Soichiro Kametani

43 Gb/s DQPSK pre-equalization employing 6-bit, 43GS/s DAC integrated LSI for cascaded ROADM filtering

Electronic pre-equalization for 43 Gb/s DQPSK has been demonstrated for the first time. Waveform distortion caused by bandwidth narrowing to 18.1 GHz by cascaded 10 Gb/s ROADMs has been adequately pre-equalized by a SiGe-BiCMOS LSI with 6-bit, 43 GS/s digital-to-analog converters.

Soft decision LSI operating at 32 Gsample/s for LDPC FEC-based optical transmission systems

We have developed a 2-bit 32 Gsample/s soft decision LSI for low-density parity-check code FEC at 100 Gb/s in 0.13 mum SiGe-BiCMOS which generates confidence bit with 25 mVpp sensitivity.

43 Gb/s DQPSK transmission over fibre with 2450 ps/nm of dispersion using electronic pre-equalization

Electronic pre-equalization of chromatic dispersion for 43 Gb/s DQPSK has been demonstrated employing a developed test chip. The chip enables the BER in fibre with 2450 ps/nm of dispersion to be improved to 7.6E-05 without an optical dispersion compensator.

16-QAM modulation by polar coordinate transformation with a single dual drive Mach-Zehnder Modulator

16-QAM modulation by a single dual-drive Mach-Zehnder modulator with minimum drive voltage employing polar coordinate transformation instead of a vector I/Q modulator was demonstrated. Clear signal separation was observed with 6-bit DAC resolution.

Maximizing transmission capacity of superchannels using rate-adaptive FEC

We investigated the use of per-channel rate-adaptive FEC for superchannels, in the presence of fiber nonlinearity, inter-channel interference, and power variations. We found 3~4% peak capacity and ~ 0.3dB nonlinear power threshold increase in most cases compared to the conventional method.

A practicable rate-adaptive FEC scheme flexible about capacity and distance in optical transport networks

We propose a practicable rate-adaptive FEC scheme defeating degradation due to high baud rate and increase of circuit complexity. The preferable coding gains of 13.0-17.5 dB are obtained for 25.5-149.5% redundancies.

Han–Kobayashi and Dirty-Paper Coding for Superchannel Optical Communications

Superchannel transmission is a candidate to realize Tb/s-class high-speed optical communications. In order to achieve higher spectrum efficiency, the channel spacing shall be as narrow as possible. However, densely allocated channels can cause non-negligible inter-channel interference (ICI) especially when the channel spacing is close to or below the Nyquist bandwidth. In this paper, we consider joint decoding to cancel the ICI in dense superchannel transmission. To further improve the spectrum efficiency, we propose the use of Han-Kobayashi superposition coding. In addition, for the case when neighboring subchannel transmitters can share data, we introduce dirty-paper coding for pre-cancelation of the ICI. We analytically evaluate the potential gains of these methods when ICI is present for sub-Nyquist channel spacing.

Interference management with Han-Kobayashi coding: Dual-carrier coherent optical communications

We propose to use Han-Kobayashi (HK) coding and dirty-paper coding (DPC) to cope with inter-carrier interference (ICI) in dual-carrier transmissions. We show the considerable benefit of those methods to increase throughput in presence of strong ICI for dense carrier spacing.

100/150/200 Gb/s real-time demonstration of SD-FEC employing MSSC-LDPC codes for flexible coherent transport

To support forthcoming flexible coherent transport, we demonstrate a multiple-structured spatially-coupled LDPC with BCH codes which offers modulation flexibility, rate-adaptability and pilot-aided cycle-slip mitigation.

Optical path configuration in subcarrier aggregation networks employing rate-adaptive FEC

Subcarrier aggregation approach employing rate-adaptive coding is proposed for optical path configuration. Simulation results present the proposed approach increases accommodation efficiency by 19% and 22% in backbone and metro network respectively.