Topic
Adaptive beamformer
About: Adaptive beamformer is a research topic. Over the lifetime, 4934 publications have been published within this topic receiving 93100 citations.
Papers published on a yearly basis
Papers
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Patent•
23 Jun 1997
TL;DR: In this paper, the adaptive filter weights are converted into the frequency domain where the frequency representation values in a selected frequency range are truncated to avoid signal leakage involving narrow band signals, and colorizing filters are used to produce the cancelling signals having a flat frequency spectrum.
Abstract: An adaptive system and method for reducing interference in a signal received from an array of sensors. Adaptive filters are used to generate cancelling signals that closely approximate the interference present in the received signal. The adaptive filter weights are converted into the frequency domain where the frequency representation values in a selected frequency range are truncated to avoid signal leakage involving narrow band signals. Decolorizing filters are used to produce the cancelling signals having a flat frequency spectrum. Normalized power difference is used to limit the operation of the adaptive filters to the case where there is some directional interference to be eliminated.
100 citations
TL;DR: A novel modified projection method is proposed in this paper, which is robust against the signal steering vector mismatch and covariance matrix uncertainty and can work well even at low signal-to-noise ratio.
100 citations
06 Apr 2020
TL;DR: In this article, an adaptive phase shifter design based on hierarchical codebooks and feedback from the mobile station is proposed for both accurate positioning and high data-rate transmission in RIS-aided MIMO systems.
Abstract: The concept of reconfigurable intelligent surface (RIS) has been proposed to change the propagation of electromagnetic waves, e.g., reflection, diffraction, and refraction. To accomplish this goal, the phase values of the discrete RIS units need to be optimized. In this paper, we consider RIS-aided millimeter-wave (mmWave) multiple-input multiple-output (MIMO) systems for both accurate positioning and high data-rate transmission. We propose an adaptive phase shifter design based on hierarchical codebooks and feedback from the mobile station (MS). The benefit of the scheme lies in that the RIS does not require deployment of any active sensors and baseband processing units. During the update process of phase shifters, the combining vector at the MS is sequentially refined. Simulation results show the performance improvement of the proposed algorithm over the random phase design scheme, in terms of both positioning accuracy and data rate. Moreover, the performance converges to that of the exhaustive search scheme even in the low signal-to-noise ratio regime.
100 citations
TL;DR: In this article, an adaptive noise cancelling scheme was proposed to overcome the problem that the target signal is degraded, leading to poorer intelligibility, by selectively disabling the adaptive filter from changing its filter values.
Abstract: The invention provides an adaptive noise cancelling apparatus which operates to overcome a problem encountered in conventional noise cancelling circuitry when the signal-to-noise ratio at the sensor array is high--to wit, that the target signal is degraded, leading to poorer intelligibility. An apparatus constructed in accord with the invention selectively inhibits the adaptive filter from changing its filter values in these instances and, thereby, prevents it from generating a noise-approximating signal that will degrade the target component of the output signal.
99 citations
TL;DR: Frequency-domain blind source separation is shown to be equivalent to two sets of frequency-domain adaptive beamformers (ABFs) under certain conditions and an interpretation of BSS from a physical point of view is given.
Abstract: Frequency-domain blind source separation (BSS) is shown to be equivalent to two sets of frequency-domain adaptive beamformers (ABFs) under certain conditions. The zero search of the off-diagonal components in the BSS update equation can be viewed as the minimization of the mean square error in the ABFs. The unmixing matrix of the BSS and the filter coefficients of the ABFs converge to the same solution if the two source signals are ideally independent. If they are dependent, this results in a bias for the correct unmixing filter coefficients. Therefore, the performance of the BSS is limited to that of the ABF if the ABF can use exact geometric information. This understanding gives an interpretation of BSS from a physical point of view.
98 citations