User guide

6-12
BreezeNET DS.11b User’s Guide
Manual Version 1.0
Figure 6-24 illustrates an example of the “hidden station” problem. Both station
A and station B are within range of the Base Station however, station B cannot
“hear” station A, therefore station A is a “hidden station” for station B.
When station B starts to communicate with the Base Station, it might not notice
that station A is already using the wireless medium. When station A and station
B send messages at the same time, they might collide when arriving
simultaneously at the Base Station. The collision will most certainly result in a
loss of messages for both stations.
In situations as pictured Figure 6-24, RTS/CTS medium reservation may
provide a solution to prevent message collisions by handing over transmission
control to the Base Station.
Troubleshooting a “hidden station” problem usually provides the best results
when it is performed on the suspected stations that suffer from errors as a
result of the “hidden station” problem.
When configuring the PC Card parameters of an individual station you can
enable the RTS/CTS Medium Reservation parameter:
! To enable RTS/CTS Medium Reservation parameter, choose
Add/Edit
configuration profile
in the Client Manager, select the Advanced tab and
enable
RTS/CTS Medium Reservation.
You can enable RTS/CTS Medium Reservation on individual stations, i.e. the
setting of this parameter does not have to be the same for all BreezeNET
equipped devices in your network.
Figure 6-25: Medium Reservation “Request to Send”
About the Medium Reservation Mechanism
When you enable RTS/CTS medium reservation on a suspect “hidden station”,
this station and its Base Station will use a Request to Send/Clear to Send
protocol (RTS/CTS).
! The station will send an RTS to the Base Station, that will include
information about the length of the frame that the station would like to
transmit (see Figure 6-25).