OFDM Subcarriers Coding for Enhancing Spectrum Notch

Because of its flexible spectrum shaping, OFDM technologies can be used for cognitive radio as signaling method. Spectrum notches can be generated through turning off subcarriers to protect primary users (licensee users), but the intercarrier interference may limit the notch depth. This paper focuses on the enhancing methods to deepen spectrum notch and proposes two kinds of OFDM subcarriers coding methods. These methods can deepen spectrum notch efficiently without causing much system complexity. They also have respective advantages that can be applied to different situations.