COBRA
COBRA
Radio over Multimode Fibre Networks
Ton Koonen, María García Larrodé, Hejie Yang
COBRA Institute
dept. Electrical Engineering
Eindhoven University of Technology
e-mail: a.m.j.koonen@tue.nl
Workshop on Optical/Wireless Integration
OFC’08, San Diego, Feb. 25, 2008
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Outline
COBRA
z
In-home network architecture for integrated broadband
services
z
Radio-over-MMF using the Optical Frequency
Multiplying technique
z
OFM system experiments
z
Reconfigurable Radio-over-MMF networks
z
Concluding remarks
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Versatile BB in-home networks
COBRA
Converged in-home
backbone network,
integrating wired &
wireless services
z reduces installation and
maintenance efforts
z eases introduction and
upgrading of services
Satellite dish/
FWA dish
optical
fibre
webcam
mobile
POF
Optical Fibre
network
Coax Cable
network
PC
optical
fibre
Twisted Pair
network
coax
laptop
HDTV
VoIP
RG
mp3
download
fax
print
PDA
SMF
→ converged in-home network on POF
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Radio over Fibre
COBRA
increase capacity Ö
big cells have to
shrink
To increase capacity:
Smaller cells Æ more antenna sites
Higher frequencies Æ more complexity
Optical Fibre
Unlimited
bandwidth
Low loss
Light weight
EM immunity
Radio over
Fibre
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Radio over multimode fibre
COBRA
fsw
+ data
= 6.4 GHz
CW
LD
ϕ
λ0
+ϕ
periodic
filter
τ
Antenna Station
fmm = 2N · fsw
fibre
link
PD
BPF
-ϕ
i(t)
- data
“Optical Frequency Multiplying”
z low-cost technology
z simple antenna stations
z very pure microwave → high wireless capacity
z dispersion-tolerant → for SMF and MMF
RF power [dBm]
Central Station
-30 38.4GHz
< 100Hz
-60
-90
-500
0
+500
Freq. offset from 38.4 GHz carrier [Hz]
120 Mbit/s
64 QAM
@ 17.2 GHz
after 4.4 km
silica MMF
[A.M.J. Koonen, Patent NL 1019047]
[M. Garcia Larrode et al., EL 2006]
I
Q
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OFM system analysis
COBRA
λ sweep
signal ωsw
+ data
+ϕ
LD
ω0
fibre
τ
z
z
z
PD
ampl.
RF
n·ωsw
-ϕ
i(t)
- data
z
BPF
n·ωsw
MZI
Monochromatic laser, optical frequency ω0 sinusoidally swept over range 2β⋅ωsw
with sweep freq. ωsw
Periodic 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
i (t ) = I 0 ⋅ { 1 + cos[2 β ⋅ sin ( 12 ω swτ ) ⋅ cos (ω sw (t − 12 τ ) ) + ω 0τ ] }
containing even harmonic frequency components at 2k⋅ωsw with relative amplitude
(
cos(ω 0τ ) ⋅ J 2 k 2 β ⋅ sin( 12 ω swτ )
)
and odd harmonic frequency components at (2k+1)⋅ωsw with relative amplitude
(
sin(ω 0τ ) ⋅ J 2 k −1 2 β ⋅ sin( 12 ω swτ )
)
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OFM generated microwave harmonics
th
power nnth harmonic
harmonic[dBr]
[dBr]
power
COBRA
00 nn==11
z
-10
-10
-20
-20
-30
-30
22
-40
-40
66
-50
-50
33
11
44
Assumptions:
- sweep freq. fsw=2 GHz
- MZI FSR ∆νFSR =10 GHz
- at each harmonic, ω0 τ is
optimised for max. power
55
-60
-60
11
22
33
44
55
66
77
88
ββ
z
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)
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Impact of laser linewidth
COBRA
z Output signal of photodiode, assuming laser linewidth
(δω )2 , and
neglecting fibre dispersion
i (t ) = I 0 ⋅ { 1 + cos[2 β ⋅ sin ( 12 ω swτ )⋅ cos (ω sw (t − 12 τ ) ) + ω 0τ + δω ⋅τ ] }
→ OFM effectively suppresses laser phase noise,
provided that δωrms·τ << π / 2 i.e. laser linewidth is much
smaller than a quarter of the FSR of the MZI ∆ωFSR = π / 2τ
Î OFM generates very pure microwave carriers
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Impact of MMF modal dispersion
COBRA
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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)
z
neglecting chromatic dispersion, the impulse response of an MMF is a series of delayed
impulses from the individual modes
→ frequency response | HIM(ω) | shows multiple lobes
z
without mode coupling: amplitudes of OFM generated harmonics can be shown to scale
linearly with | HIM(ω) |
→ deploy the extended frequency response lobes of MMF
(or the wide frequency response of a well-equalised graded-index MMF)
z
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’s
differential mode delays
[A.M.J. Koonen, A. Ng'oma, Wiley 2006]
[M. Garcia Larrode, A.M.J. Koonen, JLT 2008]
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Higher-order transmission lobes in GI-MMF
COBRA
H_IM [dB]
| HIM(ω) | [dB]
00
-5-5
-10
-10
-15
-15
0
0.0E + 00
5G
5.0E + 09
10 G
1.0E + 10
freq. [Hz]
fre q [Hz ]
15 G
1.5E + 10
20 G
2.0E + 10
simulation
MMF length L=5 km
parabolic refr. index
core dia. 50 µm
full NA launching, NA=0.2
negligible mode mixing
monochromatic source
λ=1.3 µm
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64-QAM experiment over silica GI-MMF
COBRA
z
fsw=2.867 GHz
z
VSG
z
LD
1.3 µm
z
PM
IM
SOA
z
MZI
z
LNA
VSA
PD
BPF
17.2 GHz
µ-wave carrier freq. 17.2 GHz
64-QAM on subcarrier freq. 127 MHz
symbol rate 20 MBaud → 120 Mbit/s
over 4.4 km silica GI-MMF
also over 25 km SMF @ 39.9 GHz
multi-tone (up to 10 tones) 64-QAM
operation at 18.3 GHz over the
GI-MMF link shown
4.4 km
MMF
I
VSG = Vector Signal Generator
VSA = Vector Signal Analyzer
Q
[A. Ng’oma et al., OFC2005]
EVM = 4.8 % (< 5.6 % req.)
