The Experts below are selected from a list of 249 Experts worldwide ranked by ideXlab platform
Alenka Zajic - One of the best experts on this subject based on the ideXlab platform.
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d Band Channel measurements and characterization for indoor applications
IEEE Transactions on Antennas and Propagation, 2015Co-Authors: Seunghwan Kim, Wasif Tanveer Khan, Alenka Zajic, J PapapolymerouAbstract:This paper presents measurements and characterization of D-Band indoor Channels. The measurements are performed in line-of-sight (LoS), obstructed-LoS (OLoS), and reflected non-LoS (RNLoS) environments. For OLoS sceanrio, cylindrical objects of different materials are used as an obstruction. For RNLoS, different surfaces are used as reflectors. From the large set of LoS and OLoS measured data, the parameters for single-slope path loss model with shadowing are devised. Furthermore, the analysis of multipath propagation is performed. The results show that strong multiple reflections from the transmitter and receiver electronics are present both in LoS and OLoS environments. Additionally, the results show that glass and ceramic objects in the propagation path produce surface-diffracted rays which clock-wise and counter clock-wise superposition leads to frequency-dependent path loss. Finally, the results show that the RNLoS measured path loss with aluminum plate as a reflector is very similar to free-space path loss when the angle of incidence and the angle of reflection are equal.
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impact of moving scatterers on vehicle to vehicle narrow Band Channel characteristics
IEEE Transactions on Vehicular Technology, 2014Co-Authors: Alenka ZajicAbstract:A three-dimensional (3-D) geometrical propagation model that includes both stationary and moving scatterers around the transmitter and receiver for narrowBand multiple- input multiple-output (MIMO) vehicle-to-vehicle (V-to-V) com- munications is proposed. Based on the geometrical model, a 3-D parametric reference model for narrowBand MIMO V-to- V multipath fading Channels is developed. From the reference model, the corresponding space-time correlation function and space-Doppler power spectral density are derived for a 3-D non- isotropic scattering environment. Finally, the theoretical results are compared with measured data in urban surface street and Interstate highway road surfaces. The close agreement between the analytically and empirically obtained Channel statistics con- firms the utility of the proposed model and shows the importance of including moving scatterers into propagation models.
Sales Zaragozá Vicente - One of the best experts on this subject based on the ideXlab platform.
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Redes de acceso UDWDM operadas con láseres aleatorios de sintonía limitada
Universitat Politècnica de Catalunya, 2017Co-Authors: Sales Zaragozá VicenteAbstract:A new passive optical network (PON) for access, making use of ultra-dense wavelength division multiplexing (UDWDM) by densely spacing Channels by a few gigahertz and introducing the "wavelength-to-the-user" concept, is proposed in this thesis. The key challenge will be developing low-cost coherent transceivers that provide an excellent selectivity while avoiding optical filters and furnishing high sensitivity, which will allow high splitting ratios, large numbers of users, and long-distance reach. The optical distribution network (ODN) at the outside plant is based on splitters and is kept compatible with legacy systems. Optical network unit (ONU) designs realized with coherent transceivers using one or two lasers are presented. Employing a unique laser diode as transmitter and receiver local oscillator at the ONU to realize a cheap terminal implies to use the same wavelength for both up and down directions; therefore, in Full-Duplex (FD) transmission mode the Rayleigh Backscattering (RB) crosstalk will drastically perturb the reception. In this thesis, a Half-Duplex (HD) solution to avoid the RB disturbance is proposed and analyzed in different scenarios of reach and splitting ratios. Moreover, using Full-Duplex solutions, different spectral Band Channel structures are presented and adapted to the diverse transceivers options and laser selections. Two optical line terminal (OLT) architectures are introduced, a classical splitting-based structure and a new AWG-based structure, with two interleaving AWGs with no blocking Channel features and lower insertions losses. The new structure allows saving the optical amplification