RoFSO: An Enabling Technology for Heterogeneous Broadband Networks Kamugisha KAZAURA 1 ,Edward MUTAFUNGWA 1 , Pham DAT 1 ,...
<ul><li>Introduction </li></ul><ul><li>FSO and RoFSO technology </li></ul><ul><li>FSO system performance consideration </l...
Mobile phone users in EA <ul><li>The telecommunication landscape if dominated by mobile phone users who account for almost...
Wireless communication systems 2 Global  Suburban  Macro-Cell Urban  Micro-Cell In-Building  Pico-Cell Home-Cell  Personal...
Wireless communication systems 3 UWB Full-optical FSO system 10 Gbps MM wave  communication 1 Gbps 100 Mbps 10 Mbps 1 Mbps...
Overview of FSO/RoFSO communications <ul><li>Merits  </li></ul><ul><li>Secure wireless system not easy to intercept </li><...
FSO technology application scenarios <ul><li>Terrestrial </li></ul><ul><ul><li>Metro network extension </li></ul></ul><ul>...
<ul><li>Conventional FSO system </li></ul><ul><ul><li>Operate near the 800nm wavelength band </li></ul></ul><ul><ul><li>Us...
Evaluation of FSO/RoFSO systems FSO/RoFSO performance Internal parameters (design of FSO/RoFSO system) External parameters...
Reduces the optical beam power at the receiver point and causes burst errors Atmospheric turbulence has a significant impa...
Experiment devices and setup beacon beam  output windows fiber connection port primary mirror secondary  mirror FPM collim...
Experimental results 1 Communication system performance evaluation setup Transmission quality performance evaluation 2.5 G...
Experimental results 2 C n 2  September 2005 (Summer) Strongest  C n 2   (noon): 3.35 • 10 -13  m -2/3 Minimum  C n 2  (su...
Experimental setup for RF signal transmission RF-FSO antenna specification WCDMA  signal tx test parameters RF-FSO antenna...
Evaluation of RF signal transmission quality 1 <ul><li>Measure and log WCDMA signal quality metrics like ACLR, EVM and PCD...
Evaluation of RF signal transmission quality 2 WCDMA received signal spectrum ACLR variation during rainfall Clear weather...
Summary <ul><li>Successfully developed and demonstrated a full-optical FSO communication system operating at 1550 nm capab...
Ahsanteni sana kwa kunisikiliza. This work is supported by a grant from the  Acknowledgement: Supported by
Backup slides
Comparisons of RF and FSO based systems Eye safety limits No Possible Health issue Interference No Yes Side lobes Up to –1...
DWDM RoFSO antenna Optical system components showing optical paths Antenna specifications BS1 Si PIN QPD InGaAs  PIN QPD F...
C n 2  measurement Where: σ I 2  scintillation index (normalized variance of irradiance fluctuations) I  optical wave irra...
Results and analysis 3 Cumulative frequency of occurrence Less than 2% Jan. ‘06 71.88% 28.12% Sept. ’05 1 • 10 -14  < C n ...
Results and analysis 4 Cumulative frequency of occurrence Selection based on availability of measured data which could be ...
Link budget estimation using experimental data and simulation <ul><li>Determining RF-FSO system link budget </li></ul><ul>...
Collaborating entities <ul><li>Waseda University </li></ul><ul><li>Osaka University </li></ul><ul><li>Hamamatsu Photonics ...
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  • First of all I would like to thank the organizers and sponsors of this remarkable event. Honestly, I did not expect it will attract this kind of interest with speakers who are experts in their field from many different countries and regions. The diversity of the participants in itself is something the organizers should be very proud of to have achieved. I would like to apologize that my presentation will not be exact as the flow of what I wrote in the paper, due to the request I received from the secretariat of the conference that I should consider members whose background is not directly related to my specialized field. In doing so, I have decided to add some slides which will give a good overview I believe of the technology described in the paper. And I hope, from the presentation, most will then get a clear picture of the work we are doing.
