1. C.-H. Lee, 03/04/11 1 광통신 : Evolution to Next Step Chang-Hee Lee (chl@ee.kaist.ac.kr) Korea Advanced Institute of Science and Technology 2003.4.11

2. C.-H. Lee, 03/04/11 2 Optical Networks Metro Core C/DWDM OC48/192 CO Metro Core C/DWDM OC48/192 CO Metro Core C/DWDM OC48/192 CO Access ring OC48/GbE Access ring OC48/GbE Access ring OC48/GbE Access ring OC48/GbE OC3 T1 Access ring OC48/GbE GbE PON Business Residential PON Business Residential GbEs Long-haul DWDM OC48/192/768 Long-haul DWDM OC48/192/768 POP

3. C.-H. Lee, 03/04/11 3 Traffic Growth Slow growth for Voice Exponential growth for data –# of subscriber * data size * connection time –Not exponential in Korea High capacity WDM networks were required to meet demands. However, there is big mismatch between expectation and reality (factor of 8 ~ 10). Revenue growth is slow. Data Voice 19961997199819992000 100 1 50 % 2001 * Lightwave 98/4, M. Shariff, Cisco systems Inc.

4. C.-H. Lee, 03/04/11 4 Recovery Scenarios (Optical Components)

5. C.-H. Lee, 03/04/11 5 1996 1998 2000 2002 Technology Evolution WDM transmission WDM transmission with Add/Drop OADM WDM Rings with node addressing WDM Rings with full connectivity Interconnected rings and mesh topologies OXC “Road map towards the optical communication” 1998, 5, ACTS WDM Backbone Network Evolution (delayed due to down turn) 1996 1998 2002/3 2005/6

6. C.-H. Lee, 03/04/11 6 Backbone Networks (North America case) Huge bandwidth in backbone due to cost effective DWDM technology – Huge investment, but small revenue Restructuring carriers and vendors – Many big players with relatively small growth How many carriers and vendors will survive? Carriers and vendors are looking for next generation systems/networks – Mesh networks based on 10 Gb/s or 40 Gb/s ultra-long reach

7. C.-H. Lee, 03/04/11 7 High capacity WDM systems Wide bandwidth L-band S-band New band Spectral efficiency 40 Gb/s or higher Bidirectional transmission Modulation format(duobinary …) Polarization mux. Long reach Dynamic gain flattening Raman/hybrid Modulation format(CS-RZ, RZ) Dispersion and PMD management FEC

8. C.-H. Lee, 03/04/11 8 Key Technologies (long reach systems) Raman amplifier FEC(Forward Error Correction) Dynamic gain flattening Dynamic dispersion compensation PDM compensation All optical regeneration (3 R) Optimization of modulation format

9. C.-H. Lee, 03/04/11 9 1.2 1.0 0.8 0.6 0.4 0.2 0 0 6 12 18 24 30 36 42 FREQUENCY SHIFT (THz) RAMAN GAIN (x10 -13 m/W) p =1  m Raman Gain Spectrum

10. C.-H. Lee, 03/04/11 10 Raman Amplifiers P out P in P in ’ Transmission fiber without Raman Pump source with Raman Raman amplifier increase input power to EDFA or to detector

11. C.-H. Lee, 03/04/11 11 Add/drop multiplexing of bundle of circuits(path) at each node Add/drop multiplexing of bundle of circuits(path) at each node Though Traffic & Dropped Traffic (connection of many nodes) 1 Total traffic in link for full-mesh connectivity. Node-to-node traffic * N (N-1) / 2 Dropped traffic. Node-to-node traffic * (N-1) Dropping ratio = 2 / N 234 N N-1 Ring topology

12. C.-H. Lee, 03/04/11 12 Evolution of Path Networks All nodes........ LT MUX ADM/DCS SDH 16 or 64 OE/EOMUX/DMUX Terminations of total line capacity and its cross-connection Electrical path networks Path termination nodes Optical path networks OADM Terminations of a portion of line capacity and cross-connection LT MUX ADM/DCS n x SDH 16 or 64 Path through nodes OADM n x SDH 16 or 64

13. C.-H. Lee, 03/04/11 13 Protection in ring networks ADM UPSR Working Protection Switch ADM ULSR Working Protection ADM BLSR/4 Working Protection 2 working + 2 protection fiber ADM BLSR/2(bi) Working Protection 1 working + 1 protection fiber

14. C.-H. Lee, 03/04/11 14 Unidirectional Ring vs. Bidirectional Ring ADMs SwItchSwItch SwItchSwItch WDMWDM WDMWDM Working Protection Unidirectional Ring Bidirectional Ring(4-f) ADMs SwItchSwItch SwItchSwItch WDMWDM WDMWDM Working Protection SwItchSwItch SwItchSwItch WDMWDM WDMWDM Working Protection

15. C.-H. Lee, 03/04/11 15 Mesh Networks Cross connect Fiber cut Normal operation Restoration path High capacity survivable network High degree of wavelength reusability

