Aki Karttunen

• D.Sc. (Tech.)
• Tampere University

Radio wave propagation simulations based on the ray-optical approximation have been widely adopted in coverage analysis for a range of situations, including the outdoor-to-indoor scenario. This work presents O2I ray-tracing simulations utilizing a laser-scanned point cloud of the building interior. The simulated radio channels are compared to their...

Positioning is considered one of the key features in various novel industry verticals in future radio systems. Since path loss (PL) or received signal strength-based measurements are widely available in the majority of wireless standards, PL-based positioning has an important role among positioning technologies. Conventionally, PL-based positioning...

The use of above-100 GHz radio frequencies would be one of promising approaches to enhance the fifth-generation cellular further. Any air interface and cellular network designs require channel models, for which measured evidence of largescale parameters such as pathloss, delay and angular spreads, is crucial. This paper provides the evidence from q...

The communications between two driving vehicles along a narrow street may be limited by the presence of a third vehicle blocking the transmission. In this work, we investigate radio wave propagation at 28 GHz in an urban street canyon scenario by conducting channel measurements, where the vehicle(s) occlude(s) the line-of-sight path. We quantify th...

In this paper, we investigate typical glazing structures and their radio frequency signal losses at all the frequency bands considered for the fifth-generation (5G) cellular mobile communications from 0.6 to 95 GHz. The signal loss through glazing is one of the significant factors in determining indoor signal coverage from outdoor base stations. Th...

In this paper, we have characterized dielectric properties of low-loss radome materials with three different measurement methods, at microwave and mmWave frequencies. The techniques include an over-the-air (OTA) far-field measurement at 55-95 GHz, a Fabry-Perot open resonator (10-60 GHz), and a split-post dielectric resonator whose empty resonance...

In this work, we present the results of a wideband measurement campaign at 60 GHz conducted inside a Linkker electric city bus. Targeting prospective millimeter-wave (mmWave) public transportation wearable scenarios, we mimic a typical deployment of mobile high-end consumer devices in a dense environment. Specifically, our intra-vehicle deployment...

In this paper, we parameterize an excess loss-based multipath component (MPC) cross-polarization ratio (XPR) model in indoor and outdoor environments for above-6 GHz frequency bands. The results are based on 28 measurement campaigns in several frequency bands ranging from 15 to 80 GHz. A conventional XPR model of an MPC assuming a constant mean val...

In this paper, we parameterize an excess loss-based multipath component (MPC) cross-polarization ratio (XPR) model in indoor and outdoor environments for above-6 GHz frequency bands. The results are based on 28 measurement campaigns in several frequency bands ranging from 15 to 80 GHz. A conventional XPR model of an MPC assuming a constant mean val...

In this paper, we propose a new technique for the future fifth generation cellular network wireless backhauling. We show that hundreds of bits per second per Hertz (bits per second per Hz) of spectral efficiency can be attained at a high carrier frequency (such as 26 GHz) between large antenna arrays deployed along structures (such as lamp posts) t...

In this paper, we compare the radio propagation channels characteristics between 28 and 140 GHz bands based on the wideband (several GHz) and directional channel sounding in a shopping mall environment. The measurements and data processing are conducted in such a way to meet requirements for a fair comparison of large- and small- scale channel para...

This paper analyzes the frequency dependency of the radio propagation channel's root mean square (rms) delay spread (DS), based on the multi-frequency measurement campaigns in the mmMAGIC project. The campaigns cover indoor, outdoor, and outdoor-to-indoor (O2I) scenarios and a wide frequency range from 2 to 86 GHz. Several requirements have been id...

This paper considers a fundamental issue of path loss (PL) modeling in urban micro cell (UMi) environments, namely the spatial consistency of the model as the mobile station (MS) moves along a trajectory through street canyons. The work is motivated by the observed non-stationarity of the PL. We show that the traditional model of power law PL plus...

This deliverable describes the extensive multi-frequency channel measurement and simulation campaigns conducted in the mmMAGIC project, covering mm-wave 5G propagation scenarios. The data is evaluated to characterize environment-specific propagation effects. Based on the findings, refined modelling approaches are developed and embedded in a geometr...

In wireless channel measurements, the relatively weak cross-polarized multipath components (MPCs) are typically severely affected by the measurement noise level. As shown in this letter, the typical cross-polarization ratio (XPR) model parameter estimation, which ignores the existence of censored samples, may lead to significant errors. We demonstr...

