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Wireless Optical Transmission at 10 Gbps and Beyond Connectivity Unlimited TM Table of Contents PART I – CURRENT TECHNOLOGY OVERVIEW •Bandwidth Blowout (RF vs. IR) •Trade-offs •Comparison with Fiber Optics •The atmosphere Attenuation Scattering •Equipment Fade Margins PART II – The PHOTONIC AIR LINK •Basic concept •Fiber limitations are dominant •RF plus IR •WDM extends bandwidth •Optical Transformers •Our wish list for the future Slide No. 2 Connectivity Unlimited TM Wireless Spectrum Carrier Frequencies Fig. 1 Wireless Spectrum Carrier Frequencies RF IR Beams Frequency 350THz No restrictions 0.8-1.5 m Mm and sumbmillimeter 18-90 GHz wave Spread Spectrum 10 GHz 900-5500 100 MHz MHz Unlicensed bands Licence required 5-10 mm 3 cm 10-30 cm TV carriers 3m Wavelength Slide No. 3 Connectivity Unlimited TM Trade-offs between RF and IR Slide No. 4 Connectivity Unlimited TM Wireless Infrared Principles Slide No. 5 Connectivity Unlimited TM Comparison of Fiber Optics & FSO (Virtual Fiber) Yyyyyyyyy yyyyyyy <50 dB Slide No. 6 Connectivity Unlimited TM Atmospheric Transmission at Sea Level Slide No. 7 Connectivity Unlimited TM Definition of types of ray path Slide No. 8 Connectivity Unlimited TM Polar diagram of scattering of red light Slide No. 9 Connectivity Unlimited TM Visibility & Losses The Visibility (or visual range) is defined as that distance where the radiance of a visible light source is reduced to 1/50 of its initial value: V(in km) = ln 50/ (in km-1) In FSO, scattering and absorption losses are represented in dB/km(S) so: S(dB/km) ≈ 17/V(km) Slide No. 10 Connectivity Unlimited TM Scattering Attenuation of Optical Beams Weather Condition Attenuation Visibility (km) (dB/km) at 850 nm Clear weather, light haze 0 to 3 50 to 6 Light rain 3 to 6 6 to 3 Heavy rain 6 to 17 3 to 1 Snow 10 to 35 1.5 to 0.5 Light fog 17 to 70 1 to 0.25 Heavy fog 80 to 200 0.2 to 0.08 Clouds 300 to 500 0.06 to 0.03 Slide No. 11 Connectivity Unlimited TM Neither snow nor sleet… UWIN802 installed in Riga, Latvia by “Erseta” in September, 1996. Ethernet 10 Mbps, ~200 m “….it works quite well and we have no problems”. Slide No. 12 Connectivity Unlimited TM Fade Margin Calculation Fade Margin calculation AB • Loss Factor = L.F. = 10 log AB/AR [dB] AR -AB = Beam area; AR = Receiver area -AB ~ R2HV where -H = azimuth angle AB -V = elevation angle, R = distance Loss Budget = L.B. = 10 log PB/Pt [dB] H AR -PB = Power in the beam -Pt = Threshold power R Fade Margin = F.M. = L.F. - L.B. [dB] Slide No. 13 Connectivity Unlimited TM Today, the Photonic Air Link has a special niche in a niche technology Tomorrow, it may become the key commodity in a mainstream market Slide No. 14 Connectivity Unlimited TM Wireless Interconnection without Electronics Slide No. 15 Connectivity Unlimited TM Current MMF Fibers Used in FSO Fiber type Core diam. (microns) NA Bandwidth MHz.km Max length at Gigabit ETH (meters) Graded Index 62.5 100 125 0.28 0.29 0.30 400 100 100 200 50 50 200 400 600 0.37 0.39 0.39 100 10 8 50 10 5 Graded Index Semi GI Semi GI Step Index Step Index Note: Gradium lens 50 mm diam. has focal length 80 mm (NA ≈ 0.3) Slide No. 16 Connectivity Unlimited TM Key Components of High Bandwidth Transmission System connectors TX Network switch, PABX, etc TX f.o cable NIU Up to 50 m RX Network Interface Unit (in or near the equipment closet) Slide No. 17 Duplex f.o. cable RX Optical Antenna Module (OAM) (on Roof or Tower) Connectivity Unlimited TM Media Converter Designs Fig 2.2 Media Converter Designs All λ MC or APD RCVR TX f.o. RX at 1550 O To PAL TX 850 nm S W 850,1310,1550 8 dBm VCSEL at 850 RX 200 or 400 micron fiber f.o. TX at 850 Si Pin or APD RCVR Protocol – independent Wavelength – independent Frequency independent Slide No. 18 Connectivity Unlimited TM Media Converter Designs Fig.2.3 Media Converter Designs (For 1550 nm switches only) Protocol-independent Media Converter To PAL TX TX O Any EDFA SMF 10-20 dBm Switch S W From PAL RX 200 micron fiber RX SMF (or MMF) f.o. 1550 TX InGaAs pin or APD RSVR (200 µ) Slide No. 19 Connectivity Unlimited TM RFIR 100 System Fig. 2.1 RFIR 100 System On the roof or tower NIU RF antenna FSRF duplex coax RADIO lenses f.o. XcVR &MC To & from the network Patch cable duplex f.o. FSIR RFIR 100 The Optical Antenna (IR) Slide No. 20 Connectivity Unlimited TM MUX/DeMUX with MMF 1549 nm Slide No. 21 1557 nm Connectivity Unlimited TM Optical Wireless WDM Experimental Arrangement Slide No. 22 Connectivity Unlimited TM Experimental test under FSO conditions of Nanonics OPT XF MMF PAL RCVR. SOURCE (Note 1) Plano-convex f = 80 mm collimator 1.5 meters FC/PC 22 μW MMF NANONICS DEVICE OPT XF POWER METER Nanonics Taper (62.5 to 9 microns) SMF 9μ 400 nW 17 dB loss Experimental test under FSO conditions of Nanonics OPT XF Note: Same experiment repeated with taper from 200 to 70 microns and 75 micron photodiode 10 microns distant, 1 dB loss. Slide No. 23 Connectivity Unlimited TM Future Research • Large core broadband fiber with high N.A. (BW>200 MHz-km for d>150 microns) • CWDM demux with large core common input fiber • Large core EDFA •Low capacitance, large area photodiodes (MSM?) (BW ≈10 GHz, d≥80 microns) •Migration to 10 micron wavelength Slide No. 24 Connectivity Unlimited TM