ITU-T Kaleidoscope 2009
Innovations for Digital Inclusion
RoFSO: A Universal Platform for
Convergence of Fiber and Free-Space
Optical Communication Networks
Kamugisha Kazaura1, Kazuhiko Wakamori2, Mitsuji Matsumoto2,
Takeshi Higashino3, Katsutoshi Tsukamoto3 and Shozo Komaki3
1Research
Institute for Science and Engineering, Waseda University
2Global Information and Telecommunication Institute, Waseda University
3Graduate School of Engineering, Osaka University
kazaura@aoni.waseda.jp
Mar del Plata, Argentina, 31 Aug – 1 Sep 2009
Contents
Overview of FSO systems
Proposed RoFSO system
Performance evaluation of RoFSO
system
Mobile cellular W-CDMA service
Wireless LAN service
Conclusion
Mar del Plata, Argentina, 31 Aug – 1 Sep 2009
ITU-T Kaleidoscope 2009 – Innovations for Digital Inclusion
2
Overview of FSO systems
FSO: Transmission of a modulated visible or infrared beam through the
atmosphere to obtain broadband communication.
Advs: Secure, easy to deploy, license free, high data rate.
Disadvs: Influenced by weather and can not propagate through obstacles.
New generation FSO system
Seamless connection of
free-space and fiber
Optical fiber
FSO
antenna
WDM FSO
channel
New generation FSO system
Uses 1550nm wavelength
Seamless connection of free-space
and optical fiber.
Multi gigabit per second data rates
(using optical fiber technology)
Compatibility with existing fiber
infrastructure
Protocol and data rate independent
Cellular
RoFSO
antenna
RoF
WDM RoFSO
channel
Various wireless
service signals
DVB
RoF
WiFi
WiMAX
Developed RoFSO system
Mar del Plata, Argentina, 31 Aug – 1 Sep 2009
ITU-T Kaleidoscope 2009 – Innovations for Digital Inclusion
Developed RoFSO system
Uses 1550nm wavelength
Transport multiple RF signals using
WDM RoFSO channels
Universal platform for providing
heterogeneous wireless services
e.g. WLAN, 3 GPP Cellular systems,
terrestrial digital TV etc
3
Proposed RoFSO system 1
Features of Radio-on-FSO technology
RoFSO = FSO + RoF
RoF: Technique of modulating RF subcarriers onto an optical carrier for
distribution over fiber network.
Advs: Transmission of RF signals at low costs, longer distance and low attenuation.
Disadvs: Dependent on availability of installed optical fiber.
Application areas
Metro network extension
Last mile access
Enterprise connectivity
Fiber backup
Interconnectivity of distributed
antenna systems
Internet
Mountainous terrain
Metro network
extension
RoFSO transceiver and
remote base station
Backhaul
(~5 km)
Areas with no
fiber connectivity
RoFSO link
Optical fiber link
RF based links
Remote located
settlements
Mar del Plata, Argentina, 31 Aug – 1 Sep 2009
ITU-T Kaleidoscope 2009 – Innovations for Digital Inclusion
RoFSO transceiver
Application scenario
4
Proposed RoFSO system 2
RoFSO terminal
Main transmit and
receive aperture
Si PIN QPD for
coarse tracking
Main transmit and
receive aperture
BS1
Collimator
BS2
SMF
FPM
Beacon signal
transmit aperture
Beacon signal
transmit aperture
InGaAs PIN QPD
for fine tracking
RoFSO antenna optical path and devices layout
RoFSO antenna photo
Specifications of the RoFSO antenna
Parameter
Beacon source
Specification
Operating wavelength band
1550 nm
Transmit power
100 mW (20 dBm)
Antenna aperture
80 mm
Coupling loss
5 dB
Beam divergence
± 47.3 µrad
Frequency range of operation
more than 5 GHz
Fiber coupling technique
Direct coupling using FPM
Tracking method
Automatic using QPD
Rough: 850 nm; Fine: 1550 nm
Key features:
Optimized for transmission of
RF signals with frequency range
of operation more than 5 GHz.
Can suppress most
atmospheric turbulence
induced effects like scintillation,
beam wander, AOA fluctuations
which have significant impact on
performance of RoFSO signal
propagating through free-space.
5
Performance evaluation of RoFSO system 1
RoFSO
antenna
RoFSO
antenna
Output
monitor
3dB
coupler
SMF
1 km
Optical IF unit
EDFA
EDFA
Optical IF unit
100 mW
Power
meter
2.5 Gbps
Opt. Tx.
Optical
SA
2.5 Gbps
Opt. Rx.
RF IF unit
RF IF unit
Atten. BERT
Data
logging PC
W-CDMA WLAN
SA
SA
RF circulator
ISDB-T
Power splitter
SA
5 GHz amplifier unit
WLAN
AP
TV
Bldg. 55S Okubo Campus
Filter
BERT
3GPP/WLAN/
ISDB-T SGs
Data
logging PC
WLAN throughput
measurement PC
Bldg. 14 Nishi Waseda Campus
SA: Signal Analyzer
SG: Signal Generator
Experimental setup for evaluation of the RoFSO system.
