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See Through Walls

with Wi-ViFadel Adib Dina Katabi

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Can your cellphone give you X-ray vision?

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Key Idea

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Challenges

Wall refection is 1!" stronger than reflectionsco#ing fro# $ehind the wall

Trac%ing people fro# their reflections

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Wi-Vi' S#all! (ow-)ower! Wi-*i

Eliminate the walls reflection

Track eole from reflections

Gesture!based interface

"mlemented on software radios

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+ow Can We ,li#inatethe Walls .eflection?

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"dea# transmit two waves that cancel

each other when they reflect off staticob$ects but not moving ob$ects

%all isstatic

Peole tendto move

disaears

detectable

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,li#inating the Walls .eflection

Trans#it

&ntennas

.eceive&ntenna'

&'

'

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,li#inating the Walls .eflection

h/

h1

y 0 h1 " h/2"(

& ) !h* +h,

.eceive&ntenna'

&'

'

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,li#inating &ll Static.eflections

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,li#inating &ll Static.eflections

y 0 h1 " h/2"

-tatic ob$ects .wall/

furniture/ etc01 haveconstant channelsy 0 h1 " h/3-

h14 h/5"

(

Peole move/

therefore theirchannels change

y 0 h1" h/3-

h14 h/5"6ot 7ero

h2

h1

x

x

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+ow Can We Trac% 8sing.eflections?

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9irection ofreflection

:

&ntenna

Trac%ing ;otion

2F source

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:

&ntenna

Trac%ing ;otion

9irection of#otion

&t any point in

ti#e! we have asingle#easure#ent

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:

&ntenna

Trac%ing ;otion9irection of

#otion

:9irection

of #otion

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:

&ntenna

Trac%ing ;otion9irection of

#otion

:9irection

of #otion+u#an #otion e#ulates

antenna arra

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& Through-Wall

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=it >1=it >

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I#ple#entation and ,valuation

7-2P software radios#

%i!Fi signals# ,08G9:/ ;FDumber of distinct curves at the same timecorresonds to the number of humans

Two +u#ans Three +u#ans

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&uto#atic ,sti#ation' 6u#$er of)eople

Detected

Actual( * , ?

( *((@ (@ (@ (@

* (@ *((@ (@ (@

, (@ (@ =@ *=@

? (@ (@ *(@ B(@

3lassification algorithm in the aer

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=uilding ;aterials

Free -ace *0C= wood door concret(

,(

8((

(

*((*(( *(( *(( *((

C0=

&

ccuracy3?5

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.elated Wor% Designed for military

23P*(

, G9: bandwidth

Harge ower source

9uge antenna array

Attemt at using %i!Fi 3-%*,

>eeds to install a receiver in the imaged room andconnect it to a receiver outside the room via wire

7coming work in

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6ew Version' )re-pu$lication