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COBRA COBRA

Radio over Multimode Radio over Multimode FibreFibre NetworksNetworksTon Koonen, María García Larrodé, Hejie Yang

COBRA Institute dept. Electrical Engineering

Eindhoven University of Technologye-mail: a.m.j.koonen@tue.nl

Workshop on Optical/Wireless IntegrationOFC’08, San Diego, Feb. 25, 2008

COBRA COBRA

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COBRA COBRA OutlineOutline

In-home network architecture for integrated broadband services

Radio-over-MMF using the Optical Frequency Multiplying technique

OFM system experiments

Reconfigurable Radio-over-MMF networks

Concluding remarks

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COBRA COBRA Versatile BB inVersatile BB in--home networkshome networks

Converged in-homebackbone network,integrating wired &wireless services

reduces installation and maintenance effortseases introduction and upgrading of services

Coax Cable network

Twisted Pair network

RG

PCHDTVmobile

laptop

VoIP

faxprint PDA

mp3 download

Satellite dish/FWA dish

optical fibre

optical fibre

webcam

Optical Fibrenetwork

→ converged in-home network on POF

coax

POF

SMF

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COBRA COBRA Radio over Radio over FibreFibre

Optical FibreUnlimited bandwidth Low lossLight weightEM immunity

To increase capacity:Smaller cells more antenna sitesHigher frequencies more complexity

increase capacity big cells have to shrink

Radio over Fibre

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COBRA COBRA Radio over multimode Radio over multimode fibrefibre

“Optical Frequency Multiplying”low-cost technologysimple antenna stationsvery pure microwave → high wireless capacitydispersion-tolerant → for SMF and MMF

[A.M.J. Koonen, Patent NL 1019047]

fsw= 6.4 GHz

CWLD

+ϕ

-ϕ

- data

PD

fibrelink

λ0

fmm = 2N · fsw

Central Station Antenna Station

BPF

i(t)

τ

periodic filter

+ data

I

Q

120 Mbit/s64 QAM

@ 17.2 GHzafter 4.4 km

silica MMF

Freq. offset from 38.4 GHz carrier [Hz]

38.4GHz< 100Hz

RF p

ower

[dBm

] -30

-60

-90-500 0 +500

ϕ

[M. Garcia Larrode et al., EL 2006]

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COBRA COBRA OFM system analysisOFM system analysis

Monochromatic laser, optical frequency ω0 sinusoidally swept over range 2β⋅ωswwith sweep freq. ωswPeriodic bandpass filtering before the fibre (is equivalent to filtering after the fibre)MZI with Free Spectral Range ∆ΩFSR = 2π / τ , locked to laser freq. ω0 Neglecting fibre dispersion, photodiode output signal

containing even harmonic frequency components at 2k⋅ωsw with relative amplitude

and odd harmonic frequency components at (2k+1)⋅ωsw with relative amplitude

( ) ( )[ ] τωτωτωβ 021

21

0 )(cossin2cos1)( +−⋅⋅+⋅= tIti swsw

( ))sin(2)cos( 21

20 τωβτω swkJ ⋅⋅

( ))sin(2)sin( 21

120 τωβτω swkJ ⋅⋅ −

fibre

LDω0

BPFn·ωswPD

λ sweepsignal ωsw ampl.

i(t)

τMZI

+ϕ

-ϕ

+ data

- data

RFn·ωsw

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COBRA COBRA OFM generated microwave harmonics OFM generated microwave harmonics

-60

-50

-40

-30

-20

-10

0

1 2 3 4 5 6 7 8

β

pow

er n

th h

arm

onic

[dB

r]

n=1

2 34 5

61

-60

-50

-40

-30

-20

-10

0

1 2 3 4 5 6 7 8

β

pow

er n

th h

arm

onic

[dB

r]

n=1

2 34 5

61

Optical FM modulation index β to be optimised for max. power in preferred harmonic(e.g., βopt ≈ 6.3 for n=6, so for the 12 GHz harmonic)

Assumptions:- sweep freq. fsw=2 GHz- MZI FSR ∆νFSR =10 GHz- at each harmonic, ω0 τ is

optimised for max. power

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COBRA COBRA Impact of laser Impact of laser linewidthlinewidth

( ) ( )[ ] τδωτωτωτωβ ⋅++−⋅⋅+⋅= 021

21

0 )(cossin2cos1)( tIti swsw

Output signal of photodiode, assuming laser linewidth , and neglecting fibre dispersion

→ OFM effectively suppresses laser phase noise, provided that δωrms·τ << π / 2 i.e. laser linewidth is muchsmaller than a quarter of the FSR of the MZI ∆ωFSR = π / 2τ

OFM generates very pure microwave carriers

( )2δω

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COBRA COBRA Impact of MMF modal dispersionImpact of MMF modal dispersion

MMF small signal intensity modulation transfer function due to modal dispersion, neglecting chromatic dispersion

| HIM(ω) |= Φout(ω) / Φin(ω)where Φout(ω) is the Fourier transform of the output power signal Pout(t) of the MMF, and

Φin(ω) of the input power signal Pin(t)

neglecting chromatic dispersion, the impulse response of an MMF is a series of delayedimpulses from the individual modes→ frequency response | HIM(ω) | shows multiple lobes

without mode coupling: amplitudes of OFM generated harmonics can be shown to scalelinearly with | HIM(ω) |→ deploy the extended frequency response lobes of MMF(or the wide frequency response of a well-equalised graded-index MMF)with mode coupling: the MMF itself also contributes to the OFM process; → the MZI contribution dominates as long as its delay τ exceeds the MMF’sdifferential mode delays

