Jan Järveläinen

Propagation Path Loss Models for 5G Urban Micro- and Macro-Cellular Scenarios

This paper presents and compares two candidate large-scale propagation path loss models, the alpha-beta-gamma (ABG) model and the close-in (CI) free space reference distance model, for the design of fifth generation (5G) wireless communication systems in urban micro- and macro-cellular scenarios. Comparisons are made using the data obtained from 20 propagation measurement campaigns or ray- tracing studies from 2 GHz to 73.5 GHz over distances ranging from 5 m to 1429 m. The results show that the one-parameter CI model has a very similar goodness of fit (i.e., the shadow fading standard deviation) in both line-of-sight and non-line-of-sight environments, while offering substantial simplicity and more stable behavior across frequencies and distances, as compared to the three-parameter ABG model. Additionally, the CI model needs only one very subtle and simple modification to the existing 3GPP floating-intercept path loss model (replacing a constant with a close-in free space reference value) in order to provide greater simulation accuracy, more simplicity, better repeatability across experiments, and higher stability across a vast range of frequencies.

A Statistical Spatio-Temporal Radio Channel Model for Large Indoor Environments at 60 and 70 GHz

Millimeter-wave radios operating at unlicensed 60 GHz and licensed 70 GHz bands are attractive solutions to realize short-range backhaul links for flexible wireless network deployment. We present a measurement-based spatio-temporal statistical channel model for short-range millimeter-wave links in large office rooms, shopping mall, and station scenarios. Channel sounding in these scenarios at 60 and 70 GHz revealed that spatio-temporal channel characteristics of the two frequencies are similar, making it possible to use an identical channel model framework to cover the radio frequencies and scenarios. The sounding also revealed dominance of a line-of-sight and specular propagation paths over diffuse scattering because of weak reverberation of propagating energy in the scenarios. The main difference between 60 and 70 GHz channels lies in power levels of the specular propagation paths and diffuse scattering which affect their visibility over the noise level in the measurements, and the speed of power decay as the propagation delay increases. Having defined the channel model framework, a set of model parameters has been derived for each scenario at the two radio frequencies. After specifying the implementation recipe of the proposed channel model, channel model outputs are compared with the measurements to show validity of the channel model framework and implementation. Validity was demonstrated through objective parameters, i.e., pathloss and root-mean-square delay spread, which were not used as defining parameters of the channel model.

Sixty gigahertz indoor radio wave propagation prediction method based on full scattering model

In radio system deployment, the main focus is on assuring sufficient coverage, which can be estimated with path loss models for specific scenarios. When more detailed performance metrics such as peak throughput are studied, the environment has to be modeled accurately in order to estimate multipath behavior. By means of laser scanning we can acquire very accurate data of indoor environments, but the format of the scanning data, a point cloud, cannot be used directly in available deterministic propagation prediction tools. Therefore, we propose to use a single-lobe directive model, which calculates the electromagnetic field scattering from a small surface and is applicable to the point cloud, and describe the overall field as fully diffuse backscattering from the point cloud. The focus of this paper is to validate the point cloud-based full diffuse propagation prediction method at 60 GHz. The performance is evaluated by comparing characteristics of measured and predicted power delay profiles in a small office room and an ultrasonic inspection room in a hospital. Also directional characteristics are investigated. It is shown that by considering single-bounce scattering only, the mean delay can be estimated with an average error of 2.6% and the RMS delay spread with an average error of 8.2%. The errors when calculating the azimuth and elevation spreads are 2.6° and 0.6°, respectively. Furthermore, the results demonstrate the applicability of a single parameter set to characterize the propagation channel in all transmit and receive antenna locations in the tested scenarios.

60 GHz radio wave propagation prediction in a hospital environment using an accurate room structural model

Accurate radio wave propagation prediction is crucial in designing wireless instruments for medical use. In this paper we simulate the 60 GHz radio channel in a hospital ultrasonic inspection room using ray tracing based on single-bounce scattering. The scattering is calculated with a single-lobe directive model and the room structure is modeled with a large point cloud, acquired via laser scanning. It is shown that the scattering model is able to predict the power delay profile with a proper scattering parameter. It is also noticed that measuring the environment dimensions with laser scanning is a suitable method in order to obtain appropriate prediction of the propagation channel.

