Rodolfo Feick

• Universidad Técnica Federico Santa María

Next generation wireless and mobile networks will utilize millimeter-wave (mmWave) communication to achieve significantly increased data rates. However, since mmWave radio signals experience high path loss, the operation of mmWave networks will require accurate channel models designed for specific deployment sites. In this paper, we focus on the de...

At millimeter-wave (mmWave) frequencies, radio propagation links are more vulnerable to obstructions, causing coverage losses and power fades. This paper characterizes shadow fades for 28 GHz links caused by vehicles blocking line-of-sight (LOS) propagation, with results which may be applied to sidelink vehicle to vehicle (V2V) communications. The...

Outdoor-to-indoor signal propagation poses significant challenges to millimeter-wave link budgets. To gain insight into outdoor-to-indoor millimeter-wave at 28GHz, we conducted an extensive measurement campaign consisting of over 2,200 link measurements in West Harlem, New York City, covering seven highly diverse buildings. A path loss model constr...

Directional measurements of over 2600 links in four distinct factories at 28 GHz are used to formulate the path gain and azimuth gain models to allow reliable 90% coverage estimates. A simple theoretical model of path gain, dependent on ceiling and clutter heights, is found to represent path gain across the four factories with 4.4 dB root-mean-squa...

Outdoor-to-indoor (OtI) signal propagation further challenges the already tight link budgets at millimeter-wave (mmWave). To gain insight into OtI mmWave scenarios at 28 GHz, we conducted an extensive measurement campaign consisting of over 2,200 link measurements. In total, 43 OtI scenarios were measured in West Harlem, New York City, covering sev...

We investigate propagation characteristics for wireless channels, applicable to Integrated Access and Backhaul (IAB) and relay-based networks with lamppost-height nodes at 5.5 GHz. We compare our empirical results with a variety of models that have been proposed for system simulation. Our work is based on an extensive measurement campaign in an urb...

The performance of a modified solar chimney is studied numerically and experimentally. In this solar chimney, the classical solar collector array is replaced by a heat exchanger located in the middle section of the chimney. The natural convection inside is simulated by the commercial Computational Fluid Dynamics (CFD) code COMSOL. This software is...

Path gain and effective directional gain in azimuth in urban canyons from actual rooftop base station sites are characterized based on a massive data set of 3000 links on 12 streets in two cities, with over 21 million individual continuous wave power measurements at 28 GHz using vertically polarized antennas. Large street-to-street path gain variat...

Fixed wireless access is becoming a major 5G application. We measured received power for 72 urban fixed wireless links at 5.8 GHz over a period of 48 hours each. We find that 5-minute power averages show temporal variations requiring additional fade margins close to 6 dB at the 90th percentile. The average power temporal variation was found to incr...

In this work, we propose the use of Computational Fluid Dynamics (CFD) as a useful design tool for the construction and improvement of a vertical 4He evaporation refrigerator. This approach provides a cost-effective solution for improving the performance of such systems designed through the use of traditional heat transfer and fluid mechanics-based...

The design and test results for a prototype laboratory device capable of condensing and solidifying gases is presented. This equipment is a new approach to the fabrication of NH3 material for polarized target experiments in nuclear physics experiments. The formed solids have a cylindrical geometry with 32 mm diameter and 50 mm height. With Computat...

Adequate coverage with high gain antennas is key to realizing the full promise of the bandwidth available at mm/cm wave bands. We report extensive indoor measurements at 28 GHz (1000 links, 9.9 million individual power measurements, 10 offices, 2 buildings), with/without line-of-sight (LOS) using a continuous wave channel sounder, with a 10° spinni...

Next generation wireless and mobile networks will utilize millimeter-wave (mmWave) communication to achieve significantly increased data rates. However, since mmWave radio signals experience high path loss, the operation of mmWave networks will require accurate channel models designed for specific deployment sites. In this paper, we focus on the de...

Achieving adequate coverage with high gain antennas is key to realizing the full promise of the wide bandwidth available at cm/mm bands. We report extensive outdoor measurements at 28 GHz in suburban residential areas in New Jersey and Chile, with over 2000 links measured for same-street link types (vegetation blocked LOS) from 13 streets and other...

