“Welcome”

Seminar presentation

ByHarikrishnan V . s7 ECE of

COLLEGE OF ENGINEERING ATTINGALKERALA

DISCLAIMER This slide presentation contains images and representation owned by a third party.All rights lie within the respective holders. I deserve no rights for the images and GIF files used in this presentation.Harikrishnan. V

The “Last Mile” Bottleneck Problem

Wide Area Networks between major cities are extremely fast

• Fiber based

• >2.5 Gbps

Local Area Networks in buildings are also fast >100Mbps

The connections in between are typically a lot slower

• 0.3-1.5 Mbps

Wire-line fiber optic solutions such as STM64 technology can provide up to 1Gbps high speed connectivity

But…Only about 5% of commercial buildings are lit

with fiber

Let us explore…why…

• Cost

• Rights for the way

• Trenching

• Time

September 11 2001 NY

FREE SPACE OPTICS

…an effective means for last mile delivery for telecom services

Free space optics• It is a line of sight technology-cost effective solution for last mile problem.

Uses invisible light beams to provide optical bandwidth connections.

Can send and receive voice, video, and data information up to 1.25Gbps at a distance of 4 miles

Doesn’t require securing spectrum license of Radio Frequency Solutions

• Due to the advanced tracking mechanism, implementation of DWDM, they are capable of offering speed up to 10Gbps

• FSO technology has enormous upside potential for short distance wireless connections.

• Was originally developed by military and NASA.• The invention of lasers in the 1960s revolutionized free

space optics• FSO has been used for more than three decades in

various forms

The evolution…

The Working!!

?Light Source

Glass Fiber Strands

Detector

Detector

Light Source

Network device

Network device

• Pulses of light communicate the data

• “ON” = 1• “OFF = 0

How a fiber optic cable work

1 Network traffic converted into pulses of invisible light representing 1’s and 0’s

2

Transmitter projects the carefully aimed light pulses into the air

5 Reverse direction data transported the same way.

• Full duplex

3 A receiver at the other end of the link collects the light using lenses and/or mirrors

4 Received signal converted back into fiber or copper and connected to the network

Anything that can be done in fiber can be done with FSO

FSO

working

THE TRANCEIVER

Front view

Laser transmitter

Laser receiver

Rear view

Fundamental conceptsSmall Angles - Divergence & Spot Size

HIGHLIGHTS

1.Very Narrow and directional beams.Beams only a few meters in diameter at a kilometerAllows VERY close spacing of links without interferenceNo side lobesHighly secureEfficient use of energyRanges of 20m to more than 8km possible

2. Deployment behind windows

Rapid installations without trenching and permitting

Direct connection to the end user

Bypasses the building owner• No roof rights• No riser rights

3.The FSO “Value Proposition”

No interferenceUnlicensedEasy to installHighly secureFiber-like data ratesMany deployment optionsFungible equipment

Is it eye-safe ?Laser beams with wavelengths in the range of

400 to 1400 nm emit light that passes through the cornea and lens and is focused onto a tiny spot on the retina

Wavelengths above 1400 nm are absorbed by the cornea and lens, and do not focus onto the retina.

It is possible to design eye-safe laser transmitters at both the 800 nm and 1550 nm wavelengths but the allowable safe laser power is about fifty times higher at 1550 nm.

CHALLENGES..

Environmental factors

Each of these factors can “attenuate” (reduce) the signal. However, there are ways to mitigate each

environmental factor

Atmospheric attenuation-F O G

Absorption or scattering of optical signals due to airborne particles

Can result in a complete outageFSO wavelengths and fog droplets are

close to equal in size

• (Mie Scattering)Typical FSO systems work 2-3X further

than the human eye can seeHigh availability deployments require

short links that can operate in the fog

Atmospheric attenuation-Low Clouds, Rain, Snow and Dust

• Low Clouds• Very similar to fog• May accompany rain and snow

• Rain• Drop sizes larger than fog and wavelength of light• Extremely heavy rain (can’t see through it) can

take a link down• Water sheeting on windows

• Heavy Snow• May cause ice build-up on windows• Whiteout conditions

• Sand Storms• Likely only in desert areas; rare in the urban core

Scintillation

Beam spreading and wandering due to propagation through air pockets of varying temperature, density, and index of refraction.

Almost mutually exclusive with fog attenuation.Results in increased error rate but not complete outage

Window attenuation

• Uncoated glass attenuates 4% per surface due to reflection

• Tinted or insulated windows can have much greater attenuation

Building motion

Type Cause(s) Magnitude Frequency

Tip/tilt Thermal expansion High Once per day

Sway Wind Medium Once every several seconds

Vibration Equipment (e.g., HVAC), door slamming, etc.

Low Many times per second

SOLUTIONS

Wide beam technology™ Using multi beam system/ wide beam system, we can address the

effects of scintillation

Active beam tracking system™

This system reduces the attenuation caused due to building sway/seismic activity by automatically keeping the terminals aligned(longer security and higher distance transmission)

Rapid Spanning tree(automatic failover switching protocol) and Open Shortest path first(routing protocol)

With these, connection can be maintained during dense fog events.

The DSL connection or RF radio link*, though slower will establish 100% connectivity in conjunction with the above protocols.

The *slower connections are used only 0.1% of the time, compared to the 99.9% operational Gigabit Ethernet FSO systems

Where is its application??

Large Industrial estates Science parks etc..

In prohibited and sensitive areas

Military applications

• Air Force • Its potential for low

electromagnetic emanation when transferring sensitive data

• Navy• Secure communication with

submerged submarines.

A technology to look up on. . .FSO is be applied to solve the Internet “last-mile” interconnectivity problem

It can be the unlimited bandwidth solution for the metro urban core of downtown building-to-building communication

An optimal technology for home-to-home and office-to-office connectivity

Technology used by NASA in latest Mars exploration

A robust, reliable and secure communication technology for military

REFERENCES

• Lightpointe• SONABeam• Freespace optics.org• Wikipedia

Any Questions ?

Thank You