Deterministic field prediction has been widely used to provide channel data for coverage analysis. Among these prediction tools, point cloud-based methods have been developed for millimeter-wave frequencies in order to characterize the environment with higher precision, but they have not taken into account all the necessary propagation mechanisms....

Path loss models are the most fundamental part of wireless propagation channel models. Path loss is typically modelled as a (single-slope or multi-slope) power-law dependency on distance plus a log-normally distributed shadowing attenuation. Determination of the parameters of this model is usually done by fitting the model to results from measureme...

The new services available through smart devices require very high cellular network capacity. The capacity requirement is expected to increase exponentially with the forthcoming 5G networks. The only available spectrum for truly wideband communication (>1 GHz) is at millimeter wavelengths. The high free space loss can be overcome by using the direc...

In this report, the end user scenarios, test cases and requirements envisioned by the METIS project are mapped to propagation scenarios. Furthermore they are analysed for deriving a new set of requirements relevant for radio channel and propagation modelling. Since none of the existing channel models in the literature satisfies all these requiremen...

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 scen...

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 th...

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, thi...

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 poi...

In this report, the results of the measurement campaigns are provided based on the propagation scenarios defined in METIS project. Channel modelling approaches are discussed and the Initial METIS Channel Model is described in detail. The initial METIS channel model includes both stochastic (generic) and map-based (site-specific) models. Moreover, t...

The main objective of this paper is to present major challenges regarding the fifth generation (5G) mobile communications propagation modelling work in the European 7 th framework project METIS (Mobile and wireless communications Enablers for the Twenty-twenty Information Society). The goal of the propagation work in METIS is to provide adequate pr...

Millimeter-wave radios operating at unlicensed 60 GHz and licensed 70 GHz bands are attractive solutions to realize short-range backhaul links for future flexible network deployment. In this work, we report directional radio channel sounding performed at 60 and 70 GHz in large indoor short-range scenarios such as offices, a shopping mall, and a rai...

Flat dielectric lens antennas for millimetre-wave beam-steering with fan-beam are studied in this paper. Two different configurations are studied: a dielectric slab waveguide (DSW) lens and a parallel plate waveguide (PPW) lens. Both lenses are made of PREPERM L450 commercial plastic developed for high frequency antenna applications. Two prototype...

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 e...

An integrated lens antenna design for beam-steering with small scan loss is presented. The lens is based on a well known extended hemispherical lens. By placing the feed elements on a spherical bottom surface of the lens, instead of a conventional planar one, all of the feed antennas are oriented towards the collimating part of the lens. The presen...

The conventional integrated lens antennas (ILAs) for beam steering suffer from internal reflections that deteriorate the scanning properties. The internal reflections are known to affect side lobes, cross-polarisation level, input impedance of the feed, and mutual coupling. In this paper, ILAs are designed to exhibit very low reflection loss, i.e.,...

This paper discusses the prospects of millimeter-wave beam steering antennas, such as tuneable high-impedance surface, dielectric rod waveguide with an integrated phase shifter, tuneable leaky-wave antenna, active reflectarray, and shaped lens antenna with an integrated switched feed array. In these antennas the necessary phase change for antenna e...

In many emerging applications of millimeter waves, electronic focusing and beam steering is needed. We present a survey of mm-wave beam steering antennas, where the necessary phase change for antenna elements is achieved using various electronically tuneable elements, e.g. microelectromechanical systems (MEMS), such as tuneable leaky-wave antennas,...

This article presents an integrated lens antenna design that allows two-dimensional beam-steering with a non-symmetrical beam. The lens design is based on a traditional integrated lens concept. It is shown that, with a simple modification, the beam-shape can be changed without compromising the beam-steering properties. The limitations and propertie...

Design and measurement results of a beam-steering integrated lens antenna at 77 GHz are presented. An 8-element LTCC aperture coupled patch antenna feed array with a switching network is used to electrically steer the main beam in H-plane. A 100-mm diameter Rexolite (ε r = 2.53) lens is simulated and tested. The eccentricity of the lens is optimize...

In this paper, the eccentricity of a large integrated lens antenna is optimised for a high-gain beam-steering antenna. With low permittivity lens materials, conventional integrated lens types, namely the extended hemispherical and the elliptical ones, have different characteristics when used in beam-steering applications. An optimal eccentricity is...

Department of Radio Science and Engineering at Aalto University is studying and developing antenna measurement techniques at mm- and submm-wavelengths. The research projects are ranging from meter-scale satellite antenna testing to millimetre-sized focal plane array (FPA) element characterization for imaging application. The expertise and novel res...

