<s>
A	O
wireless	B-General_Concept
ad	I-General_Concept
hoc	I-General_Concept
network	I-General_Concept
(	O
WANET	B-General_Concept
)	O
or	O
mobile	B-General_Concept
ad	I-General_Concept
hoc	I-General_Concept
network	I-General_Concept
(	O
MANET	B-General_Concept
)	O
is	O
a	O
decentralized	O
type	O
of	O
wireless	B-General_Concept
network	I-General_Concept
.	O
</s>
<s>
The	O
network	O
is	O
ad	O
hoc	O
because	O
it	O
does	O
not	O
rely	O
on	O
a	O
pre-existing	O
infrastructure	O
,	O
such	O
as	O
routers	B-Protocol
or	O
wireless	B-Device
access	I-Device
points	I-Device
.	O
</s>
<s>
Instead	O
,	O
each	O
node	B-Protocol
participates	O
in	O
routing	B-Protocol
by	O
forwarding	B-Protocol
data	O
for	O
other	O
nodes	O
.	O
</s>
<s>
The	O
determination	O
of	O
which	O
nodes	O
forward	O
data	O
is	O
made	O
dynamically	O
on	O
the	O
basis	O
of	O
network	O
connectivity	O
and	O
the	O
routing	B-Protocol
algorithm	I-Protocol
in	O
use	O
.	O
</s>
<s>
Such	O
wireless	B-General_Concept
networks	I-General_Concept
lack	O
the	O
complexities	O
of	O
infrastructure	O
setup	O
and	O
administration	O
,	O
enabling	O
devices	O
to	O
create	O
and	O
join	O
networks	O
"	O
on	O
the	O
fly	O
"	O
.	O
</s>
<s>
Each	O
device	O
in	O
a	O
MANET	B-General_Concept
is	O
free	O
to	O
move	O
independently	O
in	O
any	O
direction	O
,	O
and	O
will	O
therefore	O
change	O
its	O
links	O
to	O
other	O
devices	O
frequently	O
.	O
</s>
<s>
Each	O
must	O
forward	O
traffic	O
unrelated	O
to	O
its	O
own	O
use	O
,	O
and	O
therefore	O
be	O
a	O
router	B-Protocol
.	O
</s>
<s>
The	O
primary	O
challenge	O
in	O
building	O
a	O
MANET	B-General_Concept
is	O
equipping	O
each	O
device	O
to	O
continuously	O
maintain	O
the	O
information	O
required	O
to	O
properly	O
route	O
traffic	O
.	O
</s>
<s>
This	O
becomes	O
harder	O
as	O
the	O
scale	O
of	O
the	O
MANET	B-General_Concept
increases	O
due	O
to	O
1	O
)	O
the	O
desire	O
to	O
route	O
packets	B-Protocol
to/through	O
every	O
other	O
node	B-Protocol
,	O
2	O
)	O
the	O
percentage	O
of	O
overhead	O
traffic	O
needed	O
to	O
maintain	O
real-time	O
routing	B-Protocol
status	O
,	O
3	O
)	O
each	O
node	B-Protocol
has	O
its	O
own	O
goodput	O
to	O
route	O
independent	O
and	O
unaware	O
of	O
others	O
needs	O
,	O
and	O
4	O
)	O
all	O
must	O
share	O
limited	O
communication	O
bandwidth	B-Algorithm
,	O
such	O
as	O
a	O
slice	O
of	O
radio	O
spectrum	O
.	O
</s>
<s>
MANETs	B-General_Concept
usually	O
have	O
a	O
routable	B-Protocol
networking	O
environment	O
on	O
top	O
of	O
a	O
link	B-Protocol
layer	I-Protocol
ad	O
hoc	O
network	O
.	O
</s>
<s>
The	O
earliest	O
wireless	O
data	O
network	O
was	O
called	O
PRNET	B-Protocol
,	O
the	O
packet	B-Application
radio	I-Application
network	O
,	O
and	O
was	O
sponsored	O
by	O
Defense	O
Advanced	O
Research	O
Projects	O
Agency	O
(	O
DARPA	O
)	O
in	O
the	O
early	O
1970s	O
.	O
</s>
<s>
These	O
early	O
packet	B-Application
radio	I-Application
systems	I-Application
predated	O
the	O
Internet	O
,	O
and	O
indeed	O
were	O
part	O
of	O
the	O
motivation	O
of	O
the	O
original	O
Internet	O
Protocol	O
suite	O
.	O
</s>
<s>
Later	O
DARPA	O
experiments	O
included	O
the	O
Survivable	O
Radio	O
Network	O
(	O
SURAN	B-Protocol
)	O
project	O
,	O
which	O
took	O
place	O
in	O
the	O
1980s	O
.	O
</s>
<s>
A	O
successor	O
to	O
these	O
systems	O
was	O
fielded	O
in	O
the	O
mid-1990s	O
for	O
the	O
US	O
Army	O
,	O
and	O
later	O
other	O
nations	O
,	O
as	O
the	O
Near-term	B-General_Concept
digital	I-General_Concept
radio	I-General_Concept
.	O
</s>
<s>
Another	O
third	O
wave	O
of	O
academic	O
and	O
research	O
activity	O
started	O
in	O
the	O
mid-1990s	O
with	O
the	O
advent	O
of	O
inexpensive	O