in networks with a modest number of users and/or reach. The ONUs at the customer premises have lasers with limited thermal tunability, and their wavelengths are randomly distributed in a Band. To avoid full-tunable lasers, static and dynamic wavelength assignment paradigms (SWA and DWA) and heuristic assignment schemes for spectrum management are proposed, simulated, and compared. By using the heuristic static and dynamic wavelength assignment schemes, the required optical Band is obtained and optimized. In activation processes, ONU acceptances up to 99.9% are achieved. The PON is dimensioned according to the number of deployed users and system reach; moreover, power safety and fiber nonlinearity constraints are evaluated, illustrating the characteristics of the projected network. Furthermore, in operation scenarios under indoor (soft) and also under outdoor (harsh) environmental conditions, ONU blocking probabilities below 0.1% and ONU availability ratios (OARs) up to 99.9% are demonstrated modifying the heuristic schemes developed previously and extending the original working Band. As the laser tuning and temperature stabilization are achieved by heating or cooling control, and the power consumption varies depending on the wavelength position in a tuning window and environmental conditions. The power consumption of the developed DWA schemes under different environmental condition scenarios in the network are evaluated and compared, since energy efficiency is important to reduce the green-house gas emissions. Finally, activation process taking account the different spectral Band structures, DWA schemes and transceivers are proposed.Una nova xarxa d'accés òptica i passiva (PON) és desenvolupada usant multiplexors per longitud d'ona ultra densa (UDWDM) mitjançant una separació del canals de pocs gigahertzs i introduint el concepte d'una longitud d'ona per usuari és proposat en aquesta tesis. El repte clau serà aconseguir desenvolupar transceptors coherents de baix cost que aporten una excel·lent selectivitat, evitant els filtres òptics, i a més a més gran sensibilitat, el que permetrà grans ràtios als divisors de potència, gran nombre d'usuaris i grans àrees de cobertura.La xarxa de distribució òptica (ODN) a la planta externa serà basada en divisor de potència i serà compatible amb els sistemes actuals. Dissenys del equipament d'usuari (ONU) amb transceptors coherents i amb un o dos làsers són presentats.Utilitzar un únic díode làser com a transmissor i oscil·lador local del receptor a la ONU per realitzar un terminal barato implicarà usar la mateixa longitud en tots dos sentits, de pujada i baixada, per tant, en una transmissió en mode Full-Duplex (FD) la diafonia provocada per la dispersió de Rayleigh (RB) pertorbarà dràsticament la recepció. En aquesta tesis és proposat i estudiat una solució Half-Duplex (HD) per a evitar l'alteració produïda per RB i és analitzada en diferents escenaris de cobertura i ràtios en los divisor de potència.Usant solucions Full-Duplex, diferents estructures de Bandes espectrals en los canals són presentades, adaptades a les diverses opcions de transceptors i a les seleccions de làsers.Dues arquitectures per a l'equipament terminal de línia (OLT) són introduïdes, una estructura clàssica basada en divisors de potència i una nova estructura basada en AWGs, amb dos AWGs entrellaçat, que permet utilitzar tots els canals i presentar menys pèrdues d'inserció. Aquesta nova estructura permet estalviar l'amplificació òptica en xarxes amb un nombre modest d'usuaris i/o àrees de cobertura.Les ONUs a les instal·lacions de l'usuari tenen làsers sintonitzables tèrmicament i les seves longituds d'ona són distribuïdes aleatòriament dins d'una Banda. Per a evitar l'ús de làsers completament sintonitzables, metodologies d'assignació de longitud d'ona dinàmics i estàtics, juntament amb esquemes heurístics per la gestió de l'espectre són proposats, simulats y comparats.Mitjançant l'ús dels esquemes d'assignació de longitud d'ona heurístics, tant estàtics com dinàmics, és obtinguda la Banda òptica necessària i optimitzada. Durant el procés d'activació és aconseguit un índex d'acceptació del 99.9% .D'acord amb el nombre d'usuaris i l'àrea de cobertura s'ha dimensionat la PON, a més a més, les restriccions per motius de seguretat i no linealitats a la fibra són avaluats, il·lustrant les característiques del projecte de xarxa.Tot seguit, en una escenari d'operació baix condicions ambientals, tan interior (suaus), com exteriors (severes), probabilitats de bloqueig inferiors a 0.1% i ràtios de disponibilitat (OAR) de dels ONUs del 