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Welcome at Communication by light

Free space optics for GSM/UMTS networks

• CBL - about the company;

• The task;

• Arguments for free space optics (FSO);

• Available systems;

• Physics behind free space optics;

• Presentation of products and discussion

Dr.-Ing. Hermann Lentke General - Manager

CBL GmbH - Germany

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Who is CBL GmbH?

• CBL is a manufacturer of free space optical links, fiber optic systems and fiber optic OEM products;

• 1991 founded by a team of engineers;

• Private financed, no venture capital, independent;

• Letter capital of 333.000 Euros;

• Since 1995 own headquarter, space: 1600 square meter;

• 2003 turnover of 5 million Euros (=6 million US $);

• 25 employees in R&D, production, sales and support;

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Solutions by CBL

• Broadband wireless transmission via optical or micro-wave links mainly for private IP networks;

• Covering all datarates between 2 Mbps (E1) and 1250 Mbps (Gigabit Ethernet);

• Distances up to 2 km by own developed optical links and up to 50 km by OEM microwave links;

• Wavelength-multiplexers for fiber optic systems with data rates between 2 .. 2.000 MBit/s and distances up to 150 kilometers.

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Free space optics in carrier networks

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Combination of MW and FSO

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Arguments for free space optics

1. Simple construction reduces system’s cost.

Classic Microwave system

Free space optical link

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Arguments for free space optics

1. Simple construction reduces costs per link.

Your benefit: Cheaper than classic microwave links.

Classic Microwave:

• Splitted IDU/ODU concept

• High efficiency modulation required (narrow RF-channels)

• Only one antenna

Free space optical link:

• Cheaper “all-in-one” concept

• Mod- and demodulation very easy

• Generation of light instead of radio frequencies

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Arguments for free space optics

2. Communication by invisible infrared light - there fore no frequency coordination required.

Different lightbeams don’t disturb each other; no fresnel zone.

Your benefit: Quicker planning and installation of links.

3. FSO can carry datarates at STM-1 and beyond very

easy.

Much more space in electromagnetic spectrum around 850 nm wavelength than in full mm-range.

Your benefit: Enough bandwidth in the air even with increasing demand.

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Arguments for free space optics

4. No stringent radio licensing regulations.

FSO is free in most countries.

Your benefit: Saving of license fees.

5. Environment safe installation and operation.

FSO: Eyesafe, without acceptance problems, discrete installation.

Your benefit: Easier aquisition of roof rights.

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Arguments for FSO - summary

+ Significant lower price in comparison to microwave links.

Quicker link planning and installation.

Really high bandwidth today and in future.

No license fees.

Easier aquisition of roof rights.

- FSO can only be integrated in GSM/UMTS networks in addition to microwave links, fiber optic and copper cables.

Distance is limited to several hundreds of meters.

Availiability is lower than for microwave links.

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Maximum recommended distance

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LaserLink 4E1 in a GSM application

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Available systems

PDH: LaserLink 4E1 for 4x2 Mbps

SDH: LaserLink STM-1 for 155 Mbps

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IP: AirLaser IP100/IP1000 for Fast/Gigabit-Ethernet with SNMP/web-based management

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LaserLink 4E1/300

• Bidirectional wireless optical link for 300 meters

• 4xE1 120 Ohm interface

• Loop - function on all channels

• Diagnostics: built in bit error indicator local & remote, indication data present local & remote and monitor for all data ports

• Dry alarm contact

• Built in telescopic sight

• Eyesafe laser class 1m

• 230VAC and/or 48VDC

• Options: Automatic transmit power control (ATPC) and tunneling of external alarms from remote site;

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Frontview of LaserLink 4E1/300

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Operation panel of LaserLink 4E1/300

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LaserLink 4E1- back panel

• RX/TX data Ch. 1 .. 4 and data/monitor connectors

• Bit-error indicator for local and remote site

• Loop status indicator

• Button for different loops

• Bargraph indicator for optical power in

• Switch for power reduction and ATPC

• Local, remote and external alarms

• Telescopic sight

• Power connector

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LaserLink- samples of installation

