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Telecommunications�Network TechnologiesTelecommunications�Network Technologies

Telecommunications

Network

Technologies

Telecommunications

Network

Technologies

Technologies for establishing a base net-work infrastructure including optical net-works, wireless and satellite, all of which are essential to guaranteed bandwidth and broadband telecommunication.

IP Network

Userperception

Terminaldesign

parameters

NW planning/managementparameters

Subjectivequalityfactors

NW qualityparameters

Jitter bufferoverflow

Jitter bufferdelay

Terminalquality

parameters

ListeningMOS*1

ConversationalMOS

IP packet delay IP packet loss

Delay jitter

Link utilization

CODEC*2

Jitter buffer

Packet size

Listeningquality

NW packetloss

Codingdistortion

Loudness Latency

NW delay

Echo

Objective quality estimation

Qualitymanagement

Subjective qualityassessment

Overall qualityestimation

VoIP-GW

Echocancellation Quality

planning

*1 MOS: Mean Opinion Score*2 CODEC: coder/decoder

QoS Assessment, Design and Management Technologiesfor IP-Telephony and Video Delivery Services

NTT Service Integration Laboratories

The expansion of broadband network services has led to thegrowing use of IP telephony and video streaming services. Sincethe quality of speech and video should be evaluated subjectively,the networks and connected terminals should be designed and man-aged taking into account the characteristics of subjective quality.

NTT Laboratories have developed methods for evaluating,designing, and managing the quality of IP telephony and videostreaming services. These methods include:(1) Service value assessment that provides guidelines for settingcompetitive quality levels and prices,(2) Objective quality estimation for speech and video that enablesquality to be assessed without conducting subjective evaluationexperiments,(3) Overall quality estimation of IP telephony using the qualityparameters of the networks and terminals, and(4) Quality management that enables end-to-end quality to be esti-mated based on the status of network devices and terminals.

We will continue researching and developing ways to assessspeech and video quality and will expand our scope to include theevaluation of community and collaboration services.

Study items for assessing quality of IP telephony services

Contents●QoS Assessment, Design and Management Technologies

for IP-Telephony and Video Delivery Services ………………… 12●Development and Release of VoIP Service Systems ………… 13●Optical Multi-Channel Video Signal Transmission

Employing B-PON System ……………………………………… 13●Establishment of Open Software Technologies for Next

Generation Networks: Open APIs for Adapting 3rd Party

Vendor Applications ……………………………………………… 14● Interactive Multimedia Communication Technologies ………… 14●Optical Access Distribution Technology for Rapid

and Economical Response of Optical Services ……………… 15● IP Nomadic Service Technologies ……………………………… 15●Extended IP Multicast Protocol (IGAP) for Content

Delivery Systems …………………………………………………16●Direct-Multicasting Satellite Communications System

for Nationwide Digital Contents-Gathering and

Distribution Service ……………………………………………… 16●Wireless IP Access System (WIPAS) ………………………… 17●Technologies for Protecting Network Equipment and

Network Appliances Against Lightning Damage ……………… 17●Congestion-Aware Network Admission Control Based on

Per-User Performance Statistics ………………………………… 18●Development of Technology Permitting Denser

Accommodation of Cables in Communication Tunnels ……… 18●Development of an Optical Cross Connect (OXC) System …… 19●Condominium IT Kit: Transmission System for Providin

Broadband Services in Closed Areas ………………………… 19

Telecommunications Network Technogies

Optical Multi-Channel Video SignalTransmission Employing B-PON System

NTT Access Network Service Systems Laboratories

The rapid growth of broadband users and the trend toward high-speed, broadband systems through optical fiber has attracted muchnotice of late. Against this background, NTT has developed aworld-leading transmission system that uses the transmissioncapacity of optical fiber to the full, and has conducted a joint experi-ment with SKY Perfect Communications Inc. to test the system andassociated technologies. This experiment, which was conducted ata condominium building in the Shinjuku district of Tokyo from March2002 to January 2003, employed NTT's B-PON*1 optical accesssystem featuring a peak data rate of 100 Mbit/s and simultaneoustransmission of up to 500 channels of video signals over a singleoptical fiber. The B-PON system provides a new world standard inoptical access enabling cost-efficient provision of diverse broad-band multimedia services to multiple customers.

At present, BS*2 and CS*3 broadcasting uses a total of five satel-lites to distribute video. In general, three coaxial-cable systems arerequired to enable all the channels in those broadcast signals to beviewed in condominium buildings or other residential complexes.The problem here is that most condominium buildings are con-structed with only one coaxial system preventing the viewing of atleast some channels. Video distribution using the B-PON system,however, can use the 64 QAM*4 modulation system known for itshigh spectrum efficiency enabling all channels of terrestrial, BS,and CS broadcasting to be viewed with only one coaxial system.

B-PON is expected to be used in FTTH*5 systems to providehigh-speed communications and high-quality multi-channel broad-casting and as a means of improving the viewing of satellite broad-casts in residential complexes. It is also promising as a means ofexpanding service areas for soon-to-begin digital terrestrial broad-casting and of promoting the use of information systems in thinlypopulated areas.