802.11	O
radio	O
cards	O
for	O
personal	B-Device
computers	I-Device
.	O
</s>
<s>
Current	O
wireless	B-General_Concept
ad	I-General_Concept
hoc	I-General_Concept
networks	I-General_Concept
are	O
designed	O
primarily	O
for	O
military	O
utility	O
.	O
</s>
<s>
Problems	O
with	O
packet	B-Application
radios	I-Application
are	O
:	O
(	O
1	O
)	O
bulky	O
elements	O
,	O
(	O
2	O
)	O
slow	O
data	O
rate	O
,	O
(	O
3	O
)	O
unable	O
to	O
maintain	O
links	O
if	O
mobility	O
is	O
high	O
.	O
</s>
<s>
The	O
project	O
did	O
not	O
proceed	O
much	O
further	O
until	O
the	O
early	O
1990s	O
when	O
wireless	B-General_Concept
ad	I-General_Concept
hoc	I-General_Concept
networks	I-General_Concept
were	O
born	O
.	O
</s>
<s>
The	O
growth	O
of	O
laptops	B-Device
and	O
802.11/Wi	O
-Fi	O
wireless	B-General_Concept
networking	I-General_Concept
have	O
made	O
MANETs	B-General_Concept
a	O
popular	O
research	O
topic	O
since	O
the	O
mid-1990s	O
.	O
</s>
<s>
Many	O
academic	O
papers	O
evaluate	O
protocols	O
and	O
their	O
abilities	O
,	O
assuming	O
varying	O
degrees	O
of	O
mobility	O
within	O
a	O
bounded	O
space	O
,	O
usually	O
with	O
all	O
nodes	O
within	O
a	O
few	O
hops	B-Protocol
of	O
each	O
other	O
.	O
</s>
<s>
Different	O
protocols	O
are	O
then	O
evaluated	O
based	O
on	O
measures	O
such	O
as	O
the	O
packet	B-Protocol
drop	O
rate	O
,	O
the	O
overhead	O
introduced	O
by	O
the	O
routing	B-Protocol
protocol	O
,	O
end-to-end	O
packet	B-Protocol
delays	O
,	O
network	O
throughput	O
,	O
ability	O
to	O
scale	O
,	O
etc	O
.	O
</s>
<s>
In	O
the	O
early	O
1990s	O
,	O
Charles	O
Perkins	O
from	O
SUN	O
Microsystems	O
USA	O
,	O
and	O
Chai	O
Keong	O
Toh	O
from	O
Cambridge	O
University	O
separately	O
started	O
to	O
work	O
on	O
a	O
different	O
Internet	O
,	O
that	O
of	O
a	O
wireless	B-General_Concept
ad	I-General_Concept
hoc	I-General_Concept
network	I-General_Concept
.	O
</s>
<s>
Toh	O
worked	O
on	O
a	O
new	O
routing	B-Protocol
protocol	O
,	O
which	O
was	O
known	O
as	O
ABR	O
–	O
associativity-based	B-Device
routing	I-Device
.	O
</s>
<s>
Perkins	O
eventually	O
proposed	O
DSDV	O
–	O
Destination	O
Sequence	O
Distance	O
Vector	O
routing	B-Protocol
,	O
which	O
was	O
based	O
on	O
distributed	O
distance	O
vector	O
routing	B-Protocol
.	O
</s>
<s>
Toh	O
's	O
proposal	O
was	O
an	O
on-demand	O
based	O
routing	B-Protocol
,	O
i.e.	O
</s>
<s>
ABR	O
was	O
implemented	O
successfully	O
into	O
Linux	O
OS	O
on	O
Lucent	O
WaveLAN	O
802.11a	O
enabled	O
laptops	B-Device
and	O
a	O
practical	O
ad	O
hoc	O
mobile	O
network	O
was	O
therefore	O
proven	O
to	O
be	O
possible	O
in	O
1999	O
.	O
</s>
<s>
Another	O
routing	B-Protocol
protocol	O
known	O
as	O
AODV	B-Device
was	O
subsequently	O
introduced	O
and	O
later	O
proven	O
and	O
implemented	O
in	O
2005	O
.	O
</s>
<s>
In	O
2007	O
,	O
David	O
Johnson	O
and	O
Dave	O
Maltz	O
proposed	O
DSR	O
–	O
Dynamic	B-Device
Source	I-Device
Routing	I-Device
.	O
</s>
<s>
The	O
decentralized	O
nature	O
of	O
wireless	B-General_Concept
ad	I-General_Concept
hoc	I-General_Concept
networks	I-General_Concept
makes	O
them	O
suitable	O
for	O
a	O
variety	O
of	O
applications	O
where	O
central	O
nodes	O
ca	O
n't	O
be	O
relied	O
on	O
and	O
may	O
improve	O
the	O
scalability	O
of	O
networks	O
compared	O
to	O
wireless	O
managed	O
networks	O
,	O
though	O
theoretical	O
and	O
practical	O
limits	O
to	O
the	O
overall	O
capacity	O
of	O
such	O
networks	O
have	O
been	O
identified	O
.	O
</s>
<s>
The	O
presence	O
of	O
dynamic	O
and	O
adaptive	O
routing	B-Protocol
protocols	O
enables	O
ad	O
hoc	O
networks	O
to	O
be	O
formed	O
quickly	O
.	O
</s>
<s>
A	O
mobile	B-General_Concept
ad	I-General_Concept
