Presentation is loading. Please wait.

Presentation is loading. Please wait.

T r ansmission Network Development Advanced Technology Laboratories DWDM Transmission Technology and Photonic Layer Network Chao-Xiang ShiSprint Transmission.

Similar presentations


Presentation on theme: "T r ansmission Network Development Advanced Technology Laboratories DWDM Transmission Technology and Photonic Layer Network Chao-Xiang ShiSprint Transmission."— Presentation transcript:

1 T r ansmission Network Development Advanced Technology Laboratories DWDM Transmission Technology and Photonic Layer Network Chao-Xiang ShiSprint Transmission Network Development Group Advanced Technology Laboratories 1 Adrian, Burlingame CA 94010

2 T r ansmission Network Development Advanced Technology Laboratories l l DWDM Technology in terrestrial network - DWDM capacity and transmission distance: technology review - DWDM transmission system - Span design in DWDM transmission - Optical transmitter in DWDM system: DFB laser with external modulator - Wavelength multiplex/de-multiplex technology in DWDM: AWG, Dielectric filter, and Fiber grating type - Two-stage optical fiber amplifier - Optical amplification, bandwidth, and capacity - Optical fiber nonlinearity: SPM, XPM, SBS, and FWM - Polarization mode dispersion (PMD) limitation for 10 Gbit/s and beyond Outline

3 T r ansmission Network Development Advanced Technology Laboratories - PMD compensation technology DWDM technology in Submarine network - capacity and transmission distance : technology review - uniquely designed LCF fiber and non-zero dispersion shift fiber - chromatic dispersion compensation in Submarine transmission - PMD concern in submarine transmission - one stage Er. Doped fiber amplifier - comparison of WDM transmission between terrestrial and submarine network Photonic layer network - Optical network architecture - Protection and restoration mechanism for IP/ATM directly over WDM optical network Continue

4 T r ansmission Network Development Advanced Technology Laboratories - Issues of protocols and interfaces requirements for all-optical networks - Key issue in Metro WDM network and possible solutions - Application of Metro WDM equipment in transparent transport network: Experimental Verification Emerging Technology of Optical Network - Optical CDM (CDMA) - Optical Packet Switching Network Continue

5 T r ansmission Network Development Advanced Technology Laboratories DWDM Capacity and transmission: Technology review Today Technology nm window (used to call C-band) 80 ~ 100 channels of 2.5 Gb/s (50 GHz spacing) 32 ~ 40 channels of 10 Gb/s (100 GHz spacing) 70 ~ 90 km span length 4 in-line optical amplifiers and 5 spans total 400 km transmission for 10 Gbit/s total 600 km transmission for 2.5 Gbit/s Tomorrow Technology nm window (used to call L-band) 100 ~ 200 channels of 2.5 Gb/s 64 ~ 100 channels of 10 Gb/s After… nm window by Raman amplification

6 T r ansmission Network Development Advanced Technology Laboratories OC-48/ OC-192 OC-48/ OC-192 OC-48/ OC-192 OC-48/ OC km DWDM transmission system 70-90km OSC 1510 nm or 1480 nm 1510 nm or 1480 nm Tx Uni-directional transmission Bi-directional transmission

7 T r ansmission Network Development Advanced Technology Laboratories Span design in DWDM transmission OC192 (10 Git/s) +6~8 dBm/ch 3 span: span distance 90 km, total 270 km 4 span: span distance 80 km, total 320 km 5 span: span distance 70 km, total 350 km OC 48 (2.5 Gbit/s) 3 span: span distance 120 km, total 360 km 5 span: span distance 100 km, total 500 km 8 span: span distance 80 km, total 640 km

8 T r ansmission Network Development Advanced Technology Laboratories Optical transmitter in DWDM system: DFB laser with external modulator DFB laser with External modulation (for backbone long distance) Wavelength stable, narrow band DFB laser - DFB laser spectrum width : ~ 20 mHz - wavelength stability: +/ nm DFB laser integrated with EA modulator - Low chirping effect - polarization stability - low driving power required DFB laser with external LN modulator - polarization problem - high driving power required - chirping problem DFB laser with Direct modulation (for local area short distance) - chirping problem - spectrum broaden - wavelength stability

9 T r ansmission Network Development Advanced Technology Laboratories Wavelength multiplex/demultiplex technology in DWDM: AWG, Dielectric filter, Fiber grating WDM Mux/Demux AWG (array waveguide grating) - Insertion loss : 6 ~ 8 dB (insertion loss is almost - channel crosstalk ~ 25 db - application for higher channel number Dielectric filter WDM Mux/Demux -insertion loss: increases when channel number increases -channel crosstalk: 25 ~ 30 dB -application for lower channel number WDM Mux/Demux Fiber Bragg grating - need optical circulator - cascade multipile grating to form a WDM Mux/Demux