*1 B-PON: Broadband Passive Optical Network

*2 BS: Broadcasting Satellite

*3 CS: Communication Satellite

*4 QAM: Quadrature Amplitude Modulation

*5 FTTH: Fiber To The Home

Development and Release of VoIP Service Systems

NTT Network Service Systems Laboratories,

NTT Information Sharing Platform Laboratories

Symbolizing the government's e-Japan initiative, we are seeing a very rapidrollout of xDSL*1, optical access, and other broadband services, and faced withever fiercer competition, all kinds of service providers are getting hold of reportsissued by Ministry of Public Management, Home Affairs, Posts and Telecom-munications (MPHPT) research groups, and deploying fully functional IP basedtelephony services one after another.

NTT Laboratories have been devoting R&D resources to a next-generationIP core network platform since the beginning of 2000, and VoIP*2 was one ofthe first advanced IP technologies that was made available. It is against thisbackdrop that the NTT Group is now offering businesses a number of key tech-nologies that will greatly expand the use of IP-based services.

Considering the voice service systems that businesses have in place, NTThas now developed and released a number of core systems needed to supportIP-IP and IP-PSTN*3 voice services. These include: (1) a Type1CA*4(SS*5 func-tion) with SIP*6 server function, (2) a GWSN*7 and trunking MG*8 that supportSIP-ISUP*9 conversion and interworking between the legacy PSTN and IP net-works (the Type1CA GW*10 function can also be used instead of the GWSN),(3) a VoIP network management system that supports the ordering of servicesand provides integrated management of CAs and MGs, (4) IP-IVR*11 featuringaudio guidance and other media server capabilities, and finally (5) a billing plat-form that greatly streamlines the processing of billing records (InfoBillingBrobCom).

Based on commercial servers, routers, and legacy PSTN switches, we havesubstantially enhanced these core systems by adding features and capabilitiesrequired by carriers, and this clearly differentiates our products from the othersystems that are available on the market. Providing the flexibility and agility toaccommodate service expansion in a business environment that demands highquality, high reliability, and fluidity, several business corporations are currentlyusing these systems to deploy actual services.

In future work, we will continue to emphasize the development of functionalenhancements for voice services, and the provisioning of advanced services.

*1 xDSL: x Digital Subscriber Line

*2 VoIP: Voice over Internet Protocol

*3 PSTN: Public Switched Telephone Network

*4 Type1CA: Type1 Call Agent

*5 SS: SIP Server

*6 SIP: Session Initiation Protocol

13

*1 EMS: Element Management System *2 DSLAM: Digital Subscriber Line Access Multiplexer

*3 IAD: Integration Access Device *4 ASR: Automatic Speech Recognition

*5 TTS: Text To Speech

TrunkingMG IP-IVR

ＩＡＤ*3

DSLAM*2

Router

IP-IVR

IP Network

VoIP Network Management SystemThis system provides service ordering to Type1-CA, and manages IP service network resources.

IP-IVRThis system has interface with PSTN and VoIP, and provides various services by using such function as audio guidance, DTMF recognition, audio record, ASR*4, TTS*5, and call bridge.

Ｔype1-CAThis system has a call control function for VoIP service, processing SIP signaling.It can also control the trunking MG, and connect between PSTN and the IP network on a signaling level.

VoIP NetworｋManagementSystem

CA-EMS*1

Type1-CA

InfoBillingBrobCom

SIPsignaling

Voice data

GWSN

Router

Broadband Communication Billing Platform(InfoBilling BrobCom)This system collects and correlates CDRs from NEs (Type1-CA, GWSN, etc.), consolidates them into an aggregate billing record and calculates a charge based on it for retailing and wholesale.

GWSNThis system controls the trunking MG, and connects between PSTN and the IP network on a signaling level.

Trunking MGThis system transmits voice signals between PSTN and IP networks, and provides frame conversion (i.e. STM and IP) in each network.

Service order handling,operation support, andcall record reportingsystem

PSTN��

*1 EMS: Element Management System *2 DSLAM: Digital Subscriber Line Access Multiplexer

*3 IAD: Integration Access Device *4 ASR: Automatic Speech Recognition

*5 TTS: Text To Speech

TrunkingMG IP-IVR

ＩＡＤ*3

DSLAM*2

Router

IP-IVR

IP Network

VoIP Network Management SystemThis system provides service ordering to Type1-CA, and manages IP service network resources.

IP-IVRThis system has interface with PSTN and VoIP, and provides various services by using such function as audio guidance, DTMF recognition, audio record, ASR*4, TTS*5, and call bridge.

Ｔype1-CAThis system has a call control function for VoIP service, processing SIP signaling.It can also control the trunking MG, and connect between PSTN and the IP network on a signaling level.

VoIP NetworｋManagementSystem

CA-EMS*1

Type1-CA

InfoBillingBrobCom

SIPsignaling

Voice data

GWSN

Router

Broadband Communication Billing Platform(InfoBilling BrobCom)This system collects and correlates CDRs from NEs (Type1-CA, GWSN, etc.), consolidates them into an aggregate billing record and calculates a charge based on it for retailing and wholesale.

GWSNThis system controls the trunking MG, and connects between PSTN and the IP network on a signaling level.

Trunking MGThis system transmits voice signals between PSTN and IP networks, and provides frame conversion (i.e. STM and IP) in each network.

