Shin Kaneko

Scalability of spectrum-sliced DWDM transmission and its expansion using forward error correction

This paper clarifies the scalability of spectrum-sliced dense wavelength-division-multiplexing (DWDM) transmission systems primarily intended for metro access applications. A theoretical analysis elucidates the tradeoff between the loss budget and the sliced bandwidth (i.e., the number of channels with assuming light sources with a fixed bandwidth). Moreover, the use of forward error correction (FEC) to expand scalability is studied. Based on the analysis, two spectrum-sliced DWDM transmission schemes are introduced. One demonstrates 1.25-Gb/s, eight channel spectrum-sliced DWDM transmission through the use of directly modulated super-luminescent diodes (SLDs), and the other confirms 10-Gb/s, eight channel spectrum-sliced DWDM transmission with the channel spacing of 200 GHz through the use of FEC

First system demonstration of hitless λ-tuning sequence for dynamic wavelength allocation in WDM/TDM-PON

We propose hitless wavelength-tuning sequence for dynamic wavelength allocation in WDM/TDM-PONs and demonstrate highly frequent wavelength-tunings in 100-ms intervals without data-frame loss using MAC boards. Pay-as-you-grow operation based on the proposed sequence is also shown.

High spectral efficiency DWDM-PON using an optical homodyne receiver with integral circuits based on digital signal processing

A DWDM-PON is proposed that realizes a spectral efficiency of 1 bit/s/Hz by using homodyne detection based on digital signal processing. The feasibility is confirmed with a transmission experiment, and the application area is discussed.

Demonstration of Load-Balancing Operation Based on Hitless Dynamic Wavelength Allocation on Symmetric 40-Gbit/s λ-Tunable WDM/TDM-PON

This paper reports the world-first system-level demonstration of dynamic wavelength allocation (DWA) on a wavelength-tunable (λ-tunable) wavelength division multiplexing/time division multiplexing-passive optical network (WDM/TDM-PON). To achieve DWA, a DWA calculation is necessary that determines new optical network unit assignments to the optical line terminal ports according to the bandwidth demand. In addition, a wavelength-tuning (λ-tuning) sequence that induces no data-frame loss, i.e., a hitless λ-tuning sequence, is essential. First, we propose a bidirectional hitless λ-tuning sequence and investigate its feasibility using media access control boards that we developed for symmetric 40-Gbit/s λ-tunable WDM/TDM-PONs, which are also the worlds first. Then, with a DWA calculation according to the downstream traffic loads, we show automatic dynamic load-balancing operation.

Beat Noise Mitigation of Spectral Amplitude Coding OCDMA Using Heterodyne Detection

In order to relax the limitation of the number of multiplexed signal lights caused by beat noise between signal lights, we investigate the applicability of a heterodyne detection technique to a spectral amplitude coding optical code division multiple access scheme. In this investigation, for the first time, we found analytically that the optical frequency chips that form parts of the signal and local lights require uniform phase differences even for envelope detection. We also confirm this requirement and our theoretical analysis experimentally.

Dynamic-load-balancing algorithm suppressing the number of wavelength reallocations for λ-tunable WDM/TDM-PON

We propose a dynamic-load-balancing algorithm that is derived using Jains fairness index. Simulation results show that the proposed algorithm can distribute traffic loads among PON-branches quite fairly with a very small number of wavelength reallocations compared with a round-robin approach.

Field Trial of Long-Reach and High-Splitting λ-Tunable TWDM-PON

This paper presents the worlds first field trial of a 40-km reach and over 512-split symmetric-rate 40-Gbit/s λ-tunable time and wavelength division multiplexing passive optical network (TWDM-PON) that utilizes our newly developed high-speed λ-tunable optical network unit transceivers and automatic gain controlled semiconductor optical amplifier-based PON extender for repeater and central office use. The upstream signals for C-band and downstream signals for L+-band in our developed λ-tunable TWDM-PON comply with the wavelength plan of ITU-T G.989 series. In a field trial, we successfully demonstrate error free λ-tunable transmission for the 40-km reach and 1024-split (maximum number) symmetric-rate 40-Gbit/s λ-tunable TWDM-PON over installed standard single-mode fiber links, and advanced network functions such as dynamic load balancing, incremental system upgrade, optical subscriber unit protection, and OLT equipment power saving are also confirmed.

Agile OLT-protection method based on backup wavelength and discovery process for resilient WDM/TDM-PON

We propose and demonstrate agile OLT-protection without redundant OLT ports for WDM/TDM-PONs where ONUs are re-registered after wavelength-tuning directly to pre-assigned backup wavelengths. System demonstration confirms a shorter link-up time by two-orders of magnitude at maximum and ensured signal quality.

Reliable λ-Tuning OLT-Protection Method Based on Backup-Wavelength Pre-assignment and Discovery Process for Resilient WDM/TDM-PONs

This paper proposes a novel wavelength-tuning (λ-tuning) optical line terminal (OLT) protection method for wavelength division multiplexing/time division multiplexing-passive optical networks (WDM/TDM-PONs). Since λ-tuning OLT protection achieves redundancy of OLT ports utilizing only the λ-tunability of optical network units (ONUs) that ONUs intrinsically have for colorless operation, no additional equipment such as redundant OLT ports or optical switches is necessary for the protection. The proposed method is based on backup wavelength pre-assignment and a discovery process. Since the backup wavelengths are pre-assigned, the proposed method shortens the service outage time and balances traffic loads among the active OLT ports after OLT protection. Therefore, the proposed method achieves high-level reliability cost-effectively. Through system demonstrations using media access control boards and λ-selective burst-mode transceivers for symmetric 40-Gb/s WDM/TDM-PONs, the validity of the proposal is examined based on the link-up time and throughput measurement for λ-tuning OLT-protection.

Fast OLT-protection method based on normal MPCP and backup wavelength pre-assignment on WDM/TDM-PONs [Invited]

This paper proposes a novel method for N:1 optical line terminal (OLT) protection on wavelength-division-multiplexing/time-division-multiplexing passive optical networks (WDM/TDM-PONs). The N:1 OLT protection scheme based on in-service wavelength tuning (λ-tuning) at optical network units (ONUs) provides reliable and cost-effective protection without the need for equipment specific to OLT protection on either the ONU or OLT side. Since the normal multipoint control protocol (MPCP) and backup wavelength pre-assignment are utilized, the proposed method significantly shortens the maximum protection time in N:1 OLT protection. Results of trials on a 40 Gbit/s (10 Gbit/s × 4 wavelengths) system with 40 km single mode fiber (SMF) transmission show service interruption times of less than 50 ms at all times, even with the practical -tuning time of 30 ms. The system trials also verify that the proposed method assures service interruption times of less than 50 ms, even with the split ratio on a PON of up to 512. These results verify that the proposed method is promising for next-generation multiservice convergence access networks.