Supported by KRK/OpenAccess2007 - Bagamoyo/14th Nov 2007 RoFSO: An Enabling Technology for Heterogeneous Broadband Networks Kamugisha KAZAURA 1,Edward

KRK/OpenAccess2007 - Bagamoyo/14th Nov 2007

Supported by

RoFSO: An Enabling Technology for Heterogeneous Broadband Networks

Kamugisha KAZAURA1,Edward MUTAFUNGWA1, Pham DAT1, Alam SHAH1,Toshiji SUZUKI1, Kazuhiko WAKAMORI1, Mitsuji MATSUMOTO1,

Takeshi HIGASHINO2, Katsutoshi TSUKAMOTO2 and Shozo KOMAKI2

1GITS/GITI, Waseda University, Honjo2Osaka University, Osaka

[email protected]


Supported by

Introduction FSO and RoFSO technology FSO system performance

consideration Experiment setup and results Summary

Contents


Supported by

Kenya

Tanzania

Uganda

Rwanda

Burundi

10,292,000

6,720,072

2,872,000

422,700

347,000

Mobile phone users in EA The telecommunication landscape if dominated by mobile phone users who account for almost 20.7 million users in the region– source the mobile world as of June 2007.

Technologies include: GSM, GPRS/EDGE 3 G, WCDMA, Ev-DO

(CDMA2000) 3.5 G HSDPA and/or HSUPA ??? 4 G WiMAX ???

Convenient technology for rapid provision of ICT and services to rural communities.

Wireless communication systems 1


Supported by

Global

Suburban

Macro-Cell

Urban

Micro-Cell

In-Building

Pico-Cell

Home-Cell

Personal-Cell

Wireless systems are not only limited to mobile phone technology!



Supported by


UWB

Full-opticalFSO system10 Gbps

MM wave communication

1 Gbps

100 Mbps

10 Mbps

1 Mbps

100 Kbps

1 km100 m

WiMAX

10 m 10 km1 m

Bluetooth

ZigBee

WLANa/b/g

Optical fiber communication

Communication distance

Personal areaCommunication

Optical WLAN

IrDAPAN

Long distance communication

Data rate

Visible light communications

100 km

FSO communication


Supported by

Overview of FSO/RoFSO communicationsFSO is the transmission of modulated visible or infrared (IR) beams through the atmosphere to obtain broadband communications.RoFSO contains optical carriers modulated in an analogue manner by RF sub-carriers.

Cosmic radiation T radiation V radiation IR radiation Communications radiation

X ray radiation Microwave, radar TV VHF SW

Frequency (Hz) 1020 1018 1016 1014 1012 1010 108 106

250 THz (1 THz) (1 GHz) (1 MHz)

(1 pm) (1 nm) (1 μm) (1 mm) (1 m) (100 m)

Wavelength (m) 10-12 10-9 10-6 10-3 100 102

0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2 1.3 1.4 1.5 1.6 μm

670 780 850 1300 1550 1625 nm

Visible light

Fiber transmissionwavelength range

λ = wavelengthf = frequency

C0 = 300 000 km/sC = λ x f

Visible light

Electromagnetic spectrum

Merits Secure wireless system not easy to

intercept Easy to deploy, avoid huge costs

involved in laying cables License free Possible for communication up to

several kms Can transmit high data rate

De merits High dependence on weather

condition (rain, snow, fog, dust particles etc)

Can not propagate through obstacles Susceptible to atmospheric

effects (atmospheric fluctuations)


Supported by

FSO technology application scenarios

Mountainous terrain

Backhaul(~5 km)

FSO transceiver andremote base station

Metro network extension

Remote locatedsettlements

FSO linkOptical fiber linkRF based linksFSO transceiver

Areas with nofiber connectivity

Internet

Space station

Inter-satellite link

Data relay satellite

Ground stationwith adaptive optics

Fiber optic link

Demonstration of 2.5 Gbps link

High-speed (10Gbs) optical feeder link

Terrestrial Metro network extension Last mile access Enterprise connectivity Fiber backup Transmission of

heterogeneous wireless services

Space Inter-satellite

communication (cross link) Satellite to ground data

transmission (down link) Deep space communication


Supported by

Conventional FSO system Operate near the 800nm wavelength

band Uses O/E & E/O conversion Data rates up to 2.5 Gbps Bandwidth and power limitations