hoc	I-General_Concept
network	I-General_Concept
(	O
MANET	B-General_Concept
)	O
is	O
a	O
continuously	O
self-configuring	O
,	O
self-organizing	O
,	O
infrastructure-less	O
network	O
of	O
mobile	O
devices	O
connected	O
without	O
wires	O
.	O
</s>
<s>
VANETs	B-Device
are	O
used	O
for	O
communication	O
between	O
vehicles	O
and	O
roadside	O
equipment	O
.	O
</s>
<s>
Intelligent	B-General_Concept
vehicular	I-General_Concept
ad	I-General_Concept
hoc	I-General_Concept
networks	I-General_Concept
(	O
InVANETs	B-General_Concept
)	O
are	O
a	O
kind	O
of	O
artificial	O
intelligence	O
that	O
helps	O
vehicles	O
to	O
behave	O
in	O
intelligent	O
manners	O
during	O
vehicle-to-vehicle	B-Device
collisions	O
,	O
accidents	O
.	O
</s>
<s>
VANET	B-Device
needs	O
to	O
be	O
secured	O
with	O
lightweight	O
protocols	O
.	O
</s>
<s>
A	O
SPAN	B-Application
leverages	O
existing	O
hardware	O
(	O
primarily	O
Wi-Fi	O
and	O
Bluetooth	B-Protocol
)	O
and	O
software	O
(	O
protocols	O
)	O
in	O
commercially	O
available	O
smartphones	O
to	O
create	O
peer-to-peer	O
networks	O
without	O
relying	O
on	O
cellular	O
carrier	O
networks	O
,	O
wireless	B-Device
access	I-Device
points	I-Device
,	O
or	O
traditional	O
network	O
infrastructure	O
.	O
</s>
<s>
SPANs	O
differ	O
from	O
traditional	O
hub	O
and	O
spoke	O
networks	O
,	O
such	O
as	O
Wi-Fi	O
Direct	O
,	O
in	O
that	O
they	O
support	O
multi-hop	O
relays	O
and	O
there	O
is	O
no	O
notion	O
of	O
a	O
group	O
leader	O
so	O
peers	O
can	O
join	O
and	O
leave	O
at	O
will	O
without	O
destroying	O
the	O
network	O
.	O
</s>
<s>
Apple	O
's	O
iPhone	B-Device
with	O
iOS	O
version	O
7.0	O
and	O
higher	O
is	O
capable	O
of	O
multi-peer	O
ad	O
hoc	O
mesh	O
networking	O
.	O
</s>
<s>
In	O
a	O
fully	O
connected	O
mesh	O
,	O
each	O
node	B-Protocol
is	O
connected	O
to	O
every	O
other	O
node	B-Protocol
,	O
forming	O
a	O
"	O
mesh	O
"	O
.	O
</s>
<s>
Wireless	B-General_Concept
ad	I-General_Concept
hoc	I-General_Concept
networks	I-General_Concept
can	O
take	O
the	O
form	O
of	O
a	O
mesh	O
networks	O
or	O
others	O
.	O
</s>
<s>
A	O
wireless	B-General_Concept
ad	I-General_Concept
hoc	I-General_Concept
network	I-General_Concept
does	O
not	O
have	O
fixed	O
topology	O
,	O
and	O
its	O
connectivity	O
among	O
nodes	O
is	O
totally	O
dependent	O
on	O
the	O
behavior	O
of	O
the	O
devices	O
,	O
their	O
mobility	O
patterns	O
,	O
distance	O
with	O
each	O
other	O
,	O
etc	O
.	O
</s>
<s>
Hence	O
,	O
wireless	O
mesh	O
networks	O
are	O
a	O
particular	O
type	O
of	O
wireless	B-General_Concept
ad	I-General_Concept
hoc	I-General_Concept
networks	I-General_Concept
,	O
with	O
special	O
emphasis	O
on	O
the	O
resultant	O
network	O
topology	O
.	O
</s>
<s>
While	O
some	O
wireless	O
mesh	O
networks	O
(	O
particularly	O
those	O
within	O
a	O
home	O
)	O
have	O
relatively	O
infrequent	O
mobility	O
and	O
thus	O
infrequent	O
link	O
breaks	O
,	O
other	O
more	O
mobile	O
mesh	O
networks	O
require	O
frequent	O
routing	B-Protocol
adjustments	O
to	O
account	O
for	O
lost	O
links	O
.	O
</s>
<s>
Military	O
or	O
tactical	O
MANETs	B-General_Concept
are	O
used	O
by	O
military	O
units	O
with	O
emphasis	O
on	O
data	O
rate	O
,	O
real-time	O
requirement	O
,	O
fast	O
re-routing	O
during	O
mobility	O
,	O
data	O
security	O
,	O
radio	O
range	O
,	O
and	O
integration	O
with	O
existing	O
systems	O
.	O
</s>
<s>
Military	O
MANETs	B-General_Concept
are	O
used	O
by	O
military	O
units	O
with	O
an	O
emphasis	O
on	O
rapid	O
deployment	O
,	O
infrastructureless	O
,	O
all-wireless	O
networks	O
(	O
no	O
fixed	O
radio	O
towers	O
)	O
,	O
robustness	O
(	O
link	O
breaks	O
are	O
no	O
problem	O
)	O
,	O
security	O
,	O
range	O
,	O
and	O