Service order handling,operation support, andcall record reportingsystem

PSTN��

Customer's premisesNTT central office

Internet

WDM*4 WDM

V-OLT*3

B-OLT*2

Trans-modulator

Trans-modulator

TX*1

High speed datacommunication-Peak data rate: 100 Mbit/s-Bi-directional communication

Video distributionSDTV*5: Max 500 ch（HDTV*6: Max 110 ch）

STB*9

V-ONU*8Coaxialcable

Ethernet

Optical Splitter

Optical fiber

1.49μm

1.31μm

1.55μm

*1 TX: Transmitter for video signal*2 B-OLT: Broadband-Optical Line Terminal*3 V-OLT: Video-Optical Line Terminal*4 WDM: Wavelength Division Multiplexing*5 SDTV: Standard Definition Television

*6 HDTV: High Definition Television*7 B-ONU: Broadband-Optical Network Unit*8 V-ONU: Video-Optical Network Unit*9 STB: Set Top Box

Broadcastingcenter

CS BS Terrestrialbroadcasting B-ONU*7

Network configuration overview of VoIP service systemsOutline of B-PON system

*7 GWSN: Gate Way Service Node

*8 MG: Media Gateways

*9 ISUP: ISDN User Part

*10 GW: Gate Way

*11 IP-IVR: IP-Interactive Voice Response


Establishment of Open Software Technologies for Next GenerationNetworks_Open APIs for Adapting 3rd Party Vendor Applications

NTT Network Service Systems Laboratories

In the past, most services provided by common carriers over net-works were developed either by the carriers themselves or by net-work equipment vendors, an arrangement that tended to drive upthe cost and prolong the time required to develop new services.Now open APIs*1 provide an alternative in the form of technologythat enables third parties_ i.e., companies other than the carriers_todevelop and deploy network control applications.

Two well-known examples of open APIs are JAIN*2 and Parlay(The Parlay Group). The establishment of reliability verification pro-cedures for assessing open API-based applications has greatlyreduced the amount of time and work needed to verify new servicesbefore the services are offered to the public. By applying these ver-ification procedures, network services can be developed quicklyand cost-effectively based on applications developed by ISVs*3.

A series of field trials to evaluate this approach is now inprogress in cooperation with seven software vendors_ two fromJapan and five from other countries_and once the results are in,we will present our findings in standards-making forums and tele-com exhibitions. The ability of ASPs*4 and other independent soft-ware companies to provide services should open the way to a vastexpansion of business in those areas that have always just reliedon services provided by carriers.

Other projects we are now considering to encourage more third-party application development include the establishment of a forumjust for application developers and an open tested environment oropen laboratory for assessing third-party applications. We are alsoexploring the possibility of sharing applications through allianceswith other overseas carriers.

*1 API: Application Programming Interface

*2 JAIN: Java APIs for Integrated Networks

*3 ISV: Independent Software Vendor

*4 ASP: Application Service Provider

JAIN is a registered trademark of SUN Microsystems, Inc. of USA.

Interactive Multimedia Communication Technologies


The number of Internet users is expanding, and then that ofalways-on broadband access users is rapidly growing. The Web-based download type services are already commonplace, and weare seeing many new IP-based start-ups offering interactive chat,voice over Internet, and various other real-time services. Interac-tive multimedia (IMM) technology is now being developed as a plat-form to provide the session control and presence functions, whichmake the two-way multimedia services between broadband usersmuch simple, safe, and smart to use.

In this past year, we established a simple session control applica-tion technology for networks and user presence application technol-ogy, NAT*1 traversal technology (STUN*2), and an SIP*3 protocolstack. Also, by linking these advances with community/collaborationtechnologies of NTT Laboratories, we developed an integrated col-laboration service platform including multipoint AV conferencing anduser presence exchange. In addition, we participated in the SIPit*4,and made headway in verifying the interoperability of some of ournew products with the leading-edge products of other companies.

Further efforts will be focused on providing practical technologiesfor implementing security and quality-of-service control for eachsession, which will be the important parts of core technologies forsupporting next-generation end-to-end communication services.

*1 NAT: Network Address Translator

*2 STUN: Simple Traversal of UDP through NATs

*3 SIP: Session Initiation Protocol

*4 SIPit: SIP interoperability test event

Off-the-shelf applications

Application Application

Adapting applicationson market

Service deploymentby service providers

Next Generation Network

Open-API

　Quick and low-cost service development　Expansion of service fields by taking advantages ISVs and ASPs fortes

ASP

Application

Application

Application Application Application

Application

NAT traversal technology

IP Network

Network-related SIP protocol stack

User presence application technology

Autonomous distributed QoS control scheme

Session control function application technology

SIPサーバSIP server

SIP-relatedservers

STUN serverSTUN server

NAT/FW

Session control Session control

Presenceserver

Service deployment using open API

Interactive multimedia communication technologies

14


IP Nomadic Service Technologies


IP nomadic service provides ubiquitous IP services that enableseamless connectivity over wired or wireless access from a wide vari-ety of locations. IP nomadic service allows users to communicateanytime, anywhere and with anybody, providing a communicationsenvironment that feels just like your own home network. For example,introducing a nomadic service to an office intranet enables employeesto continue to use the same IP addresses they are using in their homeoffice when they are out on the road or away from the office: theycould share electronic documents or participate in TV conferences justthe same as if they were back at the office. Moreover, once thesenomadic service capabilities are in the public-service network, userswill be able to make continuous uninterrupted communications evenas they move into totally different kinds of access networks by select-ing automatically optimized communication technology dynamically inaccordance with the mobile location and the access bandwidth.

