LDPC-Coded OFDM for Optical Communication Systems with Direct Detection

Abstract

Abstract-Low-density parity-check (LDPC) coded orthogonal frequency division multiplexing (OFDM) is proposed as an efficient coded modulation technique suitable for optical communication systems. We show that in long-haul fiber optics communications, LDPC-coded OFDM increases spectral efficiency, and reduces the influence of residual chromatic dispersion and the influence of fiber nonlinearities. LDPC-coded OFDM is as also a promising polarization-mode dispersion (PMD) compensation technique. In free space optical communications, LDPC-coded OFDM improves the immunity to the atmospheric turbulence; while in multimode fiber links, it reduces the influence of intermodal dispersion. In plastic optical fiber links it reduces the influence of dispersion and helps to overcome the bandwidth limitations. Several power efficient OFDM schemes and LDPC codes suitable for use in LDPCcoded OFDM optical communication systems are introduced.Index Terms-Fiber optics communications, free space optical communications, graded-index plastic optical fiber links, lowdensity parity-check (LDPC) codes, optical communications, orthogonal frequency division multiplexing (OFDM).

A Construction Method of LDPC Codes for Space Optical Communications Based on Protograph

“…However, an optical wave propagating trough the air experiences fluctuations in amplitude and phase due to atmospheric turbulence, also known as scintillation [4] [5]. So we have more requirements to channel coding [6].…”