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RoFSO: An Enabling Technology for Heterogeneous Broadband Networks

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

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RoFSO: An Enabling Technology for Heterogeneous Broadband Networks

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  1. 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 kazaura@toki.waseda.jp  KRK/OpenAccess2007 - Bagamoyo/14thNov 2007

  2. Contents • Introduction • FSO and RoFSO technology • FSO system performance consideration • Experiment setup and results • Summary KRK/OpenAccess2007 - Bagamoyo/14thNov 2007

  3. 10,292,000 2,872,000 Kenya Uganda 347,000 Rwanda Burundi 6,720,072 422,700 Tanzania Wireless communication systems 1 • 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 ??? Mobile phone users in EA Convenient technology for rapid provision of ICT and services to rural communities. KRK/OpenAccess2007 - Bagamoyo/14thNov 2007

  4. Wireless communication systems 2 Wireless systems are not only limited to mobile phone technology! Global Suburban Urban In-Building Macro-Cell Home-Cell Micro-Cell Pico-Cell Personal-Cell KRK/OpenAccess2007 - Bagamoyo/14thNov 2007

  5. Wireless communication systems 3 Data rate Full-opticalFSO system Optical fiber communication FSO communication 10 Gbps Visible light communications MM wave communication 1 Gbps Optical WLAN Long distance communication UWB 100 Mbps IrDA PAN WiMAX WLANa/b/g 10 Mbps Personal areaCommunication Bluetooth 1 Mbps ZigBee 100 Kbps 1 km 100 km 1 m 10 m 100 m 10 km Communication distance KRK/OpenAccess2007 - Bagamoyo/14thNov 2007

  6. Visible light 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 λ = wavelengthf = frequency C0 = 300 000 km/sC = λ x f Visible light Fiber transmissionwavelength range 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 Overview of FSO/RoFSO communications 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. 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) Electromagnetic spectrum KRK/OpenAccess2007 - Bagamoyo/14thNov 2007

  7. Data relay satellite Inter-satellite link Space station High-speed (10Gbs) optical feeder link Demonstration of 2.5 Gbps link Ground stationwith adaptive optics Fiber optic link FSO technology application scenarios Internet Mountainous terrain Metro network extension FSO transceiver andremote base station 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 Backhaul(~5 km) Areas with nofiber connectivity FSO link Optical fiber link RF based links FSO transceiver Remote locatedsettlements KRK/OpenAccess2007 - Bagamoyo/14thNov 2007

  8. FSO technology FSO antenna O/EE/Omodule O/EE/Omodule Optical fiber FSO Direct coupling of free-space beam to optical fiber (a) Conventional FSO system FSO antenna Optical fiber WDM FSO (b) New full-optical FSO system Direct connection between RoF and optical free-space Cellular RoFSO antenna DVB WiFi RoF RoF WiMAX Heterogeneous wireless service signals DWDM RoFSOchannel (c) Advanced DWDM RoFSO system • 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 KRK/OpenAccess2007 - Bagamoyo/14thNov 2007

  9. Evaluation of FSO/RoFSO systems Performance related parameters Optical powerWavelengthTransmission bandwidthDivergence angleOptical lossesBERReceive lens diameter & FOVRF efficiencyDynamic rangeSNR Internal parameters(design of FSO/RoFSO system) FSO/RoFSOperformance VisibilityAtmospheric attenuationScintillationDeployment distancePointing loss External parameters(non-system specific parameters) KRK/OpenAccess2007 - Bagamoyo/14thNov 2007

  10. Transmit power Received power Beam wander Time Time Time Time Intensity fluctuations (Scintillation) Combined effect Time Deployment environment characteristics 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 Reduces the optical beam power at the receiver point and causes burst errors KRK/OpenAccess2007 - Bagamoyo/14thNov 2007

  11. beacon beam output windows primary mirror Bldg. 14 Waseda University Nishi Waseda Campus collimation mirror Weather data recording PC QAPD/QPD Optical clock/data receiver & transmitter Power meter Fiber amplifier 1 km (b) Experiment filed (a) Optical antenna internal structure secondary mirror BERT fiber connection port CCD monitor FPM Bldg. 55 Waseda University Okubo Campus Remote adjustment & monitor PC Scintillation data recording PC RF-FSO Canobeam DT-170 antenna Atmospheric effects measurement antenna (c) Rooftop setup (d) Experimental hardware setup Experiment devices and setup KRK/OpenAccess2007 - Bagamoyo/14thNov 2007