99.9% són demostrades modificant els esquemes heurístics desenvolupats anteriorment i estenent les Bandes de treball originals.Com la sintonia del làser i la seva estabilització en temperatures són aconseguides amb un sistema de control, escalfant i refredant, la potència consumida varia depenent de la posició dins la finestra de sintonia i de les condicions ambientals. La potència consumida, baix diferents condicions ambientals, per l'ús dels esquemes DWA en la xarxa són avaluats, ja que l'eficiència energètica és important per a reduir els gasos d'efecte hivernacle.Finalment, processos d'activació tenint en compte les diferents estructures de Bandes espectrals, DWA esquemes i transceptors són propostes.Postprint (published version
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Redes de acceso UDWDM operadas con láseres aleatorios de sintonía limitada
Universitat Politècnica de Catalunya, 2017Co-Authors: Sales Zaragozá VicenteAbstract:A new passive optical network (PON) for access, making use of ultra-dense wavelength division multiplexing (UDWDM) by densely spacing Channels by a few gigahertz and introducing the "wavelength-to-the-user" concept, is proposed in this thesis. The key challenge will be developing low-cost coherent transceivers that provide an excellent selectivity while avoiding optical filters and furnishing high sensitivity, which will allow high splitting ratios, large numbers of users, and long-distance reach. The optical distribution network (ODN) at the outside plant is based on splitters and is kept compatible with legacy systems. Optical network unit (ONU) designs realized with coherent transceivers using one or two lasers are presented. Employing a unique laser diode as transmitter and receiver local oscillator at the ONU to realize a cheap terminal implies to use the same wavelength for both up and down directions; therefore, in Full-Duplex (FD) transmission mode the Rayleigh Backscattering (RB) crosstalk will drastically perturb the reception. In this thesis, a Half-Duplex (HD) solution to avoid the RB disturbance is proposed and analyzed in different scenarios of reach and splitting ratios. Moreover, using Full-Duplex solutions, different spectral Band Channel structures are presented and adapted to the diverse transceivers options and laser selections. Two optical line terminal (OLT) architectures are introduced, a classical splitting-based structure and a new AWG-based structure, with two interleaving AWGs with no blocking Channel features and lower insertions losses. The new structure allows saving the optical amplification in networks with a modest number of users and/or reach. The ONUs at the customer premises have lasers with limited thermal tunability, and their wavelengths are randomly distributed in a Band. To avoid full-tunable lasers, static and dynamic wavelength assignment paradigms (SWA and DWA) and heuristic assignment schemes for spectrum management are proposed, simulated, and compared. By using the heuristic static and dynamic wavelength assignment schemes, the required optical Band is obtained and optimized. In activation processes, ONU acceptances up to 99.9% are achieved. The PON is dimensioned according to the number of deployed users and system reach; moreover, power safety and fiber nonlinearity constraints are evaluated, illustrating the characteristics of the projected network. Furthermore, in operation scenarios under indoor (soft) and also under outdoor (harsh) environmental conditions, ONU blocking probabilities below 0.1% and ONU availability ratios (OARs) up to 99.9% are demonstrated modifying the heuristic schemes developed previously and extending the original working Band. As the laser tuning and temperature stabilization are achieved by heating or cooling control, and the power consumption varies depending on the wavelength position in a tuning window and environmental conditions. The power consumption of the developed DWA schemes under different environmental condition scenarios in the network are evaluated and compared, since energy efficiency is important to reduce the green-house gas emissions. Finally, activation process taking account the different spectral Band structures, DWA schemes and transceivers are proposed.Una nova xarxa d'accés òptica i passiva (PON) és desenvolupada usant multiplexors per longitud d'ona ultra densa (UDWDM) mitjançant una separació del canals de pocs gigahertzs i introduint el concepte d'una longitud d'ona per usuari és proposat en aquesta tesis. El repte clau serà aconseguir desenvolupar transceptors coherents de baix cost que aporten una