  • Kazaura

    1. 1. RoFSO: An Enabling Technology for Heterogeneous Broadband Networks Kamugisha KAZAURA 1 ,Edward MUTAFUNGWA 1 , Pham DAT 1 , Alam SHAH 1 , Toshiji SUZUKI 1 , Kazuhiko WAKAMORI 1 , Mitsuji MATSUMOTO 1 , Takeshi HIGASHINO 2 , Katsutoshi TSUKAMOTO 2 and Shozo KOMAKI 2 1 GITS/GITI, Waseda University, Honjo 2 Osaka University, Osaka kazaura@toki.waseda.jp 
    2. 2. <ul><li>Introduction </li></ul><ul><li>FSO and RoFSO technology </li></ul><ul><li>FSO system performance consideration </li></ul><ul><li>Experiment setup and results </li></ul><ul><li>Summary </li></ul>Contents
    3. 3. Mobile phone users in EA <ul><li>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. </li></ul><ul><li>Technologies include: </li></ul><ul><ul><li>GSM, GPRS/EDGE </li></ul></ul><ul><ul><li>3 G, WCDMA, Ev-DO (CDMA2000) </li></ul></ul><ul><ul><li>3.5 G HSDPA and/or HSUPA ??? </li></ul></ul><ul><ul><li>4 G WiMAX ??? </li></ul></ul>Convenient technology for rapid provision of ICT and services to rural communities. Wireless communication systems 1 Kenya Tanzania Uganda Rwanda Burundi 10,292,000 6,720,072 2,872,000 422,700 347,000
    4. 4. Wireless communication systems 2 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!
    5. 5. Wireless communication systems 3 UWB Full-optical FSO system 10 Gbps MM wave communication 1 Gbps 100 Mbps 10 Mbps 1 Mbps 100 Kbps 1 km 100 m WiMAX 10 m 10 km 1 m Bluetooth ZigBee WLAN a/b/g Optical fiber communication Communication distance Personal area Communication Optical WLAN IrDA PAN Long distance communication Data rate Visible light communications 100 km FSO communication
    6. 6. Overview of FSO/RoFSO communications <ul><li>Merits </li></ul><ul><li>Secure wireless system not easy to intercept </li></ul><ul><li>Easy to deploy, avoid huge costs involved in laying cables </li></ul><ul><li>License free </li></ul><ul><li>Possible for communication up to several kms </li></ul><ul><li>Can transmit high data rate </li></ul><ul><li>De merits </li></ul><ul><li>High dependence on weather condition (rain, snow, fog, dust particles etc) </li></ul><ul><li>Can not propagate through obstacles </li></ul><ul><li>Susceptible to atmospheric effects (atmospheric fluctuations) </li></ul>FSO 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. Electromagnetic spectrum Cosmic radiation T radiation V radiation IR radiation Communications radiation X ray radiation Microwave, radar TV VHF SW Frequency (Hz) 10 20 10 18 10 16 10 14 10 12 10 10 10 8 10 6 250 THz (1 THz) (1 GHz) (1 MHz) (1 pm) (1 nm) (1 μ m) (1 mm) (1 m) (100 m) Wavelength (m) 10 -12 10 -9 10 -6 10 -3 10 0 10 2 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 μ m 670 780 850 1300 1550 1625 nm Visible light Fiber transmission wavelength range λ = wavelength f = frequency C 0 = 300 000 km/s C = λ x f Visible light
    7. 7. FSO technology application scenarios <ul><li>Terrestrial </li></ul><ul><ul><li>Metro network extension </li></ul></ul><ul><ul><li>Last mile access </li></ul></ul><ul><ul><li>Enterprise connectivity </li></ul></ul><ul><ul><li>Fiber backup </li></ul></ul><ul><ul><li>Transmission of heterogeneous wireless services </li></ul></ul><ul><li>Space </li></ul><ul><ul><li>Inter-satellite communication (cross link) </li></ul></ul><ul><ul><li>Satellite to ground data transmission (down link) </li></ul></ul><ul><ul><li>Deep space communication </li></ul></ul>Mountainous terrain Backhaul (~5 km) FSO transceiver and remote base station Metro network extension Remote located settlements FSO link Optical fiber link RF based links FSO transceiver Areas with no fiber connectivity Internet Space station Inter-satellite link Data relay satellite Ground station with adaptive optics Fiber optic link Demonstration of 2.5 Gbps link High-speed (10Gbs) optical feeder link
