<s>
The	O
ETX	O
metric	O
,	O
or	O
expected	B-Protocol
transmission	I-Protocol
count	I-Protocol
,	O
is	O
a	O
measure	O
of	O
the	O
quality	O
of	O
a	O
path	O
between	O
two	O
nodes	O
in	O
a	O
wireless	O
packet	O
data	O
network	O
.	O
</s>
<s>
It	O
is	O
used	O
extensively	O
in	O
mesh	B-Architecture
networking	I-Architecture
algorithms	O
.	O
</s>
<s>
Subsequently	O
,	O
it	O
has	O
been	O
implemented	O
in	O
RoofNet/Meraki	O
and	O
OLSR	B-Protocol
mesh	B-Architecture
networking	I-Architecture
protocols	O
,	O
among	O
others	O
.	O
</s>
<s>
In	O
the	O
context	O
of	O
the	O
OLSR	B-Protocol
protocol	O
,	O
a	O
bidirectional	O
link	O
ETX	O
was	O
defined	O
.	O
</s>
<s>
Note	O
that	O
ETX	O
is	O
an	O
expected	B-Protocol
transmission	I-Protocol
count	I-Protocol
for	O
a	O
future	O
event	O
,	O
as	O
opposed	O
to	O
an	O
actual	O
count	O
of	O
a	O
past	O
event	O
.	O
</s>
<s>
An	O
equivalent	O
relation	O
is	O
used	O
for	O
bidirectional	O
links	O
in	O
the	O
context	O
of	O
the	O
OLSR	B-Protocol
protocol	O
:	O
where	O
NLQ	O
is	O
the	O
Neighbor	O
Link	O
Quality	O
of	O
the	O
link	O
and	O
LQ	O
is	O
its	O
link	O
quality	O
.	O
</s>
