Okay you are misunderstanding what im saying...
Wifi is a shared medium this means that just one client can access that medium at once...
Example(forget that you got a wired part here let just take a look to the wireless)
Let say you got 5 clients connected to the wireless, and one AP
Client 1 will transmit the data to the AP, while he is transmiting it, noone else can access the AP just the client 1
When client 1 is done then client 2 will start transmiting to the AP and so on.
The conclusion here is that just 1 client can communicate with the AP at once... this means that the 5 clients are not transmitting at the same time to the AP, this does not happen.
Now let see wired and wireless
Let say you got a wired computer, and it send a broadcast!
This broadcast reach the AP
The AP start sending this broadcast to each Client
He first send it to client 1 then send it to client 2 then send it to client 3 and so on.
While this happens noone in the Wireless side can trasmit! this really affect the wireless network... Broadcast is the enemy of the wireless network.
Broadcast filter can help, but its better having it in different vlans
Do you understand me?
i know my english is not good:P but i try my best :)
Cheers
Carlos