EXIT Chart-Aided Design of LDPC Codes for Self-Coherent Detection with Turbo Equalizer for Optical Fiber Short-Reach Transmissions

Noboru OSAWA
Shinsuke IBI
Seiichi SAMPEI

IEICE TRANSACTIONS on Communications   Vol.E102-B    No.7    pp.1301-1312
Publication Date: 2019/07/01
Publicized: 2019/01/16
Online ISSN: 1745-1345
DOI: 10.1587/transcom.2018EBP3267
Type of Manuscript: PAPER
Category: Fiber-Optic Transmission for Communications
self-coherent detection,  turbo equalizer,  LDPC,  EXIT chart,  optical fiber short-reach transmissions,  

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This paper proposed an iterative soft interference canceller (IC) referred to as turbo equalizer for the self-coherent detection, and extrinsic information transfer (EXIT) chart based irregular low density parity check (LDPC) code optimization for the turbo equalizer in optical fiber short-reach transmissions. The self-coherent detection system is capable of linear demodulation by a single photodiode receiver. However, the self-coherent detection suffers from the interference induced by signal-signal beat components, and the suppression of the interference is a vital goal of self-coherent detection. For improving the error-free signal detection performance of the self-coherent detection, we proposed an iterative soft IC with the aid of forward error correction (FEC) decoder. Furthermore, typical FEC code is no longer appropriate for the iterative detection of the turbo equalizer. Therefore, we designed an appropriate LDPC code by using EXIT chart aided code design. The validity of the proposed turbo equalizer with the appropriate LDPC is confirmed by computer simulations.