instant	O
operation	O
.	O
</s>
<s>
With	O
wireless	B-General_Concept
ad	I-General_Concept
hoc	I-General_Concept
network	I-General_Concept
technology	O
embedded	O
into	O
the	O
UAVs	O
,	O
multiple	O
UAVs	O
can	O
communicate	O
with	O
each	O
other	O
and	O
work	O
as	O
a	O
team	O
,	O
collaboratively	O
to	O
complete	O
a	O
task	O
and	O
mission	O
.	O
</s>
<s>
More	O
generally	O
,	O
aerial	O
MANET	B-General_Concept
in	O
UAVs	O
are	O
now	O
(	O
as	O
of	O
2021	O
)	O
successfully	O
implemented	O
and	O
operational	O
as	O
mini	O
tactical	O
reconnaissance	O
ISR	O
UAVs	O
like	O
the	O
BRAMOR	O
C4EYE	O
from	O
Slovenia	O
.	O
</s>
<s>
However	O
,	O
such	O
communications	O
are	O
restricted	O
by	O
delays	O
and	O
limited	O
bandwidth	B-Algorithm
.	O
</s>
<s>
Wireless	B-General_Concept
ad	I-General_Concept
hoc	I-General_Concept
networks	I-General_Concept
enable	O
ship-area-networks	O
to	O
be	O
formed	O
while	O
at	O
sea	O
,	O
enabling	O
high-speed	O
wireless	O
communications	O
among	O
ships	O
,	O
enhancing	O
their	O
sharing	O
of	O
imaging	O
and	O
multimedia	O
data	O
,	O
and	O
better	O
co-ordination	O
in	O
battlefield	O
operations	O
.	O
</s>
<s>
The	O
connectivity	O
of	O
wireless	B-Architecture
sensor	I-Architecture
networks	I-Architecture
rely	O
on	O
the	O
principles	O
behind	O
wireless	B-General_Concept
ad	I-General_Concept
hoc	I-General_Concept
networks	I-General_Concept
,	O
since	O
sensors	O
can	O
now	O
be	O
deploy	O
without	O
any	O
fixed	O
radio	O
towers	O
,	O
and	O
they	O
can	O
now	O
form	O
networks	O
on-the-fly	O
.	O
</s>
<s>
More	O
recently	O
,	O
mobile	B-Device
wireless	I-Device
sensor	I-Device
networks	I-Device
(	O
MWSNs	B-Device
)	O
have	O
also	O
become	O
an	O
area	O
of	O
academic	O
interest	O
.	O
</s>
<s>
However	O
,	O
with	O
wireless	B-General_Concept
ad	I-General_Concept
hoc	I-General_Concept
networks	I-General_Concept
,	O
robots	O
can	O
form	O
a	O
communication	O
network	O
on-the-fly	O
,	O
i.e.	O
,	O
robots	O
can	O
now	O
"	O
talk	O
"	O
to	O
each	O
other	O
and	O
collaborate	O
in	O
a	O
distributed	O
fashion	O
.	O
</s>
<s>
Another	O
civilian	O
use	O
of	O
wireless	B-General_Concept
ad	I-General_Concept
hoc	I-General_Concept
network	I-General_Concept
is	O
for	O
public	O
safety	O
.	O
</s>
<s>
Especially	O
at	O
times	O
of	O
earthquakes	O
when	O
radio	O
towers	O
had	O
collapsed	O
or	O
were	O
destroyed	O
,	O
wireless	B-General_Concept
ad	I-General_Concept
hoc	I-General_Concept
networks	I-General_Concept
can	O
be	O
formed	O
independently	O
.	O
</s>
<s>
Wireless	B-General_Concept
ad	I-General_Concept
hoc	I-General_Concept
networks	I-General_Concept
allow	O
sensors	O
,	O
videos	O
,	O
instruments	O
,	O
and	O
other	O
devices	O
to	O
be	O
deployed	O
and	O
interconnected	O
wirelessly	O
for	O
clinic	O
and	O
hospital	O
patient	O
monitoring	O
,	O
doctor	O
and	O
nurses	O
alert	O
notification	O
,	O
and	O
also	O
making	O
senses	O
of	O
such	O
data	O
quickly	O
at	O
fusion	O
points	O
,	O
so	O
that	O
lives	O
can	O
be	O
saved	O
.	O
</s>
<s>
MANETS	B-General_Concept
can	O
be	O
used	O
for	O
facilitating	O
the	O
collection	O
of	O
sensor	O
data	O
for	O
data	B-Application
mining	I-Application
for	O
a	O
variety	O
of	O
applications	O
such	O
as	O
air	O
pollution	O
monitoring	O
and	O
different	O
types	O
of	O
architectures	O
can	O
be	O
used	O
for	O
such	O
applications	O
.	O
</s>
<s>
This	O
kind	O
of	O
data	B-Application
redundancy	I-Application
due	O
to	O
the	O
spatial	O
correlation	O
between	O
sensor	O
observations	O
inspires	O
the	O
techniques	O
for	O
in-network	O
data	O
aggregation	O
and	O
mining	O
.	O
</s>
<s>
By	O
measuring	O
the	O
spatial	O
correlation	O
between	O
