Narrow-Band Interference Suppression in Impulse-Radio Ultrawideband Systems

For impulse-radio ultrawideband (IR-UWB) communications, pulse overlap often occurs in indoor dense multipath environments, where the time separation between adjacent received multipaths is typically less than one pulsewidth. Moreover, due to its low power spectral density (PSD) and its overlay usage model, the IR-UWB signal is also vulnerable to narrow-band interference (NBI) of a high power level. Taking the effect of pulse overlap into account, this paper presents an optimal prerake/postrake UWB transceiver design to counteract NBI. The prerake/postrake uses rake structures at both the transmitter and the receiver. The optimum weights for the prerake and postrake are derived by maximizing the signal-to-inference-plus-noise ratio (SINR). Furthermore, an adaptive scheme is proposed to achieve the optimal solution iteratively. Simulations show that the proposed prerake/postrake and the adaptive scheme can significantly eliminate the adverse effect of NBI and thus perform well even in the presence of severe NBI.