1,721,042 research outputs found
60 GHz UWB Channel Measurement and Model
No full textMeasurements of the 60 GHz UWB indoor channel done in a modern office building at the University of L’Aquila, Italy, are presented. The channel sounder is based on a PN-sequence correlation technique with a pulse width of 0.8 ns. Signals are recorded in different locations in line-of-sight and non-line-of-sight scenarios, and for each location the receiver is moved over a grid of 99 positions, in order to characterize both the large and the small scale behaviors. Samples of the channel impulse response are recorded at eight different carrier frequencies spanning the bands from 54 to 59 GHz and from 61 to 66 GHz. In this paper we propose an analysis of the experimental data in order to provide models for the large scale behavior of
these signals, including a study of the frequency dependence
UWB Moves up to mmWaves: A channel modeling perspective
No full textUWB has been on the scene for about two decades. Results of extensive tests and measurements, and experience acquired from the design and operation of commercial products, all concurred to depict UWB as a very promising technology in many context and applications, thanks to its intrinsic characteristics. Now, wireless communications are colonizing higher frequencies and the UWB paradigm is a valid candidate for a transmission technology even there. Since many attractive features of UWB are related to its propagation characteristics, this paper provides a synopsis of the behavior of UWB signals on channels at different frequencies, from very low frequencies, below 1 GHz, through the 3.1-10.6 GHz band, and up to the 60 GHz. Finally, a generalized expression is proposed for the channel impulse response over this huge frequency span, accounting for all phenomena and behaviors observed through a variety of channel measurement campaigns at different frequencies and in different environments
Measurements, Modeling and Simulations of the UWB Propagation Channel based on Direct-Sequence Channel Sounding
No full textThe paper presents the statistical model for the ultra-wideband (UWB) indoor channel having a bandwidth of 2.4 GHz and a central frequency of 4.78 GHz. The model is based on propagation experiments performed in different rooms on a floor of an office-laboratory building. Within each room the receiver antenna is automatically moved over a square grid of 25 x 25 locations spaced 2cm apart. A correlative channel sounding technique is employed; actually the carrier is modulated by a train of short duration (0.4 ns) pulses shaped by a PN-sequence. After coherently demodulating the detected signals and removing the PN-sequence modulation, we post-process the extracted channel impulse responses by best-fit procedures to set up a statistical tapped delay line model (STDL) of the UWB indoor channel. We characterize the path loss for line-of-sight (LOS) and non-line-of-sight (NLOS) conditions by distance-power laws and the shadowing by lognormal distributions. A clustered structure is observed in the average power-delay profiles; rays arrive at the receiver in groups, exponentially decaying with different decay constants. The small-scale effects are modeled by the Gamma distribution since it verifies with a 95%-confidence interval both the Chi-Square test and the Kolmogorov-Smirnov test applied to the experimental data.. The shape parameters of such Gamma distributions are truncated Gaussian variables spreading in the range from 1 to 3. An implementation of the derived STDL model is finally proposed and a comparison between the simulated and the measured statistics is performed proving the validity of our approach
A time domain propagation model of the UWB indoor channel in the FCC-compliant band 3.6-6 GHz based on PN-sequence channel measurements
No full textWe derive a statistical model of the UWB indoor
channel based on the experimental data collected in a modem
office building. Measurements were made in different rooms
throughout the floor and within each room the receiver antenna
was moved over a square grid of 25 x 25 locations spaced 2 cm
apart. The measnrement technique was based on the use of a
carrier at 4.78 GHz modulated by a train of short duration
(0.4 ns) pulses shaped by a PN-sequence. Thus the probe signal
coven the band 3.6 - 6 GHz. We coherently demodulate the
received signals and cross-correlate their In-phase and Q-phase
components to an opportune PN-sequence template to extraet
the channel impulse responses from the recorded profiles. Then
we post-process these '"covered" impulse responses by best-fit
procedures to set up a statistical tapped delay line model of
the UWB indoor channel. We model the path loss for LOS and
NLOS conditions by diMance power laws and the shadowing
by Lognormal distributions. The average power-delay profiles
exhibit a clustered ~t~UChlmw,h ich means that rays arrive at
the receiver in groups, each having a given decay constant. We
characterize the small-scale statistics by selecting the distribution
that verifies with a 95%-co&dence interval both the Chi-square
test and the Kolmogorov-Smimov test applied to the experimental
data. The Gamma distribution verifies the above-mentioned
tests in most cases. The shape parameters of such Gamma
distributions spread in the range of 1 i 3, and remain roughly
constant around 2 with the excess delay
A multi-wall path loss model for UWB indoor propagation
No full textThe paper presents a propagation experiment performed in a modern office/laboratory building to investigate the UWB indoor channel behavior over the band 3.6 − 6 GHz.