Mar del Plata, Argentina, 31 Aug – 1 Sep 2009
ITU-T Kaleidoscope 2009 – Innovations for Digital Inclusion
6
Performance evaluation of RoFSO system 2
RoFSO system experiment devices
ISDB-T IF
Unit
Bldg. 14 Nishi
Waseda campus
Weather
device
RoFSO
antenna
Digital Mobile Radio
Transmitter Tester
Optical IF
Unit
Spectrum
Analyzer
RF IF
Unit
802.11a
amplifier
Antenna tracking
adjustment PC
Optical
source
RF-FSO
antenna
Boost
EDFA
802.11a
IF Unit
Atmospheric effects
measurement antenna
Bldg. 55S Okubo campus rooftop
Atmospheric effects
recording PC
Devices setup on the rooftop
Bit Error Rate
Tester (BERT)
Opt. spectrum
Analyzer
Optical
power meter
Digital
Oscilloscope
Devices setup in the laboratory
Mar del Plata, Argentina, 31 Aug – 1 Sep 2009
ITU-T Kaleidoscope 2009 – Innovations for Digital Inclusion
7
Performance evaluation of RoFSO system 3
Wireless signal wavelength assignment
Channel #
Downlink
Uplink
Wavelength
Wireless service
Frequency
29
1554.13 nm
WLAN IEEE 802.11a
5.2 GHz
30
1553.33 nm
WLAN IEEE 802.11g
2.4 GHz
31
1552.52 nm
Cellular W-CDMA
2 GHz
32
1551.72 nm
ISDB-T*1
473 MHz
33
1550.92 nm
Free*2
34
1550.12 nm
Cellular W-CDMA
2 GHz
35
1549.32 nm
WLAN IEEE 802.11g
2.4 GHz
36
1548.52 nm
WLAN IEEE 802.11a
5.2 GHz
Received WDM spectrum
ISDB-T
W-CDMA 802.11g 802.11a
1551.72 1552.52 1553.33 1554.13
nm
nm
nm
nm
Note:
*1ISDB-T: Integrated Services Digital
Broadcasting – Terrestrial is Japanese
standard for digital television (DTV).
*2 Channel 33 is used for evaluating the
RoFSO system performance in terms of
BER by transmitting digital signal at 2.5
Gbps.
8
Performance evaluation of RoFSO system 4
Mobile cellular W-CDMA service
23rd December 2009
60
0
5 MHz offset
Received power
-5
45dB
50dB
10 MHz offset
Received W-CDMA signal ACLR
spectrum (3GPP Test Signal)
ACLR [dB]
ACLR (-10 MHz offset)
50
-10
45
-15
ACLR (-5 MHz offset)
40
-20
35
ACLR -10 MHz offset -25
ACLR -5 MHz offset
Received power (dBm)
-30
15:00
18:00
21:00
24:00
30
0:00
03:00
06:00
09:00
12:00
Time
ACLR and received optical power characteristics
ACLR is a quality metric parameter specified by the 3GPP for evaluating W-CDMA signal transmission.
3GPP specifies ACLR value of 45 dB at 5 MHz offset and 50 dB at 10 MHz offset.
ACLR: Adjacent Channel Leakage Ratio
Mar del Plata, Argentina, 31 Aug – 1 Sep 2009
ITU-T Kaleidoscope 2009 – Innovations for Digital Inclusion
9
Received power (dBm)
55
Performance evaluation of RoFSO system 5
Wireless LAN service
20th December 2008
20
WLAN 802.11g spectrum mask
2.4 GHz with 54 Mbps, 64 QAM
Rx throughput
-4
12
8
-8
Tx trhoughput
-12
Received power
4
0
0:00
Received power(dBm)
Template: Pass
Throughput (Mbps)
16
0
-16
Tx throughput (Mbps)
Rx throughput (Mbps)
Received power (dBm)
03:00
06:00
09:00
12:00
15:00
18:00
21:00
-20
24:00
Time
Template: Fail
WLAN 802.11a spectrum mask
5 GHz with 54 Mbps, 64 QAM
WLAN 802.11g throughput and received
optical power characteristics
10
Conclusion
Presented a new innovative broadband wireless communication
system based on RoFSO suitable for application as universal
platform for providing convergence of fiber and free-space.
Transmission performance evaluation of the proposed RoFSO system
has demonstrated consistent performance in terms of specified
quality metric parameters for the various wireless service
signals in the absence of severe weather conditions and using
properly design interface units.
Confirmed that the technology is well suited for deployment as an
advanced wireless communication system in the emerging NGN
having potential to play a key role in Digital Inclusion.
For rapid maturity and adaptation of the technology, early
initiatives for standardization studies will be beneficial.
Future work involves further experiments with redesigned interface
units and in different weather conditions to derive data for the
system design optimization and performance enhancement.
Mar del Plata, Argentina, 31 Aug – 1 Sep 2009
ITU-T Kaleidoscope 2009 – Innovations for Digital Inclusion
11
Supported by
This work was supported by a grant from the National Institute of Information and
Communications Technology (NICT) of Japan
Thank you for your attention!
