Topic
Interference (wave propagation)
About: Interference (wave propagation) is a research topic. Over the lifetime, 26086 publications have been published within this topic receiving 321110 citations.
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TL;DR: This novel approach to fading channel prediction is combined with transmitter signal optimization to mitigate the effects of "deep fades", which severely limit the performance of mobile radio systems.
Abstract: In wireless communication systems, the direct signal and the reflected signals form an interference pattern resulting in a received signal given by the sum of these components. They are distinguished by their Doppler shifts at the mobile. Since the parameters associated with these components are slowly varying, the fading coefficients can be accurately predicted far ahead. This novel approach to fading channel prediction is combined with transmitter signal optimization to mitigate the effects of "deep fades", which severely limit the performance of mobile radio systems. This capability will potentially help to reduce power requirements for wireless channels and improve the system performance.
204 citations
Book•
01 Jan 1968
TL;DR: In this paper, the forced Oscillator and Coupled Oscillations are used to simulate simple harmonic motion. But they do not account for the effects of non-linear oscillations and chaos.
Abstract: Introduction to First Edition. Introduction to Second Edition. Introduction to Third Edition. Introduction to Fourth Edition. Introduction to Fifth Edition. Introduction to Sixth Edition. 1 Simple Harmonic Motion. 2 Damped Simple Harmonic Motion. 3 The Forced Oscillator. 4 Coupled Oscillations. 5 Transverse Wave Motion. 6 Longitudinal Waves. 7 Waves on Transmission Lines. 8 Electromagnetic Waves. 9 Waves in More than One Dimension. 10 Fourier Methods. 11 Waves in Optical Systems. 12 Interference and Diffraction. 13 Wave Mechanics. 14 Non-linear Oscillations and Chaos. 15 Non-linear Waves, Shocks and Solitons. Appendix 1: Normal Modes, Phase Space and Statistical Physics. Appendix 2: Kirchhoff's Integral Theorem. Appendix 3: Non-Linear Schro..dinger Equation. Index.
204 citations
TL;DR: In the sense of a quantum eraser, the distinguishability of the different two-photon Feynman amplitudes leading to a coincidence detection is removed by delaying the compensation until after the output of an unbalanced two-Photon interferometer.
Abstract: We report on a ``postponed compensation'' experiment in which the observed two-photon entangled state interference cannot be pictured in terms of the overlap of the two individual photon wave packets of a parametric down-conversion pair on a beam splitter. In the sense of a quantum eraser, the distinguishability of the different two-photon Feynman amplitudes leading to a coincidence detection is removed by delaying the compensation until after the output of an unbalanced two-photon interferometer.
202 citations
TL;DR: It is shown that the adaptive minimum mean square error (MMSE) multiuser detection (MUD) receivers are able to gather multipath energy and reject intersymbol and interchip interference for these channels to a much greater extent than RAKE receivers with 4 and 8 arms.
Abstract: We demonstrate the effectiveness of multiuser detection for an ultra-wideband (UWB) pulse based direct sequence spread spectrum system using code division multiple access. Extensive simulations were run using channel soundings of the 2-8 GHz band collected in a residential setting and characterized by a high level of multipath fragmentation. We show that the adaptive minimum mean square error (MMSE) multiuser detection (MUD) receivers are able to gather multipath energy and reject intersymbol and interchip interference for these channels to a much greater extent than RAKE receivers with 4 and 8 arms. We also demonstrate the adaptive MMSE is able to reject a narrowband IEEE 802.11a OFDM interferer, even for signal-to-interference ratio as severe as -30 dB. We show the adaptive MMSE exhibits only a 6 dB penalty relative to the single user case for the heavy multi-access interference (number of asynchronous users equal to spreading code length). The practical RAKE receivers were incapable of effectively rejecting either the strong narrowband interference or the heavily loaded wideband interference. Even more moderate levels of interference caused significant degradation in the performance of the practical RAKE receivers.
202 citations
TL;DR: A technique utilizing a combination of adaptive noise canceling and conventional signal processing is developed to enhance electrocardiographic monitoring in the operating room by reducing the noise interference that is created by an electrosurgical instrument.
Abstract: A technique utilizing a combination of adaptive noise canceling and conventional signal processing is developed to enhance electrocardiographic monitoring in the operating room by reducing the noise interference that is created by an electrosurgical instrument. Significant amounts of interference are eliminated by radio frequency shielding, passive and active low-pass filtering, and optical isolation. A digital adaptive canceler using the least mean-square algorithm of Widrow and Hoff is used to reduce the remainder of the interference, yielding an improvement in signal-to-noise ratio of approximately 110 dB. Clear electrocardiograms have been obtained with electrocautery equipment in operation.
202 citations