<s>
A	O
mobile	B-Device
wireless	I-Device
sensor	I-Device
network	I-Device
(	O
MWSN	B-Device
)	O
can	O
simply	O
be	O
defined	O
as	O
a	O
wireless	B-Architecture
sensor	I-Architecture
network	I-Architecture
(	O
WSN	B-Architecture
)	O
in	O
which	O
the	O
sensor	B-Device
nodes	I-Device
are	O
mobile	O
.	O
</s>
<s>
MWSNs	B-Device
are	O
a	O
smaller	O
,	O
emerging	O
field	O
of	O
research	O
in	O
contrast	O
to	O
their	O
well-established	O
predecessor	O
.	O
</s>
<s>
MWSNs	B-Device
are	O
much	O
more	O
versatile	O
than	O
static	O
sensor	B-Architecture
networks	I-Architecture
as	O
they	O
can	O
be	O
deployed	O
in	O
any	O
scenario	O
and	O
cope	O
with	O
rapid	O
topology	B-Architecture
changes	O
.	O
</s>
<s>
Commonly	O
,	O
the	O
nodes	O
consist	O
of	O
a	O
radio	O
transceiver	O
and	O
a	O
microcontroller	B-Architecture
powered	O
by	O
a	O
battery	O
,	O
as	O
well	O
as	O
some	O
kind	O
of	O
sensor	O
for	O
detecting	O
light	O
,	O
heat	O
,	O
humidity	O
,	O
temperature	O
,	O
etc	O
.	O
</s>
<s>
Broadly	O
speaking	O
,	O
there	O
are	O
two	O
sets	O
of	O
challenges	O
in	O
MWSNs	B-Device
;	O
hardware	O
and	O
environment	O
.	O
</s>
<s>
Price	O
limitations	O
often	O
demand	O
low	O
complexity	O
algorithms	O
for	O
simpler	O
microcontrollers	B-Architecture
and	O
use	O
of	O
only	O
a	O
simplex	O
radio	O
.	O
</s>
<s>
The	O
major	O
environmental	O
factors	O
are	O
the	O
shared	O
medium	O
and	O
varying	O
topology	B-Architecture
.	O
</s>
<s>
This	O
is	O
often	O
done	O
using	O
a	O
medium	B-Protocol
access	I-Protocol
control	I-Protocol
(	O
MAC	O
)	O
scheme	O
,	O
such	O
as	O
carrier-sense	O
multiple	O
access	O
(	O
CSMA	O
)	O
,	O
frequency-division	O
multiple	O
access	O
(	O
FDMA	O
)	O
or	O
code-division	B-Protocol
multiple	I-Protocol
access	I-Protocol
(	O
CDMA	B-Protocol
)	O
.	O
</s>
<s>
The	O
varying	O
topology	B-Architecture
of	O
the	O
network	O
comes	O
from	O
the	O
mobility	O
of	O
nodes	O
,	O
which	O
means	O
that	O
multihop	O
paths	O
from	O
the	O
sensors	O
to	O
the	O
sink	O
are	O
not	O
stable	O
.	O
</s>
<s>
Currently	O
there	O
is	O
no	O
standard	O
for	O
MWSNs	B-Device
,	O
so	O
often	O
protocols	O
from	O
MANETs	O
are	O
borrowed	O
,	O
such	O
as	O
Associativity-Based	B-Device
Routing	I-Device
(	O
AR	O
)	O
,	O
Ad	B-Device
hoc	I-Device
On-Demand	I-Device
Distance	I-Device
Vector	I-Device
Routing	I-Device
(	O
AODV	B-Device
)	O
,	O
Dynamic	B-Device
Source	I-Device
Routing	I-Device
(	O
DSR	O
)	O
and	O
Greedy	O
Perimeter	O
Stateless	O
Routing	O
(	O
GPSR	O
)	O
.	O
</s>
<s>
MANET	O
protocols	O
are	O
preferred	O
as	O
they	O
are	O
able	O
to	O
work	O
in	O
mobile	O
environments	O
,	O
whereas	O
WSN	B-Architecture
protocols	O
often	O
are	O
n't	O
suitable	O
.	O
</s>
<s>
Topology	B-Architecture
selection	O
plays	O
an	O
important	O
role	O
in	O
routing	O
because	O
the	O
network	B-Architecture
topology	I-Architecture
decides	O
the	O
transmission	O
path	O
of	O
the	O
data	O
packets	O
to	O
reach	O
the	O
proper	O
destination	O
.	O
</s>
<s>
Here	O
,	O
all	O
the	O
topologies	B-Architecture
(	O
Flat	O
/	O
Unstructured	O
,	O
cluster	O
,	O
tree	O
,	O
chain	O
and	O
hybrid	O
topology	B-Architecture
)	O
are	O
not	O
feasible	O
for	O
reliable	O
data	O
transmission	O
on	O
sensor	B-Device
nodes	I-Device
mobility	O
.	O
</s>
<s>
Instead	O
of	O
single	O
topology	B-Architecture
,	O
hybrid	O
topology	B-Architecture
plays	O
a	O
vital	O
role	O
in	O
data	O
collection	O
,	O
and	O
the	O
performance	O
is	O
good	O
.	O
</s>
<s>
Hybrid	O
topology	B-Architecture
management	O
schemes	O
include	O
the	O
Cluster	O
Independent	O
Data	O
Collection	O
Tree	O
(	O
CIDT	O
)	O
.	O
</s>
<s>
and	O
the	O
Velocity	O
Energy-efficient	O
and	O