excel·lent selectivitat, evitant els filtres òptics, i a més a més gran sensibilitat, el que permetrà grans ràtios als divisors de potència, gran nombre d'usuaris i grans àrees de cobertura.La xarxa de distribució òptica (ODN) a la planta externa serà basada en divisor de potència i serà compatible amb els sistemes actuals. Dissenys del equipament d'usuari (ONU) amb transceptors coherents i amb un o dos làsers són presentats.Utilitzar un únic díode làser com a transmissor i oscil·lador local del receptor a la ONU per realitzar un terminal barato implicarà usar la mateixa longitud en tots dos sentits, de pujada i baixada, per tant, en una transmissió en mode Full-Duplex (FD) la diafonia provocada per la dispersió de Rayleigh (RB) pertorbarà dràsticament la recepció. En aquesta tesis és proposat i estudiat una solució Half-Duplex (HD) per a evitar l'alteració produïda per RB i és analitzada en diferents escenaris de cobertura i ràtios en los divisor de potència.Usant solucions Full-Duplex, diferents estructures de Bandes espectrals en los canals són presentades, adaptades a les diverses opcions de transceptors i a les seleccions de làsers.Dues arquitectures per a l'equipament terminal de línia (OLT) són introduïdes, una estructura clàssica basada en divisors de potència i una nova estructura basada en AWGs, amb dos AWGs entrellaçat, que permet utilitzar tots els canals i presentar menys pèrdues d'inserció. Aquesta nova estructura permet estalviar l'amplificació òptica en xarxes amb un nombre modest d'usuaris i/o àrees de cobertura.Les ONUs a les instal·lacions de l'usuari tenen làsers sintonitzables tèrmicament i les seves longituds d'ona són distribuïdes aleatòriament dins d'una Banda. Per a evitar l'ús de làsers completament sintonitzables, metodologies d'assignació de longitud d'ona dinàmics i estàtics, juntament amb esquemes heurístics per la gestió de l'espectre són proposats, simulats y comparats.Mitjançant l'ús dels esquemes d'assignació de longitud d'ona heurístics, tant estàtics com dinàmics, és obtinguda la Banda òptica necessària i optimitzada. Durant el procés d'activació és aconseguit un índex d'acceptació del 99.9% .D'acord amb el nombre d'usuaris i l'àrea de cobertura s'ha dimensionat la PON, a més a més, les restriccions per motius de seguretat i no linealitats a la fibra són avaluats, il·lustrant les característiques del projecte de xarxa.Tot seguit, en una escenari d'operació baix condicions ambientals, tan interior (suaus), com exteriors (severes), probabilitats de bloqueig inferiors a 0.1% i ràtios de disponibilitat (OAR) de dels ONUs del 99.9% són demostrades modificant els esquemes heurístics desenvolupats anteriorment i estenent les Bandes de treball originals.Com la sintonia del làser i la seva estabilització en temperatures són aconseguides amb un sistema de control, escalfant i refredant, la potència consumida varia depenent de la posició dins la finestra de sintonia i de les condicions ambientals. La potència consumida, baix diferents condicions ambientals, per l'ús dels esquemes DWA en la xarxa són avaluats, ja que l'eficiència energètica és important per a reduir els gasos d'efecte hivernacle.Finalment, processos d'activació tenint en compte les diferents estructures de Bandes espectrals, DWA esquemes i transceptors són propostes
Branka Vucetic - One of the best experts on this subject based on the ideXlab platform.
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millimeter wave wireless transmissions at e Band Channels with uniform linear antenna arrays beyond the rayleigh distance
International Conference on Communications, 2014Co-Authors: Peng Wang, Xiaojun Yuan, Lingyang Song, Branka VuceticAbstract:In this paper, we study the point-to-point E-Band millimeter wave wireless Channel with uniform linear antenna arrays (ULAs) deployed at both link ends and present an analytical approach to characterize the Channel behavior. We first derive explicit expressions for some Channel eigenvalues at certain discrete system settings. The asymptotic behavior and the effective multiplexing distance (EMD) of the E-Band Channel are then investigated, where the latter is defined as the end-to-end distance at which the Channel can support a certain number of spatially independent streams at finite signal-to-noise ratios (SNRs). We analytically show that the EMD for a given number of parallel signal transmissions is mainly determined by the product of the aperture sizes of the transmit and receive ULAs. This finding provides useful insights into the design of practical multi-gigabits wireless communication systems over E-Band.
