Studies on Next Generation Access   Technology using Radio over      Free-Space Optic LinksKamugisha Kazaura1, Pham Dat1, ...
Contents Introduction Overview of FSO/RoFSO systems Experiment setup Results and analysis Summary                 2
IntroductionWireless communication systems                                           Global                               ...
Introduction cont.Wireless communication technologies and standards                                                       ...
Introduction cont.    FSO roadmap                                                                                   Wirele...
Overview of FSO/RoFSO systemsFSO is the transmission of modulated visible or infrared (IR) beams through theatmosphere to ...
Overview of FSO/RoFSO systems cont.FSO technology application scenarios                                       Internet    ...
Overview of FSO/RoFSO systems cont.        Optical source        FSO                             antenna                  ...
Overview of FSO/RoFSO systems cont.                                       Free-space beam directly                        ...
Overview of FSO/RoFSO systems cont.Challenges in design of FSO systems        Beam divergence, θ  FSO antenna             ...
Overview of FSO/RoFSO systems cont.FSO system performance related parameters                                   Optical pow...
Overview of FSO/RoFSO systems cont. Factors influencing performance of FSO systems Visibility under different weather cond...
Overview of FSO systems cont.Factors influencing performance of FSO systemsAtmospheric effectsAtmospheric turbulence has a...
Experimental field                                                 Bldg. 14 Waseda University                             ...
New RoFSO system experiment setup cont.                RoFSO antenna installed                  on Bldg 14 rooftop        ...
Main transmit and                                                     receive aperture                          Si PIN QPD...
New RoFSO system experiment setup diagram                               RF-FSO          RF-FSO                            ...
New RoFSO system experiment    Characteristics of FSO antennas used in the experiment                                     ...
Results: CNR and ACLR characteristics for RF-FSO cont.                      Effects of weather condition                  ...
Results: CNR and ACLR characteristics for RF-FSO                           150                                            ...
Results: BER and received power characteristicsRoFSO system                       1 00                                    ...
Results: CNR characteristicsRF-FSO system                150                                                              ...
Results: ACLR and optical received power measurementRoFSO system                                      With EDFA:          ...
Results: EVM measurement    RoFSO system                                                             Error Vector Magnitud...
Summary   Presented characteristics of RF signals transmission using FSO links    under various weather conditions reflec...
Supported byThis work is supported by a grant from the  National Institute of Information and     Communication (NICT) of ...
Overview of DWDM RoFSO Link research           I. Development of an Advanced DWDM RoFSO Link System           - Transparen...
Overview of FSO systems cont.Atmospheric effects suppression techniques Aperture averaging    Reducing scintillation eff...
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Studies on next generation access technology using radio over free space optic links

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  • The spectral properties of a signal are measured by the adjacent channel leakage ratio (ACLR), which is defined as the ratio of the amount of leakage power in an adjacent channel to the total transmitted power in the main channel. The 3GPP specifies one main channel and two adjacent channels. The standard requires the ACLR to be better than 45 dB at 5 MHz offset and 50 dB at 10 MHz offset. As ACLR is a more stringent parameter of W-CDMA signal transmission in our experiment we focus on measuring this parameter.
  • The EVM is the ratio in percent of the difference between the reference waveform and the measured waveform. EVM metrics are used to measure the modulation quality of the transmitter. The 3GPP standard requires the EVM not to exceed 17.5%
  • Studies on next generation access technology using radio over free space optic links

