광대역 통합망을 위한 광대역 통합망을 위한

광전송 기술광전송 기술

2009. 3. 25.2009. 3. 25.

서울시립대학교 서울시립대학교

전자전기컴퓨터공학부전자전기컴퓨터공학부

김철한김철한

OutlineOutline

광대역 통합망 (BcN)

광가입자망 (FTTH)

광통신 시스템 구성 일반

구성 요소 : 광섬유 , 광원 , 광수신기

주요 잡음원 : 감쇠 , 분산 , 비선형 , 누화

대용량 장거리 광전송망

요약

차세대 통합 네트워크물류 /유통금융

교통건설 레저 환경 /의료

교육

농수산업

다양한 접속 융합형 서비스 고품질 서비스

음성 /데이터 통합 유 /무선 통합 통신 /방송 융합

BroadbandQoS

Security

Open API

IPv6

홈 네트워크융합형 정보 단말 /가전

Information + Entertainment + Commercial + Content + etc

미래 통합망의 비전미래 통합망의 비전

MIC2003

Broadband Convergence Network (BcN)Broadband Convergence Network (BcN)

MIC2003

Network EvolutionNetwork Evolution

Single service networks Circuit switched network

Intelligence in circuit switch

Wired/wireless telephony service

Multi-service networks Packet switched network

Intelligence in router, server

Multi-service via wired/wireless access

BcN BcN 구현을 위한 핵심 요소 기술 구현을 위한 핵심 요소 기술

MIC2003

Regional & Long Haul

IOF ROADM

Any S

ervic

e

Any S

ervice

Any Service

Edge ROADM (future)

CentralOffice

CentralOffice

MetroAccess

Courtesy of AT&T

Transport Network: Local to Long-HaulTransport Network: Local to Long-Haul

Change in the market

전화 / 인터넷 서비스 시장의 포화

새로운 시장 개척의 필요성 ( 통방 , 유무선 번들 서비스 )

시장 경쟁 가속화 - 전화 , TV, 위성 사업자

Change in user’s life style

PC 사용의 생활화 - > 멀티미디어 서비스에 친숙

인터넷의 확산 -> 네트워크에 친숙

홈페이지 , E-mail, 정보검색 , 네트워크 게임 등의 활성화

Change in demands

Always on, always available information on-demand

빠른 데이터 액세스 요구

Data, Voice 및 Video 의 통합

Access EnvironmentsAccess Environments

국내 가입자망 서비스 국내 가입자망 서비스

Future ServicesFuture Services

Services Bandwidth (Mbps)

Streaming

Video(HD)

Live TV 20

VoD* or e-shopping 20

EoD / GoD * 20

Video Conference* 2~10

Internet* 10

Remote sensing/ control 1

IP phones 1

Total Bandwidths 74 ~ 84

* symmetric bandwidth is required

Bandwidth DemandBandwidth Demand

BcN BcN 목표 목표

MIC2003

2009~2010 2011~2013

백본망유선전화망 IP 화 30%

70% (‘15 년

100%)

이동전화망 IP 화 - 15%

가입자망

유선

광대역 (50M~100M) 1,200 만 1,450 만

초광대역 ( 최대 1G) -상용서비스 (‘12 년 ),

20 만 (‘13 년 )

무선

광대역 (1M~2M) 2,800 만 4,600 만

초광대역 ( 평균 10M) -상용서비스 및 30 만

(‘13 년 )

방송망디지털 지상파 방송 커버리지 93% 96%

디지털 케이블 TV 홈패스율 93% 96%

센서망 망고도화 공공부문 센서망 연계 (‘12)

초광대역통합망 초광대역통합망 (UBcN) (UBcN) 구축 세부목표 구축 세부목표

방송통신위원회 2009

April 19, 2023 14

Last Mile ProblemLast Mile Problem

유선 전송 매질 유선 전송 매질

Twisted Pair (Telephone Line) 52 Mb/s up to 300 m using vDSL 100 Mb/s Ethernet using CAT-5 1 Gb/s using CAT-5e