data	O
sampled	O
by	O
different	O
sensors	O
,	O
a	O
wide	O
class	O
of	O
specialized	O
algorithms	O
can	O
be	O
developed	O
to	O
develop	O
more	O
efficient	O
spatial	O
data	B-Application
mining	I-Application
algorithms	O
as	O
well	O
as	O
more	O
efficient	O
routing	B-Protocol
strategies	O
.	O
</s>
<s>
Also	O
,	O
researchers	O
have	O
developed	O
performance	O
models	O
for	O
MANET	B-General_Concept
to	O
apply	O
queueing	O
theory	O
.	O
</s>
<s>
Several	O
books	O
and	O
works	O
have	O
revealed	O
the	O
technical	O
and	O
research	O
challenges	O
facing	O
wireless	B-General_Concept
ad	I-General_Concept
hoc	I-General_Concept
networks	I-General_Concept
or	O
MANETs	B-General_Concept
.	O
</s>
<s>
The	O
obvious	O
appeal	O
of	O
MANETs	B-General_Concept
is	O
that	O
the	O
network	O
is	O
decentralised	O
and	O
nodes/devices	O
are	O
mobile	O
,	O
that	O
is	O
to	O
say	O
there	O
is	O
no	O
fixed	O
infrastructure	O
which	O
provides	O
the	O
possibility	O
for	O
numerous	O
applications	O
in	O
different	O
areas	O
such	O
as	O
environmental	O
monitoring	O
[1],	O
[2],	O
disaster	O
relief	O
 [ 3 ] – [ 5 ] 	O
and	O
military	O
communications	O
 [ 3 ] 	O
.	O
</s>
<s>
Since	O
the	O
early	O
2000s	O
interest	O
in	O
MANETs	B-General_Concept
has	O
greatly	O
increased	O
which	O
,	O
in	O
part	O
,	O
is	O
due	O
to	O
the	O
fact	O
mobility	O
can	O
improve	O
network	O
capacity	O
,	O
shown	O
by	O
Grossglauser	O
and	O
Tse	O
along	O
with	O
the	O
introduction	O
of	O
new	O
technologies	O
.	O
</s>
<s>
One	O
main	O
advantage	O
to	O
a	O
decentralised	O
network	O
is	O
that	O
they	O
are	O
typically	O
more	O
robust	O
than	O
centralised	O
networks	O
due	O
to	O
the	O
multi-hop	O
fashion	O
in	O
which	O
information	O
is	O
relayed	O
.	O
</s>
<s>
For	O
example	O
,	O
in	O
the	O
cellular	O
network	O
setting	O
,	O
a	O
drop	O
in	O
coverage	O
occurs	O
if	O
a	O
base	O
station	O
stops	O
working	O
,	O
however	O
the	O
chance	O
of	O
a	O
single	O
point	O
of	O
failure	O
in	O
a	O
MANET	B-General_Concept
is	O
reduced	O
significantly	O
since	O
the	O
data	O
can	O
take	O
multiple	O
paths	O
.	O
</s>
<s>
Further	O
advantages	O
of	O
MANETS	B-General_Concept
over	O
networks	O
with	O
a	O
fixed	O
topology	O
include	O
flexibility	O
(	O
an	O
ad	O
hoc	O
network	O
can	O
be	O
created	O
anywhere	O
with	O
mobile	O
devices	O
)	O
,	O
scalability	O
(	O
you	O
can	O
easily	O
add	O
more	O
nodes	O
to	O
the	O
network	O
)	O
and	O
lower	O
administration	O
costs	O
(	O
no	O
need	O
to	O
build	O
an	O
infrastructure	O
first	O
)	O
.	O
</s>
<s>
Wireless	B-General_Concept
ad	I-General_Concept
hoc	I-General_Concept
networks	I-General_Concept
can	O
operate	O
over	O
different	O
types	O
of	O
radios	O
.	O
</s>
<s>
All	O
radios	O
use	O
modulation	B-Application
to	O
move	O
information	O
over	O
a	O
certain	O
bandwidth	B-Algorithm
of	O
radio	O
frequencies	O
.	O
</s>
<s>
Given	O
the	O
need	O
to	O
move	O
large	O
amounts	O
of	O
information	O
quickly	O
over	O
long	O
distances	O
,	O
a	O
MANET	B-General_Concept
radio	O
channel	O
ideally	O
has	O
large	O
bandwidth	B-Algorithm
(	O
e.g.	O
</s>
<s>
Given	O
radio	O
spectrum	O
is	O
shared	O
and	O
regulated	O
,	O
there	O
is	O
less	O
bandwidth	B-Algorithm
available	O
at	O
lower	O
frequencies	O
.	O
</s>
<s>
Picking	O
a	O
MANET	B-General_Concept
radio	O
and	O
modulation	B-Application
has	O
many	O
trade-offs	O
;	O
many	O
start	O
with	O
the	O
specific	O
frequency	O
and	O
bandwidth	B-Algorithm
they	O
are	O
allowed	O
to	O
use	O
.	O
</s>
<s>
Radios	O
can	O
be	O
UHF	O
(	O
300	O
–	O
3000MHz	O
)	O
,	O
SHF	B-Algorithm
(	O
3	O
–	O
30GHz	O
)	O
,	O
and	O
EHF	O
(	O
30	O
–	O
300GHz	O
)	O
.	O
</s>
<s>
Army	O
tactical	O
radios	O
