1 research outputs found
Design of Robust, Protograph Based LDPC Codes for Rate-Adaptation via Probabilistic Shaping
In this work, the design of robust, protograph-based low-density parity-check
(LDPC) codes for rate-adaptive communication via probabilistic shaping is
considered. Recently, probabilistic amplitude shaping (PAS) by B\"ocherer et
al. has been introduced for capacity approaching and rate-adaptive
communication with a bitwise-demapper and binary decoder. Previous work by the
authors considered the optimization of protograph based LDPC codes for PAS and
specific spectral efficiencies (SEs) to jointly optimize the LDPC code node
degrees and the mapping of the coded bits to the bit-interleaved coded
modulation (BICM) bit-channels. We show that these codes tend to perform poor
when operated at other rates and propose the design of robust LDPC codes by
employing a min-max approach in the search for good protograph ensembles via
differential evolution. The considered design uses a single 16
amplitude-shift-keying (ASK) constellation and a robust 13/16 rate LDPC code to
operate between 0.7 to 2.7 bits per channel use. For a blocklength of 16224
bits and a target frame error rate of 1e-3 the proposed code operates within
1.32 dB of continuous AWGN capacity for 0.7 to 1.3 bpcu and within 1.05 dB for
1.3 bpcu to 2.7 bpcu.Comment: Accepted for Publication in the Proceedings of 2016 9th International
Symposium on Turbo Codes and Iterative Information Processing (ISTC), Invited
paper for the special session on "Recent Advances in Coding for Higher Order
Modulation