Path gain and effective directional gain in urban canyons from actual rooftop base station sites are characterized based on a massive data set of 3000 links on 12 streets in two cities, with over 21 million individual measurements. Large street-to-street path gain variation is found, with median street path gain varying over 35 dB at similar distan...

We measured channel dynamics for fixed wireless indoor channels at 28 GHz. We characterize pedestrian-induced fades in open indoor spaces and the effectiveness of beamswitching to mitigate them. We find that fades of the dominant propagation path may be as deep as 9 dB at the 90th percentile and that alternative signal paths are typically not stron...

Empirical characterization of the achievable rates for a wearable multi-antenna terminal shows the potential advantages of deploying a large number of antennas at the user end. We focus on the challenges and requirements of the broadband communication in future emergency communication systems, specifically addressing the outdoor–to–indoor propagati...

Achieving adequate coverage with high gain antennas is key to realizing the full promise of the wide bandwidth available at mm/cm bands. We report extensive outdoor measurements at 28 GHz in suburban residential areas in New Jersey and Chile, with over 2000 links measured for same-street links (vegetation blocked LOS) from 13 streets and other-stre...

Fixed wireless access at mm/cm bands has been proposed for high-speed broadband access to suburban residential customers and building penetration loss is a key parameter. We report a measurement campaign at 28 GHz in a New Jersey suburban residential neighborhood for three representative single-family homes. A base antenna is mounted at 3-meter hei...

Fixed wireless access at mm/cm bands has been proposed for high-speed broadband access to suburban residential customers and building penetration loss is a key parameter. We report a measurement campaign at 28 GHz in a New Jersey suburban residential neighborhood for three representative single-family homes. A base antenna is mounted at 3-meter hei...

Achieving adequate coverage with high gain antennas is key to realizing the full promise of the wide bandwidth available at mm/cm bands. We report extensive indoor measurements at 28 GHz, with over 1000 links with and without Line-of-Sight (LOS) using a specialized narrowband channel sounder, capable of reliable measurements up to 171 dB path loss...

The applicability of COST231, WINNER+, ITU-R, and 3GPP urban microcell outdoor-to-indoor path loss prediction models is empirically tested in 100 m radius urban femtocells. The analysis is based on more than 500 link measurements. Considerations not specified in the models such as the inclusion of antenna gains and the effect of base station locati...

Theory of normal mode propagation in a line-ofsight street scenario is extended to include propagation into buildings through coupling to a diffuse indoor field. Signal strength predictions are in close agreement with measurements, producing 2 dB and 3:5 dB root-mean-square model-data difference, in line-of-sight and outdoor-indoor scenarios, respe...

We present an empirically based comparison of the effectiveness of spatial and angular diversity systems in outdoorto- indoor fixed wireless links.We concentrate on the simple to implement, single RF-chain selection diversity systems. We find that for such systems, angular diversity very significantly outperforms spatial diversity using comparative...

Based on measurements for a street-canyon-type femto-cell, we compare the downlink spectral efficiencies of various intra-cell interference mitigation systems. This includes zero-forcing (ZF), regularized ZF (RZF), and dirty-paper coding (DPC). As a reference for comparison, we consider subsectorization and time-division multiple access (TDMA). Out...

Theory of normal mode propagation in a LOS street scenario is extended to include propagation into buildings through coupling to a diffuse indoor field. Resulting signal strength predictions show close agreement with measurements, 4.2 dB rms errors in an outdoor-indoor scenario. The model allows prediction of actual signal directions, important for...

We present an empirically based model for the gain of an indoor antenna array. This corresponds to the re-parametrization of the Greenstein-Erceg model, as applied to 5 m - 50 m, narrowband outdoor-indoor links. Our model is applicable to a few adjacent tones in an OFDM femtocell system such as LTE. We find that as much as 14 out of 16 dB of antenn...

This paper presents closed-form expressions for the space-frequency (SF) second-order statistics for the power gain of indoor wideband channels. These expressions hold for channel models in which multi-path components are clustered, both in their arrival angles and their arrival times. Assuming that the arrival times are independent of the angles o...

