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BANASTHALI UNIVERSITY

Shivi ChauhanB.Tech 3rd yr (EC)presents Seminar

on

“Wi-Vi Technology”

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Outline:-

Introduction what can wi-vi do? Working Challenges faced

Flash effect Tracking human movements

Methods used to overcome the challenges how we can track using reflections? Applications Advantages & limitations future scope Reference

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Introduction

Wi-Vi was created by Dina Katabi , a professor in MIT, and her graduate student Fadel Adib.

Wi-vi stands for wireless vision.

It captures moving objects behind the wall.

Device uses typically wi-fi hardware.

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What can wi-vi do?

Detect the number of moving humans in a closed room.

Determine the relative locations of moving humans.

Enable communication through a wall without carrying a wireless device.

Identify simple gestures from behind a wall.

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Working

Wi-vi uses two transmitting antennas and a single receiver.

Transmitting signals are low power wi-fi signals.

The two antennas transmit almost identical signals, except the second antenna’s signal is the inverse of the first, resulting in interference.

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Challenges faced

flash effect

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Flash effect:

When you take a device, point it at a wall, and transmit Wi-Fi signals, a huge amount of reflection is going to come from the wall itself.

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Tracking human movement: when we get reflections from behind the wall ,we

will get reflections from everything in the environment: the chairs ,tables , and so on. How can we tease out the person’s reflections from all of these reflections? And once we do that, how can we track a person based on these reflections.

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Method used to overcome the challenges:

Idea: transmit two waves that cancel each other when they reflect off static objects but not moving objects

wall is static disappears

people tend detectable to move

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How can we track using reflections?

• Human reflects the signal, it’s as if he is the source of that signal.

• We know that if you want to track an RF source, you can do that using an antenna array.

• By steering the beam of the array, we can find the direction of from which the signal is coming.

• Now, when a person moves, that direction would change, and we are able to track him.

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All reflections from static objects are cancelled out, and the only thing registered by the device is the moving humans

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Advantages:

Wi-vi require same bandwidth & operates in the same range as wi-fi.

Wi-vi can perform through wall imaging without access to any device on the other side of the wall.

Wi-vi employs signals whose wavelength are 12.5 cm.

Extend human vision beyond the visible electromagnetic range, allowing us to detect objects in the dark or in smoke.

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Limitations:

Display has very low resolution.

We cannot detect humans behind concrete walls thicker than 8” .

To achieve a narrow beam the human needs to move by about about 50 cm.

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Future scope:

Wi-vi could be built into a smartphones or a special handheld device.

Evolution of seeing humans through denser building material and with a longer range.

High quality images.

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References:

[1]http://people.csail.mit.edu/fadel/wivi/

[2] Fadel adib and Dina katabi, see through walls with wi-fi, ACM SIGCOMM’13 hongkong august 2013.

[3] http://geekshots.in /2013/12/16/wi-vi-wifi-vision-behind-the walls/

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Thank you....queries????