Hidden Terminals
The hidden terminal problem is a common problem on medium access control for wireless networks and is ilustrated by the example below:
Attach:/Users/leonardo/Desktop/hidden.jpg
In the picture above, suppose node A is transmitting a message to node B. At some point during such transmission, node C detects that the channel is clear (because it is out of A's transmitting range) and alsi starts transmitting a message to B or to any other node in its range. The message transmitted by node C colides with the message from A as B, and B can't receive none of the transmissions properly. In this example, C and A act as hidden nodes to each other. One common way to solve the hidden terminals problem is to use a RTS-CTS scheme.