Henrik Asplund

The COST259 Directional Channel Model-Part I: Overview and Methodology

This paper describes a model for mobile radio channels that includes consideration of directions of arrival and is thus suitable for simulations of the performance of wireless systems that use smart antennas. The model is specified for 13 different types of environments, covering macro- micro- and picocells. In this paper, a hierarchy of modeling concepts is described, as well as implementation aspects that are valid for all environments. The model is based on the specification of directional channel impulse response functions, from which the impulse response functions at all antenna elements can be obtained. A layered approach, which distinguishes between external (fixed), large-scale-, and small-scale- parameters allows an efficient parameterization. Different implementation methods, based on either a tapped-delay line or a geometrical model, are described. The paper also derives the transformation between those two approaches. Finally, the concepts of clusters and visibility regions are used to account for large delay and angular spreads that have been measured. In two companion papers, the environment-specific values of the model parameters are explained and justified

Clustering of scatterers in mobile radio channels-evaluation and modeling in the COST259 directional channel model

We analyze the clustering of scatterers in mobile radio channels, i.e, the fact that scatterers are usually not located uniformly in the whole coverage area, but tend to occur in clusters. While this has been recognized for some time, a realistic model for this phenomenon has been lacking up to now. We first analyze measurements to extract the distribution of the number of observed clusters. We then present a model that reflects not only this distribution, but also reproduces the appearance and disappearance of clusters as the mobile station moves through the cell. Our approach has been adopted as an important part of the COST259 directional channel model, a standard model for directional mobile radio channels. Finally, we discuss the implications of the model for the system performance of CDMA and SDMA systems.

Propagation Characteristics of Polarized Radio Waves in Cellular Communications

Narrowband and wideband measurements of the radio channel using different combinations of transmit and receive polarization have been performed. The measurements cover a range of scenarios including urban, suburban and open terrain, as well as both outdoor and indoor terminals. The vertical-to-vertical (V-V) and horizontal-to-horizontal (H-H) polarization combinations are found to provide equal received power on average, while the cross-polarized combinations (V-H) and (H-V) typically provide 5-15 dB weaker received power due to the limited amount of cross-polarization scattering in the radio channel. Fast fading variations are further found to be uncorrelated between different combinations of transmit and receive polarization.

5G 3GPP-Like Channel Models for Outdoor Urban Microcellular and Macrocellular Environments

For the development of new 5G systems to operate in bands up to 100 GHz, there is a need for accurate radio propagation models at these bands that currently are not addressed by existing channel models developed for bands below 6 GHz. This document presents a preliminary overview of 5G channel models for bands up to 100 GHz. These have been derived based on extensive measurement and ray tracing results across a multitude of frequencies from 6 GHz to 100 GHz, and this document describes an initial 3D channel model which includes: 1) typical deployment scenarios for urban microcells (UMi) and urban macrocells (UMa), and 2) a baseline model for incorporating path loss, shadow fading, line of sight probability, penetration and blockage models for the typical scenarios. Various processing methodologies such as clustering and antenna decoupling algorithms are also presented.

Carrier Frequency Effects on Path Loss

To study the carrier frequency effects on path loss, measurements have been conducted at four discrete frequencies in the range 460-5100 MHz. The transmitter was placed on the roof of a 36 meters tall building and the receive antennas were placed on the roof of a van. Both urban and suburban areas were included in the measurement campaign. The results show that there is a frequency dependency, in addition to the well known free-space dependency 20 log10(f), in most of the areas included in the measurements. In non line of sight conditions, the excess path loss is clearly larger at the higher frequencies than at the lower. A model capturing these effects is presented

MIMO channel characteristics in a small macrocell measured at 5.25 GHz and 200 MHz bandwidth

The purpose of this work is to improve the radio channel characterization in macrocellular scenarios. The effort has been put on the wideband and MIMO aspects. Measurements have been performed at two outdoor and three indoor locations at 5.25 GHz with bandwidth of 200 MHz using a vector network analyzer. An optical fiber was used to achieve distances between transmitter and receiver up to 300m. The channel parameters were estimated by means of maximum likelihood estimation, modeling the channel with a set of discrete plane waves. Based on the estimates joint double directional, delay and polarimetric distributions were determined. Moreover, clustering and statistical distribution of path amplitudes were studied.