To build a robust network service platform supporting IP nomadicservices, NTT Laboratories are working on three key technologies:mobile IP technology, seamless access management technology, andnomadic presence technology. Mobile IP technology enables users tocontinue to receive communications and content delivery using theirfixed IP addresses even when they move about, and receive home-network services at different roaming destinations. And, the seamlessaccess management technology provides an authentication platformthat supports multiple kinds of access, thus permitting roaming thatcuts across different access networks (Inter-media handover). Finally,nomadic presence technology provides optimum service support tai-lored to a user's particular circumstances including real time manage-ment of a terminal's mobile location, access bandwidth, and terminaltype.

By interworking more closely with ITS* and sensor networks, futureR&D efforts will focus on developing and deploying ubiquitous servic-es that support seamless communications not only with other peoplebut with all sorts of agents and objects.

* ITS: Intelligent Transport System

Optical Access Distribution Technology for Rapidand Economical Response of Optical Services


With NTT's launch of B-FLET'S, broadband IP communications servicebased on FTTH*1 technology, power companies and other players have enteredthe broadband connection business one after another resulting in intense com-petition for a share of the broadband market. To accelerate the spread of FTTHservices and compete effectively in this fierce business environment, NTT Lab-oratories have developed and implemented technologies for achieving "costreductions" so that reasonable fees can be set, and "service responsiveness"so that customers can be provided with desired services quickly and reliably.

As a distribution technology in the aerial interval, we have recently deployeda non self-support aerial optical cable that requires no supporting wire. Up tonow, we have been using bundled-fiber installation technology, which uses ahelix-shaped hanger that facilitaties construciton of new optical facilities withoutlimiting installation points. The addition of circular aerial cable to this technolo-gy makes installation work even moere economical. We have also developedseparation technology that improves optical fiber usage rate at aerial wiringpoints by switching from 4-fiber tape operation to single-fiber operation so thatwiring can be dropped to households in units of single fiber.

At present, however, optical facilities are being constructed in an "overlay"configuration with metallic facilities. To make more efficient use of space whendropping optical fiber to customer, we have downsized the optical cabinet anddeveloped composite protectors that the cabinet could share space with exist-ing metallic facilities. In addition, we have made the connecting of optical fibersmore effective cost through mechanical splicing technology that specializes insingle-fiber connections with a simplified splicing structure that lowers costs.Finally, by changing to glass FRP*2 as the material for the tension member indrop optical fiber, we have achieved noninductive wiring requiring no grounding.This IF*3 drop optical fiber and optical fiber protection cases can further shortenthe time for beginning optical services.

NTT Laboratories plan to continue developing and deploying innovativeproducts like the ones described above with the aim of spreading FTTH servic-es even further and becoming a leader in this market.


*2 FRP: Fiber Reinforced Plastics

*3 IF: Induction Free

*1VPN: Virtual Private Network　 *2AAA: Authentication, Authorization and Accounting server　 *3xSP: x Service Provider

Inter-media handover Content delivery

xSP*3 connectivity roaming

Mobile VPN*1

Seamless Connection Services

Interactive services

Mobile IP

Mobile IPMobile IP

Mobile IP

Contentserver

Contentserver

- Broadband seamless access and always-on connectivity- Mobility in the IP layer- Secure virtual home environment services at any location

xSP

Outside office

Airport

Home

Intranet

Mobile IP tunneling

IP NomadicService Network

3G Mobile3G Mobile　Netwク（IP/ATM）

3G MobileNetwork（IP/ATM）

Move

Hot spot

Mobile networkservices

Multi-accessauthentication

database

Presenceserver

AAA*2

Broadband Access Network（Wireless LAN, FTTH）

Broadband Access NetwBroadband Access Networork（Wireless LAN, FTTHWireless LAN, FTTH）

Broadband Access Network(Wireless LAN, FTTH)

ONU*3

IDM*4 OLT*5

*1IDF: Intermediate Distribution Frame*2MDF: Main Distribution Frame*3ONU: Optical Network Unit

*4IDM: Integrated Distribution Modules*5OLT: Optical Line Terminal

Compact optical cabinet Non self-support aerialoptical cable

Induction free drop optical fiber cable

Compact optical cabinet for 8 fibers

Optical cabinet merged withsubscriber protector case

Induction free dropoptical fiber cable

Optical fiberprotection case

Subscriberprotector casefor 10 users

Eliminates supporting wire

Self-supporttype

Non self-supporttypeCase to setCase to set

optical cabinet optical cabinet

Case to setoptical cabinet

Tensionensionmembermember(glass FRP)(glass FRP) OpticalOptical

fiberfiber

Tensionmember(glass FRP) Optical

fiber

IDF*1

IDF

MDF*2

ONU

Technology for making use ofindividual fiber in ribbon

Fiber ribbonfan out tool

Fiber ribbon fanout supporting tool

Aerial optical closure to realizethe improvement of fiber utilization

Revised splice method Single-fiber mechanical splice

Splice tool

Deployment technologies for rapid and economical response to optical-access service orders IP nomadic services