New full-optical FSO system Uses 1550nm wavelength Seamless connection of space and

optical fiber. Multi gigabit per second data rates

(using optical fiber technology) Compatibility with existing fiber

infrastructure Protocol and data rate independent

Advanced DWDM RoFSO system Uses 1550nm wavelength Transport multiple RF signals using

DWDM FSO channels Realize heterogeneous wireless

services e.g. WLAN, Cellular, terrestrial digital TV etc

FSO technology

Optical fiber O/EE/O

module

O/EE/O

module

FSO

FSO antenna

(a) Conventional FSO systemDirect coupling of free-space

beam to optical fiber

WDM FSOOptical fiber

FSO antenna

(b) New full-optical FSO system

Heterogeneous wireless service signals

RoF RoF

DWDM RoFSOchannel

Direct connection between RoF and optical free-space

RoFSO antenna

DVB

WiFi

WiMAX

Cellular

(c) Advanced DWDM RoFSO system


Supported by

Evaluation of FSO/RoFSO systems

FSO/RoFSOperformance

Internal parameters(design of FSO/RoFSO

system)

External parameters(non-system specific

parameters)

VisibilityAtmospheric attenuationScintillationDeployment distancePointing loss

Optical powerWavelengthTransmission bandwidthDivergence angleOptical lossesBERReceive lens diameter & FOVRF efficiencyDynamic rangeSNR

Performance related parameters


Supported by

Reduces the optical beam power at the receiver point and causes burst errors

Beam wander

Intensity fluctuations (Scintillation )

Time

Time

Transmit power

Received power

Combined effect

Time

Time

Time

Atmospheric turbulence has a significant impact on the quality of the free-space optical beam propagating through the atmosphere.

Other effects include:

- beam broadening and

- angle-of-arrival fluctuations

Mitigation techniques include:

- Aperture averaging

- Diversity techniques

- Adaptive optics

- Coding techniques

Deployment environment characteristics


Supported by

Experiment devices and setupbeacon beam

output windows

fiber connection port

primary mirror

secondary mirrorFPM

collimation mirror

QAPD/QPD

(a) Optical antenna internal structure

BERT

Power meter

Weather data recording PC

Scintillation data recording PC

Fiber amplifier

CCD monitor

Remote adjustment & monitor PC

Optical clock/data receiver & transmitter

(d) Experimental hardware setup

Bldg. 55 Waseda University Okubo Campus

Bldg. 14 Waseda University Nishi Waseda Campus

1 km

(b) Experiment filed

RF-FSO Canobeam DT-170 antenna

Atmospheric effects measurement antenna

(c) Rooftop setup


Supported by

Experimental results 1

2.5 Gbps transmission

0:00 3:00 6:00 9:00 12:00 15:00 18:00 21:00 24:0010

-12

10-10

10-8

10-6

10-4

10-2

100

Time

0

10

20

30

40

50

60Bit error rateReceived power (dBm)

Temperature (C)

Visibility (km)

Date: 30 October 2005

Lo

g(B

ER

)

Error free

Te

mp

era

ture

( C)/

Vis

ibili

ty (

km)

0

-10

-20

-30

Re

ceiv

ed

po

we

r (d

Bm

)

10 Gbps transmission

18:00 20:00 22:00 24:00 02:00 04:00 06:0010

-12

10-10

10-8

10-6

10-4

10-2

100

Time

0

10

20

30

40

50

60Bit error rateReceived power (dBm)

Temperature (C)

Visibility (km)

Lo

g(B

ER

)

Error free

Te

mp

era

ture

( C)/

Vis

ibili

ty (

km)

0

-10

-20

-30

Re

ceiv

ed

po

we

r (d

Bm

)

Date: 26 ~ 27 January 2006

Communication system performance evaluation setup

Transmission quality performance evaluation


Supported by

Experimental results 2

Cn2 September 2005 (Summer)

