Primary receiver detection using load modulation in cognitive radio

A new primary receiver detection method in cognitive radio for OFDM system is proposed in this paper. In the proposed method, the OFDM signal is modulated by load modulation at the primary system. Due to the modulation, spurious components appear in guard band of the OFDM system. Then, the secondary receiver detects the direction of the primary receiver through estimating the direction of the spurious components. Numerical results shows that the primary receiver in several meters from the secondary receiver can be detected using the radio wave of terrestrial digital broadcasting.