3G LTE Simulations Using Measured MIMO Channels

In this article we present downlink simulation results for a realistic implementation of the LTE (Long Term Evolution) 3G standard. In contrast to previous studies, actual measured channels (as opposed to computer generated artificial channels) have been used in the simulation. The used 2 times 2 MIMO channels were measured using two realistic receiver mockups, one laptop and one handset, as well as a pair of reference dipole antennas. The results suggest that LTE is able in practice to support multi stream transmission with very high data rates, even for small hand held terminals. Also, the improvements of 2 times 2 MIMO over SISO transmission are clearly shown.

Measurements and analysis of a MIMO macrocell outdoor-indoor scenario at 1947 MHz

Narrowband MIMO channel measurements at 1947 MHz have been performed in an urban macrocellular outdoor-indoor scenario. The spatial characteristics of the channel have been analyzed, showing an angular spread of 5-10/spl deg/ at the base station and 30-60/spl deg/ at the mobile station. The maximum theoretical capacity that the channel can support has been evaluated for various antenna spacings and number of antenna array elements. Only about 50% of ideal gain, relative to capacity with fully correlated antenna array elements, was obtained with a 2/spl lambda/ antenna spacing at the base station. However, measured Ricean K factors indicate that the gain would be about 90% for sufficiently large antenna spacing.

15 GHz propagation properties assessed with 5G radio access prototype

This paper presents coverage and penetration loss measurements in an urban environment at 15 GHz to provide insight into the design and deployment of future 5G systems in higher frequency bands. The measurements are performed using a 5G radio access prototype including two transmission points (TPs) and a mobile terminal over a 200 MHz bandwidth. The TPs and the mobile terminal each consists of multiple antennas, enabling spatial multiplexing of multiple data streams. Coverage measurements are performed for both outdoor and outdoor-to-indoor scenarios. Penetration losses are measured for human body, normal and coated windows, a metallic white board, and a concrete pillar. Outdoor microcellular coverage in line-of-sight (LOS) and lightly shadowed areas is shown to be possible with similar antenna directivities as in the existing cellular networks. Transitions into non-line-of-sight (NLOS) bring additional losses in the order of 20 dB, thereby making the NLOS coverage challenging. Outdoor-to-indoor coverage seems to be limited to areas that are in almost LOS with the outdoor TP. Moreover, the penetration loss of indoor blocking objects seems to further restrict the indoor coverage. Potentials of beamforming as a means to improve the coverage are also evaluated via simulations.

Indoor 5G 3GPP-like channel models for office and shopping mall environments

Future mobile communications systems are likely to be very different to those of today with new service innovations driven by increasing data traffic demand, increasing processing power of smart devices and new innovative applications. To meet these service demands the telecommunications industry is converging on a common set of 5G requirements which includes network speeds as high as 10 Gbps, cell edge rate greater than 100 Mbps, and latency of less than 1 msec. To reach these 5G requirements the industry is looking at new spectrum bands in the range up to 100 GHz where there is spectrum availability for wide bandwidth channels. For the development of new 5G systems to operate in bands up to 100 GHz there is a need for accurate radio propagation models which are not addressed by existing channel models developed for bands below 6 GHz. This paper presents a preliminary overview of the 5G channel models for bands up to 100 GHz in indoor offices and shopping malls, derived from extensive measurements across a multitude of bands. These studies have found some extensibility of the existing 3GPP models (e.g. 3GPP TR36.873) to the higher frequency bands up to 100 GHz. The measurements indicate that the smaller wavelengths introduce an increased sensitivity of the propagation models to the scale of the environment and show some frequency dependence of the path loss as well as increased occurrence of blockage. Further, the penetration loss is highly dependent on the material and tends to increase with frequency. The small-scale characteristics of the channel such as delay spread and angular spread and the multipath richness is somewhat similar over the frequency range, which is encouraging for extending the existing 3GPP models to the wider frequency range. Further work will be carried out to complete these models, but this paper presents the first steps for an initial basis for the model development.