- Strategy for Global Megamedia Network (GMN)

- An Application Platform for Information Sharing by Enterprise (Nex'BASE)

- Internet-Connection Platform Utilizing SS7 Technologies

- Measurement, Evaluation, and Analysis of ATM Traffic ---Traffic Monitor: ATM Probe98

- Implementing a Best-Effort and Guarantee Service (The ATM Share Link Service)

- IC Telephone Card System through Advanced Intelligent Network Technology

- A High-Performance and Low-Power 40-Gbit/s ATM Core Switching System (MHN-Aπ)

- Opening up the Local Switch Functions through Signaling Network Interconnection

- Fibre Channel ---ATM Interworking Unit (FC-IWU)

- Intermediate and High-Speed Communication Technology Using the π-System Platform

- EA Modulator Integrated DFB Laser Module Operating in the 1580-nm Band

- Low-Cost, High-Speed and High-Responsivity Edge-Illuminated Refracting-Facet Photodiode Module

- Hybrid-Integrated Optical Transceiver Module for ATM-PDS Systems

- Plastic Ferrule and Sleeve for Single-Mode Fiber-Optic Connectors

- A Compact and Light Automated Tool for Optical Line Testing (mini-TEM)

- Revolutionary Low-Power Card-Size ONU for ISDN Terminals

- 20-Mbit/s Ethernet-Based Wireless LAN System

- 1.9-GHz Subscriber Wireless Access System (λSystem) ---Service Start-up and Functional Improvement

- An RF Power MOSFET for 2-GHz Wireless Terminals

- Electromagnetic Environment Design System

- Successful Test of a Large Deployable Antenna for Next-Generation Communication Satellites

- High-Speed Batch Transfer of Large-Volume Information by Satellite Communication System

- Development of a Satellite Internet Receiving Adapter Board with Built-in Tuner Unit

- Multi-Service Line Card

The names of the research laboratories listed are those before the establishment of provisional headquarters.

CONTENTS

Telecommunication Network Technologies

Application software

Applications platform

GMN middleware

GMN access & core network

Authentication server

Transport server

Network service middleware

Multi-protocol transport middleware

Session manager

Address server

Information sharing application platform service

Information Delivery platform service

Multi-protocol transport service

Basic transport service

ONU CS ONU CS

GMN Architecture Layered Services

An Application Platform for Information Shar-ing by Enterprise (Nex'BASE) Application systems that use the World Wide Web are rooted inthe standard Internet service provision technology, but to providemore attractive services, construction of a system through coop-eration of external systems and applications is needed. Nex'BASErealizes the early development of a WWW system that uses van-guard technology by providing the following features.(1) Nex'BASE provides an application construction environmentthat employs a scripting language that is capable of efficientlydescribing HTTP control, HTML and XML text generation, andrelational database operations. The scripting language producescode that has as little as one-fourth the volume of CGI-type appli-cation programs. It also supports compound data types and func-tion definitions and so can also be used to write advanced pro-grams.(2) Nex'BASE is written in Java, so there is a wide selection ofservers and relational databases. Thus systems can be con-structed through combinations that meet performance and costobjectives.(3) Java applications and libraries can be used in scripts. Thatmakes it possible to construct systems by combining the copiousJava resources that are available, such a distributed processingsystem that employs the CORBA* library or an information shar-ing system that employs the XML library. Also, the platform inde-pendence of Java achieves high portability of the application pro-grams. Making use of the features described above, our laboratoriesare experimenting with the construction of an information sharingsystem by using Nex'BASE to bring together the technologies ofour laboratories.

(Software Laboratories)* CORBA: Common Object Request Broker Architecture

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Strategy for Global Megamedia Network (GMN) With the aim of achieving information sharing services and toplan for their research and development, the vision and strategyof a Global Megamedia Network are established. Four targets ofGMN are as follows. (1) Performance capable of transferring amegabyte-class block of information instantaneously; (2) secureand reliable network services for conducting financial activitiesover the network; (3) network functions that can be used by allcustomers in an easy, comfortable, and convenient manner; and(4) network-service cost equivalent to that of telephone services. The GMN strategy includes provision of four layers of servicearchitecture arranged in a hierarchical manner. The Basic Trans-port Service will provide GMN access and core network transmis-sion functions, and the Multi-protocol Transport Service will sup-port various types of networking protocol in IP*1 packet transferfunctions and the like. The Information Delivery Platform Ser-vice, on the other hand, will provide advanced functions for opti-mal setting of network resources and support/setting of usageenvironments. These functions can be applied, for example, tohighly efficient information delivery in a mass delivery system(MDS). Finally, the Information sharing Application Platform Ser-vice will provide linked functions as a platform for specific appli-cations in society, such as authentication, approval, digital cash,and IC*2 cards. The GMN can accommodate ongoing technical developmentand service development in a hierarchical manner. In the firststep (GMN-1), the IP network will be upgraded to a high perfor-mance and high functionality level. In the next step (GMN-2),genuine multimedia services will be provided to achieve the basicobjectives of GMN. In the third step (GMN-3), the plan is to pro-vide innovative services. In order to implement new information sharing services as soonas possible, "GEMnet*3" is being constr ucted as a test bed forincorporating the latest R&D achievements. With GEMnet, NTTplans to cultivate an internationally competitive information shar-ing service as well as provide a means of evaluating and testingresearch results for elemental technologies and visualizing busi-ness-directed services.

(Technology and Development Support Center)*1 IP: Internet Protocol*2 IC: Integrated Circuit*3 GEMnet: Global Electrum Cyber Society and Megamedia Network for NTT

　　　　　　R&D Testbed

Configuration of a Nex'BASE system

GMN layered services platform architecture

6

Nex’BASEscript

Web clientsScript-based

service composition Service components

HTMLVRMLXML（SMIL etc.）

RDB, ORDB

Businessdata

Documentdata

Picturedata

Structureddata

ERP

XML products

Informationsharingplatform

Presentation/operationplatform

(browser, PDA, etc.)

