Results 1 - 10 of 1,526

Multipath Beamforming UWB Signal Design Based on Ternary Sequences

by Di Wu, Predrag Spasojević, Ivan Seskar
"... We study an adaptive transmission approach that exploits the increased phase coherence of ultra-wideband (UWB) channels with a “discrete ” number of reflectors relative to narrowband wireless channels. The proposed multipath beamforming technique suggests selecting a ternary or multilevel sequence f ..."
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for an impulsive direct sequence UWB signal waveform based on the signs of the reflection coefficients corresponding to a few strongest paths so that the signal energy at the output of a non-adaptive correlator is enhanced. The approach to beamforming signal design is illustrated by several example designs. 1

Space-time block codes from orthogonal designs

by Vahid Tarokh, Hamid Jafarkhani, A. R. Calderbank - IEEE Trans. Inform. Theory , 1999
"... Abstract — We introduce space–time block coding, a new paradigm for communication over Rayleigh fading channels using multiple transmit antennas. Data is encoded using a space–time block code and the encoded data is split into � streams which are simultaneously transmitted using � transmit antennas. ..."
Abstract - Cited by 1524 (42 self) - Add to MetaCart
. The received signal at each receive antenna is a linear superposition of the � transmitted signals perturbed by noise. Maximumlikelihood decoding is achieved in a simple way through decoupling of the signals transmitted from different antennas rather than joint detection. This uses the orthogonal structure

The Cricket Location-Support System

by Nissanka B. Priyantha, Anit Chakraborty, Hari Balakrishnan , 2000
"... This paper presents the design, implementation, and evaluation of Cricket, a location-support system for in-building, mobile, locationdependent applications. It allows applications running on mobile and static nodes to learn their physical location by using listeners that hear and analyze informatio ..."
Abstract - Cited by 1058 (11 self) - Add to MetaCart
than U.S. $10. We describe the randomized algorithm used by beacons to transmit information, the use of concurrent radio and ultrasonic signals to infer distance, the listener inference algorithms to overcome multipath and interference, and practical beacon configuration and positioning techniques

Grassmannian beamforming for multiple-input multiple-output wireless systems

by David J. Love, Robert W. Heath, Jr., Thomas Strohmer - IEEE TRANS. INFORM. THEORY , 2003
"... Transmit beamforming and receive combining are simple methods for exploiting the significant diversity that is available in multiple-input and multiple-output (MIMO) wireless systems. Unfortunately, optimal performance requires either complete channel knowledge or knowledge of the optimal beamformi ..."
Abstract - Cited by 329 (38 self) - Add to MetaCart
beamforming vector which are not always realizable in practice. In this correspondence, a quantized maximum signal-to-noise ratio (SNR) beamforming technique is proposed where the receiver only sends the label of the best beamforming vector in a predetermined codebook to the transmitter. By using

Joint Tx-Rx beamforming design for multicarrier MIMO channels: a unified framework for convex optimization

by Daniel Pérez Palomar, John M. Cioffi, Miguel Angel Lagunas - IEEE TRANS. SIGNAL PROCESSING , 2003
"... This paper addresses the joint design of transmit and receive beamforming or linear processing (commonly termed linear precoding at the transmitter and equalization at the receiver) for multicarrier multiple-input multiple-output (MIMO) channels under a variety of design criteria. Instead of consid ..."
Abstract - Cited by 297 (19 self) - Add to MetaCart
This paper addresses the joint design of transmit and receive beamforming or linear processing (commonly termed linear precoding at the transmitter and equalization at the receiver) for multicarrier multiple-input multiple-output (MIMO) channels under a variety of design criteria. Instead

Ranging in a Dense Multipath Environment Using an UWB Radio Link

by Joon-yong Lee, Robert A. Scholtz - IEEE JSAC , 2002
"... A time-of-arrival (ToA)-based ranging scheme using an ultra-wideband (UWB) radio link is proposed. This ranging scheme implements a search algorithm for the detection of a direct path signal in the presence of dense multipath, utilizing generalized maximum-likelihood (GML) estimation. Models for cr ..."
Abstract - Cited by 177 (5 self) - Add to MetaCart
A time-of-arrival (ToA)-based ranging scheme using an ultra-wideband (UWB) radio link is proposed. This ranging scheme implements a search algorithm for the detection of a direct path signal in the presence of dense multipath, utilizing generalized maximum-likelihood (GML) estimation. Models

Locating the Nodes -- Cooperative localization in wireless sensor networks

by Neal Patwari, Joshua N. Ash, Spyros Kyperountas, Alfred O. Hero III, Randolph L. Moses, et al. , 2005
"... Accurate and low-cost sensor localization is a critical requirement for the deployment of wireless sensor networks in a wide variety of applications. Low-power wireless sensors may be many hops away from any other sensors with a priori location information. In cooperative localization, sensors work ..."
Abstract - Cited by 305 (12 self) - Add to MetaCart
useful to describe time-of-arrival (TOA), angle-of-arrival (AOA), and received-signal-strength (RSS) measurements in wireless sensor networks. Wideband and ultra-wideband (UWB) measurements, and RF and acoustic media are also discussed. Using the models, we show how to calculate a Cramér-Rao bound (CRB

TOWARDS BEAMFORMING FOR UWB SIGNALS

by Sigmar Ries, Thomas Kaiser
"... Beamforming for UWB signals has some special prop-erties that are different from the narrowband case. The investigation of ideal time-delay beamforming for short pulses shows a striking feature, namely the absence of grating lobes in the beampattern. This means that the spacing of the array elements ..."
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Beamforming for UWB signals has some special prop-erties that are different from the narrowband case. The investigation of ideal time-delay beamforming for short pulses shows a striking feature, namely the absence of grating lobes in the beampattern. This means that the spacing of the array

Differential space-time modulation

by Brian L. Hughes - IEEE Trans. Inform. Theory , 2000
"... Abstract—Space–time coding and modulation exploit the presence of multiple transmit antennas to improve performance on multipath radio channels. Thus far, most work on space–time coding has assumed that perfect channel estimates are available at the receiver. In certain situations, however, it may b ..."
Abstract - Cited by 269 (1 self) - Add to MetaCart
codes. This approach can be applied to any number of transmit and receive antennas, and any signal constellation. We also derive low-complexity dif-ferential receivers, error bounds, and modulator design criteria, which we use to construct optimal differential modulation schemes for two transmit

Multipath Beamforming for UWB: Channel Unknown at the Receiver

by Di Wu , Predrag Spasojević , Ivan Seskar
"... Abstract We study two ..."
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Abstract We study two
Results 1 - 10 of 1,526