wireless optical transmission at 10 gbps and beyond · slide no. 11 connectivity unlimited tmtm...

Connectivity Unlimited Connectivity Unlimited TMTM

Wireless Optical Transmission at 10 Gbps and Beyond

Connectivity Unlimited Connectivity Unlimited TMTMSlide No. Slide No. 22

Table of Contents

PART I – CURRENT TECHNOLOGY OVERVIEW•Bandwidth Blowout (RF vs. IR)

•Trade-offs

•Comparison with Fiber Optics

•The atmosphereAttenuationScattering

•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


Wireless Spectrum Carrier Frequencies

Wireless Spectrum Wireless Spectrum Carrier FrequenciesCarrier Frequencies

Wavelength

0.8-1.5 µm 5-10 mm 3 cm 10-30 cm 3 m

100MHz

900-5500MHz

Unlicensed bands

10 GHz18-90 GHz

Licence required

Frequency

TV carriers

SpreadSpectrum

µwaveMm and sumbmillimeter

RF

350THz

No restrictions

IR Beams

Fig. 1


Trade-offs between RF and IR


Wireless Infrared Principles


Comparison of Fiber Optics & FSO (Virtual Fiber)Yyyyyyyyy

yyyyyyy

<50 dB


Atmospheric Transmission at Sea Level


Definition of types of ray path


Polar diagram of scattering of red light


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/α (in km-1)

In FSO, scattering and absorption losses are represented in dB/km(S) so:

S(dB/km) ≈ 17/V(km)


Scattering Attenuation of Optical Beams

0.06 to 0.030.06 to 0.03300 to 500300 to 500CloudsClouds0.2 to 0.080.2 to 0.0880 to 20080 to 200Heavy fogHeavy fog

1 to 0.251 to 0.2517 to 7017 to 70Light fogLight fog1.5 to 0.51.5 to 0.510 to 3510 to 35SnowSnow

3 to 13 to 16 to 176 to 17Heavy rainHeavy rain

6 to 36 to 33 to 63 to 6Light rainLight rain

50 to 650 to 60 to 30 to 3Clear weather, light Clear weather, light hazehaze

Visibility (km)Visibility (km)AttenuationAttenuation(dB/km) at 850 nm(dB/km) at 850 nm

Weather ConditionWeather Condition


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”.


AR

AB

θH

AB

AR

Fade Margin Calculation

Fade Margin calculation

• Loss Factor = L.F. = 10 log AB/AR [dB]

-AB = Beam area; AR = Receiver area

-AB ~ R2θHθV where

-θH = azimuth angle

-θV = elevation angle, R = distance

• Loss Budget = L.B. = 10 log PB/Pt [dB]

-PB = Power in the beam

-Pt = Threshold power

• Fade Margin = F.M. = L.F. - L.B. [dB]R


Today, the Photonic Air Link has a special niche in a niche technology

Tomorrow, it may become the key commodity in a mainstream market


Wireless Interconnection without Electronics


Current MMF Fibers Used in FSO

55880.390.39600600Step IndexStep Index101010100.390.39400400Step IndexStep Index50501001000.370.37200200Semi GISemi GI50501001000.300.30125125Semi GISemi GI50501001000.290.29100100Graded IndexGraded Index2002004004000.280.2862.562.5Graded IndexGraded Index

Max length Max length at Gigabit at Gigabit

ETH ETH (meters)(meters)

BandwidthBandwidthMHz.kmMHz.km

NANACore Core diamdiam. . (microns)(microns)

Fiber typeFiber type

Note: Gradium lens 50 mm diam. has focal length 80 mm (NA ≈ 0.3)


Key Components of High Bandwidth Transmission System

Network switch,

PABX, etc

Network Interface Unit

(in or near the equipment closet)

TX

RX

f.o cable NIU Duplex f.o. cable

connectors

Up to 50 m

Optical Antenna Module (OAM)

(on Roof or Tower)

TX

RX


Media Converter Designs

Media Converter DesignsMedia Converter DesignsAll All λλ MCMC

S

W

TXVCSEL at 850

RX

850,1310,1550f.o. TX at 850 Si Pin or APD RCVR

f.o. RX at 1550 8 dBm

Protocol – independent

Wavelength – independent

Frequency independent

Fig 2.2

O To PAL TX850 nm

or APD RCVR

200 or 400 micron fiber


Media Converter Designs

Media Converter DesignsMedia Converter Designs(For 1550 nm switches only)(For 1550 nm switches only)

O

S

W

EDFATX

To PAL TX10-20 dBm

RX

SMF (or MMF)

f.o. 1550 TX

InGaAs pin or APD RSVR (200 µ)

From PAL RX 200 micron fiber

Fig.2.3

Any

Switch

Protocol-independent Media Converter

SMF


RFIR 100 System

RFIR 100 SystemRFIR 100 System

RADIO

f.o. XcVR&MC

NIU

To & from the network

On the roof or tower

RF antenna

FSRF

Patch cable

The Optical Antenna (IR)

lenses

FSIRRFIR 100

duplex f.o.

duplex coax

Fig. 2.1


MUX/DeMUX with MMF

1549 nm 1557 nm


Optical Wireless WDM Experimental Arrangement


Experimental test under FSO conditions of Nanonics OPT XF

SOURCE (Note 1)

Experimental test under FSO conditions of Nanonics OPT XF

PAL RCVR.

MMF

Plano-convex collimator

f = 80 mm

1.5 meters

OPTXF

FC/PC22 µW

MMF

SMF 9 µ

POWER METER

NANONICS DEVICE

400 nW

Nanonics Taper(62.5 to 9 microns)

17 dB loss

Note: Same experiment repeated with taper from 200 to 70 microns and 75 micron photodiode 10 micronsdistant, 1 dB loss.


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

wireless optical transmission at 10 gbps and beyond · slide no. 11 connectivity unlimited tmtm...

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