<s>
The	O
error	B-Error_Name
floor	I-Error_Name
is	O
a	O
phenomenon	O
encountered	O
in	O
modern	O
iterated	O
sparse	O
graph-based	O
error	B-Error_Name
correcting	I-Error_Name
codes	I-Error_Name
like	O
LDPC	B-Error_Name
codes	I-Error_Name
and	O
turbo	B-Error_Name
codes	I-Error_Name
.	O
</s>
<s>
When	O
the	O
bit	O
error	O
ratio	O
(	O
BER	O
)	O
is	O
plotted	O
for	O
conventional	O
codes	O
like	O
Reed	B-Error_Name
–	I-Error_Name
Solomon	I-Error_Name
codes	I-Error_Name
under	O
algebraic	O
decoding	O
or	O
for	O
convolutional	B-Error_Name
codes	I-Error_Name
under	O
Viterbi	O
decoding	O
,	O
the	O
BER	O
steadily	O
decreases	O
in	O
the	O
form	O
of	O
a	O
curve	O
as	O
the	O
SNR	O
condition	O
becomes	O
better	O
.	O
</s>
<s>
For	O
LDPC	B-Error_Name
codes	I-Error_Name
and	O
turbo	B-Error_Name
codes	I-Error_Name
there	O
is	O
a	O
point	O
after	O
which	O
the	O
curve	O
does	O
not	O
fall	O
as	O
quickly	O
as	O
before	O
,	O
in	O
other	O
words	O
,	O
there	O
is	O
a	O
region	O
in	O
which	O
performance	O
flattens	O
.	O
</s>
<s>
This	O
region	O
is	O
called	O
the	O
error	B-Error_Name
floor	I-Error_Name
region	O
.	O
</s>
<s>
Error	B-Error_Name
floors	I-Error_Name
are	O
usually	O
attributed	O
to	O
low-weight	O
codewords	O
(	O
in	O
the	O
case	O
of	O
Turbo	B-Error_Name
codes	I-Error_Name
)	O
and	O
trapping	O
sets	O
or	O
near-codewords	O
(	O
in	O
the	O
case	O
of	O
LDPC	B-Error_Name
codes	I-Error_Name
)	O
.	O
</s>