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Indoor installation of LaserLink

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LaserLink - special installations

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LaserLink - samples of installation

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LaserLink - samples of installation

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Birds crossing LaserLink

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LaserLink 4E1 - front view

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LaserLink 4E1

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LaserLink 4E1 - operation panel

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LaserLink 4E1 LaserLink STM-1

Optical system budget 29 dB @ 800 m 26 dB @ 800 m

Th. distance @ 10 dB/km 2.100 m 1.850 m

Th. distance @ 30 dB/km 950 m 800 m

Min. visibility @ 800 m 470 m 500 m

Divergence TX 10 mrad 6 mrad

Dimensions TX/RX 4x60 mm/257mm

Sensitivity +3..-45 dBm -6..-43 dBm

MTBF > 100.000 hours

Power consumption 17 VA 27 VA

Some technical data of LaserLink

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Installed LaserLink

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Installed LaserLink and microwave terminal

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Installed LaserLink and microwave terminal

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Base Station with LaserLink and microwaves

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• Wireless optical link for distances up to 2 km;

• Optimized for Fast Ethernet link with full duplex 100 Mbps datarate;

• Weather independent system availability 99,99% guaranteed due to integrated license-free 2,4 GHz radio link as back-up;

• Permanent monitoring of the optical link enables an automatic switching;

• Advanced SNMP/web-based management. Alarms can be transmitted to a maximum of four email addresses;

• Redundant power supply with 230 or 115 VAC and additional 48 VDC.

AirLaser for IP traffic only

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AirLaser IP 100

Transmitter and receiver

Transmitter(up to 4 VCSEL-

Lasers)

Antennas for radio link backup

2-axle mounting for

rough adjustment

Fresnel lense fordata reception

Telescopic sight

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AirLaser: Web-based management

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AirLaser: Web-based management

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Physics behind FSO

• Effects in the air

• Transmitter for FSO

• Receiver for FSO

• Level diagram

• Influence of weather

• Availability of wireless optical links

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Geometrical attenuation

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Geometrical attenuation vs. distance

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Geometrical attenuation vs. distance

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Scintilla

tion

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Scatter attenuation vs. visibility

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Physical relations

Transmitter

LED of LaserLink 4E1/ 300

VCSEL Laser-diode in

Laser-Link 155/2000

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Physical relations

• PIN- or APD-diodes, active area < 1 mm2

• Lenses or mirrors focussing the incoming light

• Acceptance angle < 8 mrad

• High sensitivity, typ. -43 dBm @ 100 MBit/s and

BER 10-9 with APD-diodes

• Daylight IR filter with 130 nm bandwidth

Receiver

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Receiver

PIN of LaserLink 4E1/300

APD diode in

Laser-Link 155/2000

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Level diagram

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Weather dependent level diagram

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Distribution of visibility in Europe

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Minimal visibility vs installed distance

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Availability in diffrent climes (statistical)

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Maximum recommended distance

• Transmitter‘s power, divergence, receiver‘s area and sensitivity give the

system‘s budget;

• Comparison at 1km hop length - system‘s performance;

• Expected local weather determines the attenuation of the atmosphere;

• Important: Availability over a certain distance; CBL recommends to use

FSO only up to 2000 meters;

• CBL‘s customers prefer availability instead of distance!

• Therefore: Maximum distance without availability is off value!

• We limit our systems to 2000 m.

• What is 4000 m hop length with less than 99 % availa bility?

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Summary: FSO for GSM/UMTS

• Half the cost of classic microwave links - shorter return of investment

• No frequency coordination required

• FSO ready for PDH and SDH traffic

• Well suited for distances below 2000 meter depending on local weather

• “Discrete” and quick installation indoor and outdoor

• For GSM new, but proven technology in IP world

• Lower availability than microwave links

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Thank you for

your

Attention!