[A.M.J. Koonen, A. Ng'oma, Wiley 2006][M. Garcia Larrode, A.M.J. Koonen, JLT 2008]

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COBRA COBRA HigherHigher--order transmission lobes in GIorder transmission lobes in GI--MMFMMF

-15

-10

-5

0

0.0E +00 5.0E +09 1.0E+10 1.5E+10 2.0E+10

fre q [Hz]

H_I

M [d

B]

simulationMMF length L=5 kmparabolic refr. indexcore dia. 50 µm

monochromatic sourceλ=1.3 µm

|HIM

(ω)|

[dB

]

freq. [Hz]5 G 10 G 15 G 20 G0

0

-5

-10

-15

full NA launching, NA=0.2negligible mode mixing

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COBRA COBRA 6464--QAM experiment over silica GIQAM experiment over silica GI--MMFMMF

fsw=2.867 GHz

PM IM SOA MZI

VSG

4.4 kmMMFBPF

17.2 GHzVSA

LNA PD

LD1.3 µm

µ-wave carrier freq. 17.2 GHz64-QAM on subcarrier freq. 127 MHzsymbol rate 20 MBaud → 120 Mbit/sover 4.4 km silica GI-MMFalso over 25 km SMF @ 39.9 GHzmulti-tone (up to 10 tones) 64-QAM operation at 18.3 GHz over the GI-MMF link shown

EVM = 4.8 % (< 5.6 % req.)

I

Q

[A. Ng’oma et al., OFC2005]

VSG = Vector Signal GeneratorVSA = Vector Signal Analyzer

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COBRA COBRA BiBi--directional systemdirectional system

freq.-division duplexupstream: TDMA, or SCMA,incl. MAC protocol

MMFlink

fsw

CWLD

+ϕ

-ϕ

- data down

λ0

Central Station

PDLPF

data up

+ data down

λ1

PD

Antenna Station

BPFfmm

xLPFLD

antenna

circulator

λ1

λ0

mixer

λ0λ1

WDM WDM

τ

periodic BPF

xfshift

fIF

-ϕ

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COBRA COBRA BiBi--directional OFM linkdirectional OFM link

Remote LO deliveryLow cost uplink

[M. Garcia Larrode et al, IEEE PTL 2006]

DL: 64-QAM, 24Mbit/s, at 5.8 GHz; fsc_DL=200MHzfLO=6 GHz4.4 km silica GI-MMFUL: 64-QAM, 24Mbit/s, at fIF_UL=200MHz

UL

5.8 GHz

DL

5.8 GHz

fsc_ULfsc_UL

200 MHz

6 GHz

3 GHz

MMF

200 MHz

fsc_DLfsc_DL fRF

n·fsw

fRF

n·fsw

6 GHz

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COBRA COBRA BiBi--dir. 16dir. 16--QAM experiment over GIQAM experiment over GI--POFPOF

downstream and upstream link: 100m 50µm core GI-POFPD BW=25 GHz, 50µm core MMFλdown = 1316 nmsweep freq. fsw = 2.867 GHzµ-wave carrier freq. 17.2 GHz (6th harmonic)subcarrier freq. 300 MHzsymbol rate 25 MBaud →100 Mbit/s

[A. Ng'oma et al., AP-MWP 2007]

Constellation diagramEVM=4.8% (<5.6%)

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COBRA COBRA InterInter--room room µµ--wave wireless communicationwave wireless communication

transparent for any wireless signal formatany-to-any room communicationmulti-casting

HCC: Home Communication Controller

fibres(POF)

accessnetwork

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COBRA COBRA WavelengthWavelength--routed routed RoMMFRoMMF networknetwork

[M. Garcia Larrode, A.M.J. Koonen, Trans. MTT 2008]

1300 1305 1310 1315 1320

−70

−60

−50

−40

wavelength, nm

Po, d

Bm

ADM−15drop port

1300 1305 1310 1315 1320

−70

−60

−50

−40

wavelength, nm

Po, d

Bm

ADM−15through port

RoMMF add/drop node(MMF FBG with BW=100 GHz)

drop and through portsDownlink: 120 Mbit/s 64-QAM, at 23.7 GHzUplink: 64-QAM, at fIF=300 MHz, with IM/DDλ1=1303.8 nm, λ2=1310.1 nm, λ3=1314.8 nm

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COBRA COBRA Concluding remarksConcluding remarks

Future-proof, versatile and high-capacity service provisioning of multiple services in in-home networks can efficiently be done using silica or polymermultimode fibre.

Radio-over-fibre facilitates the overlay of wireless communication services in a wired infrastructure, and the convergence of wirebound and wireless services in In-Home networks.

With the Optical Frequency Multiplying technique microwave radio signals with high spectral purity and high capacity can be generated, and transported over dispersive multimode (and single-mode) fibre links.

In combination with flexible wavelength routing, reconfigurable multi-standard wireless pico-cell LANs can be created.

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COBRA COBRA AcknowledgementAcknowledgement

Funding from

the European Commission, in FP7 project ALPHA – Architectures for fLexible Photonic Homeand Access networks,FP6 Network of Excellence e-Photon/ONe +,FP6 Network of Excellence ISIS,FP7 Network of Excellence BONE

the Dutch Ministry of Economic Affairs, in the IOP Generieke Communicatie projectsRoF Broadband In-House Systems and Future Home Networks

is gratefully acknowledged.