15


Direct-Multicasting Satellite Communications System forNationwide Digital Contents-Gathering and Distribution Service

NTT Service Integration Laboratories

Satellites are often used for multicast communications due totheir ability to distribute information to multiple receiving pointssimultaneously. The multicast satellite communications systemscurrently available commercially are mainly star-type systems com-posed of a center hub and very small aperture terminal (VSAT).Therefore individual dedicated terrestrial lines connected to the hubare needed for contents gathering, which increases the systemcost.

We have developed a direct-multicasting satellite communica-tions system for economical distribution of digital contents directlyfrom the VSATs to all receiving points without relay by the hub.This system is based on the use of a group modem and a highlyefficient channel-assignment control program. The group modemenables simultaneous communication of video signals, IP data, andaudio data with multiple points at any data rate. The control pro-gram manages allocated bandwidth of the satellite transponder anddistributes the necessary channel capacity to the transmitting VSATautomatically.

The system provides a full-mesh satellite network that enablesreal-time contents gathering from and distribution to multiple accesspoints easily and cost-effectively. It realizes efficient use of thetransponder bandwidth through dispersed assignment of the discon-tinuous bandwidth due to an ability of the group modem to integratethe discontinuous spectrum into one communications channel.

NTT will contribute to the creation of new business by pioneeringnew satellite communication markets through its economical directmulticasting satellite communications system using VSATs.

Extended IP Multicast Protocol (IGAP) for Content Delivery Systems

NTT Network Innovation Laboratories, NTT Access Network Service Systems Laboratories,

NTT Network Service Systems Laboratories, NTT Cyber Solution Laboratories

Content delivery is expected to be a killer application for broad-band networks. Content delivery over a network requires the effi-cient delivery of information to multiple users. Although the multi-casting technique used in current IP multicasting systems isremarkable, it is not sufficient for providing commercial servicesbecause neither user authentication nor accounting functions areprovided.

We have developed a multicast group management protocol withuser authentication and accounting called "IGAP*1" (IGMP*2 withuser authentication). IGAP enables user access to be controlled byusing the user information in a content request message. A net-work node monitors the request messages sent by subscribers andsends user information to a management system. The manage-ment system provides subscriber behavior to content providers andcreates accounting methods that match the properties of eachprovider's content. IGAP enables the collection of user behaviorinformation in near real time, so content providers can distributecontent attractive to subscribers in a timely manner. IGAP also pro-vides IGMP capabilities, so it is easy to deploy in existing networks.We are now working on the standardization of IGAP in the IETF*3.

We are also developing a content delivery platform based onIGAP. IGAP offers not only content delivery as a carrier service butalso commercial-content delivery services over closed networks,such as VOD*4 service in a hotel. We are researching and develop-ing a similar protocol framework for the IPv6 network and alsoapplying IGAP to other service areas.

*1 IGAP: Internet Group Membership Authentication Protocol

*2 IGMP: Internet Group Management Protocol

*3 IETF: Internet Engineering Task Force

*4 VOD: Video-On-Demand

*1AAA: Authentication, Authorization and Accounting server　 *2EPG: Electronic Program Guide*3RADIUS: Remote Authentication Dial-In User Service　 *4xSP: x Service Provider

Broadbandhome users

- Accounting function - EPG*2 function- Management function

Multipurpose protocol

（HTTP, etc.）- Efficient programming based

on audience share - Delivery of individual

information

Multicastprotocol

Managementprotocol

Authentication server（AAA*1, etc.）

Authentication protocol

（RADIUS*3, etc.）- Security/user access control （Authentication）

Multicast deliverycontrol system

Accounting data Program dataManagement data

Content�provider

Carrier/xSP*4

Edge node(Edge router)

Authenticationhistory

Broadbandhome users

IGAP

�

Multipurpose protocol （HTTP, etc.）- Accounting method/information service matches user/content

- User trends report（User ID, program, location）

Group modem

Video IP Data Voice

Group modem

Video Video

Video Video

Group modem

IP Data IP Data Voice

Group modem

Video IP Data Voice

Group modem

Simultaneous modulation and demodulationof multiple-signals

Efficient bandwidthsharing among

applications

Dispersed assignmentof discontinuous

spectrum

Variable bandwidth(carrier by carrier)

Independent Channels with Different Bandwidths

Multi-rate/multi-carrier modulation and demodulation from 32 kbit/s to 30 Mbit/s with one unit

Group modem

- Various access methods for full-mesh satellite network- Multimedia user interface- Scalability and optimization due to hierarchical

control system structure over three levels - Efficient sharing of transponder bandwidth

Highly efficient channel assignment control progHighly efficient channel assignment control program

Content delivery system using IGAP Direct-multicasting satellite communications system

16


Technologies for Protecting Network Equipment andNetwork Appliances Against Lightning Damage

NTT Energy and Environment Systems Laboratories

The phenomenal growth of the Internet has led to an enormous increase in communi-cations equipment, including ordinary terminal equipment and all kinds of network appli-ances such as terminal adapters (TAs) and other PC peripherals. As the transmissionspeed of this equipment becomes faster, the devices used in the equipment becomeincreasingly vulnerable to lightning surges, and as opportunities to interconnect homeequipment and PC proliferate, this creates more complex paths of lightning surge entry.