Javaapplications

JDBClibrary

CORBAlibrary

XMLlibrary

System-depending

library

Informationsharing

service hub(Nex’BASE)

CollaborationCustomercontact

Java

ATM switchOpticalcoupler

Probe

Probe

Probe

Opticalcoupler

ATM switch

Manager

Terminal

［WWW server］

ATM switch ATM switch

ATM switch

Terminalmultiplexer

ATM switch

Internet

Internet

Internet

Internet

Internet-Connection Platform Utilizing SS7 Technologies As demand for IP-related communications, such as access tothe Internet, continues to increase, demand for dial-up Internetconnections through PSTN*1/ISDN*2 access lines will increase.Network-platform technologies integrated with PSTN and IP net-works via SS7*3 will thus be required. The Network Service Sys-tems Laboratories have developed an Internet-connection plat-form that enables the Internet dial-up NNI*4 connection servicesdescribed below. It results from the development and connectiontesting of a remote access server (RAS) that provides a gatewayfunction between SS7 and IP networks. In addition, the NetworkService Systems Laboratories are developing a service platformthat will provide new IP-related services, such as Internet callwaiting, explained below.(1) Internet dial-up NNI connection services To efficiently transmit dial-up Internet traffic through PSTNs andISDNs, a new system platform was established by using NNI con-nection technologies between the local switch and the RAS sys-tem and deploying the RAS in NTT's networks. This platformprovides a short cut through the IP network to the ISP. This sys-tem platform enables carriers to make effective investments inPSTN/ISDN equipment and NTT to outsource the access-pointequipment to ISPs. This platform is expected to reduce the costof communication access.(2) New IP-related services We have established a service platform for new IP-related ser-vices that is integrated with PSTN/ISDN and IP networks. Theseservices include Internet call waiting, Web click-to-dial (and back)services, and toll-free services that work with intelligent networks.

(Network Service Systems Laboratories)*1 PSTN: Public Switched Telephone Network*2 ISDN: Integrated Services Digital Network*3 SS7: Signalling System No.7*4 NNI: Network Node Interface

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Measurement, Evaluation, and Analysis of ATMTraffic ---Traffic Monitor: ATM Probe98 Asynchronous transfer mode (ATM) networks have been applied to theInternet backbone and to Intra/Extranets and the number of such applica-tions has increased year by year. Traffic of various applications and pro-tocols can flow on an ATM network, and this capability has generated aneed for an economical and flexible traffic monitor that can perform manytypes of measurements in the ATM and upper layers. Such a monitorshould also support traffic management, quality of service management,and security management. In response to this need, NTT Laboratories have developed the ATMProbe98 traffic monitor. The Probe98 system can measure, evaluate,and analyze traffic information on each protocol layer for traffic flowing onan ATM network. The system configuration of Probe98 is shown as figure. Users selectthe measurements they want and set the measurement conditions througha home page provided by a WWW server (Manager). The Manager thensends SNMP*1 messages to Probes to configure them. Probe98 usesVxWorks and the Manager uses Windows NT as operating systems.(VxWorks is suitable for real time processing.) The ATM Probe98 traffic monitor has the following eight measurementfunctions. Measurement units are shown in parentheses.(1) Traffic over each virtual path (VP) (in bytes or number of packets)(2) Traffic for each protocol on a specified VP or all VPs (in bytes or number of packets)(3) Traffic for each application on a specified VP or all VPs (in bytes or number of packets)(4) Traffic matrices on a specified VP or all VPs (in bytes or number of packets)(5) Traffic matrices of every application on a specified VP or all VPs (in bytes)(6) Top 100 traffic sources(7) Top 100 traffic destinations(8) Number of cells arriving each ms Probe98 also provides a queue simulation function. In this function,the buffer capacity and output speed of three virtual queues can be set.These are used to simulate the number of cells lost and the sojourn time. Probe98 is already being used in the TAO*2 gigabit network and theScience Information Network in Japan. It is expected to be used for mea-suring actual traffic loads and traffic patterns in these networks, analyzingthe effects of changing output speed on queue performance through queuesimulation, etc. As a future research target, we plan to improve the functions of qualityof service management, and security management on ATM Probe98.

(Multimedia Networks Laboratories)*1 SNMP: Simple Network Management Protocol*2 TAO: Telecommunication Advancement Organization of Japan

Internet-connection platform utilizing SS7 technologies

Probe98 configuration

7

�

GW : GatewayRAS : Remote Access ServerSG : Signaling GatewayMG : Media GatewayGK : Gate KeeperAPL Server : Application Server

TEL FAX PC Call center

RAS

MG

SGGK APL server

GW

Web

Enterprise LAN

InternetPSTN/ISDN

SS7-Network

High speed IP Network

SCP

Line IF

Line IF

Network Element

MaximumBit rate

SharedBand Width

MinimumBit rate

When the buffer overflows, all cellswhich compose one IP-Packet are discarded.

Cells are sequentiallyread from each VCbuffer.

Implementing a Best-Effort and Guarantee Ser-vice (The ATM Share Link Service) Provision of the ATM Mega Link Service, a guaranteed band-width ATM service, began in April of 1997. That was followed inDecember 1998 by the introduction of the ATM Share Link Ser-vice, a best-effort and guarantee type service. The ATM ShareLink Service offers customers virtual channels (VC) that have guar-anteed line speeds of from 200 kbit/s to 9 Mbit/s and best-effort(maximum, but not guaranteed) speeds of from 1 Mbit/s to 10Mbit/s. A feature of this service is that customer contracts mayspecify asymmetrical channels, in which the line speeds of theupward and downward lines differ. To implement this service, we developed a Guaranteed FrameRate (GFR) function for control of best-effort and guaranteed linespeed at the VC level and an Early Packet Discard function, apacket-unit cell discarding function, for control at the packet level.The GFR function reads cells in turn from VC, while maintainingthe guaranteed line speeds of the respective multiple VCs thatshare a constant bandwidth. If one VC-buffer is empty, the cellsof other VCs are read so that the maximum line speed permittedby the available bandwidth is provided. The EPD* function dis-cards all of the cells from which an IP packet is composed whenthe cell is discarded because of buffer overflow. Doing so pre-vents the sending of IP packets that have missing data and thusincrease the efficiency of IP transfers. In future work, we plan to increase the diversity and functional-ity of the service to meet new customer requirements.(Access Network Systems Laboratories, Multimedia Systems