16. C.-H. Lee, 03/04/11 16 Electrical Path STM-64 STM-1 STM-16 STM-64 STM-1 STM-16 Controller MUXDMUX............ MUX DMUX............ MUXDMUX............ VC-n Cross-connect matrix VC-1/VC-3 10Gb/s 2.5Gb/s 155Mb/s 10Gb/s 2.5Gb/s 155Mb/s VC-3 or VC-4 VC-3 or VC-4 All nodes........ LT MUX ADM/DCS SDH 16 or 64 OE/EOMUX/DMUX Electrical path networks Terminations of total line capacity and its cross-connection

17. C.-H. Lee, 03/04/11 17 Optical Cross-connect System     n 1 2 m Input 1 2 m Output Control Circuit Space switch(n x n)     n  .... WDWD.... WMWM............ WDWD.... WMWM............ WDWD.... WMWM........ n n n x STM 64 n x STM 16 Add signal n x STM 64 n x STM 16 Drop signal

18. C.-H. Lee, 03/04/11 18 Evolution of Optical Path Improved efficiency and control Path-oriented WDM Optical and Data Networks –WDM optical networks utilize physical paths –Data networks utilize logical paths Create associations logical and physical paths Enables mgmt of optical I/F and mgmt services WDM Optical Network ATM SONET/SDH IP ATM IP Intelligent Layer Internetworking Source : OIF

19. C.-H. Lee, 03/04/11 19 Bottleneck in Metro/Access Equivalent BW/subscribers Subscriber Access Metro Backbone 64 kb/s 1 Mb/s 20 Mb/s

20. C.-H. Lee, 03/04/11 20 Bottleneck Moves to Access Backbone network –Rich of bandwidth; DWDM (100 Gb/s ~ multi Tb/s) –SONET, RPR, POS, MPLS,.. Metro-core –Establishing bandwidth rapidly; C/DWDM(2.5 Gb/s ~ 100 Gb/s) –SONET, RPR, POS, MPLS, Ethernet… Access –Copper based network; 100 kb/s ~ Mb/s depends on distance –However, SME requires up to Gb/s services and advanced home more than 20 Mb/s. –ADSL, VDSL, Ethernet, ATM, ….

21. C.-H. Lee, 03/04/11 21 Bandwidth Demands and Subscriber Estimation Services Bandwidth [Mb/s] Three DTV MPEG Video Streams (VDD) 15 Telecommuting/VPN2 Video Conferencing1 Web Surfing1.5 Interactive Gaming1 High Definition TV19.2 Two Phone services0.128 Total bandwidth39.828 Bandwidth demandsSubscribers in Korea Source: Ministry of Information and Communication (MIC) Business subscribers require about ~ Gb/s services

22. C.-H. Lee, 03/04/11 22 WDM-PON Access Solutions Bit Rate [Mb/s] Distance [km] 2 1000 4 1 3 6 5 20 100 1 10 52 26 VDSL ADSL 3 6 8 30 E-PON (w/ 32 ONU)  Source: ITU-T

23. C.-H. Lee, 03/04/11 23 Why Fiber Solution ? Copper solution Source; MIC Fiber solutions FTTH Fiber solutions FTTC 0 5 10 15 20 25 Subscriber speed [Mb/s] 1999200120032005 Year Plan 1.6 Mb/s 1.0 Mb/s Result - Copper based solution cannot provide broadband services. - TDM-PON cannot meet long-term bandwidth requirement. - WDM-PON is the only solution for next generation Broadband access.

24. C.-H. Lee, 03/04/11 24 General Considerations on (Optical Solutions) Physical topology – P-t-P, P-t-MP P-t-MP solutions; Ring, Single star, Double star – Passive vs. active networks – Multiple access methods TDMA, WDMA, SCMA, CDMA Access and communication protocol; ATM, Ethernet, SONET, … Costs – Initial deployment cost  Equipment cost – Provisioning and maintenance costs –Upgrade cost

25. C.-H. Lee, 03/04/11 25 Access network Architectures (P-t-P) CO ONU # 1 ONU # 2 ONU # 4 ONU #… ONU # N ONU # 3 N (or 2N) fibers 2N transceivers High fibers and management cost High cost

26. C.-H. Lee, 03/04/11 26 Access Network Architectures (P-t-MP) CO ONU #N ONU #1 ONU #2 ONU #4 ONU #5 Active remote Passive remote node Passive optical power splitter 234 3 2 4 time

27. C.-H. Lee, 03/04/11 27 Access Network Architectures (P-t-MP) CO ONU #N ONU #1 ONU #2 ONU #4 ONU #5 123 45 123 45 1 2 3 4 5 Passive optical power splitter

28. C.-H. Lee, 03/04/11 28 Comparison of PONs Architecture Access method Protocol transparency Security Offered BW Transmission Link budget > Gb/s possibility Cost P-t-P None Yes High Unlimited Any Highest Yes High (Fiber cost) TDMA No Low Limited Any Low No Low WDMA Yes Low Limited Fixed Lowest Limited Medium (Source cost) WDMA Yes High Unlimited Fixed * High Yes Medium (Source cost) P-t-MP(S)P-t-MP(R) * If router has high temperature dependency, it may need tunable sources.

29. C.-H. Lee, 03/04/11 29 Summary Basic principles of optical communication were reviewed. - Optical transmitter - Optical receiver - Optical amplifier - Wavelength division multiplexing - Optical networking Optical communication/network is essential for future information highway