NTT Laboratories conducted a survey of recent equipment failures (centering on theKanto area in the years 2000-2001) that not only clarified the types of problems that wereoccurring, but also revealed the vulnerability of equipment to lightning by plotting thedegree of risk to lightning damage on a 5-km grid. This information was then used todevelop strategies for prioritizing and streamlining our lightning protection measures, andalso to produce a map showing the degree of risk exposure to lighting strikes. Using thismap to implement actual lighting countermeasures, we were able to reduce superfluousefforts and resources by 20% to 50%.

As IT equipment has been upgraded to broadband, lightning surge entry paths havebecome more complex and device protection against lightning surges has diminished.This means that design work based on simulations is critically important to develop moreeffective techniques to protect IT equipment from lightning surges. Employing a SPICE*-based lightning protection simulation method, we developed SPICE models for surge pro-tection devices, IT equipment, communication lines, and other elements. So then, wewere able to simulate the paths of entry of lightning surges for the system as a whole,including access system equipment, communications equipment, and other network.

As network equipment and network appliances become more diversified, the numberof multi-port communication paths and equipment with its own power source will onlyincrease in the years ahead. In order to meet this challenge, we are committed toimprove the reliability and robustness of information and communications equipmentagainst lightning and power surges in accordance with the lightning protection standardsand technical requirements of each port.

* SPICE: Simulation Program with Integrated Circuit Emphasis

Wireless IP Access System (WIPAS)


High-speed Internet access over optical fiber, ADSL, CATV, and othernetworks has become rapidly available in recent years. Yet there are stillmany users who do not enjoy access to these broadband environment dueto the difficulties posed by deploying fiber-optic cable or simply becauseservices have not been made available in their areas due to cost considera-tions. With the goal of bringing high-speed Internet access to these neglect-ed pockets of users, the Access Network Service Systems Laboratories hasdeveloped a wireless IP access system (STEP 1) that is a P-MP*1 typeFWA*2 system using quasi-millimeter-waves in the 26-GHz band.

The STEP 1 system provides "best-effort" IP service at a wireless trans-mission rate of 40 Mbit/s, and a maximum Ethernet frame data delivery rateof 23 Mbit/s. One AP*3 can manage 239 WTs*4. Services were made avail-able over this STEP 1 system beginning in September 2002 when NTT Eastand NTT West added it to their menus of B-FLET'S service offerings.

Now a second generation of the wireless IP access system has beendeveloped the STEP 2 system that doubles the transmission rate of theSTEP 1 system and is implemented much more compactly. The maximumwireless transmission rate of the STEP 2 system is 80 Mbit/s, and the maxi-mum Ethernet frame data delivery rate is 46 Mbit/s. In addition, the sub-scriber-side equipment has been significantly reduced in size and weight bycombining the antenna/RF module (RFU*5) and base-band processing mod-ules (IFU*6) that were implemented separately in the STEP 1 system, andby adopting a compact flat antenna. The IFU of AP was also substantiallydown-scaled.

Services based on the Wireless IP Access System (STEP 2) will bemade available beginning in 2003. In the future, we will add QoS*7, andadaptive modulation functions, and develop a repeater for WIPAS.

*1 P-MP: Point to Multi Point

*2 FWA: Fixed Wireless Access

*3 AP: Access Point

*4 WT: Wireless Terminal

*5 RFU: Radio Frequency Unit

*6 IFU: Interface Unit

*7 QoS: Quality of Service

WT-adapter

W T

AP-RFU

WT

E/O

WT

AP

Optical fiber cable

AP-IFU

IPNetwork

Items SpecificationsFrequency

Tx/MOD scheme

Radio capacity

Tx power

User/NW IF

Tx distance

Max number of WTs

26 GHz band

TDMA/TDD, QPSK/16QAM

Max. 80 Mbit/s

14 dBm (QPSK), 11 dbm (16QAM)

10/100BASE-TX, 100BASE-FX

Max. 700 m

Approx. 200 WT/AP

Size: 190×190×55 mm Weight: 2.0 kg

Size: 90×40×36 mmWeight: 0.1 kg

Size: 150 ø×600 mmWeight: 7 kg

(Omni-antenna-type) 3 kg

(Horn-antenna-type)

Omni and sector-antenna-type

Horn-cassegrain-antenna-type

Size: 270×320×160 mmWeight: 6.5 kg

26 GHz26 GHz

4000�3000�2000�1000�0�

-1000

電圧（V）�

12�10�8�6�4�2�0�-2

電流（A）�

時間（S）�0.0 0.5 1.0 1.5 2.0

Input voltage (Power line terminal)

Telecommunicationline current

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-0.02�

-0.04

時間（us）�0 10 20 30 40 50

Input voltage (Telecommunications

line terminal)

Power plug voltage

Analytic value Measured value

Development of methodto model equipment

Development of anarrestor model

Indoor line

Power cord

Informationtechnologyequipment

Powerline

Lead-inline

Indoorwiring

ColumnartransformerSubscriber protector

Modularcord Network�

appliance

Overview of Wireless IP Access System (STEP 2)

Lightning damage risk map

Lightning surge simulation technology

17


Congestion-Aware Network Admission ControlBased on Per-User Performance Statistics


When real-time applications such as video streaming are run onan IP network, network performance directly affects application per-formance. To maintain end-to-end video quality for all users, it isnecessary to combine a TCP*1-like per-flow control scheme with anetwork-resource control scheme that analyses network conges-tion, performs network admission, and allocates the best deliveryroute for each user.

