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IGC 3009
Full-service access network
using multimode fibre
Ton Koonen, Jianming Zeng, Henrie van den Boom – TU/e
Kees van Bochove, Robert Taniman - UT
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Final Symposium IOP GenCom ‘Een Wereld voorbij WiFi’
- Evoluon, Eindhoven, Nov. 20, 2014
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COBRA
Goal
1
To develop cost-effective techniques for integration of multiple
groups of services in a short-range (Fibre to the Home) network
based on multimode optical fibre
Single-mode optical fibre
Laser diode
9 m
Lens system and connector/splice with very high accuracy is required for
high coupling efficiency.
Multimode optical fibre
displacement
50 m core
Laser diode
Easier alignment; less impact of misalignment, and of
scratches/dust particles
But: MMF has low-pass
characteristic due to
modal dispersion 
COBRA
Subcarrier multiplexing
2
Use multimode fibre beyond its low-pass band: use higher-order lobes
of its characteristic for transporting multiple groups of services
0.62
GHz
0
3.0 5.47
GHz GHz
20GHz
COBRA
Subcarrier multiplexed FttH network
data down
analogue
headend node
3
user nodes
amplifier
+ filter
x
f
LO f1
(VCO)
digital
POF
x
f-mux
f
...
LO
f2
CWDM
CWDM
x
x
data up 2
data up N
x
data up 1
f-demux
LO
LO fN
LO f1 control
PD
f
selected channel
data down
LO
control
LO
x
f
amplifier
+ filter
PD
LD
data up
LD
x
x

Realised system demonstrations:
1.25Gbit/s transmission at 3GHz subcarrier
15.3Gbit/s with 16-QAM, 64-QAM and 256-QAM over 4.4km MMF

Heuristic subcarier assignment algorithm

Stable-matching based subcarrier assignment with bit loading
COBRA
Multi-subcarrier M-QAM transmission setup
Baseband M-QAM
generation
(offline processing)
4
I
RF
Mod
ARB
Q
1310 nm
DFB
Optical
Attenuator
Vector Signal
Analyzer
Amplifier
Photo
diode
Multimode
Fibre
Eye and constellation
diagram of a
subcarrier channel
COBRA
5
COBRA

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