  12. 2.5 Gbps transmission 10 Gbps transmission Experimental results 1 Transmission quality performance evaluation Communication system performance evaluation setup KRK/OpenAccess2007 - Bagamoyo/14thNov 2007

  13. Experimental results 2 Refractive-index structure constant parameter, Cn2 The most critical parameter along the propagation path in characterizing the effects of atmospheric turbulence Typical Cn2 values – measured for one month (different seasons) Cn2 September 2005 (Summer)Strongest Cn2(noon): 3.35•10-13 m-2/3Minimum 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 KRK/OpenAccess2007 - Bagamoyo/14thNov 2007

  14. RF-FSOantenna RF-FSOantenna Bldg. 14 Nishi Waseda campus Weather measurement device Atmospheric turbulence 1 km Signal generator(Agilent E4438C) Signal analyzer(Anritsu MS2723B) Bldg. 14 Nishi Waseda Campus Bldg. 55S Okubo Campus RF-FSO Canobeam DT-170 antenna Atmospheric effects measurement antenna Bldg. 55S Okubo campus Experimental setup for RF signal transmission RF-FSO antenna specification WCDMA signal tx test parameters KRK/OpenAccess2007 - Bagamoyo/14thNov 2007

  15. Evaluation of RF signal transmission quality 1 • Measure and log WCDMA signal quality metrics like ACLR, EVM and PCDE. • Correlate performance with weather conditions and atmospheric effects related characteristics like Cn2. • This work is ongoing. Example performance related characteristics during rain event 30th Sept KRK/OpenAccess2007 - Bagamoyo/14thNov 2007

  16. Clear weather Presence of rainfall Evaluation of RF signal transmission quality 2 WCDMA received signal spectrum ACLR variation during rainfall KRK/OpenAccess2007 - Bagamoyo/14thNov 2007

  17. Summary • Successfully developed and demonstrateda 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) KRK/OpenAccess2007 - Bagamoyo/14thNov 2007

  18. Supported by Ahsanteni sana kwa kunisikiliza. Acknowledgement: This work is supported by a grant from the KRK/OpenAccess2007 - Bagamoyo/14thNov 2007

  19. Backup slides KRK/OpenAccess2007 - Bagamoyo/14thNov 2007

  20. Comparisons of RF and FSO based systems KRK/OpenAccess2007 - Bagamoyo/14thNov 2007

  21. BS1 Si PIN QPD BS2 Fiber collimator FPM InGaAs PIN QPD Photo of new DWDM RoFSO antenna DWDM RoFSO antenna Optical system components showing optical paths Antenna specifications KRK/OpenAccess2007 - Bagamoyo/14thNov 2007

  22. Cn2 measurement Scintillation theory The variance of the log-amplitude fluctuations, σA2 can be related to the Cn2.For horizontal path considering a spherical wave the following relations are applicable in determining Cn2: Where:σI2 scintillation index (normalized variance of irradiance fluctuations)I optical wave irradianceCn2 (m-2/3)index of refraction structure parameterk optical wave number (k=2π/λ) (785 nm)L (m) propagation path length (1,000 m) Normalized intensity variance KRK/OpenAccess2007 - Bagamoyo/14thNov 2007

  23. Results and analysis 3 Cumulative frequency of occurrence KRK/OpenAccess2007 - Bagamoyo/14thNov 2007

  24. Results and analysis 4 Cumulative frequency of occurrence Increased occurrence of higher Cn2 values in Sept & Mar as compared to Nov & Jan is due to higher solar radiation 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. KRK/OpenAccess2007 - Bagamoyo/14thNov 2007

  25. 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 KRK/OpenAccess2007 - Bagamoyo/14thNov 2007

  26. Collaborating entities • Waseda University • Osaka University • Hamamatsu Photonics K.K. • Olympus Corporation • NICT • Canon KRK/OpenAccess2007 - Bagamoyo/14thNov 2007

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