We have developed a network control scheme that estimates thevideo quality of each user based on the transport and applicationperformance received by each user, estimates the degree of con-gestion for each network area by analyzing the user-level perform-ance statistics, and admits new requests for video delivery basedon the degree of network congestion. We clarified through softwareprototyping that the scheme can detect a sign of congestion accu-rately by using the transport layer performance parameters, suchas the number of ARQ*2 packets or the filling of delay adjustingbuffer, and that degradation in video quality can be predicted accu-rately based on the performance parameters of the picture framehandling layer. We also clarified that the scheme can maintain thevideo quality of all users by prohibiting new video delivery requestswhen it detects a sign of congestion.

The proposed scheme is applicable not only to the businessmodel for end-to-end CDNs*3, but also to the model that for contentdistribution to the users of interconnected network providers. Thevideo quality monitoring function is applicable to such value-addedservices as SLA*4 monitoring and viewer rating surveys.

We plan to develop an autonomous algorithm for controlling net-work resources and maintaining delivery quality by combining theproposed scheme with a scheme for allocating routes andresources for individual users. The aim is to use network and serv-er resources efficiently and to maintain application performance forall network users.

*1 TCP: Transmission Control Protocol

*2 ARQ: Automatic Repeat reQuest

*3 CDN: Contents Delivery Network

*4 SLA: Service Level Agreement

Development of Technology Permitting Denser Accom-modation of Cables in Communication Tunnels


The communication tunnels in which optical cables are deployed are equipped withdisaster prevention walls to prevent fire or flood waters from spreading to NTT build-ings in the event that a fire or a flood should occur in a tunnel. These fire and waterprotection functions are essential, and the disaster prevention walls also limit theamount of cabling that can be accommodated in the tunnel. Due to the "dead space"that was created when the cables were initially deployed, the tunnels are already over-crowded thus creating an impasse. Today, some 30% of communication tunnels incentral Tokyo already exceed 80% of their cable holding capacity. Furthermore, thetrend toward greater congestion will only increase in the years ahead considering theneed to accommodate FTTH*1 and ADSL services and to provide obligatory servicesto business corporations based on interconnection agreements with other carriers.

The demand for a technology that would permit a denser concentration of cables incommunication tunnels led to our development of the multi-waterproofing equipment, adevice that will support growing future demand for cable without impairing the functionsof the disaster prevention walls.

The key features of the multi-waterproofing equipment are summarized as follows:(1) Maintains the waterproof pressure function corresponding to the communicationtunnel environment (98 kPa).(2) Capable of accommodating up to three maximum-diameter fiber cables (1000-fiberSM*2-type optical fiber WBB-FR*3 cable).(3) Permits all optical cables deployed in a communications tunnel in a multi-level con-figuration (6 levels) to be networked by an adapter.(4) By adopting a partitioned structure, the equipment can be used not only in newducts but also in ducts where cable was previously installed. The equipment can alsobe flexibly adapted to disaster prevention walls with a high cable accommodation rate.(5) Can be applied to all disaster prevention walls.

The new waterproofing equipment permits more efficient use of the communicationtunnel space. Also, the additional space created by denser concentration of cables inthe tunnels can be used for all sorts of other purposes to increase profits for the com-pany. The multi-waterproofing equipment began to be installed and put into service inthe forth quarter of 2002.


*2 SM: Single Mode

*3 WBB-FR: WaterBlocking B-cable-Flame Retardant

＜User A＞＜NW area A＞Videoquality

AP

TP

Use

r di

strib

utio

n

Threshold

TP performance AP performance

Severe

Sign

Normal

Threshold

Degree ofcongestion

→Request

←OK/NGCongestion-aware networkadmission control

Sign of congestionNW area ANW area ANW area A WWW

Video server

Video player Video server

IP Network

Data center

Perfor-mance

Per user video quality analysis Network congestion level analysis

Real-time

analysis

Decoding EncodingFramecontrol

Buffer Buffer Framecontrol

IP

Transport (TP)Application (AP)

Good Degrade

Time

Parameters forsevere congestion

Parametersfor a sign ofcongestion

Disaster prevention wall

Multi-waterproofing equipment

Concept of congestion-aware network admission control

Disaster prevention wall in communication tunnel and multi-waterproofing equipment

18


Development of an Optical Cross Connect (OXC) System

NTT Network Service Systems Laboratories,

NTT Network Innovation Laboratories

In order to cope with the recent explosive increase in IP traffic, an inno-vative network system that makes the utmost use of new technology isrequired. NTT Laboratories have been researching and developing a pho-tonic network that introduces the concept of an optical path that employswavelength as the unit. Here, we report on an optical cross connect (OXC)system that has been developed at the NTT Laboratories. That system isbased on silica-based PLC*1 type optical switches which have features ofhigh reliability, and stable operation. It also offers excellent expandability,allowing flexible response to increases in traffic demand.