Link-aware	O
Cluster-Tree	O
(	O
VELCT	B-General_Concept
)	O
;	O
both	O
have	O
been	O
proposed	O
for	O
mobile	B-Device
wireless	I-Device
sensor	I-Device
networks	I-Device
(	O
MWSNs	B-Device
)	O
.	O
</s>
<s>
Since	O
there	O
is	O
no	O
fixed	O
topology	B-Architecture
in	O
these	O
networks	O
,	O
one	O
of	O
the	O
greatest	O
challenges	O
is	O
routing	O
data	O
from	O
its	O
source	O
to	O
the	O
destination	O
.	O
</s>
<s>
Generally	O
these	O
routing	O
protocols	O
draw	O
inspiration	O
from	O
two	O
fields	O
;	O
WSNs	B-Architecture
and	O
mobile	B-Protocol
ad	I-Protocol
hoc	I-Protocol
networks	I-Protocol
(	O
MANETs	O
)	O
.	O
</s>
<s>
WSN	B-Architecture
routing	O
protocols	O
provide	O
the	O
required	O
functionality	O
but	O
cannot	O
handle	O
the	O
high	O
frequency	O
of	O
topology	B-Architecture
changes	O
.	O
</s>
<s>
Whereas	O
,	O
MANET	O
routing	O
protocols	O
can	O
deal	O
with	O
mobility	O
in	O
the	O
network	O
but	O
they	O
are	O
designed	O
for	O
two	O
way	O
communication	O
,	O
which	O
in	O
sensor	B-Architecture
networks	I-Architecture
is	O
often	O
not	O
required	O
.	O
</s>
<s>
Protocols	O
designed	O
specifically	O
for	O
MWSNs	B-Device
are	O
almost	O
always	O
multihop	O
and	O
sometimes	O
adaptations	O
of	O
existing	O
protocols	O
.	O
</s>
<s>
For	O
example	O
,	O
Angle-based	O
Dynamic	B-Device
Source	I-Device
Routing	I-Device
(	O
ADSR	O
)	O
,	O
is	O
an	O
adaptation	O
of	O
the	O
wireless	O
mesh	O
network	O
protocol	O
Dynamic	B-Device
Source	I-Device
Routing	I-Device
(	O
DSR	O
)	O
for	O
MWSNs	B-Device
.	O
</s>
<s>
Also	O
,	O
Low	B-Device
Energy	I-Device
Adaptive	I-Device
Clustering	I-Device
Hierarchy	I-Device
(	O
LEACH	O
)	O
protocol	O
for	O
WSNs	B-Architecture
has	O
been	O
adapted	O
to	O
LEACH-M	O
(	O
LEACH-Mobile	O
)	O
,	O
for	O
MWSNs	B-Device
.	O
</s>
<s>
Multipath	O
protocols	O
provide	O
a	O
robust	O
mechanism	O
for	O
routing	O
and	O
therefore	O
seem	O
like	O
a	O
promising	O
direction	O
for	O
MWSN	B-Device
routing	O
protocols	O
.	O
</s>
<s>
Furthermore	O
,	O
Robust	O
Ad-hoc	O
Sensor	O
Routing	O
(	O
RASeR	O
)	O
and	O
Location	O
Aware	O
Sensor	O
Routing	O
(	O
LASeR	O
)	O
are	O
two	O
protocols	O
that	O
are	O
designed	O
specifically	O
for	O
high	O
speed	O
MWSN	B-Device
applications	O
,	O
such	O
as	O
those	O
that	O
incorporate	O
UAVs	O
.	O
</s>
<s>
Whereas	O
,	O
LASeR	O
relies	O
on	O
taking	O
advantage	O
of	O
geographical	O
location	O
information	O
that	O
is	O
already	O
present	O
on	O
the	O
mobile	O
sensor	B-Device
node	I-Device
,	O
which	O
is	O
likely	O
the	O
case	O
in	O
many	O
applications	O
.	O
</s>
<s>
There	O
are	O
three	O
types	O
of	O
medium	B-Protocol
access	I-Protocol
control	I-Protocol
(	O
MAC	O
)	O
techniques	O
:	O
based	O
on	O
time	O
division	O
,	O
frequency	O
division	O
and	O
code	B-Protocol
division	I-Protocol
.	O
</s>
<s>
The	O
vast	O
majority	O
of	O
MAC	B-Protocol
protocols	I-Protocol
that	O
have	O
been	O
designed	O
with	O
MWSNs	B-Device
in	O
mind	O
,	O
are	O
adapted	O
from	O
existing	O
WSN	B-Architecture
MACs	O
and	O
focus	O
on	O
low	O
power	O
consumption	O
,	O
duty-cycled	O
schemes	O
.	O
</s>
<s>
Protocols	O
designed	O
for	O
MWSNs	B-Device
are	O
usually	O
validated	O
with	O
the	O
use	O
of	O
either	O
analytical	O
,	O
simulation	O
or	O
experimental	O
results	O
.	O
</s>
<s>
Simulations	O
can	O
be	O
performed	O
using	O
software	O
such	O
as	O
OPNET	O
,	O
NetSim	O
and	O
ns2	B-Language
and	O
is	O
the	O
most	O
common	O
method	O
of	O
validation	O
.	O
</s>
<s>
The	O
advantage	O
of	O
allowing	O
the	O
sensors	O
to	O
be	O
mobile	O
increases	O
the	O
number	O
of	O
applications	O
beyond	O
those	O
for	O
which	O
static	O
WSNs	B-Architecture
are	O
used	O
.	O
</s>
