 640 and coupling width $$m_s=1$$ m s = 1 , we explore various design trade-offs, including row- and column-wise decoding, non-overlapping and overlapping window scheduling, and processor pipelining. To the best of our knowledge, this is the first description of a column-wise SC-LDPC decoding architecture in the literature. We complement the algorithmic investigation with the virtual silicon implementation of all presented decoders in a 22nm FD-SOI technology.

Physical layer error correction for free-space optical links

“…This irregularity is highly challenging for the design of a decoder architecture. 21 To maintain a regular window decoder structure for 1 < T ≤ W , there are two possibilities: i) add flexibility to the routing network or ii) move the decoding window by T spatial positions. A flexible routing network requires all possible connections to be physically reflected, e. g., use of a shifter network.…”

“…This locality can be exploited for efficient decoding. [19][20][21] A standard block LDPC decoder architecture with a small block size is moved as a window over the diagonal structure of the parity check matrix structure. The block decoder is a node parallel decoder in which CNs and VNs are one-to-one instantiated in hardware and the connections between the nodes are implemented as wires.…”