Rodolfo Feick - Profile on Academia.edu (original) (raw)

Papers by Rodolfo Feick

GLOBECOM - IEEE Global Telecommunications Conference

conference, Dec 1, 2006

In this paper we consider hybrid automatic repeat request transmission based on binary phase shif... more 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 considerably improve the performance if multidimensional modulation is applied. We evaluate the theoretical limits of bit-interleaved coded modulation with MR, verify the functioning of the practical coding scheme, and propose to improve the performance via iterative detection-decoding (BICM-ID) which brings considerable gains. In particular, for high coding rates, a 4 dB SNR gain over transmission without MR may be achieved.

Microwave and Optical Technology Letters, 2004

Mutual coupling between two planar inverted-F antennas (PIFAs) based on a ground plane is studied... more 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 0.1 to 0.9 are examined at the design frequency of 2.45 GHz, and in the 2.0-3.0-GHz frequency band.

Proceedings of the Twenty-Third International Symposium on Theory, Algorithmic Foundations, and Protocol Design for Mobile Networks and Mobile Computing

Outdoor-to-indoor (OtI) signal propagation further challenges link budgets at millimeter-wave (mm... more Outdoor-to-indoor (OtI) signal propagation further challenges link budgets at millimeter-wave (mmWave). To gain insight into OtI mmWave at 28 GHz, we conducted an extensive measurement campaign consisting of over 2,000 link measurements in West Harlem, New York City, covering seven highly diverse buildings. A path loss model constructed over all links shows an average of 30 dB excess loss over free space at distances beyond 50 m. We find the type of glass to be the dominant factor in OtI loss, with 20 dB observed difference between clustered scenarios with low-and high-loss glass. Other factors, such as difference in floor height, are found to have an impact between 5ś10 dB. We show that for urban buildings with high-loss glass, OtI data rates up to 400 Mb/s are supported for 90% of indoor users by a base station (BS) up to 49 m away. For buildings with low-loss glass, such as our case study covering multiple classrooms of a public school, data rates over 2.8/1.4 Gb/s are possible from a BS 68/175 m away when a line-of-sight path is available. We expect these results to be useful for the deployment of OtI mmWave networks in dense urban environments and the development of scheduling and beam management algorithms. CCS CONCEPTS • General and reference → Measurement; • Networks → Network measurement; Wireless access networks; Physical links.

60 GHz Outdoor to Indoor (O2I) Propagation Measurements in a University Campus

2022 IEEE 23rd International Workshop on Signal Processing Advances in Wireless Communication (SPAWC)

BER Evaluation of BICM-ID via

Abstract—In this paper, we evaluate the bit error rate (BER) of bit-interleaved coded modulation ... more Abstract—In this paper, we evaluate the bit error rate (BER) of bit-interleaved coded modulation (BICM) receivers that operate with aprioriinformation obtained from the decoder during the socalled 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. The results are shown to be useful for the convergence analysis of the iterative demapping via the so-called extrinsic information transfer (EXIT) charts and for the evaluation of the coded performance of BICM with iterative demapping (BICM-ID). Index Terms—BICM with iterative demapping (BICM-ID), bit-interleaved coded modulation (BICM), Bonferroni bounds, iterative demapping, turbo decoding, turbo demapping. I.

Long Term Fade Margin for 90% Availability in Fixed Wireless Links With Diversity

IEEE Wireless Communications Letters, 2020

Fixed wireless access is becoming a major 5G application. We measured received power for 72 urban... more 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 increase with the excess path loss of the link. We propose a model that accurately characterizes first and second order link statistics. Spatial and frequency diversity measurements allowed us to also assess the effectiveness of the corresponding fade mitigation techniques. From them we conclude that the long-term fades appear to be consistent with time-varying multipath propagation, as opposed to shadowing.

IEEE Access, 2022

We investigate propagation characteristics for wireless channels, applicable to Integrated Access... more 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 urban environment, where we simultaneously measured base-relay, relay-mobile and base-mobile links. This simultaneity allows us to conclude that low-height relay nodes offer a minor path-loss advantage over the base-user link. Moreover, within the range of relay heights that we measured of 2.8 and 4.7 m, we observed no significant gain associated with choosing the higher relay placement. Our results however also show that the base-relay link is quite stable over time and thus will lend itself to multi-antenna techniques requiring a small overhead in channel state information feedback. Our results add to the empirical data that the standards models are based on, providing path-loss results obtained simultaneously for all links of an urban relay-based system. INDEX TERMS Channel models, integrated access and backhaul, 5G IAB, path loss, propagation, relay networks.