Development Center)* EPD: Early Packet Discard

IC Telephone Card System through AdvancedIntelligent Network Technology The rampant use of counterfeit telephone cards has become atrue social problem. In an effort to solve this problem once andfor all, NTT Laboratories have developed a new IC TelephoneCard System using an IC-card Data Processing System and Ad-vanced Intelligent Network (AIN) technology. This service waslaunched in March 1999. The service features a function that prevents the counterfeitingof cards or the modification of call units (e.g., illegal increasing ofcall units) by having the network side authenticate each and ev-ery IC telephone card and manage call units through AIN technol-ogy. The AIN consists of a Service Management Function, ServiceControl Function, and Service Switching Function, which can beassociated with a Service Management Point (SMS*1), ServiceControl Point (MHN-SCP*2), and Service Switching Point (MHN-S*3), respectively, in the physical network. A special feature of theAIN is that it breaks down software for achieving a service intomodules. These modules are stored in switches (MHN-S) andare controlled by a Service Control Point (MHN-SCP) at whichservice control functions (scenarios) have been centrally located. Because IC telephone cards can provide a high level of secu-rity, sales have resumed of high-priced cards (2,000- and 3,000-yen cards) whose sale was previously suspended due to rampantcounterfeiting, and international dialing is now limited to IC tele-phone cards. In the future, we plan to enhance the IC Telephone Card Sys-tem with a function for communicating over two B-channels andwith extensive maintenance and operation functions. As part of this service, we will also be studying Universal Per-sonal Telecommunication (UPT) using AIN technology, numberportability, and a service linking the Internet protocol network withthe Public Switched Telephony Network and Integrated ServicesDigital Network (PSTN/ISDN).

(Network Service Systems Laboratories)*1 SMS: Service Management System*2 MHN-SCP: Multimedia Handling Node-Service Control Point*3 MHN-S: Multimedia Handling Node-STM

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GFR and EPD mechanism

8

IC telephone card system by AIN technologyC

omm

on Channel

Signaling N

etwork

IC telephone card

IC public telephone

Network

ISDN circuitSwitch

Information Transfer Network

IC telephonecard units

Service ManagementPoint(SMS)

Service ControlPoint

(MHN-SCP)

SS7

NTT's networkINAP message

SCP

SS7

S-POI

Competitor's network

＊ SAP：Service Access Point

Gateway functionsAdditional module

D70-SAP＊� MHN-S

A High-Performance and Low-Power 40-Gbit/sATM Core Switching System (MHN-A π ) NTT Laboratories developed a high-performance and low-powerATM switching system, called MHN-Aπ*1, in the NS8000 series.This system is operating as a core switching system in the "JapanGigabit Network" for Telecommunications Advancement Organi-zation of Japan (TAO) in cooperation with NTT Long Distanceand Global Provisional Headquarters. This network crosses theentire Japanese archipelago and features ATM switching systemsinstalled at 10 bases throughout the country and Gigabit/s-classultra-high-speed optical fiber lines (main bases are shown in thefigure). It is used for research and development by R&D institu-tions, local governments, and corporations throughout the coun-try. Construction of the network began in earnest in January 1999,and service began on April 1, 1999 without a hitch. The MHN-Aπswitching system that is being used as a core system here fea-tures large-capacity characteristics including a switching capac-ity of 40 Gbit/s and a buffer memory of 200,000 cell/line. More-over, by adopting low-power LSIs and combining several pack-ages, MHN-Aπ achieves a compact and low-power configurationroughly one-third that of the previous system (MHN-A). As forfunctions, the MHN-Aπ switching system features various inter-face packages from 1.5 Mbit/s to 2.4 Gbit/s, various bearer-ser-vice functions, and abundant traffic-control and OAM*2 functions.It can also provide stable service due to its high-reliability andhigh-maintainability characteristics developed from previous ap-plication in other types of networks. Over the next five years,we plan to operate this Japan Gigabit Network with the aim ofproviding users with needed services and to achieve a systemthat is even easier to use.

(Network Service Systems Laboratories)*1 MHN-Aπ: Multimedia Handling Node-ATMπ*2 OAM: Operation Administration and Maintenance

Opening up the Local Switch Functions throughSignaling Network Interconnection If the local switch functions in D70 and MHN-S are opened up,which is part of NTT's open network plan, then competitors' SCPs*1

will be able to directly control the switches by using INAP*2 andprovide various services. In order to provide such interconnec-tion, it is necessary to monitor INAP messages from SCPs con-tinuously and reject any invalid messages. Therefore, we devel-oped an application gateway function having three sub-functions:SCP carrier-related information management, INAP messagemonitoring, and collection of compensation-related information. In the case of MHN-S, this gateway function was installed ineach node. For D70, however, we had to develop an additionalmodule to provide it. We made the software for the gateway func-tion in MHN-S by modifying the software developed for the D70module, which reduced the overall software development cost andresulted in software portability. We expect the following effects to result from this opening upof the local switch functions.(1) Reduction of service development cost Since INAP is service-independent, NTT does not need tomodify its local switches in order to provide services for a com-petitor.(2) Promotion of service competition Service competition will be promoted because competitors candevelop new service individually.(3) Development of competitive telecommunication markets NTT will also use these opened local switch functions in pro-viding its own services, so equal conditions for telecommunica-tion services will be developed. From now on, various effective local switch functions, e.g., in-terconnection for the PHS network or cellular network, will beopened up for diverse telecommunication services.

(Network Service Systems Laboratories)*1 SCP: Service Control Point*2 INAP: Intelligent Network Application Protocol

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Network configuration of Japan Gigabit Network

Network configuration for opening up the local switch functions

9

：Gbit/s-class line between ATM switching systems

：ATM switching system

：Shared use research and development center

：TAO research center

：Transit switching system

Sapporo

Sendai

Tsukuba

Makuhari

Tokyo

Nagano

Kanazawa

Nagoya

Osaka

Keihanna

Okayama

Takamatsu

Kochi

Fukuoka

Kitakyushu

Fibre Channel ---ATM Interworking Unit (FC-IWU) With the increase in the amount of data being processed, new

methods for transmitting and storing large volumes of data havebeen needed in post production, medicine, and three-dimensionalCAD*1 systems. Also, backup of large volumes of data is neededin financial companies and administrative organizations for safety.Fibre Channel is a high-speed communication technology stan-dardized by ANSI*2. It enables the transmission of large volumesof data at gigabit-per-second rates between computers and stor-age devices. FC-IWUs*3 enable FC networks to be interconnectedthrough an ATM network, thereby enabling high-speed transmis-sion between FC networks in different sites. The throughput ofthe FC-IWU is high enough to enable full use of the 150-Mbit/sbandwidth of an ATM circuit in bi-directional transmission. Be-cause an FC-IWU is connected to an FC switch via an ANSI stan-dard E_Port interface and can handle any upper-layer protocol,such as SCSI*4, TCP/IP*5, or audio-video, transparently, it allowsdirect access to storage devices from remote computers with theSCSI protocol. Moreover, it simultaneously allows communica-tion among computers with TCP/IP on the same ATM circuit. In-terconnecting FC networks through an ATM network enables ser-vices provided in the local FC networks to be offered to a widerarea. For example, large volumes of data can be backed up toremote storage devices and video post-production can be donecollaboratively from various sites. FC-IWUs have been sold byNTT Long Distance and Global Provisional Headquarters sincelast December. The ATM interfaces for using new ATM servicessuch as ATM Share-Link will be supported in the FC-IWU to de-crease the cost of the interconnection between FC networks viaan ATM network.

