Results 1 
6 of
6
Ultrawide bandwidth timehopping spread spectrum impulse radio for wireless access communications
 IEEE Trans. Commun
, 2000
"... Abstract—Attractive features of timehopping spreadspectrum multipleaccess systems employing impulse signal technology are outlined, and emerging design issues are described. Performance of such communications systems in terms of achievable transmission rate and multipleaccess capability are esti ..."
Abstract

Cited by 277 (12 self)
 Add to MetaCart
Abstract—Attractive features of timehopping spreadspectrum multipleaccess systems employing impulse signal technology are outlined, and emerging design issues are described. Performance of such communications systems in terms of achievable transmission rate and multipleaccess capability are estimated for both analog and digital data modulation formats under ideal multipleaccess channel conditions. Index Terms—Impulse radio, ultrawide bandwidth. I. INTRODUCTION TO IMPULSE RADIO SYSTEMS THE TERM wideband, as applied to communication systems, can have different meanings. In conventional systems, “wideband ” implies a large modulation bandwidth and thus a high data transmission rate. In this paper, a spreadspectrum
Characterization of ultrawide bandwidth wireless indoor channels: a communicationtheoretic view
 IEEE Journal on Selected Areas in Communications
, 2002
"... Abstract—An ultrawide bandwidth (UWB) signal propagation experiment is performed in a typical modern laboratory/office building. The bandwidth of the signal used in this experiment is in excess of 1 GHz, which results in a differential path delay resolution of less than a nanosecond, without specia ..."
Abstract

Cited by 75 (6 self)
 Add to MetaCart
Abstract—An ultrawide bandwidth (UWB) signal propagation experiment is performed in a typical modern laboratory/office building. The bandwidth of the signal used in this experiment is in excess of 1 GHz, which results in a differential path delay resolution of less than a nanosecond, without special processing. Based on the experimental results, a characterization of the propagation channel from a communications theoretic view point is described, and its implications for the design of a UWB radio receiver are presented. Robustness of the UWB signal to multipath fading is quantified through histograms and cumulative distributions. The all Rake (ARake) receiver and maximumenergycapture selective Rake (SRake) receiver are introduced. The ARake receiver serves as the best case (bench mark) for Rake receiver design and lower bounds the performance degradation caused by multipath. Multipath components of measured waveforms are detected using a maximumlikelihood detector. Energy capture as a function of the number of singlepath signal correlators used in UWB SRake receiver provides a complexity versus performance tradeoff. Biterrorprobability performance of a UWB SRake receiver, based on measured channels, is given as a function of signaltonoise ratio and the number of correlators implemented in the receiver. Index Terms—All Rake receiver (ARake), biterror probability (BEP), energy capture, propagation channel, selective Rake (SRake) receiver, spreadspectrum, ultrawide bandwidth (UWB). I.
A unified spectral analysis of generalized timehopping spreadspectrum signals in the presence of timing jitter
 IEEE J. Select. Areas Commun
, 2002
"... Abstract—This paper characterizes the power spectral density (PSD) of various timehopping spreadspectrum (THSS) signaling schemes in the presence of random timing jitter, which is characterized typically by a discretetime stationary random process (independent of the TH sequences and data sequen ..."
Abstract