Proceedings of the 3rd ACM Workshop on Millimeter-wave Networks and Sensing Systems - mmNets'19, 2019

Next generation wireless and mobile networks will utilize millimeter-wave (mmWave) communication ... more 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 deployment area of the PAWR COSMOS testbed [1, 2] in New York City and report extensive 28 GHz channel measurements. These include over 24 million power measurements collected from over 1,500 links on 13 sidewalks in 3 different sites and in different settings during March-June, 2019. Using these measurements, we study the effects of the setup and environments (e.g., transmitter height and seasonal effects). We then discuss the obtained path gain values and their fitted lines, and the resulting effective azimuth beamforming gain. Based on these results, we also study the link SNR values that can be supported on individual sidewalks and the corresponding theoretically achievable data rates. We believe that the results can inform the COSMOS testbed deployment process and provide a benchmark for other deployment efforts in dense urban areas. CCS CONCEPTS • General and reference → Measurement; • Networks → Network measurement; Wireless access networks; Physical links.

IEEE Transactions on Antennas and Propagation, 2020

Adequate coverage with high gain antennas is key to realizing the full promise of the bandwidth a... more 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 o spinning horn, capable of capturing a full azimuth scan every 200 ms, in up to 171 dB path loss to characterize coverage with 90% confidence level. The environment had prominent corridors and rooms, as opposed to open/mixed offices in latest 3GPP standards. Guiding in corridors leads to much lower RMS azimuth spread (7 o median in corridor non-LOS vs. 42 o in 3GPP) and higher penetration loss into rooms and around corners (30-32 dB, some 12 dB more loss than 3GPP at 20 m non-LOS). Measured path gain in non-LOS is predicted by a mode-diffusion model with 3.9 dB RMS error. Scattering degraded azimuth gain by up to 4 dB in the corridor and 7 dB in rooms with 90% probability. Link simulations in a canonical building indicate every corridor needs an access point to provide 1 Gbps rate to adjoining rooms within 50 m using 400 MHz of bandwidth.

IEEE Wireless Communications Letters, 2017

The applicability of COST231, WINNER+, ITU-R, and 3GPP urban microcell outdoor-to-indoor path los... more 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 location on the street are evaluated. We find that for our scenarios, discrepancies among the models can reach up to 10 dB at the median. Using the WINNER+ model path loss with free-space antenna gains yields the best match to our measurements.

IEEE Transactions on Wireless Communications, 2016

Based on measurements for a street-canyon-type femto-cell we compare the downlink spectral effici... more 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 Zero-Forcing (RZF) and Dirty-Paper Coding (DPC). As a reference for comparison we consider subsectorization and TDMA. Out-of-cell interference, treated as additive Gaussian noise, is included in two modes: a) all cells transmit simultaneously and b) neighboring cells transmit in alternated time slots. We find that ZF, RZF and DPC can offer increases in spectral efficiency over subsectorization and TDMA by factors of around 4 under interference-limited conditions. This contrasts with estimated gains of only around 2 when using a standard 3GPP mode instead of our measured data. This difference is due to the greater inter-cell isolation that characterizes our street-canyon-type test environment. We find that RZF achieves over 80% of the DPC's spectral efficiency under virtually all operating conditions.

Mediciones de Propagación EM en ambientes confinados

Revista Facultad de Ingeniería - Universidad de Tarapacá, 2005

En este trabajo se presentan los resultados obtenidos de mediciones de la respuesta en frecuencia... more 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 diversos grados de obstrucción de enlace, diferente polarización de las antenas, y distinta distancia entre transmisor y receptor. Se obtuvieron parámetros como el Ancho de Banda de Coherencia, Retardo de Exceso Promedio y Dispersión Temporal RMS. En base a los datos empíricos se obtuvieron relaciones entre la Dispersión Temporal RMS y el Ancho de Banda de Coherencia, las que se contrastan con resultados publicados por otros autores. Palabras clave: Canal multitrayecto, medición de canal, ancho de banda de coherencia, dispersión temporal RMS, desvanecimiento selectivo en frecuencia.

IEEE GLOBECOM 2007-2007 IEEE Global Telecommunications Conference, 2007

In this paper we develop formulas for the probability density function (PDF) of the reliability m... more In this paper we develop formulas for the probability density function (PDF) of the reliability metrics in bitinterleaved coded modulation (BICM) for arbitrary M 2-ary quadrature amplitude modulation (M 2-QAM) with Gray mapping. The advantage of this approach over an entirely general one proposed previously, is that the resulting formulas are obtained without resorting to any algorithmic steps. We also propose Gaussian mixture approximations that are analytically tractable, and we analyze their accuracy when evaluating uncoded bit error rate (BER) and BICM capacity.