(Multimedia Networks Laboratories)*1 CAD: Computer Aided Design*2 ANSI: American National Standards Institute

*3 FC-IWU: Fibre Channel-ATM Interworking Unit

*4 SCSI: Small Computer System Interface*5 TCP/IP: Transmission Control Protocol/Internet Protocol

Intermediate and High-Speed CommunicationTechnology Using the π-System Platform The explosive demand for Internet access and the increase incorporate computer use in recent years are increasing the demandfor computer communications. At present, individual users aremainly employing low-speed services from 32 kbit/s to 128 kbit/sover metallic cable for computer communications, but this shouldchange as intermediate and high-speed services (from severalhundreds kbit/s to 10 Mbit/s) become cheaper. To deal with thisdemand, an optical access system has been developed that canprovide computer communications at a peak speed of about 10Mbit/s (minimum about 300 kbit/s). It is based on NTT's π-systemthat provides telephone and ISDN services at low cost. More specifically, we have developed a shared-access technol-ogy in order to economically provide an effective high-speed trans-mission capacity. This technology makes full use of the π-systemfeatures of broadband transmission and the sharing of one unit ofoffice-side equipment by multiple subscribers. In this way, avail-able transmission capacity can be allocated in a fair manner tousers (shared access). In short, among multiple optical networkunits (ONU) that are connected to an optical subscriber unit (OSU)via a star coupler, maximum available capacity (e.g., 10 Mbit/s)can be used by one user if only that user is currently connected,and available capacity can be allocated evenly to each user whenmultiple users (e.g., 32) are connected at the same time. Thistechnology can therefore guarantee communications with a maxi-mum speed of about 10 Mbit/s and a minimum speed of about 300kbit/s while providing telephone and ISDN services simultaneously.It enables intermediate and high-speed computer communicationservices to be added to telephone and ISDN services in a smoothmanner.

(Access Network Systems Laboratories)

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FC networks bridged by FC-IWUs via an ATM network

Overview of the shared-access technology

10

telephone / ISDN

ONU

ONU

computer

star coupler

optical fiber

shared band

individual path for telephone / ISDN

shared band for computer communication

(10 Mbit/s)

capacity

3 users2 Mbit/s for each

5 users3.3 Mbit/s for each

1 user10 Mbit/s

time

optical line terminal

OSU

ATM interface: STM-1/OC-3c (150 Mbit/s)

FC switchFC switch

Tape device Disk array Disk array

ATM�network

Transmission bySCSI protocol

1 Gbit/s 1 Gbit/s

FC-IWUFC-IWU

Transmission by IP

EA Modulator Integrated DFB Laser Module Op-erating in the 1580-nm Band A high-density wavelength division multiplexing (WDM) sys-tem is one of the best solutions to cope with the recent rapidincrease in transmission capacity. Recently, the flat-gain wave-length range of fiber amplifiers has been rapidly extended to coverthe 1580-nm band as well as the conventional 1550-nm band.Therefore, a compact high-speed light source that can operate inboth these wavelength ranges is required. An electroabsorption (EA) modulator integrated distributed feed-back (DFB) laser is an attractive high-speed light source havingadvantages of compactness, low driving voltage, low chirping,and high reliability. We have already developed 10-Gbit/s EAmodulator integrated DFB lasers that operate in the 1550-nm bandand they are now commercially available. By adjusting the de-vice structure, we have now developed one operating in the 1580-nm band and confirmed its good transmission performance at 10Gbit/s over a 40-km single-mode fiber. The module is only 2.5 cm× 2.0 cm× 1.0 cm as shown in Fig. 1. The injection current ofthe DFB laser is typically 60 mA and the driving voltage of the EAmodulator is 2 V. A single longitudinal mode with a side-mode-suppression ratio of over 40 dB is shown in Fig. 2. We believe that an EA modulator integrated DFB laser will playa key role as a high-speed light source in future intranet datacommunication systems as well as in conventional transmissionnetworks.

(Opto-electronics Laboratories)

Low-Cost, High-Speed and High-ResponsivityEdge-Illuminated Refracting-Facet PhotodiodeModule The worldwide demand for rapid increases in transmission ca-

pacity is accelerating the research and development of large-ca-pacity optical-fiber transmission systems, such as ultra-high-speedtime-division-multiplexing systems and wavelength-division-mul-tiplexing systems. Because the photodiode, which detects theoptical signals, is one of the key components in these systems,NTT Laboratories have developed a low-cost, high-speed andhigh-responsivity photodiode module utilizing a newly developededge-illuminated refracting-facet photodiode (RFPD). Since theincident light refracted at an angled facet penetrates at a definiteangle to the absorption layer, the absorption length is effectivelylonger, resulting in higher internal quantum efficiency. Therefore,high quantum efficiency can be assured even when the absorp-tion layer is made thinner to obtain high-speed operation by re-ducing the carrier transit time. Another advantage of the RFPD isthat the misalignment tolerance of the optical axis in the verticaldirection is determined not by the thickness of the absorption layer,as in waveguide photodiodes, but by its length. Therefore, a largemisalignment can be tolerated. This enables the RFPD moduleto be constructed with a single-lens alignment configuration, whichreduces the number of optical alignment processes and the num-ber of optical components, resulting in a low-cost module. TheRFPD module has a responsivity as high as 1 A/W for 1.55-μm-wavelength light and a 3-dB bandwidth as large as 38 GHz. This RFPD module is expected to play an important role in de-veloping a large-capacity photonic network. We plan to furtherincrease the bandwidth and raise the output voltage under highoptical input.

(Opto-electronics Laboratories)

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EA modulator integrated DFB laser module oper-ating in the 1580-nm band

Schematic cross-sectional view of the RFPD

11

SPECTRUM10dB/div0�

��

dBm�����

-40�������

-80

-7.72

＃235 09-02�100mA 25 deg.

