Jea-Hoon Yu

Remodulation schemes with reflective SOA for colorless DWDM PON

Feature Issue on Passive Optical Network Architectures and TechnologiesThis article presents remodulation schemes with reflective semiconductor optical amplifiers (RSOAs), which have recently been developed for application to the wavelength-division-multiplexed passive optical network (WDM-PON). The remodulation schemes have a common feature that the optical signal modulated with downstream data is reused to carry the upstream data through the RSOA in the subscriber-side equipment by a series of processes such as being flattened out, reflected at the rear facet of the RSOA, and then remodulated with upstream data. The major advantage of remodulation schemes is the possibility of realizing the simplest WDM-PON optical link structure, which is directly reflected in cost-effectiveness of the network both in equipment and maintenance. Three schemes are presented; the simplest one is to use the RSOA gain saturation, the second uses the effect of frequency detuning on the extinction ratio of optical signal, and the third uses RSOA gain control by dynamically varying the current injection. Feasibilities of those schemes are discussed in the view of commercial application to WDM-PON.

First Commercial Deployment of a Colorless Gigabit WDM/TDM Hybrid PON System Using Remote Protocol Terminator

Colorless gigabit wavelength-division-multiplexing (WDM)/time-division-multiplexing (TDM) hybrid passive optical network (PON) using a remote protocol terminator is proposed and experimentally demonstrated. The system consists of reflective semiconductor optical amplifier-based WDM-PON and a legacy TDM-PON, combined with a simple and efficient remote node structure in order to provide high-speed fiber-to-the-home service to a large area with a high population density. The demonstrated system can support 512 subscribers with a single feeder fiber. The performance and feasibility of the system were evaluated by transmitting gigabit per second data including the effects of Rayleigh backscattering and 20 km attenuation. The system has been used by Korea Telecom to provide commercial services in Gwangju, Korea, since March 2009, after successfully passing through the benchmark test. This is the first commercial deployment of a WDM/TDM hybrid PON. It can accommodate field-deployed TDM-PON link without any modification and extend the maximum total reach of PON link by the use of remote protocol termination. Number of subscribers and the allocated bandwidth to the subscribers can be designed by simply changing the splitting ratio.

First commercial service of a colorless Gigabit WDM/TDM hybrid PON system

We describe the first RSOA-based WDM/TDM hybrid PON system to enter commercial service. The system, consisting of a 16 × 1.25 Gb/s colorless Gigabit WDM-PON and a legacy TDM-PON with optical-electrical-optical converters, provides the triple-play service using fiber-to-the-home and fiber-to-the-node in a new residential area in Korea.

Effects of RSOA gain ripples on upstream transmission in a SML-seeded loop-back WDM-PON

In a SML-seeded loop-back WDM-PON, the upstream BER plots show variation of power penalty by 2 dB, depending on the difference of seed and ripple peak wavelength, which is related to the RSOA transient chirp.

Wavelength Re-use Scheme with Reflective SOA for WDM-PON Link

Among the various solutions to the optical subscriber network realization, the wavelength-division-multiplexed passive optical network(WDM-PON) has been considered as an ultimate next-generation solution. This article presents the wavelength re-use scheme with the reflective semiconductor optical amplifier(RSOA), which has recently been developed for application to the WDM-PON. The wavelength re-use scheme has a common feature that the optical signal modulated with downstream data is re-used to carry the upstream data through the RSOA in the subscriber-side equipment by a series of processes such as being flattened out, reflected at the rear facet of the RSOA, and then re-modulated with upstream data. The major advantage with the wavelength re-use scheme would be the possibility of realizing the simplest WDM-PON optical link structure, which is directly reflected on cost-effectiveness of the network both in equipment and maintenance costs. The gain saturation scheme is presented here; it uses the fact that the optical gain of RSOA decreases as the injection power into RSOA increases. Experimental results show that it is possible to achieve error-free bidirectional transmission with 1.25 Gbps for upstream and 2.5 Gbps for downstream data rates over 20 km transmission distance.

Mobile signaling structures of IMT-2000 exchange

This paper proposes mobile signaling structures as well as a physical configuration to be useful for an ATM-based IMT-2000 (International Mobile Telecommunication-2000) exchange. We carefully examined the IMT-2000 reference model of the ITU-T to build our mobile signaling structures and physical configuration. This paper shows the functions of the IMT-2000 exchange, which are extracted from the interfaces and signal transport structure of GSM. It also describes the reason why the IMT-2000 exchange should use ATM technology from the point of view of IMT-2000 service capability and application. This paper mainly deals with the configuration and interfaces of the IMT-2000 exchange. It is essential to define the configuration and interfaces of the integrated IMT-2000 exchange as the wireless mobility functions are developed in addition to the existing fixed ATM exchange.

A signaling transport structure for ATM-based IMT-2000 exchange

In order to design an IMT-2000 exchange, we study why the ATM (asynchronous transfer mode) exchange among the current exchanges has to be a basis system in the view of the service capability and service application. For the purpose of adding mobility to an ATM exchange we research the configuration and interfaces of the integrated wired/wireless IMT-2000 exchange. We probe the function entities of the IMT-2000 reference model in the view of balancing of the functionality division, and what physical configuration scenario is appropriate. On the basis of the IMT-2000 functional model, we present the signaling protocol structure for ATM-based IMT-2000 exchange.

High available system control network in the packet transport system

This paper is about design and buildup of multiprocessor interconnects in the packet transport system. To keep pace with expansion and growth of internet and data communication, constant enhancement and upgrade of packet transport system is required. As network adopts new services like IPTV, VoIP, and VLAN, processing power of packet transport system should be easily and dynamically added to the system for supporting highly compute-power requiring jobs. The processing power of system depends on the number of processors, the clock speed of each processor, efficiency of operation system in data centric processing, proper distribution of system works, and robust and high bandwidth interconnects (system control network) among processors. This paper suggested several methods for the system control networking in the packet transport system and reviewed each method in the view of internal and external expansion of system control network, loop elimination, and redundancy support.

An Optical Label Access Network based on Hierarchical Wavelength Label and Wavelength Interchange Methods

We present optical label access network (OLAN) architecture based on a hierarchical wavelength-label (lambda-label) and a simple wavelength-interchange (lambda-socket) methods. The architecture routes and transmits users Internet protocol (IP) packets directly over the wavelength division multiplexing (WDM) technology. The two lambda-label and lambda-socket concepts are employed to build a simple, cost-effective OLAN, which can be scaled up to several terabits in traffic processing capacity, with using relatively low-cost optical elements and gigabit-performance switching apparatus such as gigabit Ethernet switches.

Design of Multicast Service Architecture in an Ethernet Passive Optical Network

This paper proposes the design of multicast service architecture in an optical access network based on an E-PON in order to support TPS service that is paid attention to now. An optical access network based on an E-PON is needed to provide high bandwidth required by users with an inexpensive cost and multicast service architecture is needed to support TPS service efficiently since the multicast packet is used to provide Broadcasting service that is an essential element in TPS service. To resolve these issues, we suggest the system architecture that offers the Layer 3 routing service based on a virtual interface in a VLAN-aware Layer 2 switch as well as the method processing the multicast packets efficiently and the packet processing procedure in the proposed system.