On the Mutual Orthogonality of Millimeter-Wave Massive MIMO Channels

Mutual orthogonal user channels in multiuser (MU)-multiple-input multiple-output (MIMO) systems are desirable and can be approximately obtained under independent and identically distributed (i.i.d.) Rayleigh fading assumption with a very large number of base station antennas. However, it has been shown that at millimeter-wave (mmW) frequencies, this assumption is not valid due to the limited number of multipath components and spatial channel correlation. In this paper, we examine the mutual orthogonality of a realistic 60-GHz outdoor propagation channel with practical large antenna arrays, and determine the factors deciding it based on the channel data generated by means of deterministic field prediction. The results obtained reveal relationships between mutual orthogonality, inter-user distance, number of active users, transmit array dimensions, and downlink system capacity at 60-GHz band, which are useful for designing future mmW massive MU-MIMO systems.

Radio Propagation Measurements and WINNER II Parameterization for a Shopping Mall at 60 GHz

In this paper, we derive parameters of the WINNER II channel model for a shopping mall environment at 60 GHz band, covering both line-of-sight and obstructed-line-of-sight scenarios. The model parameters are derived mostly based on channel measurements reported in this paper. Due to a large measurement bandwidth and the highly specular nature of the channel in the shopping mall, only weak clustering effects of propagation paths are found. Still, we demonstrate that the WINNER II model structure is applicable to 60 GHz channel modeling since the model reproduces the measured channels well.

Millimeter-Wave Channel Characterization at Helsinki Airport in the 15, 28, and 60 GHz Bands

Airport terminal is one of the indoor scenarios envisioned for mm-wave 5G deployment. In this paper, we characterize the propagation channel in the Helsinki airport at 15, 28, and 60 GHz bands by means of directional wideband channel sounding. The radio environment was characterized by studying the specular propagation paths, specular and diffuse power contributions, polarization, and the delay and angular spreads. All the studied metrics in different bands were compared and the frequency dependency was analyzed.

Impacts of Room Structure Models on the Accuracy of 60 GHz Indoor Radio Propagation Prediction

Accurate indoor radio wave propagation prediction requires a model of the environment which also includes fixtures such as furniture. By laser scanning we can obtain this detailed structural data in the form of a point cloud. Since conventional field prediction tools are not applicable to the point cloud data format, we predict the electromagnetic scattering by using a single-lobe directive scattering model which can be used directly with the point cloud. The focus in this letter is to study how the density of the point cloud affects the prediction accuracy. It is shown that a point cloud density of only 2·10-4 points per square wavelength is enough at 60 GHz in order to achieve good prediction accuracy between measured and predicted delay and angular spreads.

70 GHz Radio Wave Propagation Prediction in a Large Office

Site-specific millimeter-wave propagation prediction requires data of the environment under study, which is usually not available for indoor scenarios. With means of laser scanning the details of the indoor environment can be captured accurately in the form of a point cloud. The total field is estimated as a sum of paths backscattering from the point cloud, where the electromagnetic scattering for each path is calculated with a single-lobe directive model. In this paper we focus on predicting the radio wave propagation in a large office environment at 70 GHz, where the accuracy is evaluated by comparing measured and predicted mean delays and delay and azimuth spreads. We also present a method for dealing with shadowing in the indoor environment. The results show good agreement between measured and predicted delay and azimuth spreads for line-of-sight links, and also non-line-of-sight links can be predicted with reasonable accuracy.

Studies on E-band antennas and propagation

We have studied beam-steering radio in the E-band., e.g. for high-capacity communication links. Lens antennas provide high gain and are suitable for integration at millimeter wave frequencies, e.g., for beam-switching a planar antenna array with a switching network may be integrated to the surface of the lens; one patch is activated at a time for each beam direction. In order to improve the scanning characteristics and reduce reflection losses, we have studied optimization of the lens shape using ray tracing. A propagation channel model has been developed for point-to-point links in street canyons and from roof to street in an urban environment. The model is based on extensive measurements in the E-band. The substance of the channel model is in identification of multipath components in the environment. That is supported by separate measurements of radio wave reflection and scattering from various environmental structures such as building walls.