Qianjin Xiong

LDPC convolutional codes using layered decoding algorithm for high speed coherent optical transmission

We successfully realized layered decoding for LDPC convolutional codes designed for application in high speed optical transmission systems. A relatively short code with 20% redundancy was FPGA-emulated with a Q-factor of 5.7dB at BER of 10-15.

Intrachannel Nonlinearity Compensation by Inverse Volterra Series Transfer Function

The Volterra series transfer function (VSTF), in which the input-output relationship of a nonlinear system is represented by a series of nonlinear kernel functions, is an elegant tool to model nonlinear systems. The inverse of a nonlinear system can be constructed by analyzing VSTF. We propose a new electronic nonlinearity compensation scheme based on inverse VSTF. We show 1 dB improvement in Q-factor with a 256 Gb/s polarization-division-multiplexed 16-level quadratic amplitude modulation format, and 50% reduction in complexity by lowering the processing rate.

Precise, robust and least complexity CD estimation

We demonstrate robust and precise frequency domain chromatic dispersion estimation based on offline data and simulations. The blind, least complexity algorithm allows fast acquisition suitable for digital coherent receivers in switched networks.

MLSE-based nonlinearity mitigation for WDM 112 Gbit/s PDM-QPSK transmissions with digital coherent receiver

We investigate the performance of linear equalization combined with MLSE in long-haul transmission. In the nonlinear regime with high launch powers Q-factor improvement up to 1.4 dB is demonstrated with a quaternary state model.

Regularized Sparse Recovery for Optical Power Monitoring With Low-Cost Tunable Optical Filters

We propose a regularized sparse recovery (RSR) technique to monitor optical power from the broadened optical spectrum acquired by scanning a tunable optical filter (TOF). The key idea of RSR is to find a smooth but sparse signal spectrum that matches the observed data of a broadened spectrum model within a tolerable error. Experiments demonstrated that RSR can be used to monitor accurately the power of mixed 10-G/40-G wavelength-division-multiplexing channels with 50-GHz channel spacing using commercial TOFs. This technique also has higher immunity to measurement and TOF response errors than the regularized least square method. It does not require strong repeatability of TOF response and makes the low-cost TOF suitable for optical power monitoring.

Green and agile petabit optical sub-wavelength switching prototype for the future OTN multi-chassis switch cluster

A proof-of-concept prototype of optical sub-wavelength switching fabric is demonstrated. The prototype supports petabit switching capacity with agile service granularity and low power consumption.

An optical burst switching fabric of multi-granularity for Petabits/s multi-chassis switches and routers

A multi-granularity optical burst switch fabric with 80M×80M(M=2, 4, 8...) ports using Fast Tunable Lasers and ULCF-AWG is proposed. This fabric for Petabits/s multi-chassis switches and routers is also experimentally demonstrated.

A scheme for improving the performance of 100-Gb/s polarization-multiplexed RZ33 DQPSK signals using the phase regenerator and PMD compensator

We proposed a scheme of combination of phase regenerator and PMD compensator to the 100-Gbit/s Polarization-Multiplexed DQPSK System to improve its tolerance to PMD. The system performance is effectively improved after both compensation and regeneration.

Implementation of coded modulation and FEC

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.

Fast and Reliable Frequency-Domain CD Estimation

The algorithm estimates the value of residual chromatic dispersion solely from the spectra of filtered signals of a matched-filter-bank in digital coherent receivers. Robust estimation is demonstrated by extensive simulations with combined impairments.