    1. 1. Studies on Next Generation Access Technology using Radio over Free-Space Optic LinksKamugisha Kazaura1, Pham Dat1, Alam Shah1,Toshiji Suzuki1, Kazuhiko Wakamori1, Mitsuji Matsumoto1,Takeshi Higashino2, Katsutoshi Tsukamoto2 and Shozo Komaki2 Global Information and Telecommunication Institute (GITI), 1 Waseda University, Saitama, Japan Graduate School of Engineering, Osaka University, Osaka, Japan 2 kazaura@aoni.waseda.jp 17th September 2008 NGMAST 2008
    2. 2. Contents Introduction Overview of FSO/RoFSO systems Experiment setup Results and analysis Summary 2
    3. 3. IntroductionWireless communication systems Global Suburban Urban In-Building Macro-Cell Home-Cell Micro-Cell Pico-Cell Personal-Cell PAN, WSN … Satellite systems … FSO, Cellular systems, WiMAX … 3
    4. 4. Introduction cont.Wireless communication technologies and standards Full-optical Optical fiber 100 Gbps communication FSO system 10 Gbps FSO communication Visible light communications 1 Gbps MM waveData rate communication UWB Optical 100 Mbps WLAN WLAN WiMAX a/b/g 10 Mbps IrDA Personal area Long distance PAN Communication communication 1 Mbps Bluetooth ZigBee 100 Kbps 1m 10 m 100 m 1 km 10 km 100 km 4 Communication distance
    5. 5. Introduction cont. FSO roadmap Wireless BB environment Cooperation of WDM 1T fiber comm. 100G-Ether 100G SONET ( trunkData rate 10G-Ether standard 10G line) FSO 2.5G ( Eye safe ) FSO10G 1G-Ethernet standard ( WDM) FSO 1G FWA 50M 1G (5GHz) FTTH 1G FSO 100M FTTH Indoor FSO ( P-MP) FWA 46M 100M (26G) FWA 10M 11g Indoor 11a Radio on FSO FSO 10M (22 & 12M 24M 10M FSO ( P- 26G) MP ) IEEE802.11b 8M ADSL 1M 1.5M FWA 1.5M (22 & 26G) CATV , cellular phone 100K Video use Analog FSO system ISDN ~ 1995 ~ 2000 2001 2002 2003 2004 2005 ~ 2010 5
    6. 6. Overview of FSO/RoFSO systemsFSO is the transmission of modulated visible or infrared (IR) beams through theatmosphere to obtain broadband communications.RoFSO contains optical carriers modulated in an analogue manner by RF sub-carriers.Merits Secure wireless system not easy to Visible light intercept Cosmic radiation T radiation V radiation IR radiation Communications radiation Easy to deploy, avoid huge costs X ray radiation Microwave, radar TV VHF SW involved in laying cables Frequency (Hz) 1020 1018 1016 1014 1012 1010 108 106 License free 250 THz (1 THz) (1 GHz) (1 MHz) Possible for communication up to (1 pm) (1 nm) (1 μm) (1 mm) (1 m) (100 m) several kms Wavelength (m) 10-12 10-9 10-6 10-3 100 102 Can transmit high data rateDe merits C0 = 300 000 km/s λ = wavelength f = frequency C=λxf High dependence on weather condition (rain, snow, fog, dust Visible light Fiber transmission wavelength range particles etc) Can not propagate through obstacles 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 Susceptible to atmospheric effects 670 780 850 1300 1550 1625 nm (atmospheric fluctuations) Electromagnetic spectrum 6
    7. 7. Overview of FSO/RoFSO systems cont.FSO technology application scenarios Internet Mountainous terrainTerrestrial Metro network RoFSO transceiver  Metro network extension extension and remote BS  Last mile access Backhaul (~5 km)  Enterprise connectivity Areas with no  Fiber backup fiber connectivity RoFSO link  Transmission of Optical fiber link RF based links heterogeneous wireless Remote located RoFSO transceiver services settlements Data relay satelliteSpace  Inter-satellite communication Inter-satellite link (cross link) Space station  Satellite to ground data transmission (down link) Demonstration of High-speed (10Gbs) 2.5 Gbps link optical feeder link  Deep space communication Ground station 7 Fiber optic link with adaptive optics
    8. 8. Overview of FSO/RoFSO systems cont. Optical source FSO antenna Conventional FSO system module  Operate near the 800nm wavelength band  Uses O/E & E/O conversionOptical fiber FSO channel  Data rates up to 2.5 Gbps Electrical O/E and E/O  Bandwidth and power limitations signal conversion module (a) Conventional FSO system Next generation FSO system  Uses 1550nm wavelength Direct coupling of free-space beam to optical fiber FSO  Seamless connection of space and antenna optical fiber.  Multi gigabit per second data rates (using optical fiber technology) Optical fiber  Compatibility with existing fiber WDM FSO channel infrastructure (b) New full-optical FSO system  Protocol and data rate independent 8
    9. 9. Overview of FSO/RoFSO systems cont. Free-space beam directly coupled to optical fiber Cellular RoFSO antenna DVB WiFi RoF RoF WiMAX DWDM RoFSO Heterogeneous wireless channel service signals (c) Advanced DWDM RoFSO system 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 broadcasting etc 9