We derive closed-form expressions for the secondorder statistics of the power gain (as a function of frequency) of wideband microwave indoor channels. We obtain our results within a framework that is general enough to be compatible with several popular channel models, such as the Saleh–Valenzuela (SV) channel model and those proposed by the IEEE 80...

We present empirical results on the achievable cellular system throughput gains stemming from the use of remote radio heads (RRH) in an urban environment. Our work is based on simultaneous path-loss measurements of the base station (BS) and RRH links to outdoor street-level users. We calculated the increase in received power, when a RRH is added to...

In this work we present an empirical study of the added propagation losses that may be associated with providing fixed wireless service from near-ground base-stations to homes in a suburban environment. We present results for various types of environments, classified according to the existence of obstructions in the propagation path and the choice...

We present empirical results on the achievable gains stemming from the use of wireless remote radio heads (RRH) in a typical urban environment. Our work is based on simultaneous path-loss measurements of the base station and RRH links to outdoor street level users. We statistically characterize the increase in received power, when a RRH is added to...

This study presents an empirical characterisation of the wireless channel observed by static users in settings that correspond to populated open public spaces, where wireless services are increasingly being deployed. Link stability is analysed in terms of the temporal K-factor of the Ricean distribution. Second-order statistics were parameterised i...

The authors describe an empirical study to determine the accuracy of Ricean and Nakagami- m distributions for the prediction of fade margins, for 90 and 99% of temporal availability in fixed wireless links. They compare the results obtained assuming an envelope distribution (based on Ricean and Nakagami- m models) and those observed from measured d...

This paper presents an empirical study of the achievable data rates of network multiple-input multiple-output (MIMO) techniques including zero-forcing (ZF), zero-forcing dirty paper coding (ZF-DPC) and dirty paper coding (DPC) using actual 4-by-4 indoor wireless channel measurements at 3.5 GHz. Their performances are contrasted with those of conven...

This paper describes a new low-profile X antenna array separated 0.1–0.15 wavelengths from a flat or rimmed square reflector of 0.6 wavelengths in size. The array consists of two closely spaced elements: an active two-port folded-wire X antenna, which radiates two cross-polarized fields and a passive X element. This very compact double X reflector...

We derive closed form expressions for the second-order statistics of the spectral power gain of wide-band microwave indoor channels. We obtain our results within a framework general enough to be compatible with several popular channel models, such as those proposed by the IEEE 802.15.3a task group, as well as the Saleh-Valenzuela channel model. As...

In this letter we derive closed-form expressions for the probability density functions (PDFs) of the bits' reliability metrics (L-values) in bit-interleaved coded modulation (BICM) transmission over fully-interleaved fading channels. The expressions are valid for the relevant case of quadrature amplitude modulation (QAM) with Gray mapping when the...

In this paper we develop closed form approximations for the probability density function (PDF) of the reliability metrics (L-values) in bit-interleaved coded modulation (BICM). The expressions are valid for M²-ary quadrature amplitude modulations (M²-QAM) with binary reflected Gray mapping when the metrics are calculated using...

MIMO systems are usually associated with high scattering isotropic propagation while the use of directive antennas is associated with free space conditions. We found outdoor-indoor channels to be in between these two extremes, in the sense that we observed directivity - and - MIMO gain, for the same ensemble of channels. Our observation is based on...

Folded-wire X antenna with two feed ports is introduced, which can operate like a half-wave dipole, or array of two crossed dipoles depending on whether one or two ports are fed. The low-profile location of 1.8-GHz X antenna in front of flat plate makes a compact reflector antenna with a good input match in about 5% frequency band, gain of 8.5–9.0...

Some of the significant aspects of a design method a short backfire antenna (BFA) are discussed. The method consists of a number of elements, such as A feed, a surface wave (SW) structure S, and two parallel disk reflectors. The SW structure is a metal disk-on-rod construction, allowing same design method to be applied to backfire antennas with oth...

We present a summary of results based on several years of measurements for urban fixed wireless (FW) channels. Our results are aimed at providing reference data for practical applications in FW services. We discuss temporal stability and fade dynamics of outdoor-outdoor single-input single-output (SISO) channels with and without spatial diversity,...

