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Optical Transport Networks: motivation, challenges and possibilities Huaiyuan Ma PhD Trial Lecture Feb 26th, 2015 NTNU, Trondheim Optical Transport Networks : motivation, challenges and possibilities 1

Outline  Why OTN ?  Challenges  Potential solutions Optical Transport Networks : motivation, challenges and possibilities 2

Outline  Why OTN ?  Challenges  Potential solutions Optical Transport Networks : motivation, challenges and possibilities 3

Focus We focus large scale OTN, nation wide, backbone 1 st generation (SDH) → 2 nd generation OTN Optical Transport Networks : motivation, challenges and possibilities 4

Driving force for OTN evolution From Ref [7] Optical Transport Networks : motivation, challenges and possibilities 5

Driving force for OTN evolution From Ref [3] Optical Transport Networks : motivation, challenges and possibilities 6

Why OTN ? 1st Generation: SDH • Based on TDM, 8000 frames per second Based on TDM, 8000 frames per second • Hierarchical Multiplexing structure Hierarchical Multiplexing structure – Multi-level multiplexing based transmission rate Multi-level multiplexing based transmission rate From Ref [4] Optical Transport Networks : motivation, challenges and possibilities 7

SDH Cons: Cons: – Cannot provide high and dynamic data transmission rate Cannot provide high and dynamic data transmission rate → → Not statistic multiplexing Not statistic multiplexing – Low channel utilization Low channel utilization – → Fixed bandwidth allocation → Fixed bandwidth allocation – Lack of end-to-end monitoring Lack of end-to-end monitoring Pros: Pros: – Good OAM Good OAM – Optical Transport Networks : motivation, challenges and possibilities 8

Huge bandwidth resource: DWDM Large bandwidth Large bandwidth 8 ~ 160 lambdas on a single fiber 8 ~ 160 lambdas on a single fiber  Optical Transport Networks : motivation, challenges and possibilities 9

DWDM Pros: Pros: • Large bandwidth Large bandwidth • Transparent data transmission Transparent data transmission • Low energy consumption Low energy consumption Green network – Green network Cons: Cons: • A point-to-point system, not a network A point-to-point system, not a network – Lack of lambda switch capability Lack of lambda switch capability • Low lambda ( wavelength ) utilization, some unused lambdas Low lambda ( wavelength ) utilization, some unused lambdas – Subjected to wavelength continuity constraint Subjected to wavelength continuity constraint • Fiber non-linear effect Fiber non-linear effect – Higher light power Higher light power Optical Transport Networks : motivation, challenges and possibilities 10

The 2 nd Generation: OTN SDH : good OAM, network protection, … SDH  DWDM: large bandwidth DWDM  Approach: improve the bandwidth utilization of DWDM Approach  by introducing OADM/OXC to form optical network and enhance SDH by adding wavelength SDH + lambda management management (GMPLS) + = OTN DWDM + OADM/OXC Optical Transport Networks : motivation, challenges and possibilities 11

OTN Hierarchy From Ref [4] Optical Transport Networks : motivation, challenges and possibilities 12

OTN TCM (Tandem Connection Monitoring) From Ref [4] Optical Transport Networks : motivation, challenges and possibilities 13

The 2 nd Generation: OTN Stronger Forward Error Correction (FEC)  More Levels of Tandem Connection Monitoring (TCM)  Transparent Transport of Client Signals  digital wrapper  Switching scalability  Optical Transport Networks : motivation, challenges and possibilities 14

Outline  Why OTN ?  Challenges  Potential solutions Optical Transport Networks : motivation, challenges and possibilities 15

Alarming From Science 2010[6] Capacity (bits/s) growth trend Optical Transport Networks : motivation, challenges and possibilities 16

Some observations: Amdahl's rule Exponential growth (i) of data network traffic in the US (red circles) and (ii) of the (average) Exponential growth (i) of data network traffic in the US (red circles) and (ii) of the (average) processing power of the top 500 supercomputers. (Flop: floating point operation per second). processing power of the top 500 supercomputers. (Flop: floating point operation per second). Formula: 10*log(1.6)=2dB for 60% growth rate. Formula: 10*log(1.6)=2dB for 60% growth rate. From Ref [5] Optical Transport Networks : motivation, challenges and possibilities 17