usually	O
employ	O
a	O
variety	O
of	O
UHF	O
and	O
SHF	B-Algorithm
radios	O
,	O
including	O
those	O
of	O
VHF	B-Algorithm
to	O
provide	O
a	O
variety	O
of	O
communication	O
modes	O
.	O
</s>
<s>
Next	O
generation	O
Wi-Fi	O
known	O
as	O
802.11ax	O
provides	O
low	O
delay	O
,	O
high	O
capacity	O
(	O
up	O
to	O
10Gbit/s	O
)	O
and	O
low	O
packet	B-Protocol
loss	O
rate	O
,	O
offering	O
12	O
streams	O
–	O
8	O
streams	O
at	O
5GHz	O
and	O
4	O
streams	O
at	O
2.4GHz	O
.	O
</s>
<s>
Circa	O
2020	O
,	O
the	O
general	O
consensus	O
finds	O
the	O
'	O
best	O
 '	O
modulation	B-Application
for	O
moving	O
information	O
over	O
higher	O
frequency	O
waves	O
to	O
be	O
Orthogonal	B-Protocol
frequency-division	I-Protocol
multiplexing	I-Protocol
,	O
as	O
used	O
in	O
4G	O
LTE	O
,	O
5G	O
,	O
and	O
Wi-Fi	O
.	O
</s>
<s>
The	O
challenges	O
affecting	O
MANETs	B-General_Concept
span	B-Application
from	O
various	O
layers	O
of	O
the	O
OSI	O
protocol	O
stack	O
.	O
</s>
<s>
The	O
network	O
layer	O
routing	B-Protocol
protocol	O
has	O
to	O
be	O
improved	O
to	O
resolve	O
dynamically	O
changing	O
network	O
topologies	O
and	O
broken	O
routes	O
.	O
</s>
<s>
Moreover	O
,	O
the	O
bandwidth	B-Algorithm
of	O
a	O
wireless	O
channel	O
is	O
also	O
limited	O
,	O
and	O
nodes	O
operate	O
on	O
limited	O
battery	O
power	O
,	O
which	O
will	O
eventually	O
be	O
exhausted	O
.	O
</s>
<s>
These	O
factors	O
make	O
the	O
design	O
of	O
a	O
mobile	B-General_Concept
ad	I-General_Concept
hoc	I-General_Concept
network	I-General_Concept
challenging	O
.	O
</s>
<s>
The	O
cross-layer	O
design	O
deviates	O
from	O
the	O
traditional	O
network	B-Architecture
design	I-Architecture
approach	O
in	O
which	O
each	O
layer	O
of	O
the	O
stack	O
would	O
be	O
made	O
to	O
operate	O
independently	O
.	O
</s>
<s>
The	O
modified	O
transmission	O
power	O
will	O
help	O
that	O
node	B-Protocol
to	O
dynamically	O
vary	O
its	O
propagation	O
range	O
at	O
the	O
physical	O
layer	O
.	O
</s>
<s>
This	O
information	O
is	O
passed	O
from	O
the	O
physical	O
layer	O
to	O
the	O
network	O
layer	O
so	O
that	O
it	O
can	O
take	O
optimal	O
decisions	O
in	O
routing	B-Protocol
protocols	O
.	O
</s>
<s>
Routing	B-Protocol
in	O
wireless	B-General_Concept
ad	I-General_Concept
hoc	I-General_Concept
networks	I-General_Concept
or	O
MANETs	B-General_Concept
generally	O
falls	O
into	O
three	O
categories	O
,	O
namely	O
:	O
proactive	O
routing	B-Protocol
,	O
reactive	O
routing	B-Protocol
,	O
and	O
hybrid	O
routing	B-Protocol
.	O
</s>
<s>
This	O
type	O
of	O
protocols	O
maintains	O
fresh	O
lists	O
of	O
destinations	O
and	O
their	O
routes	O
by	O
periodically	O
distributing	O
routing	B-Protocol
tables	O
throughout	O
the	O
network	O
.	O
</s>
<s>
As	O
in	O
a	O
fix	O
net	O
nodes	O
maintain	O
routing	B-Protocol
tables	O
.	O
</s>
<s>
"	O
Direction	O
"	O
usually	O
means	O
the	O
next	O
hop	B-Protocol
address	O
and	O
the	O
exit	O
interface	O
.	O
</s>
<s>
"	O
Distance	O
"	O
is	O
a	O
measure	O
of	O
the	O
cost	O
to	O
reach	O
a	O
certain	O
node	B-Protocol
.	O
</s>
<s>
Each	O
node	B-Protocol
maintains	O
a	O
vector	O
(	O
table	O
)	O
of	O
minimum	O
distance	O
to	O
every	O
node	B-Protocol
.	O
</s>
<s>
RIP	B-Protocol
uses	O
the	O
hop	B-Protocol
count	I-Protocol
of	O
the	O
destination	O
whereas	O
IGRP	B-Protocol
takes	O
into	O
account	O
other	O
information	O
such	O
as	O
node	B-Protocol
delay	O
and	O
available	O
bandwidth	B-Algorithm
.	O
</s>
<s>
This	O
type	O
of	O
protocol	O
finds	O
a	O
route	O
based	O
on	O
user	O
and	O
traffic	O
demand	O
by	O
flooding	O
the	O
network	O
with	O
Route	O
Request	O
or	O
Discovery	O
packets	B-Protocol
.	O
</s>
<s>
Is	O
a	O
simple	O
routing	B-Protocol