    8. 8. <ul><li>Conventional FSO system </li></ul><ul><ul><li>Operate near the 800nm wavelength band </li></ul></ul><ul><ul><li>Uses O/E & E/O conversion </li></ul></ul><ul><ul><li>Data rates up to 2.5 Gbps </li></ul></ul><ul><ul><li>Bandwidth and power limitations </li></ul></ul><ul><li>New full-optical FSO system </li></ul><ul><ul><li>Uses 1550nm wavelength </li></ul></ul><ul><ul><li>Seamless connection of space and optical fiber. </li></ul></ul><ul><ul><li>Multi gigabit per second data rates (using optical fiber technology) </li></ul></ul><ul><ul><li>Compatibility with existing fiber infrastructure </li></ul></ul><ul><ul><li>Protocol and data rate independent </li></ul></ul><ul><li>Advanced DWDM RoFSO system </li></ul><ul><ul><li>Uses 1550nm wavelength </li></ul></ul><ul><ul><li>Transport multiple RF signals using DWDM FSO channels </li></ul></ul><ul><ul><li>Realize heterogeneous wireless services e.g. WLAN, Cellular, terrestrial digital TV etc </li></ul></ul>FSO technology Optical fiber O/E E/O module O/E E/O module FSO FSO antenna (a) Conventional FSO system Direct coupling of free-space beam to optical fiber WDM FSO Optical fiber FSO antenna (b) New full-optical FSO system Heterogeneous wireless service signals RoF RoF DWDM RoFSO channel Direct connection between RoF and optical free-space RoFSO antenna DVB WiFi WiMAX Cellular (c) Advanced DWDM RoFSO system
    9. 9. Evaluation of FSO/RoFSO systems FSO/RoFSO performance Internal parameters (design of FSO/RoFSO system) External parameters (non-system specific parameters) Visibility Atmospheric attenuation Scintillation Deployment distance Pointing loss Optical power Wavelength Transmission bandwidth Divergence angle Optical losses BER Receive lens diameter & FOV RF efficiency Dynamic range SNR Performance related parameters
    10. 10. Reduces the optical beam power at the receiver point and causes burst errors 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 Beam wander Intensity fluctuations (Scintillation ) Time Time Transmit power Received power Combined effect Time Time Time
    11. 11. Experiment devices and setup beacon beam output windows fiber connection port primary mirror secondary mirror FPM 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
    12. 12. Experimental results 1 Communication system performance evaluation setup Transmission quality performance evaluation 2.5 Gbps transmission 10 Gbps transmission
    13. 13. Experimental results 2 C n 2 September 2005 (Summer) Strongest C n 2 (noon): 3.35 • 10 -13 m -2/3 Minimum C n 2 (sunrise): 1.10 • 10 -16 m -2/3 C n 2 January 2006 (Winter) Most C n 2 values less than 1 • 10 -13 m -2/3 Noon maximum value of C n 2 changed by a factor of 2.3 Typical C n 2 values – measured for one month (different seasons) Refractive-index structure constant parameter, C n 2 The most critical parameter along the propagation path in characterizing the effects of atmospheric turbulence
    14. 14. Experimental setup for RF signal transmission RF-FSO antenna specification WCDMA signal tx test parameters RF-FSO antenna RF-FSO antenna 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 Automatic tracking Tracking method ± 0.5 μrad Beam divergence 100 mm Transceiver aperture 785 nm Operating wavelength Specification Parameter Test Model 1 w/64 DPCH WCDMA test model 30 kHz Resolution bandwidth 120 MHz Center frequency - 5 dBm Input power Specification Parameter