We present an empirically based comparative study of spectral efficiency for a variety of transmission systems applicable to a fixed or repositionable wireless environment, in the context of Wi-Fi, WiMAX or MuniNet systems. A narrowband 4times4 multiple input multiple output (MIMO) channel sounder was constructed and a series of outdoor to indoor m...

In this paper, we evaluate the bit error rate (BER) of bit-interleaved coded modulation (BICM) receivers that operate with a priori information obtained from the decoder during the so-called turbo iterations. We use Bonferroni-type lower and upper bounds to tightly estimate the BER performance in the range of signal-to-noise ratio (SNR) of interest...

Signal field coverage improvements by means of antenna passive repeaters is explored by introducing a signal phase shifter to the traditional antenna passive repeater scheme, aimed at optimizing indoor signal distribution. The possible passive repeater schemes include an elevated outdoor high- or medium-gain omnidirectional antenna, and two antenna...

In general, MIMO systems are associated with high scattering isotropic propagation while the use of directive antennas is associated with free space or narrow angular spread conditions. We found outdoor-indoor channels to be in between these two extremes, in the sense that we observed directivity - and - MIMO gain, for the same ensemble of channels...

A new electromagnetic bandgap (EBG) spatial power combiner is proposed. The prototype consists of the design of the EBG ground holes structure, the active-EBG coupler, and the Vivaldi antenna array. A 17 dB system gain coupled with a 5.5 GHz of impedance bandwidth and good out-of-band suppression has been achieved. © 2008 Wiley Periodicals, Inc. Mi...

We show how a wire inverted-F antenna can be made more compact without significant alteration of its impedance and radiation characteristics. Two modified inverted-F antennas, one in air and another with solid dielectric casing, were computer-simulated for the 2.4-GHz band and their input match loss and bandwidth were validated experimentally. © 20...

In the popular bit-interleaved coded modulation (BICM) the output of the channel encoder and the input of the modulator are separated by a bit-level interleaver. From the decoder's point of view, the modulator, the transmission channel, and the demodulator (calculating bits' reliability metrics) become a memoryless BICM channel with binary inputs a...

In this paper we develop closed-form approximations for the coded BER in bit-interleaved coded modulation (BICM) transmission over Rayleigh fading channels. To obtain the desired expressions we apply the so-called saddle point approximation and use analytical forms of the probability density functions (PDF) of the reliability metrics. Numerical exa...

The major computation cost of pseudo-spectral method comes from the evaluation of differentiation matrix multiplication. In the past, uniform or Chebyshev collocation points are used for sampling. The differentiation matrix multiplication was evaluated by fast Fourier transform (FFT) or fast cosine transform (FCT), in order to reduce the computatio...

An IEEE 802.11 analytical performance evaluation model for ad-hoc WLAN�s comprising terminals with different traffic source characteristics is presented. Although some publications address this issue, most of them propose to modify the original standard by some means that will affect the probability of transmission of a device when the network reac...

We present measured gains of spatial and angular diversity receivers for fixed narrowband wireless links at 2.4 GHz, in scenarios where indoor service is provided from an outdoor base station. We tested the performance of maximal ratio (MRC), equal gain (EGC) and selection (SC) combiners, and compared them to angular selection diversity using direc...

We present an empirically based comparative study of spectral efficiency for a variety of transmission systems applicable to a fixed or repositionable wireless environment, in the context of Wi-Fi, WiMAX or MuniNet systems. A narrowband 4times4 Multiple Input Multiple Output (MIMO) channel sounder has been constructed and a series of outdoor to ind...

In this paper we consider hybrid automatic repeat request transmission based on binary phase shift keying modulation. Our objective is to improve the performance of the retransmissions, keeping at the same time the complexity and the performance of the first transmission unaltered. We conclude that the so-called mapping rearrangement (MR) may consi...

In this paper we develop formulas for the probability density function (PDF) of the reliability metrics in bit- interleaved coded modulation (BICM) for arbitrary M²-ary quadrature amplitude modulation (M²-QAM) with Gray mapping. The advantage of this approach over an entirely general one proposed previously, is that the result...