1.5674 μm 1.5924 1.6174

RES 0.1nm Wp 1.5924 5nm/div

98.02.05 19:56�AUR 1

Single longitudinal mode lasing spectra

Photograph of the RFPD module

Light

Angled facet

Absorption Iayer

p-electroden-electrode

Hybrid-Integrated Optical Transceiver Module forATM-PDS Systems Asynchronous-transfer-mode passive-double star (ATM-PDS)systems are expected to provide the next-generation access net-work infrastructure that can cope with the increase in traffic andservice needs in the multimedia era. The ATM-PDS system witha single fiber uses full-duplex bi-directional transmission in whicha 1.3-μm burst signal (upstream) and 1.55-μm continuous signal(downstream) are transmitted, so the transceiver modules for thesystem require high performance for wavelength-division-multi-plexing (WDM) and high-speed burst-mode operation as well asbeing compact and inexpensive. NTT laboratories have succeeded in developing an optical trans-ceiver module for the optical network unit (ONU), whose perfor-mances cover both the class-B and class-C specifications recom-mended by ITU-T*1, using planar-lightwave-circuit (PLC) -hybrid-integration and CMOS*2-IC technologies, which are promising forreducing the cost. In this optical transceiver module, a laser diode (LD), a receiverphotodiode (R-PD), a photodiode for monitoring the output power(M-PD), and a WDM filter for dividing between the 1.3- and 1.55-μmsignals are hybridly integrated on a small PLC platform. A laserdriver IC, a preamplifier IC, and an auto-gain-control amplifier(AGC) IC, which were fabricated using CMOS process technol-ogy, are also mounted around the PLC platform. For full-duplexoperation in the module, it is essential to suppress the optical andelectrical crosstalk between the transmitter and the receiver parts.By employing a three-dimensional electromagnetic-field-analysis-design technique and designing the arrangement of the opticaldevices and the configuration of the optical circuit, we success-fully suppressed the optical crosstalk and electrical crosstalk toless than -40 dB and less than -100 dB, respectively. This module and the design and fabrication techniques will playan important role in building future optical access network sys-tems, such as ATM-PDS systems.

(Opto-electronics Laboratories)*1 ITU-T: International Telecommunication Union-Telecommunication Standard-

　　　　ization Sector*2 CMOS: Complementary Metal Oxide Semiconductor

Plastic Ferrule and Sleeve for Single-ModeFiber-Optic Connectors High-performance and low-cost fiber-optic connectors are es-sential for optical subscriber systems. The major cost factors withsuch optical connectors are their optical ferrules and alignmentsleeves, which are currently fabricated by processing ceramicmaterials. In order to produce plastic fiber-optic components withsub-micron dimensional accuracy, we investigated both moldingmaterials and the mold structure. The dimensional accuracy ofconventional molding techniques is limited to about 10μm. For the ferrule material, we used liquid crystalline polymer (LCP),which flows well even under low molding pressure and has a lowcoefficient of thermal expansion. For single-mode applicationsthere must be no greater than sub-micron eccentricity betweenthe outer diameter of the ferrule and the center of the minute holeinto which an optical fiber is inserted. We introduced an eccen-tricity control mechanism into the ferrule mold and achieved aneccentricity of less than 1μm. The sleeve material has to behighly elastic and have a low surface roughness, so we used ther-mosetting epoxy resin. We prepared the split alignment sleeveby injection molding a pipe and then forming a slit by cutting thepipe along its axis. A connection loss histogram for SC connec-tors using plastic ferrules and sleeves is shown in the figure. Allthe losses were below 0.5 dB and the average loss was 0.2 dB.The return loss was greater than 40 dB. These optical character-istics are similar to those of conventional single-mode SC fiber-optic connectors using zirconia parts. The reliability of the "plas-tic" connectors was investigated through heat-cycle and matingtests. There were no significant changes in optical characteris-tics during the tests. The use of injection molding technology and plastic optical com-ponents will usher in a low-cost and reliable optical network forthe 21st century.

(Opto-electronics Laboratories)

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Structure of a fiber-optic connector

12

Configuration of optical transceiver module

Connection loss histogram of "plastic" connectors

Photograph of optical transceiver module

PlasticFerrules

PlasticSleeve

Single-ModeOptical Fiber

100�

80�

60�

40�

20�

0�

�

N = 110�

AVG. = 0.14 dB�

S.D. = 0.10 dB�

Connection Loss (dB)0 0.4 0.8 1.2 1.6 2

Num

ber

Data in

AGC IC

LD driver IC

WDM filter

1.3μm

1.55μm

Bare-chipPreamp. IC

Data out

Reset in

M-PD LD R-PDGlass-epoxy electrical

circuit boardPLC platform

TransmitterPart

ReceiverPart

Clock in

LD driver IC

AGC IC

M-PD

R-PD

WDM filterPreamp.IC

LD

PLC platform

A Compact and Light Automated Tool for OpticalLine Testing (mini-TEM) At present, optical-cable installation testing in buildings that havenot yet introduced an optical-line maintenance support system(AURORA*1) consists of transmission-loss testing and pulse test-ing using an ID-tester*2 and OTDR*3. Testing with measurementdevices of this type, however, must be performed one optical fi-ber at a time. This means that the process of connecting a fiberto a device, taking measurements, and removing the fiber mustbe repeated many times and that the time required for makingthese connections increases proportionally to the number of opti-cal fibers. Keeping in mind, therefore, the major objective ofachieving an optical fiber network at a cost parallel to that of theconventional metal-based network, we have developed an opti-cal-line-testing support tool called "mini-TEM*4" to make opticalcable testing more efficient. The mini-TEM consists of control and measurement equipmentand a portable-type optical fiber selector, both of which are com-pact and light enough to be carried around as needed. Moreover,as the mini-TEM can be set up in most FTM*5 and easily con-nected to mechanical transferal (MT) housing, optical fiber cables,and optical couplers, it can be applied to various types of opticalcable testing. With the mini-TEM, the previously manual tasks of connectingto optical fibers, testing, analyzing, diagnosing defects, and cre-ating reports have all been automated significantly reducing con-nection time compared to conventional methods. Its automaticmeasurement function makes it possible to carry out measure-ments at night and avoid work-intensive time periods during theday, making more efficient use of idle time. In addition, by com-bining mini-TEM with the existing AURORA system, it will be pos-sible to reduce the time of much optical cable testing. Taking advantage of the above features, an optical-path dam-age-detection system incorporating mini-TEM is now under de-velopment. The purpose of this system is to enable the Mainte-nance and Service Operation Department to respond effectivelyto a disaster like the Great Hanshin Earthquake. The goal is toisolate damaged areas within half a day after the disaster strikesand to isolate damaged fibers and locations within four days. Weexpect this system to be completed by the end of March 2000.

