<s>
Vehicular	B-Device
Ad	I-Device
hoc	I-Device
Networks	I-Device
(	O
VANETs	B-Device
)	O
is	O
a	O
network	O
protocol	O
designed	O
for	O
traffic	O
safety	O
applications	O
.	O
</s>
<s>
As	O
other	O
computer	O
network	O
protocols	O
,	O
it	O
is	O
also	O
subject	O
to	O
several	O
attacks	O
that	O
can	O
have	O
fatal	O
consequences	O
due	O
to	O
the	O
VANET	B-Device
's	O
intended	O
usage	O
.	O
</s>
<s>
One	O
of	O
these	O
possible	O
attacks	O
is	O
location	O
spoofing	O
where	O
the	O
attacker	O
is	O
lying	O
about	O
a	O
vehicle	O
's	O
position	O
to	O
disrupt	O
VANET	B-Device
safety	O
application	O
.	O
</s>
<s>
VANETs	B-Device
are	O
proposed	O
for	O
improving	O
traffic	O
safety	O
.	O
</s>
<s>
With	O
the	O
help	O
of	O
these	O
periodic	O
BSM	O
advertisements	O
and	O
flooding	O
throughout	O
the	O
VANET	B-Device
,	O
every	O
vehicle	O
can	O
construct	O
a	O
traffic	O
awareness	O
from	O
a	O
very	O
large	O
area	O
and	O
take	O
preventive	O
actions	O
before	O
it	O
is	O
too	O
late	O
to	O
avoid	O
collisions	O
.	O
</s>
<s>
The	O
details	O
of	O
traffic	O
safety	O
mechanisms	O
in	O
VANETs	B-Device
and	O
their	O
special	O
network	O
protocol	O
stack	O
design	O
can	O
be	O
found	O
in	O
VANET	B-Device
standards	O
.	O
</s>
<s>
In	O
VANET	B-Device
network	O
protocol	O
stack	O
,	O
WAVE	O
standards	O
defines	O
mechanisms	O
from	O
Application	O
Layer	O
to	O
Network	O
Layer	O
while	O
IEEE	O
802.11p	O
specifies	O
the	O
Link	O
Layer	O
and	O
Physical	O
Layer	O
.	O
</s>
<s>
VANET	B-Device
's	O
protocol	O
stack	O
is	O
designed	O
specially	O
to	O
address	O
network	O
issues	O
that	O
come	O
with	O
high	O
mobility	O
and	O
high	O
network	O
overhead	O
.	O
</s>
<s>
In	O
VANET	B-Device
scenarios	O
,	O
every	O
vehicle	O
including	O
emergency	O
vehicles	O
will	O
be	O
equipped	O
with	O
communication	O
capabilities	O
.	O
</s>
<s>
They	O
can	O
produce	O
fake	O
locations	O
to	O
cause	O
accidents	O
,	O
mask	O
the	O
true	O
location	O
of	O
a	O
criminal	O
's	O
vehicle	O
in	O
a	O
police	O
chase	O
and	O
disrupt	O
many	O
other	O
VANET	B-Device
safety	O
applications	O
.	O
</s>
<s>
Easiest	O
way	O
for	O
attackers	O
to	O
achieve	O
location	O
spoofing	O
would	O
be	O
spoofing	O
other	O
existing	O
vehicles	O
 '	O
identities	O
;	O
however	O
,	O
Public	O
Key	O
Infrastructure	O
(	O
PKI	O
)	O
deployed	O
in	O
VANETs	B-Device
makes	O
this	O
a	O
very	O
challenging	O
task	O
.	O
</s>
<s>
Since	O
traffic	O
safety	O
applications	O
are	O
highly	O
dependent	O
on	O
accurate	O
vehicle	O
positions	O
,	O
there	O
has	O
been	O
significant	O
research	O
in	O
the	O
literature	O
towards	O
efficiently	O
verifying	O
the	O
location	O
advertisements	O
by	O
the	O
vehicles	O
in	O
VANETs	B-Device
.	O
</s>
<s>
They	O
use	O
the	O
stationary	O
base	O
stations	O
,	O
aka	O
Road	O
Side	O
Units	O
(	O
RSUs	O
)	O
located	O
at	O
the	O
side	O
of	O
the	O
roads	O
all	O
around	O
the	O
map	O
in	O
VANETs	B-Device
,	O
to	O
perform	O
the	O
localization	O
.	O
</s>
<s>
They	O
can	O
listen	O
to	O
VANET	B-Device
messages	O
and	O
they	O
are	O
all	O
connected	O
to	O
each	O
other	O
by	O
wired	O
connections	O
through	O
the	O
infrastructure	O
.	O
</s>
<s>
The	O
algorithm	O
solves	O
the	O
below	O
formula	O
as	O
an	O
optimization	O
problem	O
where	O
Mean	B-Algorithm
Squared	I-Algorithm
Error	I-Algorithm
(	O
MSE	O
)	O
is	O
minimized	O
by	O
varying	O
the	O
vehicle	O
's	O
estimated	O
position	O
.	O
</s>
<s>
Afterwards	O
,	O
the	O
attacker	O
vehicle	O
along	O
with	O
its	O
Sybil	O
nodes	O
(	O
its	O
forged	O
identities	O
)	O
can	O
be	O
removed	O
from	O
the	O
VANET	B-Device
by	O
warning	O
all	O
the	O
victim	O
vehicles	O
so	O
that	O
they	O
can	O
drop	O
all	O
the	O
packets	O
sent	O
by	O
these	O
malicious	O
nodes	O
.	O
</s>
<s>
It	O
makes	O
use	O
of	O
front	O
and	O
rear	O
radars	O
that	O
all	O
future	O
VANET-enabled	O
vehicles	O
are	O
expected	O
to	O
have	O
.	O
</s>
<s>
If	O
these	O
two	O
paths	O
are	O
different	O
above	O
a	O
certain	O
threshold	O
,	O
which	O
is	O
set	O
and	O
constantly	O
updated	O
according	O
to	O
the	O
expected	O
inaccuracy	O
of	O
GPS	O
devices	O
,	O
the	O
target	O
vehicle	O
will	O
be	O
marked	O
as	O
a	O
malicious	O
node	O
broadcasting	O
fake	O
positions	O
and	O
all	O
the	O
vehicles	O
in	O
a	O
VANET	B-Device
will	O
isolate	O
it	O
from	O
the	O
communication	O
.	O
</s>
<s>
They	O
use	O
several	O
plausibility	O
thresholds	O
that	O
can	O
be	O
calculated	O
and	O
confirmed	O
using	O
already	O
built-in	O
mechanisms	O
of	O
VANET-enabled	O
vehicles	O
.	O
</s>
