<s>
In	O
data	O
communications	O
networks	O
,	O
packet	B-Protocol
segmentation	I-Protocol
is	O
the	O
process	O
of	O
dividing	O
a	O
data	B-Protocol
packet	I-Protocol
into	O
smaller	O
units	O
for	O
transmission	O
over	O
the	O
network	O
.	O
</s>
<s>
Packet	B-Protocol
segmentation	I-Protocol
happens	O
at	O
layer	O
four	O
of	O
the	O
OSI	O
model	O
;	O
the	O
transport	B-Architecture
layer	I-Architecture
.	O
</s>
<s>
Protocols	O
that	O
perform	O
packet	B-Protocol
segmentation	I-Protocol
at	O
the	O
source	O
usually	O
include	O
a	O
mechanism	O
at	O
the	O
destination	O
to	O
reverse	O
the	O
process	O
and	O
reassemble	O
the	O
original	O
packet	B-Protocol
from	O
individual	O
segments	O
.	O
</s>
<s>
This	O
process	O
may	O
include	O
automatic	B-Error_Name
repeat-request	I-Error_Name
(	O
ARQ	O
)	O
mechanisms	O
to	O
detect	O
missing	O
segments	O
and	O
to	O
request	O
the	O
source	O
to	O
re-transmit	O
specific	O
segments	O
.	O
</s>
<s>
In	O
a	O
communication	O
system	O
based	O
on	O
a	O
layered	O
OSI	O
model	O
,	O
packet	B-Protocol
segmentation	I-Protocol
may	O
be	O
responsible	O
for	O
splitting	O
one	O
MPDU	O
into	O
multiple	O
physical	B-Application
layer	I-Application
service	O
data	O
units	O
so	O
that	O
reliable	O
transmission	O
(	O
and	O
potential	O
re-transmission	O
via	O
ARQ	O
)	O
of	O
each	O
one	O
can	O
be	O
performed	O
individually	O
.	O
</s>
<s>
The	O
ITU-T	B-General_Concept
G.hn	I-General_Concept
standard	O
,	O
which	O
provides	O
a	O
way	O
to	O
create	O
a	O
high-speed	O
(	O
up	O
to	O
1	O
gigabit/s	O
)	O
local	B-General_Concept
area	I-General_Concept
network	I-General_Concept
using	O
existing	O
home	O
wiring	O
(	O
power	B-Device
lines	I-Device
,	O
phone	O
lines	O
and	O
coaxial	B-Protocol
cables	I-Protocol
)	O
,	O
is	O
an	O
example	O
of	O
a	O
protocol	O
that	O
employs	O
packet	B-Protocol
segmentation	I-Protocol
to	O
increase	O
reliability	O
over	O
noisy	O
media	O
.	O
</s>