We accomplished measurements employing a correlative channel
sounding technique. PN-sequence modulation is applied to a train of 0.4ns pulses and the pair of a direct sequence UWB transmitter and a correlation receiver is used. We collected data under extremely heterogeneous propagation conditions. LOS measurements are carried out along of the corridor and in office environment, while a total of 10×118 measurements are collected
in NLOS scenarios, within office rooms, for a coverage range up to about 18 m. We describe the exploited measurement technique as well as the data processing approach. Finally, a multi-wall path loss model is recommended, instead of the classical single-slope model, to fairly evaluate the power decay with the link distance,
separately taking into account the losses due to architectural obstacles intercepted by the direct paths of the propagating signals
Statistical Characterization of UWB Indoor Propagation Channels based on Extensive Measurement Campaigns
No full textThis paper summarizes the main outcomes of the ULTRAWAVES project in the characterization of the UWB propagation channel. Three measurement campaigns have been carried out in a typical office building: the first is based on the use of a direct sequence UWB transmitter and a digital sampling oscilloscope, the second on
the use of a vector network analyzer and the third on the use of the pair of direct sequence UWB transmitter and correlation receiver. Mainly based on the data of the first campaign, we derive a statistical tapped delay line model of the UWB channel. We also investigate the frequency dependence of the path loss on the basis, instead, of the data of the second campaign. Finally, an accurate analysis of the time dispersion of the UWB channel is presented
Energy/Latency Trade-offs in Geographic Routing for Ultrawideband Wireless Sensor Networks
No full textWireless Sensor Networks (WSNs) may exploit accurate localization capabilities of ultrawideband (UWB) transceivers to improve performance of high layer protocols. We analyze power consumption of a WSN accommodating both communication and positioning into the same UWB transceiver and implementing a geographic routing algorithm, either the Greedy Perimeter Stateless Routing (GPSR) or its energy aware version, the e-GPSR. Power consumption depends on beacon rate for positions' updates, the number of hops to reach the destination and the number of neighbors per node. On the other hand, the beacon rate impacts the reliability of the neighbor lists; the number of hops impacts on the end-to-end latency; the number of neighbors, i.e. the network connectivity, impacts on routing performance. The presented analysis assesses, by means of both theoretical investigations and simulation results, the main trade-offs between power consumption and latency that can be applied to obtain the best achievable performance
Minimum-Phase Impulse Response Channels
No full textWe give a sufficient condition that insures that the impulse response of a channel is of minimum phase. The condition is that the energy of the first path be larger than the power spectral density of all subsequent paths. Establishing a lower bound to the first path energy, this condition is more likely to be met if transmitter and receiver are in line-of-sight. Our results show that the Hilbert transform may give unreliable results, if used to extract the channel phase response from frequency-resolved amplitude measurements when the first path is strongly attenuated
Spectral analysis of UWB multiple access schemes using random scrambling
No full textWith the new release of the Federal Communication Commission on matters of regulation of marketing and operation of ultra-wideband (UWB) devices, an analytical framework to enable tractable analysis of the spectrum shape of these signals is needed. We extend the framework introduced by W. A. Gardner to the case of UWB signals. We introduce a generalized UWB signal model that can be specialized to represent the traditional time-hopping (TH) technique as well as the alternative multiple access technique that we indicate as delay coded sequence (DCS). The DCS technique resembles the traditional direct sequence spread spectrum techniques, but it is not based on pulse polarity inversion. The considered matrix signal formulation allows us to easily evaluate the spectral characteristics of UWB signals under many different operating conditions: continuous or discontinuous transmissions, random or periodic scrambling operations, with or without jitter. We evaluate the spectrum of the general UWB signal under the random scrambling assumption, then we specialize it to the TH and DCS cases and discuss the variability of the spectra to some critical design parameters. We obtain an asymptotic expression of the general UWB spectrum that we use to evaluate the UWB interference power at the output of a generic receiver
Statistical Analysis of Cars Induced Scattering in 60 GHz UWB Outdoor Channels
No full textMillimeter-waves radio technology is attracting great interest because large portions of radio spectrum are available from about 30 to beyond 90 GHz to support modern bandwidth-hungry applications with QoS requirements. Fifth generation of mobile communications is mainly envisaged in the spectrum around 28–40 GHz, whereas 60 GHz band is mostly used for indoor wireless local area networks (WLANs). However, with 7 GHz of available bandwidth, 60 GHz links could play a key role for outdoor backhaul, street lamps hot-spots and video surveillance. Studies of 60 GHz outdoor channels are currently limited. Outdoor channels are usually sparser than indoor channels, but the presence of scatterers like, e.g., cars, in the proximity of the link may induce specific patterns in the multipath composition. In this paper, we provide a statistical analysis of the effect of scatterers with large electromagnetic surface, namely cars, on multipath propagation of 60 GHz ultra- wideband (UWB) signals. The analysis is based on experimental data collected in two parking areas with and without parked cars, where a 60 GHz UWB radio transmits from street lamps towards collector points located in the proximity of a building. The measurements were done at eight carrier frequencies in the region 54–66 GHz, using a tunable sliding correlator, thus results also show the channel behavior vs. frequency
- …
