Cognitive radio communication system for recogninzing interference based on known signal

PURPOSE: A recognition wireless communications system of a secondary system which recognizes interference by using the signal is provided to sense the signal of the primary user efficiently by sensing the signal of the primary user. CONSTITUTION: A signal receiving unit(610) receives a message signal from a primary user in a primary system and a secondary transmitter of a secondary system. The received signal comprises the component related to the signal known as the secondary transmitter. A determining unit(620) decides the signal of the primary user based on the component related to the signal known as the received signals.