|if a station hears no response to an overheard |
RTS, then it may assume that the intended
recipient of the RTS is either down or out of
range. An example is shown in figure 4.
Station X is within range of Y, but not Z. When
Y sends traffic to Z, X will hear Y’s RTS
packets but not Z’s CTS responses. X may
therefore transmit on the channel without fear
of interfering with Y’s data transmissions to Z
even though it can hear them. In this case
MACA allows a transmission to proceed when
ordinary CSMA would prevent it unnecessarily,
thus relieving the exposed terminal problem.
Since X can hear the transmission from Y to Z,
Y can also hear the transmission from X to
another station. X and Y are inside the
communication ranges of each other. When
they send data to their receivers respectively,
don't the signals interfere each other in the
middle of each sender and receiver? The
following figure illustrates the scenario.
A capital letter stands for a station.
n stands for the border of the communication
range of station N.
The communication range of a station is the
width of 6 characters.
As shown in the figure,
(1)X cannot hear z.
(2)X can hear y.
(3)Y can hear x.
(4)Since all signals go through the same
channel, x and y collide between the right x
and the left y so that W and Z receive corrupt
Does radio communication work as (4)? Or, is
a signal corrupt for a receiver only when there
is another signal in the same channel at the