algorithm	I-Protocol
in	O
which	O
every	O
incoming	O
packet	B-Protocol
is	O
sent	O
through	O
every	O
outgoing	O
link	O
except	O
the	O
one	O
it	O
arrived	O
on	O
.	O
</s>
<s>
Flooding	O
is	O
used	O
in	O
bridging	O
and	O
in	O
systems	O
such	O
as	O
Usenet	O
and	O
peer-to-peer	O
file	O
sharing	O
and	O
as	O
part	O
of	O
some	O
routing	B-Protocol
protocols	O
,	O
including	O
OSPF	B-Protocol
,	O
DVMRP	B-Protocol
,	O
and	O
those	O
used	O
in	O
wireless	B-General_Concept
ad	I-General_Concept
hoc	I-General_Concept
networks	I-General_Concept
.	O
</s>
<s>
This	O
type	O
of	O
protocol	O
combines	O
the	O
advantages	O
of	O
proactive	O
and	O
reactive	O
routing	B-Protocol
.	O
</s>
<s>
The	O
routing	B-Protocol
is	O
initially	O
established	O
with	O
some	O
proactively	O
prospected	O
routes	O
and	O
then	O
serves	O
the	O
demand	O
from	O
additionally	O
activated	O
nodes	O
through	O
reactive	O
flooding	O
.	O
</s>
<s>
Position-based	O
routing	B-Protocol
methods	O
use	O
information	O
on	O
the	O
exact	O
locations	O
of	O
the	O
nodes	O
.	O
</s>
<s>
Links	O
are	O
influenced	O
by	O
the	O
node	B-Protocol
's	O
resources	O
(	O
e.g.	O
,	O
transmitter	O
power	O
,	O
computing	O
power	O
and	O
memory	O
)	O
and	O
behavioral	O
properties	O
(	O
e.g.	O
,	O
reliability	O
)	O
,	O
as	O
well	O
as	O
link	O
properties	O
(	O
e.g.	O
</s>
<s>
Various	O
routing	B-Protocol
methods	O
use	O
one	O
or	O
two	O
paths	O
between	O
any	O
two	O
nodes	O
;	O
flooding	O
methods	O
use	O
all	O
or	O
most	O
of	O
the	O
available	O
paths	O
.	O
</s>
<s>
In	O
most	O
wireless	B-General_Concept
ad	I-General_Concept
hoc	I-General_Concept
networks	I-General_Concept
,	O
the	O
nodes	O
compete	O
for	O
access	O
to	O
shared	O
wireless	O
medium	O
,	O
often	O
resulting	O
in	O
collisions	O
(	O
interference	O
)	O
.	O
</s>
<s>
Using	O
cooperative	O
wireless	O
communications	O
improves	O
immunity	O
to	O
interference	O
by	O
having	O
the	O
destination	O
node	B-Protocol
combine	O
self-interference	O
and	O
other-node	O
interference	O
to	O
improve	O
decoding	O
of	O
the	O
desired	O
signals	O
.	O
</s>
<s>
One	O
key	O
problem	O
in	O
wireless	B-General_Concept
ad	I-General_Concept
hoc	I-General_Concept
networks	I-General_Concept
is	O
foreseeing	O
the	O
variety	O
of	O
possible	O
situations	O
that	O
can	O
occur	O
.	O
</s>
<s>
One	O
solution	O
is	O
the	O
use	O
of	O
simulation	O
tools	O
like	O
OPNET	O
,	O
NetSim	O
or	O
ns2	B-Language
.	O
</s>
<s>
A	O
comparative	O
study	O
of	O
various	O
simulators	O
for	O
VANETs	B-Device
reveal	O
that	O
factors	O
such	O
as	O
constrained	O
road	O
topology	O
,	O
multi-path	O
fading	O
and	O
roadside	O
obstacles	O
,	O
traffic	O
flow	O
models	O
,	O
trip	O
models	O
,	O
varying	O
vehicular	O
speed	O
and	O
mobility	O
,	O
traffic	O
lights	O
,	O
traffic	O
congestion	O
,	O
drivers	O
 '	O
behavior	O
,	O
etc.	O
,	O
have	O
to	O
be	O
taken	O
into	O
consideration	O
in	O
the	O
simulation	O
process	O
to	O
reflect	O
realistic	O
conditions	O
.	O
</s>
<s>
In	O
2009	O
,	O
the	O
U.S.	O
Army	O
Research	O
Laboratory	O
(	O
ARL	O
)	O
and	O
Naval	O
Research	O
Laboratory	O
(	O
NRL	O
)	O
developed	O
a	O
Mobile	B-General_Concept
Ad-Hoc	I-General_Concept
Network	I-General_Concept
emulation	O
testbed	O
,	O
where	O
algorithms	O
and	O
applications	O
were	O
subjected	O
to	O
representative	O
wireless	B-General_Concept
network	I-General_Concept
conditions	O
.	O
</s>
<s>
The	O
testbed	O
was	O
based	O
on	O
a	O
version	O
of	O
the	O
"	O
MANE	O
"	O
(	O
Mobile	B-General_Concept
Ad	I-General_Concept
hoc	I-General_Concept
Network	I-General_Concept
Emulator	O
)	O
software	O
originally	O
developed	O
by	O
NRL	O
.	O
</s>
<s>
Each	O