Strongest Cn2 (noon): 3.35•10-13 m-2/3

Minimum Cn2 (sunrise): 1.10•10-16 m-2/3

Cn2 January 2006 (Winter)

Most Cn2 values less than 1•10-13 m-2/3

Noon maximum value of Cn2

changed by a factor of 2.3

0:00 03:00 06:00 09:00 12:00 15:00 18:00 21:00 24:0010

-16

10-15

10-14

10-13

10-12

Re

fra

ctiv

e in

de

x st

ruct

ure

Cn2 (

m-2

/3)

Local time

September 2005

0:00 03:00 06:00 09:00 12:00 15:00 18:00 21:00 24:0010

-16

10-15

10-14

10-13

10-12

Re

fra

ctiv

e in

de

x st

ruct

ure

Cn2 (

m-2

/3)

Local time

January 2006

Typical Cn2 values – measured for

one month (different seasons)

Refractive-index structure constant parameter, Cn2

The most critical parameter along the propagation path in characterizing the effects of atmospheric turbulence


Supported by

RF-FSOantenna

RF-FSOantenna

Bldg. 14 Nishi Waseda Campus

Bldg. 55S Okubo Campus

1 km

Signal generator(Agilent E4438C)

Signal analyzer(Anritsu MS2723B)

Atmospheric turbulence

RF-FSO Canobeam DT-170 antenna

Atmospheric effects measurement antenna

Weather measurement device

Bldg. 14 Nishi Waseda campus

Bldg. 55S Okubo campus

Parameter Specification

Operating wavelength 785 nm

Transceiver aperture 100 mm

Beam divergence ± 0.5 μrad

Tracking method Automatic tracking

Parameter Specification

Input power - 5 dBm

Center frequency 120 MHz

Resolution bandwidth 30 kHz

WCDMA test model Test Model 1 w/64 DPCH

Experimental setup for RF signal transmission

RF-FSO antenna specification

WCDMA signal tx test parameters


Supported by

Evaluation of RF signal transmission quality 1

0

2

4

6

8

10

12

14

16

18

20

Vis

ibili

ty (

km)

0

2

4

6

8

10

12

14

16

18

20

Te

mp

era

ture

( C)

0

2

4

6

8

10

12

14

16

18

20

Pre

cip

itatio

n (

mm

/hr)

0:00 03:00 06:00 09:00 12:00 15:00 18:00 21:00 24:0090

95

100

105

110

115

120

125

130

Time (Hr)

CN

R (

dB

) CNRavg

CNRmin

VisibilityTemperaturePrecipitation

Date: 30.09.2007

Measure and log WCDMA signal quality metrics like ACLR, EVM and PCDE.

Correlate performance with weather conditions and atmospheric effects related characteristics like Cn

2. This work is ongoing.

Example performance related characteristics during rain event 30th Sept


Supported by

Evaluation of RF signal transmission quality 2

09:00 10:00 11:00 12:0045

46

47

48

49

50

51

52

53

54

55

AC

LR

(d

B)

ACLR at -5 MHz offset (dB)Precipitation (mm/hr)

0

1

2

3

4

5

6

7

8

9

10

Pre

cip

itatio

n (

mm

/hr)

Time (Hr)

Date: 30.09.2007

107.5112.5117.5122.5127.5132.5-90

-80

-70

-60

-50

-40

-30

-20

-10

Frequency (MHz)

Re

ce

ive

d p

ow

er

(dB

)

107.5112.5117.5122.5127.5132.5-90

-80

-70

-60

-50

-40

-30

-20

-10

Frequency (MHz)

Re

ce

ive

d p

ow

er

(dB

)

Clear weather In presence of rainfall

Center freq. 120 MHz Center freq. 120 MHz

Clear weather Presence of rainfall

WCDMA received signal spectrum

ACLR variation during rainfall


Supported by

Summary

Successfully developed and demonstrated a full-optical FSO communication system operating at 1550 nm capable of offering stable and reliable transmission at 10 Gbps.

This technology is suitable for rapid provisioning of broadband access technology in remote and underserved areas.

Measured, characterized and quantified the effects of atmospheric turbulence in the deployment environment necessary for design, evaluation and comparison of FSO systems in actual operational settings.

