Juho Poutanen

The COST 2100 MIMO channel model

The COST 2100 channel model is a geometry- based stochastic channel model (GSCM) that can reproduce the stochastic properties of MIMO channels over time, frequency, and space. In contrast to other popular GSCMs, the COST 2100 approach is generic and flexible, making it suitable to model multi-user or distributed MIMO scenarios. In this article a concise overview of the COST 2100 channel model is presented. Main concepts are described, together with useful implementation guidelines. Recent developments, including dense multipath components, polarization, and multi-link aspects, are also discussed.

Angular and Shadowing Characteristics of Dense Multipath Components in Indoor Radio Channels

The dense multipath components (DMC) represent the part of the radio channel that cannot be characterized by using the specular components (SC). In this paper, the propagation characteristics of the DMC are analyzed in indoor environments based on extensive channel measurements. The results show that the contribution of the DMC to the total received power can vary as much as between 10% and 95%, being generally higher in non-line-of-sight than in line-of-sight scenarios. However, it was found that the DMC have a well distinguishable structure in the angular domain in all the investigated scenarios and, furthermore, the propagation mechanisms of the SC and DMC have large similarities. In addition, the effect of shadowing objects on the SC and DMC has been investigated.

Multi-Link MIMO Channel Modeling Using Geometry-Based Approach

Geometry-based stochastic channel models (GSCMs) are extended to support multi-link simulations by applying the concept of common clusters. This novel approach aims to control the correlation between different links, inter-link correlation, by adjusting the amount of power simultaneously propagating via the same clusters in the different links. The behavior of common clusters is analyzed based on dual-link channel measurements, and a multi-link GSCM is developed based on common clusters. In addition, the effects that the common clusters have on inter-link correlation and on sum rate capacity are investigated based on simulations. Finally, comparison between simulations and measurements is done in order to indicate the validity of the proposed multi-link GSCM.

Analysis of Correlated Shadow Fading in Dual-Link Indoor Radio Wave Propagation

In this letter, we analyze the results of dynamic, double-directional, dual-link channel sounding, where the measurement system consists of one transmitter moving along a continuous route and two fixed receivers. The results show that despite a large terminal separation at one side of the link, the fading behaviors of the two links can be strongly correlated. In this special case, correlated shadow fading was found to be caused by the similar initial signal directions at the transmitter side and due to pillars that shadowed the signals at that side of the link. The fading phenomenon has been analyzed by dividing the received power into groups of multipath components revealing similar propagation mechanisms and by investigating the properties of those multipath components that are most severely shadowed by the pillars.

Measurement-Based Evaluation of Interlink Correlation for Indoor Multiuser MIMO Channels

The properties of the single-link multiple-input-multiple-output (MIMO) propagation channels have been analyzed in many studies based on extensive propagation measurements. In this letter, we extend the measurement-based analysis to dual-link MIMO propagation channels. Here, we examine interlink correlation by evaluating the correlation of eigenvectors obtained from multiple MIMO links. We also investigated how the physical propagation phenomena produced the interlink correlation. Results indicate that interlink correlation may exist. Sometimes it is found to be very high also for far separated receive units, depending on similarity of dominant propagation mechanisms between multiple MIMO links and also on antenna array properties.

Propagation Characteristics of Dense Multipath Components

The dense multipath components (DMC) represent the part of the radio channel that cannot be characterized by a superposition of distinct plane waves, i.e., the specular components (SC). In this letter, the propagation characteristics of the DMC are analyzed in indoor environments from two perspectives. First, the proportion of DMC in the total power is studied as a function of the distance between the transmitter (TX) and receiver (RX). Second, the characteristics of the DMC and SC are compared in angular and delay domains. The measurement results show that the amount of DMC in the total power increases as the TX-RX distance increases in both line-of-sight (LOS) and non-line-of-sight (NLOS) scenarios. In addition, it is shown that the power of the DMC is concentrated around the same angles and delays as the SC.

Analysis of radio wave scattering processes for indoor MIMO channel models

In this paper radio wave scattering processes in an indoor hall environment are reported by analyzing double-directional multiple-input-multiple-output (MIMO) channel sounding data at 5.3 GHz. The pathways and scattering processes of the dominant propagation phenomena were identified using a measurement-based ray tracer (MBRT) software. It is shown that the dominant propagation phenomena included a line-of-sight (LOS) or obstructed LOS component, single, double, and triple bounce scattering processes from walls and ground. The proportion of power carried by each identified pathway was studied. The number of active pathways varied between 3 and 8, which indicates that the multipath environment changes significantly during the measurement route.

Radio Channel Modeling for 4G Networks

This chapter is dedicated to radio channel modeling for 4G networks. In addition to recent results in the area of 4G channel modeling at large, including complex environments such as aircrafts, COST 2100 has dealt with a number of specific topics which are presented in this chapter. Improved deterministic methods, including models of diffuse components are detailed in Sect. 3.2. The developed models namely propose new methods to account for macroscopic diffuse scattering in ray-tracing tools. The measurement-based modeling of the same diffuse or dense multipath components has represented one major research topic in COST 2100, especially regarding the extraction of such components from experimental data (Sect. 3.3). Another important topic of research has concerned the modeling of the polarization behavior of wireless channels (see Sect. 3.4), as multipolarized antenna arrays appear more and more as a realistic implementation of MIMO systems. The specific representation and modeling of multilink scenarios is dealt with in Sect. 3.5. Considering the correlations between multiple links is a significant requirement to design robust schemes in cooperative, relay or multihop networks. Finally, the COST 2100 model is presented in Sect. 3.6. Starting from a single-link implementation based on the COST 273 model (available online), it builds upon the work described in this chapter to propose an updated version of the COST 2100 model including enhancements such as diffuse and cross-polar components, as well as multi-link aspects.

User Effect of Antennas for Handheld DVB Terminal

The user effect study for handheld DVB antennas was performed by simulating the radiation and total efficiencies of the antennas as a function of frequency. Because of the losses caused by the user, a 4-dB margin to the realized gain specification in the antenna prototypes located in free space is needed to fulfil the DVB-H specification also when the effect of the users hands are taken into account. Also, the detuning of the matching due to the hands was examined.

Analysis of radio wave propagation from an indoor hall to a corridor

In this paper the radio wave propagation from an indoor hall to a corridor was studied by analyzing the results from a multi-link MIMO channel sounding measurement. The results showed that despite NLOS conditions, the dominant propagation mechanisms comprised direct path through the wall and specular reflections. These findings were verified by plotting the dominant pathways with a measurement-based ray tracer. In contrast to what was expected, the wave-guide propagation around the corner had almost negligible effects in this case. The results indicate that indoor localization and navigation applications using the direction or the delay of the first arriving path can be possible even in NLOS scenarios.