10 T r ansmission Network Development Advanced Technology Laboratories Two-stage Optical fiber amplifier DCF optical filter OSC 980 nm pump EDFA nm pump EDFA2 WDM 980 nm low noise pump laser for first stage EDFA 1480 nm high power pump laser for second EDFA DCF (dispersion compensation fiber) is required for 10 Gbit/s Attenuater is needed for 2.5 Gbit/s Optical isolator is used to reduce back ASE noise impact Optical filter is used for gain equalization Total gain of fiber amplifier is from 25 dB to 30 dB N.F. (noise figure): 5 ~ 7dB Output power : +17 ~ +23 dBm Flatten gain : +/- 1 dB with 30 nm ~ 40 nm over Er. gain range Dynamic input range: 15 dB

11 T r ansmission Network Development Advanced Technology Laboratories Optical amplification, bandwidth, and capacity 0.25 db 0.4 db 1310 nm 1550 nm C band: 1530 ~ 1560 nm (100 Ghz channel space for 10 Gbit/s, total 40 channels, 50 Ghz channel space for 2.5 Gbit/s, total 96 channels ) L band: 1560 ~ 1600 nm (40 channel available for 10 Gbit/s, i.e. 40 gbit/s,, and 100 channels available for 2.5 gbit/s) S band: 1480 ~ 1520 nm (40 channel available for 10 Gbit/s, i.e. 40 gbit/s,, and 100 channels available for 2.5 gbit/s) Fiber loss Wavelength ( ) Total 1.2 Tbit/s capacity S Band: Raman amplification L Band: EDFFA, Ti-EDFA C Band: EDFA

12 T r ansmission Network Development Advanced Technology Laboratories Fiber nonlinearity: SPM, XPM, SBS, and FWM SPM: Self-phase modulation - Create positive chirping, which cause pulse distortion due to fiber dispersion - Result in the optical spectrum broaden which limits the channel space XPM: Cross phase modulation - Phase modulation between two channels due to fiber Kerr effect - Convert phase noise (due to ASE) to intensity noise via fiber dispersion - Limit channel space (for 10 Gbit/s channel space is 100 Ghz, 0.8nm) SBS: Stimulated Brillouin Scattering - Creating a new wave in backward direction through interaction between light wave and acoustic wave - SBS threshold can be reduced by decreasing the power level and increasing optical spectrum. - For 10 Gbit/s, FM modulation (~100 Mhz) of DFB laser can reduce the SBS threshold from +5 dBm to +10 dBm. FWM: Four wave mixing - Optical parametric process through 3 or 4 light wave. - Cause nonlinear channel crosstalk when transmission near zero dispersion wavelength (a critical problem for dispersion-shift fiber) - Standard SMF-28 is good to suppress FWM, but has too much chromatic dispersion - True wave fiber has larger enough dispersion to suppress FWM, and small enough chromatic dispersion, but still has dispersion slope problem.

13 T r ansmission Network Development Advanced Technology Laboratories Polarization mode dispersion limitation for beyond 10 Gbit/s Y X X-polarization Y-polarization X-polarization c, ( n x - n y ) and L PMD is caused by differential group delay (DGD) between two - polarization modes PMD is a statistic process satisfying Maxwellian distribution PMD becomes serious issue for 10 Gbit/s and beyond PMD design - Instantaneous PMD should be smaller than 25% pulse width - Assuming fiber PMD is 0.3 ps/km^1/2, 400 km fiber gives mean PMD 6 ps. If we use safety number 4 for Maxwellian distribution, the instantaneous PMD is 24 ps. Which means 0.3 ps/km^1/2 PMD gives 400 km distance limitation for 10 Gbit/s.

14 T r ansmission Network Development Advanced Technology Laboratories PMD compensation technology Y X X-polarization Y-polarization Transmitter Receiver Polarization controller (PC) PM fiber Electronic process feedback control signal Long distance SM fiber PM fiber: with high PMD due to strong fiber birefringence PMD induced by long distance single mode fiber can be canceled by using a short PM fiber with a greater PMD Feedback control signal to adjust input polarization of PM fiber, so that the fast polarization axis of single mode fiber matches to the slow axis of PM fiber and vice versa.