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tens of gigabits wireless communications over e Band los mimo Channels with uniform linear antenna arrays
IEEE Transactions on Wireless Communications, 2014Co-Authors: Peng Wang, Xiaojun Yuan, Lingyang Song, Branka VuceticAbstract:This paper studies the fundamental characteristics of point-to-point E-Band Channels with uniform linear antenna arrays (ULAs) deployed at both the transmitter and receiver. We model the Channels as line-of-sight (LoS) multiple-input multiple-output (MIMO) ones and focus on the Channel eigenvalue characterization when the Rayleigh distance criterion cannot be fulfilled due to limited physical sizes of the transmitter and receiver. We first derive explicit expressions for some Channel eigenvalues at certain discrete system settings. Asymptotic analyses are then developed when the antenna numbers at the transmitter and receiver or the distance between them goes to infinity. Based on these analytical results, the maximum eigenvalue and the effective multiplexing distance (EMD) of the E-Band Channel are investigated, where EMD is defined as the end-to-end distance at which the Channel can support a certain number of simultaneous spatial streams at a given signal-to-noise ratio (SNR). We analytically show that the EMD for a given number of parallel signal transmissions is mainly determined by the product of the aperture sizes of the transmit and receive ULAs. Numerical results are provided to validate the analyses.
Alenka G. Zajić - One of the best experts on this subject based on the ideXlab platform.
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Impact of Moving Scatterers on Vehicle-to-Vehicle Narrow-Band Channel Characteristics
IEEE Transactions on Vehicular Technology, 2014Co-Authors: Alenka G. ZajićAbstract:A 3-D geometrical propagation model that includes both stationary and moving scatterers around the transmitter and the receiver for narrow-Band multiple-input-multiple-output (MIMO) vehicle-to-vehicle (V-to-V) communications is proposed. Based on the geometrical model, a 3-D parametric reference model for narrow-Band MIMO V-to-V multipath fading Channels is developed. From the reference model, the corresponding space-time correlation function (ST-CF) and space-Doppler power spectral density (SD-PSD) are derived for a 3-D nonisotropic scattering environment. Finally, the theoretical results are compared with measured data in an urban surface street and Interstate highway road surfaces. The close agreement between the analytically and empirically obtained Channel statistics confirms the utility of the proposed model and shows the importance of including moving scatterers in propagation models.
Reiner S Thoma - One of the best experts on this subject based on the ideXlab platform.
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simultaneous multi Band Channel sounding at mm wave frequencies
European Conference on Antennas and Propagation, 2016Co-Authors: Robert Muller, Stephan Hafner, Diego Dupleich, Reiner S Thoma, Gerhard Steinbock, Jian Luo, Egon Schulz, Guangjian WangAbstract:The vision of multi Gbit/s data rates in future mobile networks requires the change to millimeter wave (mm-Wave) frequencies for increasing Bandwidth. As a consequence, new technologies have to be deployed to tackle the drawbacks of higher frequency Bands, e.g. increased path loss. Development and verification of those novel technologies required an understanding of the propagation effects at mm-Wave which enabled by Channel sounding measurements and analysis. Due to the variety of considered frequency Bands and the necessity of spatial resolved measurements for e.g. testing of beamforming approaches, measurement duration and comparability becomes problematic. This paper presents multi-Band Channel sounder architectures, usable to measure up to four frequency Bands simultaneously. Furthermore, we present a measurement campaign, featuring full polarimetric and directional resolved dual-Band measurements, which comprises the microwave Band at 10 GHz and the mm-Wave Band at 30 GHz. Preliminary analysis results are presented.
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large scale parameter for the winner ii Channel model at 2 53 ghz in urban macro cell
Vehicular Technology Conference, 2010Co-Authors: Christian Schneider, M Narandzic, Martin Kaske, Gerd Sommerkorn, Reiner S ThomaAbstract:This paper presents results of wide Band Channel measurements at 2.53 GHz for a representative urban macro cell environment in Ilmenau, Germany. The extensive Channel sounding campaign covered the MIMO radio links from 22 mobile tracks to 3 different base stations and 1 relay station. The results presented in this paper provide insight into the large scale parameter analysis of the power, delay domain, including the transmission loss and the statistical distributions of the shadow fading, narrowBand k-factor and delay spread. Large scale parameters from angle domain (azimuth and elevation) are derived based on the high resolution multipath parameter estimation (RIMAX). Furthermore the cross correlation of these parameters are investigated and compared to state-of-the-art Channel models as from the IST-WINNER.
