<s>
WTCP	B-Protocol
(	O
"	O
Wireless	O
Transmission	B-Protocol
Control	I-Protocol
Protocol	I-Protocol
"	O
)	O
is	O
a	O
proxy-based	O
modification	O
of	O
TCP	O
that	O
preserves	O
the	O
end-to-end	B-Application
semantics	O
of	O
TCP	O
.	O
</s>
<s>
WTCP	B-Protocol
does	O
not	O
replace	O
the	O
TCP	O
on	O
the	O
hosts	O
,	O
but	O
is	O
placed	O
on	O
a	O
proxy	O
in	O
between	O
two	O
communicating	O
hosts	O
.	O
</s>
<s>
In	O
wireless	O
systems	O
,	O
WTCP	B-Protocol
is	O
placed	O
on	O
a	O
base	O
station	O
or	O
intermediate	O
gateway	O
between	O
a	O
source	O
host	O
and	O
a	O
mobile	O
(	O
wireless	O
)	O
host	O
.	O
</s>
<s>
When	O
the	O
mobile	O
host	O
uses	O
its	O
TCP	O
to	O
send	O
a	O
segment	O
,	O
the	O
WTCP	B-Protocol
at	O
the	O
base	O
station	O
receives	O
it	O
and	O
sends	O
it	O
on	O
through	O
the	O
network	O
,	O
where	O
it	O
eventually	O
reaches	O
the	O
awaiting	O
host	O
.	O
</s>
<s>
Despite	O
handling	O
some	O
wireless-related	O
errors	O
,	O
WTCP	B-Protocol
effectively	O
does	O
exactly	O
what	O
regular	O
TCP	O
does	O
.	O
</s>
<s>
The	O
two	O
edge	O
hosts	O
are	O
n't	O
even	O
aware	O
that	O
the	O
WTCP	B-Protocol
exists	O
.	O
</s>
<s>
Instead	O
of	O
replacing	O
TCP	O
completely	O
,	O
WTCP	B-Protocol
works	O
with	O
it	O
to	O
enhance	O
TCP	O
's	O
performance	O
over	O
wireless	O
.	O
</s>
<s>
WTCP	B-Protocol
then	O
attempts	O
to	O
mitigate	O
the	O
problem	O
by	O
retransmitting	O
a	O
lost	O
segment	O
only	O
once	O
,	O
until	O
it	O
receives	O
an	O
acknowledgment	O
back	O
from	O
the	O
mobile	O
host	O
that	O
it	O
was	O
received	O
.	O
</s>
<s>
Any	O
other	O
lost	O
segments	O
will	O
have	O
to	O
wait	O
in	O
the	O
WTCP	B-Protocol
's	O
buffer	O
until	O
the	O
first	O
one	O
is	O
confirmed	O
to	O
have	O
been	O
received	O
.	O
</s>
<s>
There	O
are	O
times	O
when	O
packets	O
will	O
sit	O
in	O
WTCP	B-Protocol
's	O
buffer	O
for	O
many	O
milliseconds	O
.	O
</s>
<s>
In	O
order	O
to	O
avoid	O
having	O
either	O
TCP	O
end	O
host	O
go	O
into	O
its	O
congestion	O
avoidance	O
mode	O
,	O
(	O
due	O
to	O
TCP	O
looking	O
at	O
a	O
segment	O
's	O
timestamp	O
and	O
determining	O
that	O
it	O
took	O
a	O
long	O
time	O
to	O
arrive	O
,	O
therefore	O
wrongly	O
assuming	O
it	O
's	O
due	O
to	O
congestion	O
)	O
WTCP	B-Protocol
uniquely	O
hides	O
the	O
time	O
spent	O
by	O
the	O
packets	O
at	O
the	O
WTCP	B-Protocol
proxy	O
,	O
so	O
that	O
the	O
RTT	O
estimation	O
is	O
not	O
affected	O
.	O
</s>
<s>
In	O
one	O
study	O
on	O
WTCP	B-Protocol
's	O
performance	O
in	O
Wireless	O
WANs	O
,	O
WTCP	B-Protocol
showed	O
an	O
improvement	O
of	O
20	O
–	O
200%	O
over	O
comparable	O
TCP	O
algorithms	O
such	O
as	O
New	O
Reno	O
,	O
Vegas	B-Protocol
,	O
and	O
Snoop	O
.	O
</s>