Coaxial Cable Higher data rates and longer distances compared to twisted pairs

A single copper pair is capableof carrying 6 phone calls

A single fiber pair is capable ofcarrying over 2.5 millionsimultaneous phone calls(64 channels at 2.5 Gb/s)

A fiber optic cable with the sameinformation-carrying capacity (bandwidth) as a comparable copper cable is less than 1% of both the size and weight

A single copper pair is capableof carrying 6 phone calls

A single fiber pair is capable ofcarrying over 2.5 millionsimultaneous phone calls(64 channels at 2.5 Gb/s)

A fiber optic cable with the sameinformation-carrying capacity (bandwidth) as a comparable copper cable is less than 1% of both the size and weight

Source: Corning Incorporated

WhyWhy FTTH?FTTH?(Fiber vs. Copper)(Fiber vs. Copper)

FTTH ArchitecturesFTTH Architectures

CO

ONU 1

ONU 2

ONU 3

ONU 4

ONU N

PassiveRN

CO

ONU 1

ONU 2

ONU 3

ONU 4

ONU N

Point-to-Point

(Home Run)

Passive Optical Network(PON)

TDM-PON vs. WDM-PONTDM-PON vs. WDM-PON

Time division multiple access Low security

Limited bandwidth

Low link budget

Low cost

Protocol dependency

CO

ONU #1

ONU #2

ONU #3

ONU #4Passive optical power splitter

3

2

4

time

1

2 3 41

PassiveWDM router

Wavelength division multiple access

High security

Unlimited bandwidth

High link budget

Protocol transparency

Medium cost (Low cost source is required)

ONU #N

ONU #2

ONU #3

ONU #4

CO

1 2 3 4

12

34

1 2 3 4

1 2 3 4

1

2

3

4

1 2 3 4 1 2 3 4

2

ONU #1

ONU #N

FTTH FTTH 망구성 망구성

E-PON E-PON 기반 기반 FTTH FTTH 망구성 망구성

Interoperability

SecurityQoS assurance

Future upgrade plan

Cost effective

Protocol transparentPhysical layer security

Dedicated bandwidth

Unlimited bandwidth

Low OPEX

Advantages of WDM TechnologyAdvantages of WDM Technology

FTTH BASED ON WDM-PONFTTH BASED ON WDM-PON

Journal of Lightwave Technology, pp.2582-2591, 2004

1970s: Development of optical fibers, semiconductor light sources & photodetectors

1980s: Very low loss single mode fibers in the 1100-1600 nm.

1990s: Optical amplifiers (e.g. EDFA), WDM (wavelength division multiplexing)

Optical Fiber communications, 3rd ed.,G.Keiser,McGraw-Hill, 2000

In 1970s, development of optical fiber by Bell lab and Corning Glass. : Loss 20 dB/km (Today 0.3 dB/km)

광통신 역사광통신 역사

Optical fiber

Light sources

Optical amplifiers

Photodetectors

주요 광소자 특징주요 광소자 특징

Optical Fiber communications, 3rd ed.,G.Keiser,McGraw-Hill, 2000

코어 (Core) 클래딩 보다 굴절률이 높음 ( 굴절률 n = c/v)

클래딩 (Cladding) 코어 보호 적절한 굴절률 차이 제공

광섬유광섬유

z=0 z=LDispersion

z=0 z=LAttenuation

광링크에서의 신호 열화광링크에서의 신호 열화

광섬유 감쇠원

산란 (scattering)

흡수 (absorption)

광신호 감쇠 원인광신호 감쇠 원인

Optical Fiber communications, 3rd ed.,G.Keiser,McGraw-Hill, 2000

색분산 색분산 (Chromatic Dispersion)(Chromatic Dispersion)

Dispersion Compensating Fiber (DCF)Dispersion Compensating Fiber (DCF)

색분산에 의한 신호 왜곡색분산에 의한 신호 왜곡

Main concern is extending the transmission distance (“reach”)

- Attenuation (power budget) and

- Dispersion (rise-time budget)