    10. 10. Overview of FSO/RoFSO systems cont.Challenges in design of FSO systems Beam divergence, θ FSO antenna FSO antenna Transmitter Receiver Transmitter Receiver wide beam narrow beamWide beam FSO systems Narrow beam FSO systems  Beam divergence in terms of several  Beam divergence in terms of several milliradians tens of microradians  Easy to align and maintain tracking  Difficult to align and maintain tracking  Less power at the receiver (the wider  More optical power delivered at the the beam the less power) receiverThe narrow transmission of FSO beam of makes alignment of FSOcommunication terminals difficult than wider RF systems. 10
    11. 11. Overview of FSO/RoFSO systems cont.FSO system performance related parameters Optical power Wavelength Transmission bandwidth Internal parameters Divergence angle (design of FSO system) Optical losses BER Receive lens diameter & FOV FSOPerformance Visibility External parameters Atmospheric attenuation (non-system specific Scintillation parameters) Deployment distance Pointing loss 11
    12. 12. Overview of FSO/RoFSO systems cont. Factors influencing performance of FSO systems Visibility under different weather conditionsClear day Cloudy day Rain eventVisibility > 20km Visibility: ~ 5.36 km Visibility: ~ 1.09 kmAttenuation: 0.06 ~ 0.19 db/km Attenuation: 2.58 db/km Attenuation: 12.65 db/km Visibility greatly influences the performance of FSO systems e.g. fog, rain, snow etc significantly decrease visibility 12
    13. 13. Overview of FSO systems cont.Factors influencing performance of FSO systemsAtmospheric effectsAtmospheric turbulence has a significant impact on the quality of the free-space optical beam propagating through the atmosphere. Transmit Received power power Other effects include: - beam broadening and Beam wander - angle-of-arrival fluctuations Time Time Suppression techniques: - Aperture averaging Time Time Scintillation - Adaptive opticsReduces the optical beam - Diversity techniquespower at the receiver point Combined - Coding techniques effectand causes burst errors Time 13
    14. 14. Experimental field Bldg. 14 Waseda University Nishi Waseda Campus 1 km Bldg. 55 Waseda University Okubo Campus Satellite view of the test area Source: Google earth 14
    15. 15. New RoFSO system experiment setup cont. RoFSO antenna installed on Bldg 14 rooftop Okubo campus Beacon Bldg. 55S signal IR viewer 15 Waseda campus Bldg 14 rooftop
    16. 16. Main transmit and receive aperture Si PIN QPD for coarse tracking using beacon signal BS1 Main transmit and receive aperture SMF BS2 collimator FPM (Fine Pointing Mirror) Beacon signal Beacon InGaAs PIN QPD Rough tracking beacon projection transmit aperture Source for fine tracking aperture Post EDFA Digital mobile radio transmitter tester (Anritsu MS8609A) Bldg. 14 Nishi Waseda campus RoFSO antenna tracking adjustment and monitoring PC Optical source BoostWeather measurement EDFA DWDM D-MUX device RF-FSO antenna Atmospheric effects measurement antenna RoFSO Bldg. 55S antennaOkubo campus 16 Atmospheric turbulence effects recording PC Bit Error Rate Tester (Advantest D3371) Optical power meter (Agilent 8163A)
    17. 17. New RoFSO system experiment setup diagram RF-FSO RF-FSO antenna antenna RF-FSO link RoFSO link RoFSO RoFSO antenna antenna Opt. circulator Opt. circulator filter EDFA Filter & ATTN Tracking PC Signal 2.5Gbps Power 2.5Gbps Opt. Analyzer Opt. Tx meter Opt. Rx Source Clock Data PC Signal PC BERT BERT Generator Bldg. 55S Okubo Bldg. 14 Nishi Waseda Campus Campus 17
    18. 18. New RoFSO system experiment Characteristics of FSO antennas used in the experiment Specification Parameter RF-FSO RoFSO Operating wavelength 785 nm 1550 nm Transmit power 14 mW (11.5 dBm) 30 mW (14.8 dBm) Antenna aperture 100 mm 80 mm Coupling loss 3 dB 5 dB Beam divergence ± 0.5 mrad ± 47.3 µrad Frequency range of 450 kHz ~ 420 MHz ~ 5 GHz operation Fiber coupling technique OE/EO conversion is Direct coupling using FPM necessary WDM Not possible Possible (20 dBm/wave) Tracking method Automatic Automatic using QPD Rough: 850 nm Fine: 1550 nm 18
    19. 19. Results: CNR and ACLR characteristics for RF-FSO cont. Effects of weather condition 55 -10 Clear weather -20 During rainfall 50 -30 45Received power [dB] ACLR: ~ 27 dB -40 ACLR (dB) 40 -50 35 -60 Attenuation 30 due to rain ACLR: ~ 51 dB -70 25 -80 Measured data Fitting line 20 -90 85 90 95 100 105 110 115 120 125 110 115 120 125 130 CNR (dB) Frequency [MHz] WCDMA received signal spectrum Relationship between CNR and ACLR WCDMA: Wideband Code Division Multiple Access CNR: Carrier to Noise Ratio ACLR: Adjacent Channel Leakage Ratio (a quality metric parameter for WCDMA signal transmission) 19
