<s>
A	O
digital	B-Application
loop	I-Application
carrier	I-Application
(	O
DLC	O
)	O
is	O
a	O
system	O
which	O
uses	O
digital	B-General_Concept
transmission	O
to	O
extend	O
the	O
range	O
of	O
the	O
local	B-Architecture
loop	I-Architecture
farther	O
than	O
would	O
be	O
possible	O
using	O
only	O
twisted	O
pair	O
copper	O
wires	O
.	O
</s>
<s>
A	O
DLC	O
digitizes	O
and	O
multiplexes	O
the	O
individual	O
signals	O
carried	O
by	O
the	O
local	B-Architecture
loops	I-Architecture
onto	O
a	O
single	O
datastream	O
on	O
the	O
DLC	O
segment	O
.	O
</s>
<s>
Subscriber	B-Application
Loop	I-Application
Carrier	I-Application
systems	O
address	O
a	O
number	O
of	O
problems	O
:	O
</s>
<s>
inductance	O
coil	O
with	O
a	O
-48	O
V	O
dc	O
potential	O
and	O
an	O
Electric	O
current	O
of	O
between	O
20	O
–	O
50	O
mA	B-General_Concept
dc	O
.	O
</s>
<s>
A	O
minimum	O
current	O
of	O
around	O
20	O
mA	B-General_Concept
dc	O
is	O
required	O
to	O
convey	O
terminal	O
signalling	O
information	O
to	O
the	O
network	O
.	O
</s>
<s>
These	O
have	O
detrimental	O
effect	O
to	O
new	O
transmission	O
technologies	O
using	O
the	O
local	B-Architecture
loop	I-Architecture
,	O
like	O
DSL	O
,	O
and	O
must	O
be	O
removed	O
.	O
</s>
<s>
The	O
DLC	O
solution	O
was	O
dubbed	O
"	O
pair	B-Protocol
gain	I-Protocol
"	O
(	O
from	O
the	O
days	O
when	O
DLC	O
was	O
deployed	O
to	O
recover	O
copper	O
pairs	O
in	O
the	O
loop	O
plant	O
environment	O
)	O
.	O
</s>
<s>
In	O
a	O
typical	O
configuration	O
,	O
DLC	O
remote	O
terminals	O
are	O
installed	O
in	O
new	O
neighbourhoods	O
or	O
buildings	O
as	O
a	O
means	O
of	O
reducing	O
the	O
labour	O
and	O
complexity	O
of	O
installing	O
individual	O
local	B-Architecture
loops	I-Architecture
from	O
the	O
customer	O
to	O
the	O
central	O
office	O
(	O
CO	O
)	O
.	O
</s>
<s>
With	O
the	O
growth	O
in	O
popularity	O
of	O
digital	B-General_Concept
subscriber	B-Architecture
line	I-Architecture
(	O
DSL	O
)	O
and	O
the	O
benefits	O
provided	O
by	O
shorter	O
metallic	O
loops	O
used	O
with	O
DLC	O
systems	O
,	O
digital	B-Application
loop	I-Application
carriers	I-Application
are	O
sometimes	O
integrated	O
with	O
digital	B-Protocol
subscriber	I-Protocol
line	I-Protocol
access	I-Protocol
multiplexers	I-Protocol
(	O
DSLAM	B-Protocol
)	O
,	O
both	O
systems	O
then	O
taking	O
advantage	O
of	O
the	O
digital	B-General_Concept
transmission	O
link	O
from	O
the	O
DLC	O
to	O
the	O
CO	O
.	O
</s>
<s>
Fibre	B-Architecture
in	I-Architecture
the	I-Architecture
loop	I-Architecture
(	O
FITL	B-Architecture
)	O
systems	O
are	O
functionally	O
equivalent	O
to	O
DLC	O
.	O
</s>
<s>
FITL	B-Architecture
accomplishes	O
the	O
same	O
two	O
primary	O
functions	O
DLC	O
was	O
intended	O
for	O
:	O
pair	B-Protocol
gain	I-Protocol
and	O
the	O
elimination	O
of	O
electrical	O
constraints	O
due	O
to	O
long	O
metallic	O
loops	O
.	O
</s>
<s>
FITL	B-Architecture
architectures	O
vary	O
from	O
simply	O
deploying	O
fibre	O
feeder	O
plants	O
(	O
between	O
central	O
office	O
and	O
remote	O
terminal	O
site	O
)	O
to	O
"	O
fibre	B-Architecture
to	I-Architecture
the	I-Architecture
curb	I-Architecture
"	O
and	O
,	O
ultimately	O
"	O
fibre	B-Architecture
to	I-Architecture
the	I-Architecture
home	I-Architecture
"	O
where	O
an	O
optical	O
network	O
unit	O
(	O
ONU	O
)	O
is	O
located	O
at	O
each	O
home	O
.	O
</s>
