How can hidden terminals be detected in 802.11?

Hidden terminal are basically known as hidden node that are out of the range in the network. The hidden terminal are basically detected by the receiver and sender according to the potential colliding of the packets. In the wireless network 802.11 we can easily detect the hidden node or terminal by using two main mechanism that are:

Active detection Passive detection

Active Detection:

In the active detection, the hidden terminal firstly generated a request in the hop which is known as "Detection request" and then all the given terminal received the request for sending the sequence of packet on the hop. In the 802.11 wireless network, terminal 0 is known as the detection terminal.

Passive detection:

In the passive detection, there is detecting terminal node interface is set in the promiscuous mode in which all the packets are process in the detecting terminal.

It is basically depend upon the CTS or RTS that is used for the transmitting the neighboring node or terminal.