(Access Network Systems Laboratories)*1 AURORA: Automatic Optical Fiber Operation Support System*2 ID-tester: Optical Fiber Identifier*3 OTDR: Optical Time Domain Refletometer*4 mini-TEM: mini-Test Equipment Module*5 FTM: Fiber Termination Module

Revolutionary Low-Power Card-Size ONU forISDN Terminals The widespread deployment of FTTH*1 targeting ISDN servicesis becoming a real possibility because of the dramatic increase inISDN circuits in recent years. The key to accelerating this de-ployment is the development of a compact ONU*2 having a highdegree of freedom in terms of installation and usage. Here, low-power operation is a major issue, as it will enable battery backupparts to be downsized and the rise in internal equipment tem-perature during operation to be suppressed. To examine the feasibility of such low-power operation and com-pact ONUs, we developed a card-size prototype single-user ONUfor ISDN terminals. This ONU, which currently is the smallest inthe world in terms of both power and size, can provide five hoursof continuous calls during a power outage using one commercialAAA-size cell. It incorporates advanced 1 V-class operation com-ponents and modules developed by NTT Laboratories for appli-cation to the 50-Mbit/s STM-PDS*3 system. The ONU also ap-plies a new configuration method that features a plug-type con-nection between the service interface part (user interface part)and the common processing part, and a high-precision moduledesign method. It has been confirmed that this ONU can achieve1/10 the power consumption (150-mW) and 1/2.5 the size (60-cc)of conventional ONUs (assuming an ISDN terminal×1 configura-tion and dispensation with a terminal power supply). As a result,the ONU is not limited to card-size units but can be applied tovarious customer-usage formats such as a built-in type within theinformation outlet. The technology used for configuring this single-user ONU canalso be applied to equipment within NTT central offices to raisethe module installation density and lower equipment cost. Our future studies in this area will focus on increasing the yieldof low-voltage operating components and modules and introduc-ing them into actual telecommunication operations.

(Access Network Systems Laboratories)*1 FTTH: Fiber To The Home*2 ONU: Optical Network Unit*3 STM-PDS: Synchronous Transfer Mode-Passive Double Star

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A configuration of prototype ONU

13

A module with ONU card and ISDN line interface plug

Package layout of mini-TEM

Portable-typeOptical Fiber Selector

Control and Measurement Equipment

Mechanical Transferal Housing

Battery holder

ISDN line interface plug

Card holder 　 & ejector

ONU card

ONU card and ISDN line interface plug attachment to battery holder

Commercial AAA-size cell(interchangeable a dry cell with a rechargeable cell)

ISDN line interface plug

Battery holder ONU card

20-Mbit/s Ethernet-Based Wireless LAN System Wireless LAN systems are being used more and more widely

used, and their bit rates are expected to become higher. To achievesuch higher-bit-rate wireless LANs, their design specifications arebeing standardized. However, higher-bit-rate transmission leadsto signal distortion caused by multipath fading. To solve this prob-lem, we have been developing a novel packet-mode orthogonalfrequency division multiplexing (OFDM) scheme. In July 1998,IEEE*1802.11 Task Group a (TGa) selected the OFDM scheme,which was jointly proposed by Lucent Technologies and us, asthe physical-layer standard for the 5-GHz band. We have developed a high-speed Ethernet-based wireless ac-cess (EWA) system that uses the OFDM scheme. We also de-veloped a prototype that is based on the IEEE802.11 TGa stan-dard with MAC*2-layer function. The EWA System provides 20-Mbit/s data rate transmission and should help bring about a 5-GHz band high-speed wireless access network. An EWA systemusing OFDM modulation enables high-quality and high-speed datacommunication to be achieved without using a complex adaptiveequalizer or an adaptive active-array antenna, which increase ter-minal size. Its seamless connection function allows mobile com-puter users to switch between a wired and a wireless interfacebetween the terminal and the network without disconnecting thenetwork-layer-protocol link. Another function that supports termi-nal movement is inter-access-point handoff control, which expandsthe service area of the wireless domain. Terminals using the EWAsystem can automatically switch between these two functions with-out user intervention. Moreover, the EWA system provides theexpanded MAC-layer functions of the IEEE802.11 standard, in-cluding the autonomous high-efficiency channel-sharing algorithm,the inter-terminal short-cut transmission technique without access-point relay, and the open-cipher key certification with FEAL*3 cryp-tography for high-level security. We are further advancing IEEE802.11 standardization and havebeen developing LSI chips that will result in PCMCIA*4-type wire-less LAN cards for commercial use.

(Wireless Systems Laboratories)*1 IEEE: The Institute of Electrical and Electronics Engineers, Inc.*2 MAC: Medium Access Control*3 FEAL: Fast Data Encipherment Algorithm*4 PCMCIA: Personal Computer Memory Card International Association

1.9-GHz Subscriber Wireless Access System(λ System) ---Service Start-up and Functional Im-provement For current wired subscriber networks, the cost per subscriberfor sparsely populated mountainous regions where homes are farapart can be several times or several tens of times the cost persubscriber for densely populated urban areas. As a fundamentalsolution to this problem, there is a demand for the construction ofa new infrastructure. With the objectives of providing advancedcommunication services to these kinds of high-cost areas andreducing the cost of facilities, the Laboratories have developedthe 1.9 G-FWA* system (nicknamed λ System) and began ser-vices in the Tokachi district of Hokkaido in November 1998. λ System is a new system in which the subscriber residencesconnected to the NTT switches are by a wireless link rather thanby copper wire. The use of existing PHS technology makes itpossible to simplify maintenance as well as to reduce the cost ofthe access system facilities, without changing the subscriber in-terface. Moreover, this system makes it possible to provide ser-vices to customers who previously could not be provided ISDNand high-speed digital transmission services (64 kbit/s and 128kbit/s) because of distance constraints. In addition, this systemuses the V5 multiplex interface, which conforms to the interna-tional standard, for the node interface, aiming at global develop-ment. In future work, we plan to provide Number Display service (acaller ID service) ISDN capacity expansion, and other advancedservices.

