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광대역 통합망을 위한 광전송 기술

광대역 통합망을 위한 광전송 기술. 2009. 3. 25. 서울시립대학교 전자전기컴퓨터공학부 김철한. Outline. 광대역 통합망 (BcN) 광가입자망 (FTTH) 광통신 시스템 구성 일반 구성 요소 : 광섬유 , 광원 , 광수신기 주요 잡음원 : 감쇠 , 분산 , 비선형 , 누화 대용량 장거리 광전송망 요약. 건설. 레저. 환경 / 의료. 교통. 교육. 금융. 차세대 통합 네트워크. 농수산업. 물류 / 유통. 다양한 접속. 융합형 서비스. 고품질 서비스.

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광대역 통합망을 위한 광전송 기술

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  1. 광대역 통합망을 위한 광전송 기술 2009. 3. 25. 서울시립대학교 전자전기컴퓨터공학부 김철한

  2. Outline • 광대역 통합망 (BcN) • 광가입자망 (FTTH) • 광통신 시스템 구성 일반 • 구성 요소: 광섬유, 광원, 광수신기 • 주요 잡음원: 감쇠, 분산, 비선형, 누화 • 대용량 장거리 광전송망 • 요약

  3. 건설 레저 환경/의료 교통 교육 금융 차세대 통합 네트워크 농수산업 물류/유통 다양한 접속 융합형 서비스 고품질 서비스 유/무선 통합 통신/방송 융합 음성/데이터 통합 IPv6 Security Open API QoS Broadband 홈 네트워크 Information + Entertainment + Commercial + Content + etc 융합형 정보 단말/가전 미래 통합망의 비전 MIC2003

  4. Broadband Convergence Network (BcN) MIC2003

  5. Network 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

  6. BcN 구현을 위한 핵심 요소 기술 MIC2003

  7. Transport Network: Local to Long-Haul Central Office Edge ROADM (future) Any Service IOF ROADM Any Service Any Service Central Office Regional & Long Haul Access Metro Courtesy of AT&T

  8. Access Environments • 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 Video의 통합

  9. 국내 가입자망 서비스

  10. Future Services

  11. Bandwidth Demand * symmetric bandwidth is required

  12. BcN 목표 MIC2003

  13. 초광대역통합망 (UBcN) 구축 세부목표 방송통신위원회 2009

  14. Last Mile Problem

  15. 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

  16. WhyFTTH? (Fiber vs. Copper) • A single copper pair is capableof carrying 6 phone calls • A single fiber pair is capable ofcarrying over2.5 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

  17. FTTH Architectures ONU 1 ONU 2 Point-to-Point (Home Run) ONU 3 CO ONU 4 ONU N ONU 1 Passive RN ONU 2 Passive Optical Network (PON) ONU 3 CO ONU 4 ONU N

  18. Time division multiple access v 2 Low security u Limited bandwidth u Low link budget u Protocol dependency u Low cost u 1 1 1 1 1 2 2 2 2 2 3 3 3 3 3 4 4 4 4 4 1 1 2 3 4 High security u Unlimited bandwidth u High link budget u Protocol transparency u Medium cost ( Low cost source is required ) u TDM-PON vs. WDM-PON ONU #1 1 ONU #2 2 2 ONU #3 CO 3 1 2 3 4 time 3 4 Passive optical power splitter ONU #4 4 ONU #N ONU #2 Wavelength division multiple access v ONU #1 CO ONU #3 l Passive WDM router ONU #4 ONU #N

  19. FTTH 망구성

  20. E-PON 기반 FTTH 망구성

  21. Interoperability Protocol transparent Physical layer security Security Dedicated bandwidth QoS assurance Unlimited bandwidth Future upgrade plan Cost effective Low OPEX Advantages of WDM Technology

  22. FTTH BASED ON WDM-PON Journal of Lightwave Technology, pp.2582-2591, 2004

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

  24. 주요 광소자 특징 Optical fiber Light sources • Optical amplifiers Photodetectors Optical Fiber communications, 3rd ed.,G.Keiser,McGraw-Hill, 2000

  25. 광섬유 • 코어 (Core) • 클래딩 보다 굴절률이 높음 (굴절률 n = c/v) • 클래딩 (Cladding) • 코어 보호 • 적절한 굴절률 차이 제공