Develop a innovative DWDM RoFSO link for heterogeneous wireless services transmission (multiple RF signals)


Supported by

Ahsanteni sana kwa kunisikiliza.

This work is supported by a grant from the

Acknowledgement:Supported by


Supported by

Backup slides


Supported by

Comparisons of RF and FSO based systems

Parameter RF IR (FSO) Implications

Max bandwidth Limited Unlimited

Subject to regulations

Yes No Delays

Propagation through obstacles

Yes No

Dominant noise Other users

Background

Limits range

Threshold - 60 dBm - 40 dBm LMDS easier with RF

Weather effects Rain Fog Up to –120 dB/km

Side lobes Yes No Interference

Health issue Possible No Eye safety limits


Supported by

DWDM RoFSO antennaBS1

Si PIN QPD

InGaAs PIN QPD

FPM

BS2

Fiber collimator

Parameter Value

Communication wavelength 1550 nm

Beacon wavelength 850 nm

Antenna aperture 80 mm

Coupling losses 5 dB

Optical system components showing optical paths

Photo of new DWDM RoFSO antenna

Antenna specifications


Supported by

Cn2 measurement

2

2

2

I

III

6/116/722 5.0 LkCnI

Where:

σI2 scintillation index (normalized variance of

irradiance fluctuations)

I optical wave irradiance

Cn2 (m-2/3)index of refraction structure parameter

k optical wave number (k=2π/λ) (785 nm)

L (m) propagation path length (1,000 m)

Scintillation theory

The variance of the log-amplitude fluctuations, σA2 can be related to the Cn

2.

For horizontal path considering a spherical wave the following relations are

applicable in determining Cn2:

Normalized intensity variance


Supported by

Results and analysis 3

MonthMeasured Cn

2 values (in m-2/3) - Midday

Cn2 > 1•10-13 1•10-14 < Cn

2 < 1•10-13

Sept. ’05 28.12% 71.88%

Jan. ‘06 Less than 2%

Sunrise: 04:30 ~ 06:30

Midday: 11:00 ~ 13:00

Night: 21:00 ~ 24:00

10-16

10-15

10-14

10-13

10-12

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

SunriseNoonNightC

um

ula

tive

fre

qu

en

cy o

f occ

urr

en

ceRefractive index structure C

n2 (m-2/3)

January 2006

10-16

10-15

10-14

10-13

10-12

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

SunriseNoonNightC

um

ula

tive

fre

qu

en

cy o

f occ

urr

en

ce

Refractive index structure Cn2 (m-2/3)

September 2005 Cumulative frequency of occurrence


Supported by

Results and analysis 4

MonthMeasured Cn

2 values (in m-2/3)

Cn2 > 6•10-14 6•10-15 < Cn

2 < 6•10-14

Sept. ’05 16.12% 41.06%

Nov. ‘05 4.98% 42.48%

Jan. ‘06 2.91% 44.83%

Mar. ‘06 14.42% 41.67%

10-16

10-15

10-14

10-13

10-12

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

Sep 2005Nov 2005Jan 2006Mar 2006C

um

ula

tive

fre

qu

en

cy o

f occ

urr

en

ce

Refractive index structure Cn2 (m-2/3)

Cumulative frequency of occurrence

Selection based on availability of measured data which could be evaluated collected on days which have no overcast (no clouds or rain) and an average of more than 6 hours of sunlight.

Increased occurrence of higher Cn2

values in Sept & Mar as compared to Nov & Jan is due to higher solar radiation


Supported by

Link budget estimation using experimental data and simulation

Determining RF-FSO system link budget Required Canobeam OPTRX/CNR for

satisfying W-CDMA quality metric Require CNR > 110 for ACLR of 45 dB

The link margin can be determined from this.

Ongoing work


Supported by

Collaborating entities

Waseda University Osaka University Hamamatsu Photonics K.K. Olympus Corporation NICT Canon

Documents

Supported by KRK/OpenAccess2007 - Bagamoyo/14th Nov 2007 RoFSO: An Enabling Technology for Heterogeneous Broadband Networks Kamugisha KAZAURA 1,Edward