User
Manual
TEW
‐
455APBO
High
Power
Wireless
Outdoor
PoE
Access
Point
22
ACK
Timeout:
ACK
timeout
is
in
the
range
of
1~372
and
set
in
unit
of
microsecond
.
The
default
value
is
48
microsecond.
All
data
transmission
in
802.11b/g
request
an
“Acknowledgement”
(ACK)
send
by
receiving
radio.
The
transmitter
will
resend
the
original
packet
if
correspondent
ACK
failed
to
arrive
within
specific
time
interval,
also
refer
to
as
“ACK
Timeout”.
ACK
Timeout
is
adjustable
due
to
the
fact
that
distance
between
two
radio
links
may
vary
in
different
deployment.
ACK
Timeout
makes
significant
influence
in
performance
of
long
distance
radio
link.
If
ACK
Timeout
is
set
too
short,
transmitter
will
start
to
“Resend”
packet
before
ACK
is
received,
and
throughputs
become
low
due
to
excessively
high
re
‐
transmission.
ACK
Timeout
is
best
determined
by
distance
between
the
radios,
data
rate
of
average
environment.
The
Timeout
value
is
calculated
based
on
round
‐
trip
time
of
packet
with
a
little
tolerance,
So,
if
experiencing
re
‐
transmissions
or
poor
performance
the
ACK
Timeout
could
be
made
longer
to
accommodate.
RTS/CTS
Adjustment
of
RTS
Threshold
can
be
done
to
turn
on
RTS.
CTS
Timeout
will
take
effect
only
when
RTS
is
turned
on.
Unlike
wired
Ethernet,
radio
transmission
may
begin
with
a
RTS
(Request
to
Send)
frame,
and
receiver
responds
with
a
CTS
(Clear
to
Send)
frame.
The
RTS/CTS
mechanism
is
called
Channel
Cleaning
,
all
stations
that
received
CTS
will
back
off
for
certain
period
of
time,
multiple
of
the
slot
time.
Each
CTS
packet
has
a
NAV
(Network
Allocation
Vector)
number
n,
the
channel
is
reserved
for
sender
and
receiver
for
additional
n
‐
millisecond
.
The
NAV
guarantees
the
channel
is
free
of
interference
in
next
n
‐
millisecond.
The
last
packet
of
ACK
will
set
NAV
to
zero,
indicated
that
connection
is
done
and
free
the
channel
to
others.
CTS
Timeout:
CTS
Timeout
is
in
the
range
of
1~744
and
set
in
unit
of
microsecond
.
The
default
value
is
48
microsecond.
CTS
Timeout
will
take
effect
only
when
RTS
is
turned
on.
Adjustment
of
RTS
Threshold
can
be
done
to
turn
on
RTS.
When
hidden
wireless
stations
are
present
in
the
wireless
network
RTS
can
be
considered
to
turn
on
to
minimize
collisions
and
increase
performance.
Ensure
CTS
timeout
is
long
enough
to
avoid
frequent
re
‐
transmission
of
RTS.
Slot
Time
and
ACK/CTS
Timeout
settings are for
long
distance
links.
It
is
important
to
tweak
settings
to
achieve
the
optimal
result
based
on
requirement.
The
device’s
default
settings
should
be
sufficient
for
most
applications.
