Narrowband Interference Mitigation in UWB Systems Utilizing Frequency Dependence of Null Formation in Array Antennas

The high precision ranging using ultra wideband (UWB) signals is expected for various applications. However, UWB requires mitigation of narrowband interference (NBI) from other wireless systems. There have been many studies of adaptive notch filters to cope with NBI at various frequencies. This paper proposes a novel NBI mitigation method which utilizes frequency dependence characteristics in array antennas. We use power inversion to direct nulls to large-power input, which realizes NBI only suppression with a small calculation cost. The results show that the proposed method can obtain lower bit error rate. The proposed method can cope with variously directional and multiple-frequency NBIs without a priori knowledge of the incident waves.