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Bi-directional system
COBRA
Central Station
fsw
CW
LD
+ data down
-ϕ
λ0
Antenna Station
MMF
link
periodic
BPF
τ
+ϕ
WDM
-ϕ
antenna
λ0
λ0
λ1
PD
circulator
fshift
x
LPF
x
LD
λ1
PD
LPF
BPF
WDM
- data down
data up
fmm
fIF
mixer
λ1
freq.-division duplex
z upstream: TDMA, or SCMA,
incl. MAC protocol
z
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Bi-directional OFM link
COBRA
n·fsw
fsc_DL
fRF
6 GHz
200 MHz
DL
5.8 GHz
UL
MMF
3 GHz
5.8 GHz
6 GHz
z Remote
z Low
LO delivery
fsc_UL
cost uplink
200 MHz
DL: 64-QAM, 24Mbit/s, at 5.8 GHz; fsc_DL=200MHz
fLO=6 GHz
4.4 km silica GI-MMF
UL: 64-QAM, 24Mbit/s, at fIF_UL=200MHz
[M. Garcia Larrode et al, IEEE PTL 2006]
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Bi-dir. 16-QAM experiment over GI-POF
COBRA
z
z
z
z
z
z
z
downstream and upstream link:
100m 50µm core GI-POF
PD BW=25 GHz, 50µm core MMF
λdown = 1316 nm
sweep freq. fsw = 2.867 GHz
µ-wave carrier freq. 17.2 GHz
(6th harmonic)
subcarrier freq. 300 MHz
symbol rate 25 MBaud →
100 Mbit/s
Constellation diagram
EVM=4.8% (<5.6%)
[A. Ng'oma et al., AP-MWP 2007]
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Inter-room µ-wave wireless communication
COBRA
access
network
fibres
(POF)
HCC: Home Communication Controller
z
z
z
transparent for any wireless signal format
any-to-any room communication
multi-casting
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Wavelength-routed RoMMF network
COBRA
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RoMMF add/drop node
−40
−50
−50
Po, dBm
−40
o
P , dBm
(MMF FBG with BW=100 GHz)
−60
−70
ADM−15
drop port
1300
z
z
z
Downlink: 120 Mbit/s 64-QAM, at 23.7 GHz
Uplink: 64-QAM, at fIF=300 MHz, with IM/DD
λ1=1303.8 nm, λ2=1310.1 nm, λ3=1314.8 nm
z
1305
1310
1315
wavelength, nm
−60
−70
1320
ADM−15
through port
1300
1305
1310
1315
wavelength, nm
1320
drop and through ports
[M. Garcia Larrode, A.M.J. Koonen, Trans. MTT 2008]
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Concluding remarks
COBRA
O
Future-proof, versatile and high-capacity service provisioning of multiple
services in in-home networks can efficiently be done using silica or polymer
multimode fibre.
O
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.
O
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.
O
In combination with flexible wavelength routing, reconfigurable multi-standard
wireless pico-cell LANs can be created.
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Acknowledgement
COBRA
Funding from
z
the European Commission, in
FP7 project ALPHA – Architectures for fLexible Photonic Home
and Access networks,
FP6 Network of Excellence e-Photon/ONe +,
FP6 Network of Excellence ISIS,
FP7 Network of Excellence BONE
z
the Dutch Ministry of Economic Affairs, in
the IOP Generieke Communicatie projects
RoF Broadband In-House Systems and
Future Home Networks
is gratefully acknowledged.
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