Cited by 26 (12 self)
 Add to MetaCart
Abstract—This paper characterizes the power spectral density (PSD) of various timehopping spreadspectrum (THSS) signaling schemes in the presence of random timing jitter, which is characterized typically by a discretetime stationary random process (independent of the TH sequences and data sequence) with known statistical properties. A flexible model for a general THSS signal is proposed and a unified spectral analysis of this generalized THSS signal is carried out using a systematic and tractable technique. The key idea is to express the basic baseband pulse in terms of its Fourier transform which allows flexibility in specifying different TH formats throughout the general derivation. The power spectrum of various THSS signaling schemes can then be obtained as a special case of the generalized PSD results. Although general PSD results are first obtained for arbitrary timing jitter statistics, specific results are then given for the cases of practical interest, namely, uniform and Gaussian distributed jitter. Applications of this unified spectral analysis includes: 1) clocked TH by a random sequence; 2) framed TH by a random sequence; and 3) framed TH by a pseudorandom periodic sequence. Detailed descriptions of these different TH techniques will be given where the first two techniques employ a random sequence (stochastic model) and the third technique employs a pseudorandom sequence (deterministic model). Index Terms—Power spectral density (PSD), spectral analysis, spreadspectrum, timehopping, timing jitter, ultrawide bandwidth (UWB). I.
Spectral density of random timehopping spread spectrum UWB signals with uniform timing jitter
 IEEE Commun. Lett
, 1998
"... Abstract — We derive the power spectral density of timehopping (TH) spreadspectrum signals in the presence of random timing jitter, which is characterized typically by a discretetime stationary process (independent of the TH sequences). Detailed descriptions of different TH schemes, employing a ra ..."
Abstract

Cited by 6 (0 self)
 Add to MetaCart
Abstract — We derive the power spectral density of timehopping (TH) spreadspectrum signals in the presence of random timing jitter, which is characterized typically by a discretetime stationary process (independent of the TH sequences). Detailed descriptions of different TH schemes, employing a random TH sequence, is given and spectral analysis of such TH signals in the presence of uniform timing jitter is carried out using a systematic and tractable technique. I.
GPS and UWB for indoor navigation
"... 10 0 C/Acode spectrum A multitude of applications would benefit from precise indoor navigation. Anywhere from automating storage in warehouses to tracking firemen in hazardous environments would make such an endeavor worthwhile. Some serverbased GPS systems, like SnapTrack, already claim some navi ..."
Abstract

Cited by 1 (0 self)
 Add to MetaCart
10 0 C/Acode spectrum A multitude of applications would benefit from precise indoor navigation. Anywhere from automating storage in warehouses to tracking firemen in hazardous environments would make such an endeavor worthwhile. Some serverbased GPS systems, like SnapTrack, already claim some navigation capabilities indoors. However, such systems are in general accurate to within a few tens of meters. Furthermore, pseudolites have been deployed for indoor use. Although some experimental setups show decent navigation performance, there is a question of whether GPS has a “good enough ” signal structure for such applications in the first place. Spread spectrum pseudoranging is susceptible to multipath that is less than one chip width away from a direct path ray. In the case of GPS C/Acode, the chip length is about 300 m. Obviously, most indoor signal reflection delays would be significantly shorter than that distance. UltraWideBand (UWB) technology is built around transmitting short discrete pulses instead of continuously modulating a code onto a carrier signal. Such pulses typically last only 12 ns, and one can distinguish pulses that are more than 12 ft apart. Thus, making UWB systems robust to multipath delays of more than one pulse width. We measured the impulse response of the RF channel at the Stanford University LAAS Laboratory. This paper quantifies that multipath channel in terms of average delay and delay spread. We found several cases where multipath components were stronger in magnitude than the direct signal. Whereas such an environment would bias pseudorange measurements of GPS C/Acode, a properly designed UWB system could resolve most multipath and accuracy would degrade more gracefully than for GPS.
ii TABLE OF CONTENTS LIST OF FIGURES LIST OF SYMBOLS
"... In this thesis we give an accurate and general model that can be used to predict shortrange/time UWB reflection. This reflection occurs when the source and the receiver are near a single reflecting boundary. Our approach uses an imagebased method based on Laplacetransform formulation of the Somme ..."
Abstract
 Add to MetaCart
In this thesis we give an accurate and general model that can be used to predict shortrange/time UWB reflection. This reflection occurs when the source and the receiver are near a single reflecting boundary. Our approach uses an imagebased method based on Laplacetransform formulation of the Sommerfeld halfspace problem. The boundary between two mediums is replaced by a point source of given strength and location. The component amplitude of the image is chosen such that transverse electric and magnetic fields are continuous across the boundary. The complete field formulation is based on a simple branchintegral consisted in the reflection coefficient. Since the analysis is done in