<s>
TCP-Illinois	B-Protocol
is	O
a	O
variant	O
of	O
TCP	B-Protocol
congestion	O
control	O
protocol	O
,	O
developed	O
at	O
the	O
University	O
of	O
Illinois	O
at	O
Urbana	O
–	O
Champaign	O
.	O
</s>
<s>
A	O
sender	O
side	O
modification	O
to	O
the	O
standard	O
TCP	B-Protocol
congestion	O
control	O
algorithm	O
,	O
it	O
achieves	O
a	O
higher	O
average	O
throughput	O
than	O
the	O
standard	O
TCP	B-Protocol
,	O
allocates	O
the	O
network	O
resource	O
fairly	O
as	O
the	O
standard	O
TCP	B-Protocol
,	O
is	O
compatible	O
with	O
the	O
standard	O
TCP	B-Protocol
,	O
and	O
provides	O
incentives	O
for	O
TCP	B-Protocol
users	O
to	O
switch	O
.	O
</s>
<s>
TCP-Illinois	B-Protocol
is	O
a	O
loss-delay	O
based	O
algorithm	O
,	O
which	O
uses	O
packet	O
loss	O
as	O
the	O
primary	O
congestion	O
signal	O
to	O
determine	O
the	O
direction	O
of	O
window	O
size	O
change	O
,	O
and	O
uses	O
queuing	O
delay	O
as	O
the	O
secondary	O
congestion	O
signal	O
to	O
adjust	O
the	O
pace	O
of	O
window	O
size	O
change	O
.	O
</s>
<s>
Similarly	O
to	O
the	O
standard	O
TCP	B-Protocol
,	O
TCP-Illinois	B-Protocol
increases	O
the	O
window	O
size	O
W	O
by	O
for	O
each	O
acknowledgment	O
,	O
and	O
decreases	O
by	O
for	O
each	O
loss	O
event	O
.	O
</s>
<s>
Unlike	O
the	O
standard	O
TCP	B-Protocol
,	O
and	O
are	O
not	O
constants	O
.	O
</s>
<s>
TCP-Illinois	B-Protocol
increases	O
the	O
throughput	O
much	O
more	O
quickly	O
than	O
TCP	B-Protocol
when	O
congestion	O
is	O
far	O
and	O
increases	O
the	O
throughput	O
very	O
slowly	O
when	O
congestion	O
is	O
imminent	O
.	O
</s>
<s>
As	O
a	O
result	O
,	O
the	O
window	O
curve	O
is	O
concave	O
and	O
the	O
average	O
throughput	O
achieved	O
is	O
much	O
larger	O
than	O
the	O
standard	O
TCP	B-Protocol
,	O
see	O
Figure	O
2	O
.	O
</s>
<s>
It	O
also	O
has	O
many	O
other	O
desirable	O
features	O
,	O
like	O
fairness	O
,	O
compatibility	O
with	O
the	O
standard	O
TCP	B-Protocol
,	O
providing	O
incentive	O
for	O
TCP	B-Protocol
users	O
to	O
switch	O
,	O
robust	O
against	O
inaccurate	O
delay	O
measurement	O
.	O
</s>
