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Optical Transport Networks: motivation, challenges and possibilities - - PowerPoint PPT Presentation

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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

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Optical Transport Networks : motivation, challenges and possibilities

Optical Transport Networks: motivation, challenges and possibilities

Huaiyuan Ma PhD Trial Lecture Feb 26th, 2015 NTNU, Trondheim

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Optical Transport Networks : motivation, challenges and possibilities

Outline

 Why OTN ?  Challenges  Potential solutions

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Optical Transport Networks : motivation, challenges and possibilities

Outline

 Why OTN ?  Challenges  Potential solutions

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Optical Transport Networks : motivation, challenges and possibilities

Focus

We focus large scale OTN, nation wide, backbone 1st generation (SDH) → 2nd generation OTN

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Optical Transport Networks : motivation, challenges and possibilities

Driving force for OTN evolution

From Ref [7]

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Optical Transport Networks : motivation, challenges and possibilities

Driving force for OTN evolution

From Ref [3]

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Optical Transport Networks : motivation, challenges and possibilities

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]

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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

SDH

Pros: Pros:

– – Good OAM Good OAM

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Huge bandwidth resource: DWDM

Large bandwidth Large bandwidth

8 ~ 160 lambdas on a single fiber 8 ~ 160 lambdas on a single fiber

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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

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The 2nd Generation: OTN

SDH + lambda management + = OTN DWDM + OADM/OXC

SDH SDH : good OAM, network protection, …

DWDM DWDM: large bandwidth

Approach Approach: improve the bandwidth utilization of DWDM by introducing OADM/OXC to form optical network and enhance SDH by adding wavelength management (GMPLS)

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OTN Hierarchy

From Ref [4]

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OTN TCM (Tandem Connection Monitoring)

From Ref [4]

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The 2nd Generation: OTN

Stronger Forward Error Correction (FEC)

More Levels of Tandem Connection Monitoring (TCM)

Transparent Transport of Client Signals

digital wrapper

Switching scalability

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Outline

 Why OTN ?  Challenges  Potential solutions

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Alarming

From Science 2010[6]

Capacity (bits/s) growth trend

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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]

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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]

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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.

From Ref [5]

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

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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

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Outline

 Why OTN ?  Challenges  Potential solutions

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Potential Solutions

Spatial Multiplexing ( SM )

Fiber bundles

Multi-core fibers

Mode Division Multiplexing (MDM)

Low-loss and low nonlinear fiber

From Ref [2]

Physical layer : Physical layer :

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Potential Solutions

Trend: More meshed network topology

Improve bandwidth utilization by ASON/GMPLS

Potentially achieve good network protection

Network layer : Network layer :

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Thanks ! Thanks !

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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