15 T r ansmission Network Development Advanced Technology Laboratories Capacity and transmission distance Current Transmission Technology 1530 ~1560 nm window of EDFA - 10 Gbit/s X 16 ch transmission (channel space 0.6 nm) - 45 ~ 50 km span length - ~ 150 in-line optical amplifiers - total 7500 km transmission without electronic regenerter for 10 Gbit/s Future Transmission Technology - 10 Gbit/s x N (N=32~50) transmission - 20 Gbit/s WDM technologies - 40 Gbit/s WDM technologies

16 T r ansmission Network Development Advanced Technology Laboratories Uniquely designed LCF fiber and non-zero dispersion shift fiber (NZ-DSF) EDFA LCF fiberNZ-DSF fiber 25 km …. LCF ( Large core fiber) - chromatic fiber dispersion -2 ps/km.nm - large effective area 75 ~ 80 um^2 - bigger dispersion slope - suppression of nonlinear effect - used in first half span distance for higher channel power NZ-DSF fiber - chromatic fiber dispersion -2 ps/km.nm - smaller dispersion slope - used in second half span for smaller power - to reduce accumulation of chromatic dispersion

17 T r ansmission Network Development Advanced Technology Laboratories Chromatic dispersion compensation in Submarine transmission EDFA LCF fiberNZ-DSF fiber 25 km..…. EDFA Standard SMF fiber 50 km …. 10 span 500 km Standard single mode fiber (SMF) is used for chromatic dispersion compensation Dispersion compensation is performed at every 10 span (500 km) In order to resolve dispersion slope problem, pre-dispersion and post-dispersion compensation are needed at transmitter and receiver ends

18 T r ansmission Network Development Advanced Technology Laboratories PMD concern in submarine transmission how is PMD impact for ultra- long distance such as Submarine transmission (7500 km)? - PMD is accumulated through the long distance transmission by both fiber cable and every optical component. - define a low PMD fiber (PMD as low as ps/km^1/2). Over 7500 km, mean fiber PMD =6.9 ps. - define each optical component with a small PMD, e.g, EDFA with 0.1 ps, WDM with 0.1ps.

19 T r ansmission Network Development Advanced Technology Laboratories One stage Er. Doped fiber amplifier Er. fiber 980 nm pump laser module Opt. isolator ASE filter Gain equalization filter 980 nm low noise pump laser module for first stage EDFA Optical isolator is used to reduce back ASE impact Optical filter is used for gain equalization ASE filter (FBG) is used to get off ASE and its accumulation Total gain of fiber amplifier is from 10 dB to 12 dB small N.F. (noise figure): ~4 dB Output power : ~ +11 dBm

20 T r ansmission Network Development Advanced Technology Laboratories Comparison of WDM transmission between terrestrial and submarine network Why submarine network can transmit over 7500 km with more than 100 span and fiber amplifiers at 10 Gbit/s, but terrestrial network can only handle 5 span over 400 km? 7500 km vs/ 400 km is a big difference! - Submarine transmission network is a pre-defined system, which is more like a well controlled experimental system in Lab. - In terrestrial network, the characteristic of fiber in underground is unknown. The system designer should build equipment to cover a lot of statistic cases.

21 T r ansmission Network Development Advanced Technology Laboratories R Router Non-IP Data Source ATM Switch SONET DCS or ADM Optical XC or ADM Optical line System R R R R R R R R R IP/SONET IP/WDM Next Generation Network IP/ATM

22 T r ansmission Network Development Advanced Technology Laboratories WDM Long Haul WDM Metro Backbone ring WDM local collecting ring WDM local collecting ring Hub Central Node Hub 1 All Optical Network: WDM Long Haul, Metro Backbone, and Local Collecting Ring

23 T r ansmission Network Development Advanced Technology Laboratories The ring size of metro backbone WDM network is defined to be from 100 km to 200 km, and WDM local collecting ring is defined from 20 km to 50 km. In order to have a transparent (protocol independent) transport optical network also for the low cost reason, no electronic regenerators should be allowed in Metro WDM rings. Optical amplifiers might be needed in WDM metro backbone ring network, but not in WDM local collecting ring. Metro WDM ring should be self-healing optical ring. network protection and restoration should be at photonic layer. Description of Metro WDM Ring

24 T r ansmission Network Development Advanced Technology Laboratories Same interconnections between routers requires 1 protection wavelength with OSPRING Interconnections between routers requires 4 protection wavelengths with path switch Optical Protection Efficiency 1+1 OSNCP (Path Switch) vs. OSPRING (Optical Line) OSPRING OSNCP

25 T r ansmission Network Development Advanced Technology Laboratories 2-Fiber OMS/SPRING (conventional switching) D Ring Switch A B C AÔCAÔC CÔACÔA AÔCAÔC CÔACÔA fiber 1 fiber 2 Working Protection fiber 1 i - N/2 N/2 - N ( i ) ( k ) Working Protection fiber 2 i - N/2 N/2 - N ( i ) ( k ) No Wavelength Conversion Required fiber cut