점점 -- 대대 -- 점점 (P-t-P)(P-t-P) 링크 설계링크 설계

-60

-50

-40

-30

-20

-10

0

10

1525 1530 1535 1540 1545

Wavelength [nm]

Rel

ativ

e In

ten

sity

[d

B]

LED LD (Laser Diode)

광원 성능

출력 파워 (output power)

선폭 (linewidth)

SMSR (side mode suppression ratio)

광원광원

- +

+-

n-p+ n+

E

Photo Diode = LED

LED: forward bias

PD: reverse bias

광수신기 광수신기 (PD)(PD)

- Power required for specified BER or SNR

- Noise power increases as BW (data rate)

- More signal power required

Optical Fiber communications, 3rd ed.,G.Keiser,McGraw-Hill, 2000

수신감도 수신감도 (Receiver Sensitivity)(Receiver Sensitivity)

0 Lrect CPP

sLrect MCPP

광 파워 설계 광 파워 설계 (Power Budget)(Power Budget)

Optical Fiber communications, 3rd ed.,G.Keiser,McGraw-Hill, 2000

Dispersion Limit: Rule of ThumbDispersion Limit: Rule of Thumb

분산 및 비선형 현상 원인분산 및 비선형 현상 원인

Kerr Effect

Self-Phase Modulation (SPM)

Cross-Phase Modulation (XPM)

Four-Wave Mixing (FWM)

Scattering Effect

Stimulated Raman Scattering (SRS)

Stimulated Brillouin Scattering (SBS)

비선형 현상의 종류비선형 현상의 종류

BroadbandLight Source

WavelengthSplitter Spectrum

Slice

Low costSemiconductor

Device

BLS based Optical SourcesBLS based Optical Sources

Only one BLS can support a number of subscribers

with only one wavelength router

BLS-based WDM PON ArchitectureBLS-based WDM PON Architecture

CO

MOD1

Rx 1

AWG

ONU 1

Rx 1

Tx 1

ONU 2

Rx 2

Tx 2

ONU N

Rx N

Tx N

Broadband Light Sources (BLSs) LED ASE from EDFA or SOA

BLS AWG

MOD2

Rx 2

MODN

Rx N

AWG

…

…

Modulated downstream

Modulated upstreamRN

SOA: semiconductor optical amplifierASE: amplified spontaneous emission

AWG

RNCO

BLS 1 BLS 2

Tx 1

Rx 1

Tx 2

Rx 2

Tx N

Rx N

AWG

ONU 1

Rx 1

Tx 1

ONU 2

Rx 2

Tx 2

ONU N

Rx N

Tx N

BLS-based WDM PON ArchitectureBLS-based WDM PON Architecture

Colorless Transmitters (Modulator + Amplifier) Wavelength-Locked FP-LD RSOA (Reflective SOA)

…

Modulated downstream

…

Modulated upstream

equivalent optical BW

spectrum-sliced ASE source 0.7 nm

FP-LD 0.3 nm

Measured Optical SpectraMeasured Optical Spectra

-60

-50

-40

-30

-20

-10

0

10

1525 1530 1535 1540 1545

Wavelength [nm]

Re

lati

ve

Inte

ns

ity

[d

B]

Wavelength (nm)

Inte

nsity

(a.

u.)

-80

-70

-60

-50

-40

-30

-20

-10

0

10

1546 1548 1550 1552 1554

directly-modulated, wavelength-locked FP-LD

EAM-modulated, spectrum-sliced ASE

spectrum-sliced ASE

Wavelength (nm)

Inte

nsity

(a.

u.)

