<s>
Passive	B-Device
Wi-Fi	I-Device
is	O
a	O
refinement	O
of	O
Wi-Fi	O
technology	O
that	O
uses	O
passive	O
reflection	O
to	O
reduce	O
energy	O
consumption	O
.	O
</s>
<s>
Wi-Fi	O
use	O
can	O
account	O
for	O
up	O
to	O
60	O
percent	O
of	O
a	O
smartphone	B-Application
’s	O
energy	O
consumption	O
.	O
</s>
<s>
The	O
technique	O
communicates	O
via	O
backscattering	B-Algorithm
,	O
reflecting	O
incoming	O
radio	O
waves	O
sent	O
from	O
a	O
separate	O
device	O
.	O
</s>
<s>
The	O
technique	O
is	O
similar	O
to	O
contactless	O
RFID	B-Application
chip	I-Application
cards	O
although	O
unlike	O
such	O
cards	O
,	O
the	O
new	O
technique	O
does	O
not	O
require	O
a	O
special	O
device	O
to	O
read	O
the	O
signal	O
.	O
</s>
<s>
Smartphones	B-Application
modify	O
and	O
reflect	O
this	O
signal	O
to	O
communicate	O
to	O
the	O
router	O
.	O
</s>
<s>
The	O
system	O
used	O
tens	O
of	O
microwatts	O
of	O
power	O
,	O
10−4	O
less	O
energy	O
than	O
conventional	O
Wi-fi	O
devices	O
,	O
and	O
one	O
thousandth	O
the	O
energy	O
of	O
Bluetooth	B-General_Concept
LE	I-General_Concept
and	O
Zigbee	B-Protocol
communications	O
standards	O
.	O
</s>
