RTS/CTS Protocol
2-10
Hidden Station
A wireless device is a hidden station when its transmissions cannot be sensed by another
wireless device in the same network. Therefore, multiple devices could transmit at the same
time. This problem can occur with clients located at opposite ends of an AP coverage area.
Figure 2-2 illustrates a hidden station example. Clients A and B are within range of the AP.
However, Client B cannot sense transmissions from Client A, since Client A is outside of
Client B’s coverage area (shown in gray). Client B could transmit while Client A is
transmitting. Therefore, messages of both Client A and B collide when arriving
simultaneously at the AP. The collision results in a loss of messages for both clients.
Figure 2-2 also illustrates that Client C is not hidden from the other clients.
Figure 2-2: Hidden Station Example
To avoid a hidden station problem, move the clients or AP if possible so that the devices
can sense each other’s transmissions. Otherwise, enable Remote RTS Threshold on the AP.
Do not change the RTS Threshold on the AP.
Enabling Remote RTS Threshold forces the client to send an RTS to the AP before
transmitting a packet that exceeds the threshold. The client waits until the AP responds with
a CTS message. However, enabling Remote RTS Threshold imposes additional network
overhead that could negatively affect the data throughput performance. You should only
use this setting when the density of clients and APs is low and you witness poor network
performance due to excessive frame collisions at the APs.
Client B
Client B
Client A
Client C