The optical switch scale of the OXC can be expandable from 8×8 to64×64 in units of 8×8 according to the traffic demand. The core switchfabric employs a DC-SW*2 architecture that is based on PLC optical switch-es and has capability of cross connection in the optical domain withoutusing optical-electrical and electrical-optical conversion. The system isequipped with 10-Gbit/s (STM*3-64/OC*4-192) SDH*5/SONET*6 interfaces,allowing connection to IP routers and existing SDH transport equipments.

OXC's are connected via optical fiber or existing WDM*7 link systems,optical paths are defined between any two OXC's and transports STM-64/OC-192 signals. In order to maintain high levels of integrity and commu-nication quality whenever a failure occurs, OXC system employs 1+1 opticalpath protection mechanism. Each optical path can be set one of two recov-ery grades; 1+1 protection and unprotected. A 1+1 optical path protectionenables protection times less than 50 ms. OSS*8 can set-up and tear-downoptical paths remotely, and manage and supervise OXC network remotely.

In future work, we intend to increase the cross connect capacity, makethe equipment smaller and more economical, and introduce the GMPLS*9

concept, with the objective of implementing a resonant network environment.

*1 PLC: Planar Lightwave Circuit

*2 DC-SW: Delivery and Coupling Switch

*3 STM: Synchronous Transfer Mode

*4 OC: Optical Carrier

*5 SDH: Synchronous Digital Hierarchy

*6 SONET: Synchronous Optical Network

*7 WDM: Wavelength Division Multiplexing

*8 OSS: Operation Support System

*9 GMPLS: Generalized Multi-Protocol Label Switching

Condominium IT Kit:Transmission System forProviding Broadband Services in Closed Areas


An increasing number of local governments and companies are deployingoptical fiber with the goal of implementing broadband Internet environments.However, the quality and performance of such environments are not morecapable than those provided by the common carriers. To address this situa-tion, it is necessary to investigate a scheme for building a new user-side net-work that improves user convenience and promotes the deployment of abroadband environment.

Recent work has culminated in the development of a condominium IT kit,a system for implementing fiber-optic-based user networks targeting specificareas. Deployed at user initiative, the system extends an optical fiber broad-band environment into condominium complexes, school campuses, andother bases. The condominium IT kit also incorporates several key carrier-grade technologies developed by NTT Laboratories into user networksincluding optical video transmission technology, PDS* transmission technolo-gy, enhanced robustness in poor reception environments, and advancedoperations support.

By combining these technologies, we achieved three key functional com-ponents: a 100-Mbit/s throughput delivery function providing a high-speedcommunication environment, a broadband video transmission functionacross the 2.6-GHz band covering the entire frequency band from digital ter-restrial broadcasting to satellite broadcasting, and a communication functionproviding lowest bandwidth guarantee for monitoring and control. In orderfor these various functions to be applied to different user network environ-ments that vary widely in terms of network scale and functional require-ments, we have adopted an architecture in which the functions are imple-mented as autonomous kits. This permits users to add, remove, modify orotherwise tailor the functions to their specific needs in block or packageunits. In addition, the functions all support optical wavelength division multi-plexing transmission to take full advantage of user optical fiber facilities.

In the coming months we plan to implement speech communication, secu-rity, and other functions in kit form, and to promote the formation of opticaluser network platform communities by providing other application technolo-gies that interwork with the high-speed communication environment.

* PDS: Passive Double Star

Optical fiber(Existing WDM line)

Optical path

IP router

Existing SDH equipment

OXC equipment

Operation Support System

- Provide 10 Gbit/s optical path- Optical path relief within 50 ms- Optical path network overlaid existing DWDM*3 system

UNI

UNI*2

UNI

UNI

Remote controland supervision

*1DCN: Data Communication Network*2UNI: User Network Interface*3DWDM: Dense Wavelength Division Multiplexing

DCN*1

PhotonicNetworkPhotonicNetwork

O/E

Condominium IT Kit Customer Service Terminal

Condominium IT kitVideo transmission unit

HA (Home Automation)

Tuner&TVInternet

(VHF,UHF,BS,CS)

Individual household

In a room near the antenna

�Internet

Management/securitycompanies

Optical trunk cable in the building

Optical fiber

Condominium IT kit Customer service unit

Video service unit10 Mbit/s communicationservice unit100-Mbit/s IP service unit

MDF room

Information system distribution boad

Overview of optical cross connect (OXC) system

Installation in condominium (Condominium IT Kit)

19

Documents

Telecommunications Network Technologies QoS ... - NTT · QoS Assessment, ... Public Switched Telephone Network *4 Type1CA: Type1 Call Agent *5 SS: ... exploring the possibility of

Telecommunications Network Technologies QoS ... - NTT · QoS Assessment, ... Public Switched Telephone Network 4 Type1CA: Type1 Call Agent 5 SS: ... exploring the possibility of