node	B-Protocol
then	O
has	O
a	O
predefined	O
fixed	O
cell	O
size	O
(	O
radio	O
range	O
)	O
.	O
</s>
<s>
A	O
node	B-Protocol
is	O
said	O
to	O
be	O
connected	O
to	O
another	O
node	B-Protocol
if	O
this	O
neighbor	O
is	O
within	O
its	O
radio	O
range	O
.	O
</s>
<s>
Different	O
mobility	O
and	O
number	O
of	O
nodes	O
present	O
yield	O
different	O
route	O
length	O
and	O
hence	O
different	O
number	O
of	O
multi-hops	O
.	O
</s>
<s>
Most	O
wireless	B-General_Concept
ad	I-General_Concept
hoc	I-General_Concept
networks	I-General_Concept
do	O
not	O
implement	O
any	O
network	O
access	O
control	O
,	O
leaving	O
these	O
networks	O
vulnerable	O
to	O
resource	O
consumption	O
attacks	O
where	O
a	O
malicious	O
node	B-Protocol
injects	O
packets	B-Protocol
into	O
the	O
network	O
with	O
the	O
goal	O
of	O
depleting	O
the	O
resources	O
of	O
the	O
nodes	O
relaying	O
the	O
packets	B-Protocol
.	O
</s>
<s>
Even	O
with	O
authentication	O
,	O
these	O
networks	O
are	O
vulnerable	O
to	O
packet	B-Protocol
dropping	O
or	O
delaying	O
attacks	O
,	O
whereby	O
an	O
intermediate	B-Protocol
node	I-Protocol
drops	O
the	O
packet	B-Protocol
or	O
delays	O
it	O
,	O
rather	O
than	O
promptly	O
sending	O
it	O
to	O
the	O
next	O
hop	B-Protocol
.	O
</s>
<s>
In	O
a	O
multicast	O
and	O
dynamic	O
environment	O
,	O
establishing	O
temporary	O
1:1	O
secure	O
'	O
sessions	O
 '	O
using	O
PKI	B-Architecture
with	O
every	O
other	O
node	B-Protocol
is	O
not	O
feasible	O
(	O
like	O
is	O
done	O
with	O
HTTPS	B-Protocol
,	O
most	O
VPNs	B-Application
,	O
etc	O
.	O
</s>
<s>
Instead	O
,	O
a	O
common	O
solution	O
is	O
to	O
use	O
pre-shared	O
keys	O
for	O
symmetric	O
,	O
authenticated	O
encryption	O
at	O
the	O
link	B-Protocol
layer	I-Protocol
,	O
for	O
example	O
MACsec	O
using	O
AES-256-GCM	O
.	O
</s>
<s>
With	O
this	O
method	O
,	O
every	O
properly	O
formatted	O
packet	B-Protocol
received	O
is	O
authenticated	O
then	O
passed	O
along	O
for	O
decryption	O
or	O
dropped	O
.	O
</s>
<s>
It	O
also	O
means	O
the	O
key(s )	O
in	O
each	O
node	B-Protocol
must	O
be	O
changed	O
more	O
often	O
and	O
simultaneously	O
(	O
e.g.	O
</s>
<s>
to	O
avoid	O
reusing	O
an	O
IV	B-Algorithm
)	O
.	O
</s>
<s>
Trust	O
establishment	O
and	O
management	O
in	O
MANETs	B-General_Concept
face	O
challenges	O
due	O
to	O
resource	O
constraints	O
and	O
the	O
complex	O
interdependency	O
of	O
networks	O
.	O
</s>
<s>
Managing	O
trust	O
in	O
a	O
MANET	B-General_Concept
needs	O
to	O
consider	O
the	O
interactions	O
between	O
the	O
composite	O
cognitive	O
,	O
social	O
,	O
information	O
and	O
communication	O
networks	O
,	O
and	O
take	O
into	O
account	O
the	O
resource	O
constraints	O
(	O
e.g.	O
,	O
computing	O
power	O
,	O
energy	O
,	O
bandwidth	B-Algorithm
,	O
time	O
)	O
,	O
and	O
dynamics	O
(	O
e.g.	O
,	O
topology	O
changes	O
,	O
node	B-Protocol
mobility	O
,	O
node	B-Protocol
failure	O
,	O
propagation	O
channel	O
conditions	O
)	O
.	O
</s>
<s>
Researchers	O
of	O
trust	O
management	O
in	O
MANET	B-General_Concept
suggested	O
that	O
such	O
complex	O
interactions	O
require	O
a	O
composite	O
trust	O
metric	O
that	O
captures	O
aspects	O
of	O
communications	O
and	O
social	O
networks	O
,	O
and	O
corresponding	O
trust	O
measurement	O
,	O
trust	O
distribution	O
,	O
and	O
trust	O
management	O
schemes	O
.	O
</s>
<s>
Continuous	O
monitoring	O
of	O
every	O
node	B-Protocol
within	O
a	O
MANET	B-General_Concept
is	O
necessary	O
for	O
trust	O
and	O
reliability	O
but	O
difficult	O
because	O
it	O
by	O
definition	O
is	O
dis-continuous	O
,	O
2	O
)	O
it	O
requires	O
input	O
from	O
the	O
node	B-Protocol
itself	O
and	O
3	O
)	O
from	O
its	O
'	O
nearby	O
 '	O
peers	O
.	O
</s>
