A hidden node is a hidden or concealed node. The hidden node problem occurs in wireless communications, and it occurs when two transmitting terminals simultaneously transmit data to a receiving terminal. In such a case, interference occurs between the radio waves of the two transmitting stations.
Due to the wave superposition and the resulting interference, the receiving terminal cannot receive data from either of the two transmitting terminals. Such a situation can occur when the distance between the transmitting terminals is large or when there are physical conditions between the transmitting terminals that impede the transmission of radio waves.
The problem is caused by the fact that the transmitting terminals already start transmitting without havingchecked the existence of other terminals.