(Access Network Systems Laboratories)* FWA: Fixed Wireless Access

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14

Prototype of the high-speed Ethernet-based wireless access system

System configuration

FWA Access Controller (WAC)

FWA Repeater Station (WRS)

Optical fiber cable

radio wave (2-GHz band)

～20km (can be extended with repeaters)

FWA Operation System

W-OpS

V Interface Protocol Translation Equipment(V-PTE)

FWA Cell Station (WCS)

FWA Subscriber Unit (WSU)

LD-SLT

WAC-BOX NTT building(RT-BOX ,etc)

V5.2

A /I-RT 32M

In door typeOut door type

PHS air interface(1.9-GHz band)

1～2km(up to 5km radius)

Base station Concrete walls 0

5

10

15

The num

ber of usable channels

�

Distributionsof the number

of usablechannels

Input (PC) Output (PC)

Buildingstructures,materials

Positionof basestations

Wirelesssystem

type

Analyze (WS)

Coverageregions

Distributionof

throughput

Propagationcharacteristics simulator・Ray tracing method

Communicationcharacteristics simulator・Digital signal analysis・2.4-GHz-band　wireless LAN・1.9-GHz-band�　cordless phone

Using CAD

this work

2GHZ

2.0 2.5 3.0 3.5 4.0

80

70

60

50

40

Drain supply voltage（V）

Pow

er a

dded

effi

cien

cy（％）

conventional

An RF Power MOSFET for 2-GHz Wireless Terminals The need is increasing for high-speed data transfer of imagesand other types of data as a means of raising the performance ofterminals used in wireless access systems. This need parallels agrowing interest in AWA*1 and wireless LAN systems, with par-ticular attention being paid to IMT2000, the next-generation wire-less access system. Against this background, the need is felt forlow-cost MMIC*2 technology featuring high-efficiency operation athigh frequencies for use in next-generation wireless-access ter-minals. To this end, research on MMIC using Si-based semicon-ductor devices is becoming quite active compared to that usingcompound semiconductor devices. Here, the application of SOI*3

technology that enables devices to operate at high frequencieswith low power consumption looks especially promising. On theother hand, power MOSFETs*4 used in conventional SOI technol-ogy suffer from low breakdown voltage due to parasitic bipolareffects, and they are not applicable to RF*5 power amplifiers thatplay a key role in wireless access terminals. To therefore solvethe problem of parasitic bipolar effects while taking advantage ofthe benefits of SOI technology, we propose a Quasi-SOI PowerMOSFET (photograph) in which the buried oxide in the body re-gion is removed and direct contact is made with the body region.Using this technology, we have developed a power MOSFET foruse in the 2-GHz band. This prototype power MOSFET featuresa source-to-drain breakdown voltage of 14 V, which is more thantwice that of devices with the conventional SOI structure, andachieves a maximum power added efficiency of 68 % (at 2 GHz)in Si-based semiconductor devices (figure). Our future efforts will focus on developing RF power modulesto lower the cost of user terminals even further and on developingpower modules for operation at 5 GHz to handle communicationsat even higher speeds.

(Integrated Information & Energy Systems Laboratories)*1 AWA: Advanced Wireless Access*2 MMIC: Microwave Monolithic Integrated Circuit*3 SOI: Silicon on Insulator*4 MOSFET: Metal Oxide Semiconductor Field Effect Transistor*5 RF: Radio Frequency

Electromagnetic Environment Design System Several kinds of private wireless communication systems, suchas 2.4-GHz-band wireless LANs and cordless phones, are nowused in many offices. As wireless systems using the same fre-quency band become more closely concentrated in offices, theirperformance may be affected by electromagnetic interference. De-signers of office systems must therefore consider the electromag-netic environment for the wireless systems. They must also de-sign the positions for base stations flexibly so that client requeststo change coverage regions and the number of base stations canbe easily accommodated. The electromagnetic environment design system (Fig. 1) pre-sents the positions for base stations in indoor environments thatmaximize communication efficiency. The positions are determinedby using computer simulation to evaluate the electromagnetic in-terference created in the electromagnetic environment and thepropagation characteristics of the building structure for variousbuilding materials. This is a computer-aided design system whoseinput parameters are the building structures and wireless systems.After analyzing the propagation characteristics of the structuresand the communication characteristics of the wireless systems,the system outputs the coverage regions, distributions of the num-ber of usable channels (Fig. 2), etc. This system can handle 2.4-GHz-band wireless LANs and 1.9-GHz-band cordless phones (in Japan). It can estimate the through-put characteristics at each receiving position because the propa-gation and communication characteristics are simulated simulta-neously. The analysis algorithm is modified to the most suitableform based on the measured data; the deviation between the simu-lated and measured electrical-field strength was below 5 dB. By using this system, we can easily design the wireless systemrequested by a client; we can also easily analyze the cause ofany communication problems and correct them. We plan to de-velop a simple version of this system that can run on a PC and todevelop a new system that can handle the wireless systems com-ing in the next generation.

(Multimedia Networks Laboratories)

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System structure

15

Cross sectional photograph of the fabricated MOSFET

Dependence of the drain supply voltageon the power added efficiency

Simulated result of usable channel distribution in building

Drain

Si

SiO2

Source • body electrode

Buried SiO2

OffsetGate

Source

Drain local interconnection

Supporting substrate

Successful Test of a Large Deployable Antennafor Next-Generation Communication Satellites A prototype 10-m-diameter large deployable antenna for mount-ing on communication satellites has been successfully deployedin a ground test performed by NTT Laboratories. Use of a largeantenna reflector makes it possible to focus a terrestrial beamand receive faint radio signals from the ground on the satelliteside. This, in turn, means that transmission speeds with the groundcan be increased and that equipment in ground systems can bemade smaller. This type of antenna is therefore expected to be akey technology for next-generation communication satellites.Moreover, if this large space structure can be constructed in a"modular configuration," design and manufacturing costs can bereduced, terrestrial tests can be simplified, and design of struc-ture dimensions can be more flexible. The prototype model in this successful deployment test wasconfigured by coupling seven basic structures referred to as "mod-ule" which has 4.8-m-diameter. Each module consists of a trussstructure that can deploy like umbrella, a metal mesh (gold-platedmetallic knitting) that acts as a reflector surface and a cable net-work. When the seven modules are coupled together, the an-tenna has a diameter of 10 m in deployed state, a diameter under1 m in stowed state, and a total weight of about 80 kg. This an-tenna therefore provides a lightweight large reflector with highstowability. In the test, deployment was achieved while suspending thecenter and periphery of each module from a 15-m-high ceilingwith cables of constant tension to mitigate the weight of the struc-ture. This test with seven coupled modules clarified the deploy-ment characteristics of the centrally placed module that is con-strained by the other modules at its periphery, and determinedantenna characteristics when each module deploys in an asyn-chronous manner. In addition, as a means of evaluating deploy-ment reliability taking advantage of the antenna's modular con-figuration, we proposed a separate deployment test on each mod-ule to determine individual characteristics, and developed an analy-sis technique that takes these individual results to calculate de-ployment characteristics of the entire more than ten-module struc-ture in orbit.