    15. 15. Evaluation of RF signal transmission quality 1 <ul><li>Measure and log WCDMA signal quality metrics like ACLR, EVM and PCDE. </li></ul><ul><li>Correlate performance with weather conditions and atmospheric effects related characteristics like C n 2 . </li></ul><ul><li>This work is ongoing. </li></ul>Example performance related characteristics during rain event 30 th Sept
    16. 16. Evaluation of RF signal transmission quality 2 WCDMA received signal spectrum ACLR variation during rainfall Clear weather Presence of rainfall
    17. 17. Summary <ul><li>Successfully developed and demonstrated a full-optical FSO communication system operating at 1550 nm capable of offering stable and reliable transmission at 10 Gbps. </li></ul><ul><li>This technology is suitable for rapid provisioning of broadband access technology in remote and underserved areas. </li></ul><ul><li>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. </li></ul><ul><li>Develop a innovative DWDM RoFSO link for heterogeneous wireless services transmission (multiple RF signals) </li></ul>
    18. 18. Ahsanteni sana kwa kunisikiliza. This work is supported by a grant from the Acknowledgement: Supported by
    19. 19. Backup slides
    20. 20. Comparisons of RF and FSO based systems Eye safety limits No Possible Health issue Interference No Yes Side lobes Up to –120 dB/km Fog Rain Weather effects LMDS easier with RF - 40 dBm - 60 dBm Threshold Limits range Background Other users Dominant noise No Yes Propagation through obstacles Delays No Yes Subject to regulations Unlimited Limited Max bandwidth Implications IR (FSO) RF Parameter
    21. 21. DWDM RoFSO antenna Optical system components showing optical paths Antenna specifications BS1 Si PIN QPD InGaAs PIN QPD FPM BS2 Fiber collimator 5 dB Coupling losses 80 mm Antenna aperture 850 nm Beacon wavelength 1550 nm Communication wavelength Value Parameter Photo of new DWDM RoFSO antenna
    22. 22. C n 2 measurement Where: σ I 2 scintillation index (normalized variance of irradiance fluctuations) I optical wave irradiance C n 2 (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, σ A 2 can be related to the C n 2 . For horizontal path considering a spherical wave the following relations are applicable in determining C n 2 : Normalized intensity variance
    23. 23. Results and analysis 3 Cumulative frequency of occurrence Less than 2% Jan. ‘06 71.88% 28.12% Sept. ’05 1 • 10 -14 < C n 2 < 1 • 10 -13 C n 2 > 1 • 10 -13 Measured C n 2 values (in m -2/3 ) - Midday Month 21:00 ~ 24:00 Night: 11:00 ~ 13:00 Midday: 04:30 ~ 06:30 Sunrise:
    24. 24. Results and analysis 4 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 C n 2 values in Sept & Mar as compared to Nov & Jan is due to higher solar radiation 42.48% 4.98% Nov. ‘05 44.83% 2.91% Jan. ‘06 41.67% 14.42% Mar. ‘06 41.06% 16.12% Sept. ’05 6•10 -15 < C n 2 < 6•10 -14 C n 2 > 6•10 -14 Measured C n 2 values (in m -2/3 ) Month
    25. 25. Link budget estimation using experimental data and simulation <ul><li>Determining RF-FSO system link budget </li></ul><ul><li>Required Canobeam OPTRX/CNR for satisfying W-CDMA quality metric </li></ul><ul><ul><li>Require CNR > 110 for ACLR of 45 dB </li></ul></ul><ul><li>The link margin can be determined from this. </li></ul>Ongoing work
    26. 26. Collaborating entities <ul><li>Waseda University </li></ul><ul><li>Osaka University </li></ul><ul><li>Hamamatsu Photonics K.K. </li></ul><ul><li>Olympus Corporation </li></ul><ul><li>NICT </li></ul><ul><li>Canon </li></ul>

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