26 T r ansmission Network Development Advanced Technology Laboratories 2-Fiber OMS/SPRING (w/G.841 undersea protocol) D Ring Switch A AÔCAÔC CÔACÔA AÔCAÔC CÔACÔA fiber 1 fiber 2 Working Protection fiber 1 i - N/2 N/2 - N ( i ) ( k ) Working Protection fiber 2 i - N/2 N/2 - N ( i ) ( k ) No Wavelength Conversion Required C B fiber cut

27 T r ansmission Network Development Advanced Technology Laboratories l l How to transport large pipes (OC-48c & above) reliably? Should OC-192 be deployed in an existing OC-48 based network? l l Should SONET be bypassed for ATM, FR, and IP transport over wavelengths? l l No standards on optical data interface, multi-vendor interoperability l l What survivability architecture best balances performance, cost, and flexibility? l l Is synchronization required for optical network? l l Mechanisms for providing OCH trail trace, mechanisms to discover fiber topology, performance monitor and management across administrative boundaries. l l Meeting latency requirements in detecting, reporting, localizing, and reacting to faults (e.g. protection switching). Optical Network Evolution Issues

28 T r ansmission Network Development Advanced Technology Laboratories Survivability Alternative Tradeoffs Distributed Mesh Facility Cost [Restoration Overbuild] SNCP MSP Maximum Outage MS/ SPRING Centralized Mesh Good Service Layer Mesh Physical Layer (SONET & Optical) Schemes Every survivability mechanism makes tradeoffs: Speed vs. Facility Cost (Overbuild) is most fundamental Every survivability mechanism makes tradeoffs: Speed vs. Facility Cost (Overbuild) is most fundamental

29 T r ansmission Network Development Advanced Technology Laboratories Central Node OADM Metro WDM Networks Key Issue: Limited Number of OADM Nodes and Small Ring Size

30 T r ansmission Network Development Advanced Technology Laboratories Central Node OADM Boost- Amp Pre- Amp Metro WDM Networks solution: Boost and Pre- Amplifiers Att.

31 T r ansmission Network Development Advanced Technology Laboratories Central Office OADM ATT. ATT 4 EDFA Input (before Tx ATT) EDFA Input (after ATT control) EDFA EDFA Output Metro WDM Networks solution: One Line- amplifier

32 T r ansmission Network Development Advanced Technology Laboratories Metro WDM Networks solution: Line-Amplifier with Gain Slope Central Office OADM EDFA Input Gain curve EDFA EDFA Output

33 T r ansmission Network Development Advanced Technology Laboratories Metro WDM Network: Experimental Set-up A B C D TX RX LR Splitter A B B A A D C B 7dB TX RX SR Client Combiner 7dB RX Switch OADM filter

34 T r ansmission Network Development Advanced Technology Laboratories Transparent WDM Network: SONET-Less, Photonic Layer Restoration By Metro WDM Equipment Metro WDM Network 1 A D Hub OADM WDM Long Haul Network OADM Metro WDM Network 2 Hub Metro WDM Network 3 c B

35 T r ansmission Network Development Advanced Technology Laboratories Hybrid WDM Metro and Long Haul: Experimental Set Up LA2 Error output Fiber cut 16 ch. Long Haul WDM Transmission 500 km Tektronix ST2400 SONET testset Transponder Metro WDM Network 1 D A C B :... E F G : : A E Fiber 40 ch. Long Haul WDM Transmission 500km E A C C F F H HP Digital Scope : LA1 LA3 LA4 TARA

36 T r ansmission Network Development Advanced Technology Laboratories Error free Error period Protection time when 16 channel long haul WDM fails

37 T r ansmission Network Development Advanced Technology Laboratories Error free Error period Protection time when 40 channel long haul WDM fails

38 T r ansmission Network Development Advanced Technology Laboratories BER results for working and protection path

39 T r ansmission Network Development Advanced Technology Laboratories Emerging Technology: Optical CDM (CDMA) using Fiber Brag Gratings FBG n... Optical circuit n d t FBG n n d t Output Input Dispersion Compensation Fiber EDFA

40 T r ansmission Network Development Advanced Technology Laboratories Optical Packet Switching Network Node Node IP/ATM Network IP/ATM Network IP/ATM Network IP/ATM Network IP/ATM Network IP/ATM Network Optical packet switching ring network …


Download ppt "T r ansmission Network Development Advanced Technology Laboratories DWDM Transmission Technology and Photonic Layer Network Chao-Xiang ShiSprint Transmission."

Similar presentations


Ads by Google