Kamugisha Kazaura
kazaura@aoni.waseda.jp
Mar del Plata, Argentina, 31 Aug – 1 Sep 2009
ITU-T Kaleidoscope 2009
Innovations for Digital Inclusion
RoFSO: A Universal Platform for
Convergence of Fiber and Free-Space
Optical Communication Networks
Kamugisha Kazaura1, Kazuhiko Wakamori2, Mitsuji Matsumoto2,
Takeshi Higashino3, Katsutoshi Tsukamoto3 and Shozo Komaki3
1Research
Institute for Science and Engineering, Waseda University
2Global Information and Telecommunication Institute, Waseda University
3Graduate School of Engineering, Osaka University
kazaura@aoni.waseda.jp
Mar del Plata, Argentina, 31 Aug – 1 Sep 2009
Backup slides
Performance evaluation of RoFSO system
Experimental field
Bldg. 14 Waseda University
Waseda Campus
1 km
Bldg. 55 Waseda University
Nishi Waseda Campus
Satellite view of the test area
Mar del Plata, Argentina, 31 Aug – 1 Sep 2009
ITU-T Kaleidoscope 2009 – Innovations for Digital Inclusion
Source: Google earth
15
Overview of FSO systems
Atmospheric turbulence has a significant impact on the quality of the
optical wireless beam propagating through the atmosphere.
Transmit
power
Time
Time
Received
power
Beam wander
Scintillation
Time
Time
Combined
effect
Time
Reduces the optical beam power at the
receiver point and causes burst errors
Geneva, 12-13 May 2008
First ITU-T Kaleidoscope Conference – Innovations in NGN
Other effects include
Beam broadening and
Angle-of-arrival
fluctuations
Mitigation techniques
include:
Aperture averaging
Diversity techniques
Adaptive optics
Coding techniques
Fast tracking technique
16
Performance evaluation of RoFSO system
Digital signal transmission
10
10
BER
10
10
10
10
3 November 2008
0
0
-2
-10
-4
-20
Burst errors
-6
-30
-8
-40
-10
-50
7
-12
Test pattern: PRBS 2. - 1
Data rate: 2.5 Gbps
0:00
03:00
06:00
BER
Received power (dBm)
09:00
12:00
Time
15:00
18:00
21:00
Received power (dBm)
10
Continuous error free
transmission BER of 10-12.
Stable optical received
power average –10 dBm.
Receiver sensitivity –27
dBm.
Occasional bursts errors
are recorded due to
insufficient tracking
dynamic range
-60
24:00
Received signal BER and received optical
power characteristics.
17
Performance evaluation of RoFSO system
Terrestrial digital TV broadcasting service
ISDB-T Transmission parameters.
Parameter
Value
Mode
3
Guard interval
1/8
Layer
A
B
Number of segments
1
12
Modulation scheme
16 QAM
64 QAM
Convolution code rate
1/2
7/8
Time interleaving
0
1
Required CNR (dB)
11.5
22.2
Ch 13
Ch 14
Movie
Clip
Test
pattern
Layer A 1seg video
6 MHz
offset
Received ISDB-T signal spectrum
Layer B 12-segment video
18
Performance evaluation of RoFSO system
Terrestrial digital TV broadcasting service
12th January 2009
30
0
25
-5
MER [dB]
20
Layer A – 1 seg (16QAM)
-10
MER Layer A
15
-15
Received power
10
5
0
0:00
-20
-25
MER Layer A
MER Layer B
Received power (dBm)
03:00
06:00
09:00
Received power (dBm)
MER Layer B
12:00
Time
15:00
18:00
21:00
-30
24:00
ISDB-T MER and received optical power
characteristics.
Standard specifies a minimum required MER values for
Layer A to be 11.5 and Layer B to be 11.5 dB and 22.2 dB.
Layer B – 12 segnment (64QAM)
19
Introduction 1
Features of ISDB-T
ƒ
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ISDB-T is one of international standard
for terrestrial digital television
broadcasting format developed and
adopted in Japan.
Provides reliable high-quality video,
audio and data broadcasting for both
fixed and mobile receivers.
Operates in the UHF band at frequencies
between 470 MHz and 770 MHz, with
total bandwidth of 300 MHz divided into
50 channels.
Each channel is further divided into 13
OFDM segments which includes a single
segment (Layer A) for mobile receivers
and remainder 12 segments (Layer B) for
HDTV.
CH13
CH14
CH62
479MHz
767MHz
6MHz
473MHz
ISDB-T frequency band
Layer A
(LDTV, Audio,
Data)
13 segments
(6 MHz bandwidth)
Layer B
(HDTV or 3 SDTV
with data)
frequency
Started in Japan at the end of 2003 with
complete switchover planned in July 2011.
For complete national coverage various
Handheld reception
Fixed and mobile
(1seg service)
reception (HDTV, etc)
delivery systems will be required and are
ISDB-T channel segments and services
under consideration.
Mar del Plata, Argentina, 31 Aug – 1 Sep 2009
ITU-T Kaleidoscope 2009 – Innovations for Digital Inclusion
20
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