Narrowband interference mitigation in angle-frequency direct product domain in UWB receivers

The high precision ranging using ultra wideband (UWB) requires mitigation of interference from other communication systems, in particular from narrowband interference (NBI). There have been many studies of adaptive notch filters (ANF) to cope with NBI at various frequencies. This paper proposes a novel adaptive NBI mitigation method which uses the direction of arrival as well as frequency selectivity. We use an array antenna and apply the optimal weight which directs nulls to large-power waves. This realizes NBI suppression because of the lower power spectrum of the UWB pulse signal. Our method does not need any iteration such as feedback loop, and thus requires only a small calculation cost. Simulations demonstrate that the proposed method is applicable to variously directional and multiple-frequency NBIs.