Microwave and Optical Technology Letters, 2010

transformers are used in both designs, which provide even mode impedances of 70.7 X with a line s... more transformers are used in both designs, which provide even mode impedances of 70.7 X with a line spacing of 0.56 mm [8]. The area of the folded layout is 30% less than the unfolded layout. The simulated and the measured results are compared in Figures 8-10. In Figure 8, the insertion loss for both designs is shown. Because the layouts are symmetrical, only |S 21 | is compared with the simulation. It is found that the measured data fits the simulations well. The insertion loss at the center frequency is 3.2 and 15 dB at 1 and 4 GHz. The one section filter response is clearly observed. The measured 3-dB bandwidth is 60%, which fits the prediction of Figure 6. The return losses for input and output ports are shown in Figure 9. The measured 10-dB input return loss bandwidths are around 33%. The isolation between the two output ports is shown in Figure 10. 5. CONCLUSION A one section filter is integrated into the PD. The concept can be realized using open-ended coupled lines and shorted-end coupled. The relations between even mode and odd mode impedance are shown. However, fabrication limits restrict the practical implementation. Therefore, an alternative loaded line circuit without coupled lines is used, which provides more flexibility in choosing the bandwidth. Two designs with a center frequency of 2.4 GHz are fabricated and measured to validate the concept. A 3-dB insertion loss bandwidth of 60% and a 10-dB return loss bandwidth of 33% are measured.

International Journal of Infrared and Millimeter Waves, 2007

A millimeter wave antenna consisting of two Fresnel zone plate lenses, plane and conical, is exam... more 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 117 GHz. The lenses are made conformal to a truncated circular cone with a base diameter of 500 mm and a plateau diameter of 250 mm. Designs for two opening semi-angles, 45°and 75°each of them with a particular lens thickness are presented. For the angle of 90°the cone lens becomes a plane ring lens, which in combination with the plateau zone lens forms a plane lens of size equal to the cone base diameter. Illuminated by directive feeds set at a focal distance of 525 mm from the cone apex, the double-dielectric and half-open compound and plane lenses, form three pairs of Fresnel zone lens antennas, the co-polar and cross-polar radiation characteristics of which have been compared numerically. The double-dielectric lens antennas examined are about 5 dB superior in gain to the half-open lens antennas, which has a gain of approximately 45 dBi. Because all lenses are of equal transverse aperture, the corresponding lens antennas exhibit the same −3 dB beamwidth of about 0.33 degrees. The plane zone lens antenna is very thin and simple. Instead, the antenna comprising a 3-D compound Fresnel zone lens is thicker but can be made conformal to a specific surface shape and possesses more levels of design and optimization freedom.

IEEE Transactions on Wireless Communications, 2011

This paper presents an empirical study of the achievable data rates of network multiple-input mul... more 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 conventional techniques, in which either the base stations are not coordinated (NC), or their interference is avoided using frequency division (FD) multiplexing. The measurements were taken in aisle-to-office and large unobstructed hall scenarios. The study of these results reveals that, at high signal-to-noise ratios (SNRs), DPC and ZF-DPC can yield more than a threefold increase in attainable data rates when compared to NC and FD. The gains obtained using ZF are smaller, but still significant. At low SNRs the system is noise-(rather than interference-) limited, and only DPC exhibits gains. The evaluations in this paper also show that collaborative systems such as DPC can benefit from interference-prone environments to yield increased transmission capacity. With regard to the propagation channel, the classical log-normal plus Rayleigh/Ricean fading model, with parameters fitted to the scenario type, was found to be good at predicting the statistics of the achievable data rates of all the strategies considered.

IEEE Transactions on Communications, 2009

In this letter we derive closed-form expressions for the probability density functions (PDFs) of ... more 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 metrics are calculated via the so-called max-log approximation. Using the developed expressions, the performance of coded BICM transmissions is efficiently evaluated, i.e., without resorting to otherwise required two-dimensional numerical integration. The BICM capacity for different fading channels and constellation sizes is also evaluated.

IEEE Transactions on Antennas and Propagation, 2003

The prediction of wall losses is a fundamental aspect in the planning of cellular systems. The br... more The prediction of wall losses is a fundamental aspect in the planning of cellular systems. The broad variety of building materials and construction codes makes accurate attenuation prediction very difficult without the support of specific construction data or measurements. In this paper, the attenuation and equivalent electric parameters and of brick and doubly reinforced concrete walls are estimated for the 900-MHz band by fitting simple ray tracing models to empirical transmission data. The measurement setup is described, and extensive experimental results justifying the quasioptical modeling are presented.

IEEE Transactions on Antennas and Propagation, 2019

Achieving adequate coverage with high gain antennas is key to realizing the full promise of the w... more 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 otherstreet link types (true NLOS) from 7 streets, using a specialized narrowband channel sounder at ranges reaching 200 m. The measurements, applicable to fixed wireless access, involved a 55 • transmit antenna placed on the exterior of a street-facing window and a 10 • receive horn antenna spinning on top of a van mast at 3 m height, emulating a lamppost-mounted base station. Measured path gain-distance dependence is well represented by power-law models, and azimuth gains at the base are degraded through scattering by more than 4.3 dB for 10% of links. It was found that, with 51 dBm EIRP at the base station and 11 dBi antenna at an outdoor mounted terminal, 1 Gbps downlink rate can be delivered up to 100 m from a base station deployed in the same street with 90% coverage guarantee.