Electrical beam steering is demonstrated using a lens antenna integrated with an LTCC feed array at 77 GHz. The Teflon lens antenna is an extended hemispherical lens with diameter of 100 mm and its extension length of 85 mm is optimised in order to provide the maximum directivity. The feed array has eight patch antenna elements, which are in a line...

In this paper, large extended hemispherical lenses are studied for a high-gain beam-steering antenna as a function of directivity of a feed element, relative permittivity of the lens material, and feed offset. Design guidelines necessary for the feed array design are provided. A wide range of permittivities and feed directivities are studied. The l...

Measurements of high-gain antennas at THz frequencies present challenges for traditional antenna measurement techniques. Far-field measurements are not feasible because of the large far-field distance requirement and therefore inevitable signal attenuation and distortions. Adequate accuracy in the collimating element manufacturing is the major issu...

A hologram-based compact antenna test range (CATR) is designed, constructed, and used to test a 1.5-m antenna at 650 GHz. The CATR is based on a 3.16-m-diameter hologram as the collimating element. So far, this is the highest frequency at which any CATR has been used for antenna tests. The quiet zone is measured and optimized before the antenna tes...

Overview of recent research activities of MilliLab and SMARAD at mm- and submm-wavelengths is presented. These activities include MEMS-tunable high-impedance surfaces, passive and active dielectric rod waveguide components, indirect holographic imaging, and measurement techniques for high-gain antennas.

At submillimeter wavelengths, planarity error of the near- field scanner may be considerable, and therefore, needs to be eliminated when high phase measurement accuracy is desired. In this paper, we consider a differential phase measurement method, where the scanner planarity profile is determined from the submillimeter-wave phase data, and thus, n...

MilliLab/Radio Laboratory at the Helsinki University of Technology (TKK) is developing a hologram-based compact antenna test range (CATR) for high gain antenna testing at millimetre and sub-millimetre wavelengths. The capabilities of the hologram CATR were demonstrated in an antenna test campaign, where the ADMIRALS RTO was tested at the frequency...

A brief review of antenna test methods at THz frequencies is presented. Two hologram-based compact antenna test ranges (CATR), one at 322 GHz and another at 650 GHz were designed, constructed, and used for testing the ADMIRALS RTO antenna of 1.5 m in diameter. These CATRs are based on 3-meter diameter computer-generated amplitude holograms.

Compact antenna test range developed at TKK Helsinki University of Technology utilizes a computer-generated amplitude hologram as the collimating element. Recently we have demonstrated its applicability for testing high-gain antennas at 650 GHz.

constructed, and used for testing the ADMIRALS RTO antenna of 1.5 m in diameter. The CATR is based on a 3.16-meter computer-generated amplitude hologram. Ordinary floor carpets with good absorbing and scattering properties were used as absorbers in the measurement room.

A compact antenna test range (CATR) based on a radio frequency hologram is a potential method for testing high-gain antennas at submillimetre wavelengths. Within a European Space Agency (ESA) project, a 1.5 m reflector antenna, ADMIRALS Representative Test Object (RTO), will be tested at 650 GHz during autumn 2006. For these antenna tests, MilliLab...

A hologram can be used as a collimating element in a compact antenna test range (CATR) at millimetre and sub-millimetre wavelengths. The performance of the CATR can be improved by using modified illumination of the hologram with a dual reflector feed system (DRFS). A 650 GHz dual reflector feed system (DRFS) was designed as part of an ESA project a...

The highest operation frequency and the measurement accuracy of compact antenna test ranges (CATRs) are limited by the manufacturing technology of the range collimating element. This paper reviews antenna pattern correction techniques, which can be used to improve the measurement accuracy of a CATR. In addition three lately developed techniques, wh...

A hologram can be used as a collimating element in a compact antenna test range (CATR) at millimetre and sub-millimetre wavelengths. The performance of a hologram can be improved by modifying the illumination of the hologram with a dual reflector feed system (DRFS). A 650 GHz dual reflector feed system (DRFS) was designed as part of an ESA project...

Prosessori Nr.11, 4 Edulliset millimetriaaltoalueen radiot mahdollistavat monia sovelluksia, joiden toteuttaminen perinteisin tekniikoin ei olisi järkevää. Vaikka tarvittavan uuden teknologian kehittäminen on haastavaa, odotettavissa oleva kaupallinen hyöty nähdään niin suureksi, että merkittävät yritykset ja tutkimuslaitokset ympäri maailman ovat...