Forward error correction in dispersion-limited lightwave systems

Abstract

A rate 0.964 forHard error correcting (FEC) code is integrated into the loa-speed tributaries of a 565-Mbit/s lightwave system as an exploratory sjstem design approach to relax requirements on laser sources in dispersion-limited operation. Experimental and simulation studies show that FEC can increase allowed spectral width up to 70 percent and wavelength offset up to 60 percent at 565 and 1200 Mbit/s. FEC is shown to qualify a mode-hopping, nearly single mode laser for use at 1200 Mhit/s under conditions that otherwise prohibit use of this laser due to a severe error-rate floor. By virtually removing error rate floors, regardless of their cause, FEC is shown to provide an increasing ahantage in conditions of greater degradation and to be effective against MPN, mode jumping, and reflection impairments. The experimental FEC code is implemented in a standard gate array. The FEC code is described and its performance is analyzed. A new system design strategy is suggested for low-cost gigahit lightwave systems using FEC. A reservation of overhead for an FEC option in the new SONET standard is suggested by the findings of this work.

Roadmap of optical communications

“…Early practical FEC experiments in the late 1980s used only the simplest possible codes (Hamming codes) [101] combined with binary modulation and hard-decision decoding. With hard-decision decoding, the demodulator outputs are quantized to the modulation level (0 or 1 for binary modulation) prior to decoding.…”

Projective geometry LDPC codes for ultralong-haul WDM high-speed transmission

“…In (2), is the th bit pulse shape, is the peak power, and is the (coded) information content , with being the extinction ratio, . Both the ASE noise components and the multipath interference (MPI) components are combined into a noise process , which is considered to be colored Gaussian with autocorrelation function given by (3) [ and are ASE and MPI autocorrelation functions, respectively].…”

“…A significant effort has been made to apply error-control techniques to various optical transmission systems [2]- [5] with a special emphasis on turbo codes [6]. In a series of articles [7]- [9], we showed that error performance and decoder hardware complexity offered by turbo codes can be greatly improved by using other types of iteratively decodable coding schemes, in particular low-density parity check (LDPC) codes.…”

Performance of affine geometry low‐density parity‐check codes in long‐haul optical communications

“…A significant effort has been made to apply error control techniques to various optical transmission systems starting with Grover's proposal for applying error control codes to improve the performance of dispersion limited lightwave systems with laser impairments [2]. Recently, particularly in transoceanic submarine systems, error-correcting codes such as the Bose Chaudhuri Hocquenghem (BCH) code or the Reed Solomon (RS) code have been selected for implementation [3].…”