-80

-70

-60

-50

-40

-30

-20

-10

0

10

1546 1548 1550 1552 1554

directly-modulated, wavelength-locked FP-LD

EAM-modulated, spectrum-sliced ASE

spectrum-sliced ASE

directly-modulated, wavelength-locked FP-LD

EAM-modulated, spectrum-sliced ASE

spectrum-sliced ASE

0

1

2

3

4

5

6

0 10 20 30 40 50 60 70

Transmission Distance (km)

Po

we

r P

en

alty

(d

B)

directly-modulated, wavelength-locked FP-LD

EAM-modulated, spectrum-sliced ASE

Dispersion-Induced PenaltyDispersion-Induced Penalty(1.25 Gb/s signal transmission)(1.25 Gb/s signal transmission)

])(51log[10 2 BLDPDispersion

(Ref. K. H. Han et al., PTL, Oct. 2004)

Effects of Crosstalk inEffects of Crosstalk inBLS based WDM PONsBLS based WDM PONs

Rx

BLS

ColorlessSource

500 ps/DIV

Xtalk Ratio = -10 dBwithout Xtalk Xtalk Ratio = -5 dB

Electrical Eye DiagramsElectrical Eye Diagrams

(P(Pinin = -20 dBm) = -20 dBm)

SummarySummary

광대역 통합망을 위한 광전송망

광가입자망 (FTTH)

장거리 광전송망 (WDM, OXC, etc)

주요 광소자

광섬유 , 광원 , 광수신기 , 광증폭기 , AWG

주요 잡음원

감쇠 , 분산 , 비선형 , 누화

1 1 0 1

SMOT-16 SMOT-16

Signal = Car Fiber = Highway

Optical Transport SystemOptical Transport System

답은 간단 !선로를 계속 포설하고 , 장비고 계속 구매하는 거야…

비경제적인 답 !돈도 많이 들고 ,시간도 많이 걸리고… .

High Capacity TransportHigh Capacity Transport

10G or 40G TDM system

SMOT-16SMOT-16

40G car 10G car

High-speed TDM은 차의 모양을 불안정하게 바꾸어야 해… . 걱정되는군…

TDM ApproachTDM Approach

Dispersion

Nonlinear Effects

High-Speed Electronics

1 1 11 1 1 1 1 1 1 1 1?00 00 0 00 00

Optical signal 의 폭이 좁을수록 분산에 매우 취약하다 .

1 1 11 1 1 1 1 1 1 1 10 00 0 00 000

Optical signal 의 키가 클수록 비선형효과에 민감하다 .

방열문제 , 임피던스 매칭문제 , 고속신호 처리문제… .

고속으로 올라갈수록 힘들다 .

TDM Limitations: Optical SignalsTDM Limitations: Optical Signals

같은 도로를 이용하기 위해서는 뭔가 구분이 필요하다 . 그것이 바로 색깔 !

광섬유의 넓은 대역폭을 이용 !

파장 [nm]

Loss [ d

B/k

m

]

1300 1550 1600

0.2dB/kmminimum loss region

0.4dB/km

WDM ApproachWDM Approach

WDM Transmission SystemWDM Transmission System

OpticalAmplifier

OpticalFiber

Transmitterpower managementwavelength managementmodulation formats

Receiverreceiver sensitivityfilter bandwidth forward error correctionelectrical compensation

Optical Fiberchromatic dispersionpolarization-mode dispersionnonlinearities (SPM, XPM, FWM, SRS, SBS)

Optical Amplifiersgain equalizationEDFA or Raman (multi-band)

Transmitter Receiver

0306kch

WDM Transport NetworksWDM Transport Networks

Reconfigurable WDM Multipoint Network

OXC

LSR Lab - 9905kch

Fixed WDM Multipoint Network

O-ADM

Technology and Market TrendsTechnology and Market Trends

Increased flexibility and intelligence p-t-p to mesh network fixed to tunable wavelength fixed to tunable mux/demux fixed to multi bit-rate static to dynamic networks wavelength to packet switching

Lower cost manual assembly to full automation bulk to integrated optics research and innovations

Lower power consumption

Higher capacity systems

Enablers of High-Capacity Enablers of High-Capacity WDM Transmission SystemsWDM Transmission Systems

Raman Amplifiers

Advanced Modulation Formats

Chromatic Dispersion Management

Polarization-Modes Dispersion Compensation

New Fiber Designs

Forward Error Correction

Multi-Band Transmission

0306kch