(Wireless Systems Laboratories)

High-Speed Batch Transfer of Large-Volume In-formation by Satellite Communication System The volume of information flowing through the network is in-

creasing rapidly due to the large amount of data in multimediacommunications that are typical of Internet access. Acquiring in-formation only though the ground-based public telephone network,however, takes a relatively long time, and a solution to this prob-lem is eagerly anticipated. To therefore provide network servicessuitable for high-speed and economical acquisition of informa-tion, development work proceeds on achieving a practical multi-media satellite communications system in which terrestrial circuitswould be used as upstream circuits and large-capacity satellitecircuits as downstream circuits. This system was subjected tojoint trials beginning in June 1996 in collaboration with Tokai Uni-versity, GAKKEN Co., Ltd. and others, and was put into commer-cial service by NTT Satellite Communications in October 1998.In addition, the Asian Multimedia Forum (AMF) has been promot-ing a satellite Internet project using this system since April 1998in cooperation with various Asian countries. This project has dem-onstrated the feasibility of asymmetric communication servicesas well as ATM-oriented applications using a newly developedATM satellite adapter (see photograph). The developed equip-ment features an OC-3c interface and can accommodate end-to-end ATM transmissions using satellite circuits. The equipmenthas also been used to deliver video data from Japan to Singaporeas part of the Singapore ONE project. NTT Laboratories plans towork on developing an even more convenient high-speed andhigh-performance satellite communications system consideringthe demand for high-speed transmission in applications.

(Technology and Development Support Center)

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16

Deployment test

ATM satellite adapter

Specifications

Item Description

Inputinterface

Operatingvoltage

Dimensions

Weight

D-sub 25-pin connectorRS-4228-bit parallel interface

SC-type connectorMultimode optical fiberOC-3c（155Mbit/s）

AC 90 V to 110 V（50/60Hz）

99mm（H）× 480mm（W）× 250mm（D）4kg

Outputinterface

POTS

Pay phone

ISDN（INS64）

New Service

Terminals

DC circuit

Controller

Flashmemory

Test equipment

AC circuit

Multi-service line card (MULC)

Interfacewith Nodeand OpS

Speech pathhighway

farmware download

changing order

Optical remote accesssystem

(RSBM-F/U, πsystem)(B-ch)

(Command)

Switching node

ISDN network

DDX network

OpS system(EOS)

OpS terminalDownload server

S-OpS/EOSserver

service modechanging order

farmware downloadorder

Protection

Development of a Satellite Internet ReceivingAdapter Board with Built-in Tuner Unit The content of the multimedia communication that is now typi-

cal of Internet use involves increasingly large amounts of dataand is rapidly increasing the flow of data over networks. To pro-vide a rapid and economical Internet access line and intranet sys-tem that can cope with such high-volume data communication,we have begun offering a multimedia satellite communication sys-tem service that employs ground lines for the upward link and alarge capacity (about 30 Mbit/s) satellite channel for the down-ward link. In the past, the hardware installed on the customer'spremises for such a system consisted of a small antenna (50-cmdiameter), a digital satellite broadcast tuner unit (about the size ofa B4 sheet of paper), and a protocol adapter unit for assemblingIP packets from MPEG2-TS*1 data (about the size of an A4 sheetof paper). To achieve local user equipment that has more ad-vanced functionality and is more economical, we developed a PCI*2

bus expansion board for personal computers that integrates theconventionally separate tuner and protocol adapter units and thefunction of MPEG2-TS video signal distribution and IP packet datacommunication into a single PCI bus card for personal comput-ers. This integrated unit makes it possible to provide to imple-ment advanced functions, such as data privacy functions in whichaccess to data carried on the satellite link signal can be restrictedto certain groups of users by means of encryption keys. Becausethis board uses the universal PCI bus interface, it can be usedwith various types of personal computers. In addition, the perfor-mance (data reception at up to about 45 Mbit/s) of the protocolprocessing LSI chip that was developed is sufficient to handle thehigher speed satellite channels of the future. In future work, we will proceed with the development of satel-lite communication technology that is more convenient and hasmore advanced functions.

(Wireless Systems Laboratories)*1 MPEG2-TS: Moving Picture Experts Group 2-Transport Stream*2 PCI: Peripheral Component Interconnect

Multi-Service Line Card With the introduction of optical fiber into access networks, re-mote access systems such as RSBM-F/U*1 or the Pi-system arebeing installed in homes and user buildings and on telephonepoles and cables. Therefore, when changing an existing serviceto another, e.g. from POTS*2 to ISDN, a maintenance worker mustgo and install the appropriate new line card (e.g. an SLIC*3 orBOCU*4 card). This raises the maintenance cost and extends thetime required to change services. A multi-service line card (MULC) could overcome some of theabove-mentioned problems by enabling a service to be changedby a control command or by software downloaded from a remotemaintenance office. Our MULC has software-programmable hard-ware and its DC/AC characteristics can be changed by changingits parameters. The software for basic services (analog telephony,analog payphone, and INS64), which is used frequently, is loadedin flash memory on the MULC, so a service can be changed sim-ply by one service change command. That design can shortenthe service changing time and prevent network traffic congestion.Moreover, new services can be offered quickly by downloadingthe appropriate software. As the MULC is compatible with exist-ing line cards, existing remote access systems can use it withoutmodification. Laboratory and field testing of the MULC has already finished,and we expect it to be introduced into service in fiscal 1999.

(Network Service Systems Laboratories)*1 RSBM-F/U: Remote Subscriber Module for Feeder Point/User Building

*2 POTS: Plain Old Telephone Service

*3 SLIC: Subscriber Line Interface Circuit*4 BOCU: Basic Office Channel Unit

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Multi-service line card

17

Satellite adapter board with built-in tuner unit