Wi-Vi Technology

1

: Wi-Fi that see through walls

Presented by –Aman RajIndian Institute of Technology(ISM), Dhanbad

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ContentsIntroductionWhat can Wi-Vi do ?ApplicationDesign MethodologyResultsAdvantagesLimitationsFuture ScopeConclusion Bibliography 2

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Introduction

Wi-Vi stands for Wireless Vision.Demonstrated by “Dina Katabi”, a MIT’s professor of

Electrical Department.Wi-Vi uses OFDM signals in ISM Band(at 2.4 GHz) and

typical WiFi hardware.Wi-Vi captures moving Objects behind the walls.

What can Wi-Vi do?Detect the Number of Moving Humans in a

Closed Room.Determine the Relative Location of Moving

Humans.Enable Communication through a wall, without

carrying a Wireless Device.Can Identify simple Gestures Behind a wall.

ContinuedWi-Vi device transmits two waves that cancel each other when they reflect from a static object but not the moving object.

Wall is Static Disappears

People tend to move Detectable

Applications

Gesture control behind the wall

Police avoids ambush

Firefighters check for humans

Personel Security

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Design MethodologyWi-Vi device consists of 3 parts; Wi-Fi signal, Transmitter and

Receiver.

Wi-Fi

Transmitter ReceiverWi-Vi

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Description of Wi-Vi: Wi-Fi device, Transmitter and Receiver

Wi-Fi Device

Receiver

Transmitter

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Wi-Vi Setup

Wi-Vi uses angle of arrival of signals to detect movement and no. of humans behind the wall.

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Results

oA prototype of Wi-Vi setup used by Dina Katabi gave the following results:

Wi-Vi can detect objects and humans moving behind opaque structural obstructions.

This applies to 8” Concrete Walls, 6” Hollow walls and 1.75” solid wooden doors.

Continued:Wi-Vi depends upon the amount of movement.To achieve a narrow beam, the human needs to move by

about 50cm.

Detected/Actual 0 1 2 3

0 100% 0% 0% 0%

1 0% 100% 0% 0%

2 0% 0% 85% 15%

3 0% 0% 15% 90%

Table. Accuracy of Automatic Detection of Humans.

Detection Accuracy of Wi-Vi for Different types of obstructions:

Free Space Tinted Glass 1.75" solid wall 6" hollow wall 8" Concrete80

85

90

95

100

105

Series 1

Advantages:

1. Wi-Vi requires only few MHz of bandwidth similar as Wi-Fi.

2. Its setup is Low-Cost and Low-Power.3. Wi-Vi can perform through wall imaging without

access to any device on the other side of the wall.4. Works as extra human senses.5. Allows to detect object in Dark or smoke.

Limitations

1.Display has very low Resolution.2.Cannot detect human behind very thick

walls(>8” thickness).3.Human needs to move at least 50 cm to be

detectable.

Future Scope:

Wi-Vi could be built into a Smartphone or a special Handheld Device.

Can be used in Search and Rescue mission by Fire Fighter and Law Enforcement.

ConclusionWi-Vi is a Wireless Technology that uses Wi-Fi signals to detect moving humans behind walls and in a closed rooms. In contrast to previous systems, which are targeted for military, Wi-Vi enables small cheap, see- through wall devices that operates in the ISM band, rendering them feasible tp the general public, without carrying any extra transmitting device.

Bibliography

http://people.csail.mit.edu/fadel/wivi/USRP N210. http://www.ettus.com. Ettus Inc.X-box Kinect. http://www.xbox.com/ Microsoft/wiviRadarVision. http://www.timedomain.com. Time Domain

CorporationHow Signal is affected. www.ci.cumberland.md.us/See Through Walls with Wi-Fi! Fadel Adib and Dina Katabi

Massachusetts Institute of Technology {fadel,dk}@mit.edu

Thank You !