An efficient algorithm using macro-basis-function (MBF) and progressive method has been proposed to analyze microstrip structure. The mutual coupling effects of all the elements are considered in each MBF by applying progressive approach. The algorithm consists of two stages. The first stage is to determine the initial current on the structure. The...

Hybrid ARQ with packet combining for high-order modulations (such as 16-QAM) may be significantly enhanced if the bits-to-symbols mappings are appropriately changed throughout the transmissions. In this paper, we analyze the relationship between such mapping rearrangement (or mapping diversity) and channel coding. We calculate the capacity of the p...

Diversity techniques can be very effective against fading. For fixed wireless terminals, antenna diversity increases spatial coverage by reducing the likelihood of all antennas being at a faded location. At the same time, temporal fade depth is reduced, as time variations are normally uncorrelated for the antennas. The analysis of temporal fade in...

In this paper we address the issue of probabilistic modelling of the extrinsic L-values, used as reliability metrics in the context of bit interleaved coded modulation with iterative demapping (BICM-ID). Starting with a simple piece-wise linear model of the L-values obtained via the max-log ap- proximation, we derive the expressions for the cumulat...

Empirical results on indoor multiple input multiple output (MIMO) channel capacity obtained through the use of planar inverted-F antennas (PIFA) are presented. An extensive statistical study done at 2.45 GHz reveals how antenna proximity and array configuration affects MIMO capacity. It is concluded that certain linear or square PIFA based arrays a...

In bit interleaved coded modulation (BICM), the probability density function (PDF) of the reliability metrics (L- values) fully defines the BICM transmission and may be used to analyze it from an information-theoretic point of view. In this paper, the closed-form expressions for the PDF of the L-values in Rayleigh fading channels for 16-QAM with Gr...

A millimeter wave antenna consisting of two Fresnel zone plate lenses, plane and conical, is examined numerically by use of the vector diffraction theory. The lenses are of Wood-Wiltse (double-dielectric) or Soret (half-open) type, and are designed for the frequency of 117GHz. The lenses are made conformal to a truncated circular cone with a base d...

A conical double-dielectric phase-reversal Fresnel-zone plate (FZP) lens is introduced. We present the lens design equations as functions of cone opening angle. As an example, the phase-reversal lens has been applied to four millimeter-wave antennas with different lens opening semi-angles: 45deg, 60deg, and 75deg (conical lenses) and 90deg (plane l...

Temporal correlation between diversity branches degrades the fade mitigation expected in a multi-antenna diversity receiver. We study the case when the receive power is unequal across the diversity array. We also include the effect of correlation among the received signals. The results are of particular interest when the diversity receiver is stati...

We present a statistical model for the dynamics of the envelope of the received signal in narrowband urban fixed wireless links, with applications to the performance evaluation of diversity receivers. The model is based on a straightforward analytical treatment based on simplifying assumptions. The assumptions are validated by an extensive empirica...

The temporal behavior of fixed wireless (FW) links is usually described in terms of fade depth distribution, level crossing rates and average fade duration. This knowledge is needed for the optimization of transceiver parameters such as modulation format, frame length, automatic gain control dynamics, etc. We present analytic and empirical results...

An analytical method to predict accurately the performance of iterative demapping in bit-interleaved coded modulation (BICM-ID) is presented. It is based on the analytical evaluation of the bit error rate at the output of the demapper and, in comparison with previously known methods (e.g., those based on EXIT charts), considerably reduces the need...

In the popular bit-interleaved coded modulation (BICM) the output of the channel encoder and the input of the modulator are separated by a bit-level interleaver. From the decoder's point of view, the modulator, the transmission channel, and the demodulator (calculating bits' reliability metrics) become a memoryless BICM channel with binary inputs a...

We present a statistical model for the dynamics of the envelope of the received signal in narrowband urban fixed wireless links, with applications to the performance evaluation of diversity receivers. The model is based on a straightforward analytical treatment based on simplifying assumptions. The assumptions are validated by an extensive empirica...