New Coding Techniques On/Off Keying (OOK) + direction detection On/Off Keying (OOK) + direction detection  Quadrature Phase Shift Keying (QPSK) + coherent detection Quadrature Phase Shift Keying (QPSK) + coherent detection   16-ary Quadrature Amplitude Modulation (16-QAM) + coherent detection 16-ary Quadrature Amplitude Modulation (16-QAM) + coherent detection Polarization-Division Multiplexing (PDM): double channel capacity Polarization-Division Multiplexing (PDM): double channel capacity  From Ref [1] Optical Transport Networks : motivation, challenges and possibilities 18

Some warnings (a) Spectral efficiency evolution of research experiments.(b) Trade-off between (single- (a) Spectral efficiency evolution of research experiments.(b) Trade-off between (single- polarization) spectral efficiency and SNR per bit in the linear regime for QAM (Quadrature polarization) spectral efficiency and SNR per bit in the linear regime for QAM (Quadrature Amplitude Modulation) formats, assuming hard-decision forward error correction (FEC) with Amplitude Modulation) formats, assuming hard-decision forward error correction (FEC) with 7% coding overhead. 7% coding overhead. 32%/year << 86%/year, new coding techniques already push the spectral efficiency to the 32%/year << 86%/year, new coding techniques already push the spectral efficiency to the limit limit From Ref [5] Optical Transport Networks : motivation, challenges and possibilities 19

Challenges  Channel capacity growth rate contributed from higher-order coding techniques almost Channel capacity growth rate contributed from higher-order coding techniques almost approaches the Shannon limit. approaches the Shannon limit. Higher spectral efficiency requires higher SNR ratio. Higher spectral efficiency requires higher SNR ratio.   Higher light power causes more fiber non-linear effects. Higher light power causes more fiber non-linear effects.  Limits the signal transmission distances. Limits the signal transmission distances. We need look for other ways to address the network capacity issue caused by data We need look for other ways to address the network capacity issue caused by data traffic growth traffic growth Optical Transport Networks : motivation, challenges and possibilities 20

Outline  Why OTN ?  Challenges  Potential solutions Optical Transport Networks : motivation, challenges and possibilities 21

Potential Solutions Physical layer : Physical layer : Spatial Multiplexing ( SM )  Fiber bundles  Multi-core fibers  Mode Division Multiplexing (MDM)  Low-loss and low nonlinear fiber  From Ref [2] Optical Transport Networks : motivation, challenges and possibilities 22

Potential Solutions Network layer : Network layer : Trend: More meshed network topology  Improve bandwidth utilization by ASON/GMPLS  Potentially achieve good network protection  Optical Transport Networks : motivation, challenges and possibilities 23

Thanks ! Thanks ! Optical Transport Networks : motivation, challenges and possibilities 24

References 1. Why complex modulated optical signals?, Lightwave, http://www.lightwaveonline.com/articles/print/volume-30/issue-4/ feature/why-complex-modulated-optical-signals.html 2. MDM, http://epic.semi.cas.cn/yjfx/201412/t20141210_271696.html 3. Cisco: Video, Internet-of-Things, mobile are prime drivers of Internet use, http://www.techtimes.com/articles/8271/20140611/cisco-video-mobi le-big-internet-use.html 4. Optical Transport Network (OTN):A comprehensive study, http://www.mapyourtech.com/entries/general/optical-transport-ne twork-otn-a-comprehensive-study 5. Winzer, P .J., "Challenges and evolution of optical transport networks," Optical Communication (ECOC), 2010 36th European Conference and Exhibition on , vol., no., pp.1,3, 19-23 Sept. 2010 6. Filling the Light Pipe, www.sciencemag.org 7. IP video to be 79% of all IP trafgic by 2018, up from 66% in 2013,http://www.digitaltvnews.net/?p=24292 Optical Transport Networks : motivation, challenges and possibilities 25