802.11b (Non-ERP)
Figure 6-2 802.11g Cell with an 802.11b Client
Now that the cell knows about the 802.11b clients, the way that data is sent within the cell
changes. When an 802.11g client sends a frame, it first must warn the 802.11b clients by
sending a request to send (RTS) message at 802.11b speed so the 802.11b clients can hear
and understand it. The RTS is not a broadcast as you might think, but rather a unicast that
is sent to the recipient of the frame that the 802.11g client wants to send to. The recipient
then responds with a clear to send (CTS) at 802.11b speed. Figure 6-3 illustrates this
process.
In Step 1, the client knows that the 802.11b client is present; therefore, before sending, it
issues an RTS at 802.11b speeds.
In Figure 6-4, the 802.11b client hears the RTS (Step 2), which includes the duration, and it
waits until the duration is over before sending its data even though it cannot hear the
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