Deyuan Chang

Huawei Technologies · Network Research Department

An adaptive joint carrier recovery and soft LDPC turbo decoding scheme in the presence of nonlinear phase noise is proposed and experimentally verified with 1.9dB coding gain in Nyquist Terabit PDM-DQPSK systems.

We report 20x224Gbps PDM-QPSK in 50GHz grid over G.652 fiber and EDFA-only link. Using Soft Output Faster than Nyquist and 7% SDFEC, 4bit/s/Hz net spectral efficiency transmission over 3040km with 21dB span loss is achieved.

In this letter, we present a method for performance estimation of forward error correction (FEC) codes using off-line data without data encoding. Only a few hundred thousand uncoded symbols are used to accurately evaluate post-FEC bit error rate of soft FEC codes decodable by the sum-product algorithm at very low error rates, e.g., 10-8 which is on...

A new class of codes is proposed for differentially encoded coherent systems. Regular Quasi Cyclic Low Density Parity Check codes concatenated with two-dimensional single parity check codes improved performance by 0.4 dB without complexity increase.

We discuss implementation aspects of LDPC based soft-decision FEC schemes for high speed optical systems. Several BICM schemes with LDPC convolutional codes are proposed and compared in respects of both performance and implementation complexity.

We propose a hybrid soft/hard decision multilevel coded modulation scheme (HMLC) which improves the performance-complexity ratio compared with conventional single LDPC scheme. An iterative multi-stage decoding algorithm between LDPC and BCH codes is presented.

We successfully applied layered decoding algorithm in decoding LDPC convolutional codes designed for applications in high speed optical transmission systems. A relatively short code was FPGA-emulated with a Q factor of 5.7dB at BER of 10-15.

This paper will at first explain the requirement of high speed optical transport network on forward error correction (FEC) codes in terms of code length, code rate, coding gain, burst error correction capability, error floor, latency, coding/decoding complexity. Then, a few code schemes used in current optical transport systems such as Reed-Solomon...

We investigate DQPSK modulation combined with QC-LDPC coding. By applying iterative demodulation and soft-decision decoding, the differential decoding penalty is reduced by 2.05dB offering an attractive solution for coherent optical systems with soft-decision FEC

We present FPGA-based emulation results of a single QC-LDPC with 20% redundancy designed for applications in 100Gb/s optical transmission systems. Error floor-free transmission is achieved at BER of 10-15 with a Q factor of 5.9dB without using component codes.

We investigate DQPSK modulation combined with QC-LDPC coding. By appling iterative demodulation and soft-decision decoding, the differential decoding penalty is reduced by 2.05dB offering an attractive solution for coherent optical systems with soft-decision FEC.

explain transport network requirements on FEC. Recent progress and future perspective of SD-FEC

The OSNR margin improvements due to FEC limit elevation in 112Gb/s PDM-DQPSK systems under two different receiver schemes, direct detection and coherent detection with digital signal processing (DSP), are analyzed. FEC limit elevation provides more benefit to the direct detection scheme than to the coherent detection scheme in 112Gb/s PDM-RZ-DQPSK...

An optimal refractive index profile of pure silica core optical fiber (PSCF) was designed, in combination with the characters of the modified chemical vapor deposition (MCVD) process. Techniques of preform fabrication by a new furnace round heating MCVD process and fiber drawing process were reviewed. Difficulties in doping fluorine in silica, wide...

The design criteria of the Panda-type erbium-doped polarization-maintaining fiber (EDPMF) are presented, which take into account the cutoff wavelength, mode field diameter, modal birefringence and background loss. The structural parameters are optimized in terms of the design criteria. A Panda-type EDPMF has been manufactured. The fabrication proce...

The finite element method with 2nd-order transparent boundary conditions is proposed to analysis the modes of photonic crystal fibers. These boundary conditions preserve the sparse matrix and offering accuracy of O(r-9/2), here r denoting the position of the computational boundary with respect to a chosen origin of the structure. The effective mode...

Erbium-doped photonic crystal fiber (EDPCF) is not in the endless single-mode as the refractive index of the core in EDPCF is higher than that of silica cladding. There is a variation between the EDPCF and the conventional PCF. The modified average population inversion iteration method is proposed for simulating the gains and noises of EDPCF amplif...

Kanakidis et al presented several kinds of all-optical chaotic communication systems using two encoding techniques and various dispersion compensation maps [1]. It shows that the permitted transmission distances are different for various dispersion compensation maps and various encoding techniques. In order to explore the upper limits of the transm...

Hole-assisted lightguide fiber (HALF) is a microstructured fiber composed of a high index core, a low index cladding and a small number of air holes surrounding the core. The characteristics of HALF are studied by using the full-vector finite element method. The contour lines of power flow intensity and transverse electric distributions are plotted...

Bragg fibres have many special characteristics. Therefore this kind of fibre attracts more and more attention. In this paper, genetic algorithm is applied to design Bragg fibres to realise desired dipersion and attenuation characteristics.

A low cost 8*10-Gb/s transmission system over 1500 km on conventional fiber using chirped fiber Bragg grating (CFBG) as dispersion compensator is demonstrated. The bit error rate (BER) below 10^(-10) at 1500 km is obtained. The channel spacing is 0.8 nm and the optical amplifier spacing is 100 km. Only 16 erbium-doped fiber amplifiers (EDFAs) are u...

In this paper, we demonstrate a chirped grating designed to compensate for both second- and third-order fiber dispersion. The fabrication technique of chirped gratings is the phase-mask beam scanning method by using a standard unchirped phase mask and by tapering a fiber in the region of the grating. We have made theoretical analysis on the chirp i...