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Control of Optical Fibre Communications Networks. Peter Farrell. Utopian Vision ALL OPTICAL NETWORK. Analogy with Internet Transmitter sends photons through the network (transparently) to Receiver Format independent Bit-rate independent Protocol independent

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utopian vision all optical network
Utopian VisionALL OPTICAL NETWORK
  • Analogy with Internet
  • Transmitter sends photons through the network (transparently) to Receiver
  • Format independent
  • Bit-rate independent
  • Protocol independent
  • The Network is very clever (BRIGHT?) and can figure everything out so that your information goes to its destination perfectly
  • A bit like
    • electricity too cheap to meter from the nuclear industryOR
    • the paper free office
interesting problems to solve to build utopia
Interesting Problems to Solve to build Utopia
  • Finance
  • All the routing problems in the Network
  • BIG optical switches
  • Control of adjustable elements in the Network
continental

Darwin

Katherine

Derby

Cairns

Cloncurry

Tennant Creek

Townsville

Mt. Isa

Hughenden

Mackay

Sth. Hedland

Charters Towers

Rockhampton

Alice Springs

Mt. Newman

Bundaberg

Meekatharra

Toowoomba

Mullewa

Brisbane

Geraldton

Glendambo

Kalgoorlie

Pt. Augusta

Ceduna

Newcastle

Parkes

Perth

Clare

Sydney

Hay

Adelaide

Esperance

Canberra

Melbourne

Established by 1993

Established by 1997

Hobart

Continental
size matters because
Size matters because …
  • Different transmission issues for
    • 100 m building / campus
    • 1 km campus
    • 10 km metro
    • 100 km metro/continental
    • 1000 km continental
    • 10000 km world
  • All optical network requires (?) 10000 km infrastructure for a 100 m connection
optical network control
Optical Network Control
  • Most published work is on making connections, fault location, contention avoidance and so on
  • Very little on control of adjustable elements in the network to optimise or at least improve the performance
  • Alternative is to grossly over engineer the hardware
point to point link impairments
Tx

Chirp

Noise

Finite extinction ratio

Mux/Demux

Filter drift

Crosstalk

Transmission fibre

Loss

Dispersion

Nonlinear effects

Amplifiers

ASE/ Noise

Crosstalk

Wavelength dependent gain

Rx

Finite sensitivity

Noise

Bandwidth

Everywhere

PMD

Tx

Tx

Rx

Rx

Point to Point Link Impairments

DisCo

point to point link adjustments

Tx

Tx

Rx

Rx

Point to Point Link Adjustments
  • Tx
    • Power, wavelength, chirp, modulation format, extinction ratio
  • MUX/DEMUX
    • Temperature
  • Amplifier
    • Gain, gain flattening filter, tilt
  • Dispersion compensation
  • Rx
    • Gain (APD or preamp gain)
    • Decision Threshold
    • Decision Point

DisCo

slide13

Long Haul Link Configuration10 Gbit/s over >1000 km

LF

LF

LF

LF

LF

LF

LF

LF

LM

LM

LM

CCC

CCC

Tx Terminal

Rx Terminal

Rx

Tx

1

C Blue

C Blue

Rx

Tx

Rx

Tx

40

DCF

DCF

Amp n

Amp1

TransmissionFibre

Transmission Fibre

Transmission Fibre

Rx

Tx

41

DCF

DCF

DCF

DCF

Rx

Tx

C Red

C Red

R

R

R

Rx

Tx

80

Tx

81

Rx

L Blue

L Blue

Tx

Rx

DCF

120

Tx

DCF

DCF

DCF

Rx

DCF

DCF

CCC

CCC

Tx

121

Rx

Tx

Rx

L Red

L Red

Tx

Rx

160

point to point link with oadm

Tx

Tx

Rx

Rx

Tx

Tx

Rx

Rx

Point to Point Link with OADM

DisCo

OADM

DisCo

lots of feedback loops amplifier

Feedback & Control

Lots of Feedback Loops …Amplifier
  • Issues
    • Measurement accuracy
    • Signal reduction
    • Transient response
lots of feedback loops dispersion compensator

Dispersion Compensator

Dispersion Measurement

Lots of Feedback Loops … Dispersion Compensator
  • Issues
    • Location
    • Accuracy
    • Signal reduction
lots of feedback loops pre emphasis
Lots of Feedback Loops … Pre-emphasis
  • Shares OSNR, BER or received power equally among channels by adjusting transmit power with time varying disturbances
  • Simple linear iterative algorithm (and variations on this theme)(Chraplyvy et al 1992)
  • Non-linear channel!!!!
  • Like to know
    • if non-linearity is significantly affecting performance
    • Origin of non-linearity
feedback loops
Feedback Loops
  • What do we measure and where?
    • BER
    • Channel Powers
    • OSNR
    • Dispersion
    • Non-linearity
    • Crosstalk
  • Local?
  • Central?
  • Tradeoffs between non linearity, dispersion and gain
  • How many channels?
  • Circuit switched or Packet switched?
  • Interaction with routing algorithms
control
Control..
  • THE WHOLE NETWORK – WORLD DOMINATION
  • Link by Link
  • Device by Device
point to point link impairments1
Tx

Chirp

Noise

Finite extinction ratio

Mux/Demux

Filter drift

Crosstalk

Transmission fibre

Loss

Dispersion

Nonlinear effects

Amplifiers

ASE/ Noise

Crosstalk

Wavelength dependent gain

Rx

Finite sensitivity

Noise

Bandwidth

Everywhere

PMD

Tx

Tx

Rx

Rx

Point to Point Link Impairments

DisCo

point to point link adjustments1

Tx

Tx

Rx

Rx

Point to Point Link Adjustments
  • Tx
    • Power, wavelength, chirp, modulation format, extinction ratio
  • MUX/DEMUX
    • Temperature
  • Amplifier
    • Gain, gain flattening filter, tilt
  • Dispersion compensation
  • Rx
    • Gain (APD or preamp gain)
    • Decision Threshold
    • Decision Point

DisCo

conclusion
Conclusion
  • Model network
  • Use standard control theory to construct a controller