    20. 20. Results: CNR and ACLR characteristics for RF-FSO 150 25 CNRavg Te m pe ra t ure [οC ]/ Pre c ipit a t ion [m m / h] 120 20112 dB C NR [dB] / AC LR [dB] CNRmin 90 15 ACLR 60 1045 dB 30 5 Temperature Precipitation 0 0 Fe b 2 Fe b 3 Fe b 4 Fe b 5 Tim e RF signal transmission characteristics measured using RF-FSO system 20
    21. 21. Results: BER and received power characteristicsRoFSO system 1 00 30 Te mpe ra t ure (οC )/ 24 ~ 25 April 2008 BER Vis ibilit y Vis ibilit y (km) 1 0- 2 Te mpe ra tu re 25 Re c e ive d Po we r 1 0- 4 20 Bit Erro r Ra t e 1 0- 6 15 - 15 1 0- 8 1 0 - 20 1 0- 1 0 5 - 25 Erro r fre e 1 0- 1 2 0 - 30 21 :00 23:00 01 :00 03:00 05:00 07:00 09:00 Time Re c e ive d po we r (dB)BER and received power characteristics measured using RoFSO system 21
    22. 22. Results: CNR characteristicsRF-FSO system 150 25 24 ~ 25 April 2008 120 20 Te m pe ra t ure (ο C )/ Vis ibilit y (km ) 90 15 C NR (dB) 60 10 30 C NRa vg 5 C NRm in Vis ibilit y Te m pe ra t ure 0 0 21:00 23:00 01:00 03:00 05:00 07:00 09:00 Tim e CNR characteristics measured using RF-FSO system 22
    23. 23. Results: ACLR and optical received power measurementRoFSO system With EDFA: Without EDFA: -24.5 dBm -15 dBm 70 Back-to-back measurement 60 RoFSO link measurement with Post EDFA 50 ACLR [dB] 40 RoFSO link measurement 30 RoFSO Tx 5 MHz RoFSO Tx 10 MHz B-to-B Tx 5 MHz 20 B-to-B Tx 10 MHz with EDFA Tx 5 MHz with EDFA Tx 10 MHz 10 -35 -30 -25 -20 -15 -10 -5 0 Optical received power [dBm] Received 3GPP W-CDMA signal ACLR spectrum Variation of ACLR with the (3GPP Test Signal 1 64 DPCH) measured received optical power 23
    24. 24. Results: EVM measurement RoFSO system Error Vector Magnitude (EVM) 40 RMS 35 Peak Error Vector Magnitude [%] 30 25 20 17.5% threshold 15 10 5 0 -35 -30 -25 -20 -15 -10 -5 Optical received power [dBm] EVM is the ratio in percent of the difference between the reference waveform and the measured waveform. EVM metric is used to measure the modulation quality of the transmitter. The 3GPP standard requires the EVM not to exceed 17.5% 24
    25. 25. Summary Presented characteristics of RF signals transmission using FSO links under various weather conditions reflecting actual deployment scenarios. Measured, characterized and quantified important quality metric parameters e.g. CNR, ACLR, EVM, BER, optical received power etc significant for evaluation of RF signal transmission using FSO links. A properly engineered RoFSO link can be used as a reliable next generation access technology for providing heterogeneous wireless services in the absence of severe weather conditions. Further work on simultaneous transmission of multiple RF signals by DWDM technology using the RoFSO system are ongoing. The results are significant in design optimization, evaluation, prediction and comparison of performance as well as implementation issues/guidelines of RoFSO systems in operational environment. 25
    26. 26. Supported byThis work is supported by a grant from the National Institute of Information and Communication (NICT) of Japan Thank you for your attention Kamugisha KAZAURA ( カムギシャ カザウラ ) kazaura@aoni.waseda.jp
    27. 27. Overview of DWDM RoFSO Link research I. Development of an Advanced DWDM RoFSO Link System - Transparent and broadband connection between free-space and optical fiber - DWDM technologies for multiplexing of various wireless communications and broadcasting servicesMobile NW DWDM DWDM Cellular Cellular RoF RoFSO BS Scintillation OE/EO FSO Digital FSO OE, EO Digital TV OE WDM TV WDM Tx,Rx Tx,Rx OE/E WLAN AP O OE/EO WLANInternet River, New New Road, etc Universal Wireless Wireless Services Remote BS Fiber-rich Area Optical Free-Space Rural Area without Broadband Fiber infrastructureIII. Long-term Demonstrative Measurements II. Development of Seamless Connecting- Pragmatic examination of advanced RoFSO link Equipments between RoF, RoFSO and Wireless system Systems- Investigation of scintillation influence on various - Wireless service zone design types of wireless services transported using the - Total link design through RoF, RoFSO, and Radio RoFSO system. Links 27
    28. 28. Overview of FSO systems cont.Atmospheric effects suppression techniques Aperture averaging  Reducing scintillation effects by increasing the telescope collecting area. Adaptive optics  Measure wavefront errors continuously and correct them automatically. Diversity techniques  Spatial diversity (multiple transmitters and/or receivers)  Temporal diversity (signal transmitted twice separated by a time delay)  Wavelength diversity (transmitting data at least two distinct wavelengths) Coding techniques  Coding schemes used in RF and wired communications systems. 28

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