  26. z=0 z=L Attenuation z=0 z=L Dispersion 광링크에서의 신호 열화

  27. 광신호 감쇠 원인 • 광섬유 감쇠원 • 산란 (scattering) • 흡수 (absorption) Optical Fiber communications, 3rd ed.,G.Keiser,McGraw-Hill, 2000

  28. 색분산 (Chromatic Dispersion)

  29. Dispersion Compensating Fiber (DCF)

  30. 색분산에 의한 신호 왜곡

  31. 점-대-점(P-t-P) 링크 설계 Main concern is extending the transmission distance (“reach”) - Attenuation (power budget) and - Dispersion (rise-time budget)

  32. 광원 LED LD (Laser Diode) • 광원 성능 • 출력 파워 (output power) • 선폭 (linewidth) • SMSR (side mode suppression ratio)

  33. - + + - n- p+ n+ 광수신기 (PD) E • Photo Diode = LED • LED: forward bias • PD: reverse bias

  34. 수신감도 (Receiver Sensitivity) - 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

  35. 광 파워 설계 (Power Budget) Optical Fiber communications, 3rd ed.,G.Keiser,McGraw-Hill, 2000

  36. Dispersion Limit: Rule of Thumb

  37. 분산 및 비선형 현상 원인

  38. 비선형 현상의 종류 • Kerr Effect • Self-Phase Modulation (SPM) • Cross-Phase Modulation (XPM) • Four-Wave Mixing (FWM) • Scattering Effect • Stimulated Raman Scattering (SRS) • Stimulated Brillouin Scattering (SBS)

  39. BLS based Optical Sources Wavelength Splitter Spectrum Slice Low cost Semiconductor Device  Broadband Light Source Only one BLS can support a number of subscribers with only one wavelength router

  40. MOD2 MODN MOD1 Rx 1 Rx N Rx 2 ONU 1 ONU N Rx 1 Rx N Rx 2 ONU 2 Tx N Tx 2 Tx 1 … … BLS-based WDM PON Architecture BLS AWG AWG AWG Modulated downstream RN CO Modulated upstream • Broadband Light Sources (BLSs) • LED • ASE from EDFA or SOA SOA: semiconductor optical amplifier ASE: amplified spontaneous emission

  41. Rx 1 Rx 2 Tx 2 Tx 1 Tx N Rx N ONU N ONU 1 ONU 2 Tx 2 Tx N Tx 1 Rx 2 Rx 1 Rx N … … BLS-based WDM PON Architecture BLS 1 BLS 2 AWG AWG Modulated downstream RN CO Modulated upstream • Colorless Transmitters (Modulator + Amplifier) • Wavelength-Locked FP-LD • RSOA (Reflective SOA)

  42. Measured Optical Spectra • equivalent optical BW • spectrum-sliced ASE source 0.7 nm • FP-LD 0.3 nm

  43. directly-modulated, wavelength-locked FP-LD EAM-modulated, spectrum-sliced ASE Power Penalty (dB) Transmission Distance (km) Dispersion-Induced Penalty (1.25 Gb/s signal transmission) (Ref. K. H. Han et al., PTL, Oct. 2004)

  44. Effects of Crosstalk in BLS based WDM PONs BLS Colorless Source Rx

  45. Electrical Eye Diagrams (Pin = -20 dBm) 500 ps/DIV without Xtalk Xtalk Ratio = -10 dB Xtalk Ratio = -5 dB

  46. Summary • 광대역 통합망을 위한 광전송망 • 광가입자망(FTTH) • 장거리광전송망 (WDM, OXC, etc) • 주요 광소자 • 광섬유, 광원, 광수신기, 광증폭기, AWG • 주요 잡음원 • 감쇠, 분산, 비선형, 누화

  47. Optical Transport System 1 0 1 1 SMOT-16 SMOT-16 Signal = Car Fiber = Highway

  48. High Capacity Transport 답은 간단! 선로를 계속 포설하고, 장비고 계속 구매하는 거야… 비경제적인 답! 돈도 많이 들고, 시간도 많이 걸리고….

  49. TDM Approach 10G or 40G TDM system SMOT-16 SMOT-16 High-speed TDM은 차의 모양을 불안정하게 바꾸어야 해…. 걱정되는군… 40G car 10G car

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