In this paper we present a novel performance analysis of bit-interleaved coded modulation (BICM) over AWGN channel for different modulation schemes considering a finite block length and suboptimal metrics calculation. Using the known BICM capacity analysis as well as the Gallager bound, we show that among many known modulations, only three M-ary qu...

The present authors reply to the comment by Minin and Minin (IEEE Trans. Antennas Propag., vol.54, no.9, p.2692, September 2006) on the original paper by Hristov et al. (IEEE Trans. Antennas Propag., vol.53, p.1912-19, June 2005)

A dual frequency assembly of two short backfire (SBF) antennas, one large for low frequencies (LF) and one small for high frequencies, is discussed. The two antennas are regarded as integrated as they are located on the same axis and have a common reflectors, such integration is cost effective, compact, robust and simple to build. For the numerical...

We study the temporal fluctuations of a fixed wireless link in an urban environment by characterizing the Ricean K-factor as a function of the positioning of the customer premises antenna. Our main observation is that temporal fluctuation of received power is due mainly to vehicular traffic close to the remote antenna. Furthermore, a strong correla...

Recibido el 8 de abril de 2005, aceptado el 10 de julio de 2005 RESUMEN En este trabajo se presentan los resultados obtenidos de mediciones de la respuesta en frecuencia del canal en la banda de 2.4 GHz. Estas fueron realizadas en ambientes interiores representativos de entornos en que se utiliza el servicio IEEE 802.11, para enlaces fijos con dive...

We analyze the methodology and present the interpretation of results obtained in the measurement of the temporal Ricean K-factor and the time-autocovariance function of the received power for fixed narrowband wireless links in urban residential environments. Our main observation is that the time-autocovariance function (and thus both the temporal K...

A generalized vector diffraction theory of the half-open curvilinear Fresnel zone plate (FZP) tens antenna that is valid for any lens profile shape is presented. It is an extension to the vector Kirchhoff diffraction theory for the plane half-open FZP lens antenna and is based on the conical-segment lens profile approximation. An equation for the e...

A diffraction field-focusing equation based on a specific conical-segment linearization procedure is derived for the Fresnel zone plate (FZP) lens of arbitrary curved profile and is applied for contrasting plane, spherical, parabolic and conical zone plate lenses, convex-side illuminated by a paraxial plane wave front. Two sets of 100-GHz curviline...

In this paper, a lens antenna comprising a compound FZP lens is proposed and studied numerically by use of the vector diffraction theory for curvilinear FZP lens antennas. The compound lens consists of two half-open FZP lenses, plane and conical, conformal to a thin low-loss plastic dome with a shape of truncated cone. Two sets of three half-open c...

Mutual coupling between two planar inverted-F antennas (PIFAs) based on a ground plane is studied numerically and experimentally. Several arrangements of collinear, orthogonal, and parallel PIFA elements with interelement spacing ranging from 0.1λ to 0.9λ are examined at the design frequency of 2.45 GHz, and in the 2.0–3.0-GHz frequency band. © 200...

2.45 GHz planar inverted-F antenna (PIFA) designs mounted on a 100 mm square ground plane are examined with regard to the feed-element shape influence on the input bandwidth (BW). While the traditional wire-fed PIFA has a BW from about 4 to 12%, the novel PIFAs with diverse feed plates (triangular, bi-triangular, rectangular, rounded-rectangular an...

A simple inexpensive on-wall Fresnel zone plate (FZP) lens for indoor focusing of microwave signals is studied. It consists of concentric metal rings mounted on the outside of an exterior building wall. In our theoretical and empirical work the on-wall FZP lens is illuminated normally by a plane or spherical wave, of vertical or horizontal polariza...

The microwave/millimeter-wave Fresnel-zone plate (FZP) lenses differ substantially in construction, technology and applications from their optical analogs and require specific design equations and methods of electromagnetic analysis. In this paper, optimum design equations for double-dielectric lossless FZP lens are derived. The best and worst choi...

A simple Fresnel zone plate for indoor focusing of 2 GHz band signals is proposed and studied. It consists of concentric metal rings mounted on the outside of an exterior wall. A three-ring zone plate has a through-wall focusing efficiency of 15 dB (measured) and 14 dB (calculated), and axial defocusing of 0.22 m.