Jukka-Pekka Nuutinen

Channel Modelling for Multiprobe Over-the-Air MIMO Testing

This paper discusses over-the-air (OTA) test setup for multiple-input-multiple-output (MIMO) capable terminals with emphasis on channel modelling. The setup is composed of a fading emulator, an anechoic chamber, and multiple probes. Creation of a propagation environment inside an anechoic chamber requires unconventional radio channel modelling, namely, a specific mapping of the original models onto the probe antennas. We introduce two novel methods to generate fading emulator channel coefficients; the prefaded signals synthesis and the plane wave synthesis. To verify both methods we present a set of simulation results. We also show that the geometric description is a prerequisite for the original channel model.

Tracking Time-Variant Cluster Parameters in MIMO Channel Measurements

This paper presents a joint clustering-and-tracking framework to identify time-variant cluster parameters for geometry-based stochastic MIMO channel models. The method uses a Kalman filter for tracking and predicting cluster positions, a novel consistent initial guess procedure that accounts for predicted cluster centroids, and the well-known KPowerMeans algorithm for cluster identification. We tested the framework by applying it to two different sets of MIMO channel measurement data, indoor measurements conducted at 2.55 GHz and outdoor measurements at 300 MHz. The results from our joint clustering-and-tracking algorithm provide a good match with the physical propagation mechanisms observed in the measured scenarios.

Analysis and measurements for indoor polarization MIMO in 5.25 GHz band

We present the results of multiple-input multiple-output (MIMO) indoor channel measurements in the 5.25 GHz band, emphasizing the case where both transmitter and receiver apply dual-polarized antennas. Wideband (100 MHz) capacity results show that dual-polarized antennas provide an attractive solution for MIMO multiplexing. This is due to the fact that the static component in a line-of-sight (LOS) channel preserves its polarization, and channels between dual-polarized antennas may still remain separated. This is not necessarily the case if spatially separated copolarized antennas are applied.

A time-variant MIMO channel model directly parametrised from measurements

This paper presents the Random-Cluster Model (RCM), a stochastic time-variant, frequency-selective, propagation-based MIMO channel model that is directly parametrised from measurements. Using a fully automated algorithm, multipath clusters are identified from measurement data without user intervention. The cluster parameters are then used to define the propagation environment in the RCM. In this way, the RCM provides a direct link between MIMO channel measurements and MIMO channel modelling. For validation, we take state-of-the-art MIMO measurements, and parametrise the RCM exemplarly. Using three different validation metrics, namely, mutual information, channel diversity, and the novel Environment Characterisation Metric, we find that the RCM is able to reflect the measured environment remarkably well.

Experimental Investigations on MIMO Radio Channel Characteristics on UHF Band

Pan-European project B21C (Broadcasting for the 21st Century) aims to develop technology for DVB-T2 (Digital Video Broadcasting, Terrestrial), which is a spectrum efficient broadcasting system for future. The evaluated technologies include MIMO, which has been widely studied in perspective of B3G (Beyond 3rd Generation) systems, but never for any UHF band systems. In addition, the latest decision of WRC (World Radiocommunication Conference) highlights that the B3G systems can be deployed in UHF bands. This paper introduces a measurement campaign performed in UHF frequency and presents the most important results with regard to channel modeling and MIMO.

WLC06-2: Cluster-Based MIMO Channel Model Parameters Extracted from Indoor Time-Variant Measurements

This paper presents a complete solution to the problem of how to parametrise cluster-based stochastic MIMO channel models from measurement data, with minimum user intervention. The method comprises the following steps: (i) identify clusters in measurement data, (ii) identify the optimum number of clusters, (iii) track clusters over consecutive time snapshots, (iv) estimate cluster parameters. These parameters are given as estimated probability density functions of the cluster power, cluster positions, delay and angular spreads of clusters and the number of paths within a cluster. Applied to high-resolution indoor MIMO measurement data at 5.2 GHz and at 2.55 GHz, the method yields coherent results of the obtained cluster parameters.

Empirical Models and Parameters for Rural and Indoor Wideband Radio Channels At 2.45 and 5.25 GHZ

The modeling results from wideband radio channel measurements are presented for two environments: rural and indoor. The paper focuses on the average and instantaneous characteristics of received power including: path loss, shadow fading, power delay profiles, and rms delay spreads. Furthermore, the cross correlation between shadowing of the path loss and the delay spread is investigated and found to be large. Doppler measurement campaigns were conducted in both environments, at 2.45 GHz and 5.25 GHz along the same measurement routes, with 100 MHz bandwidth. In this paper it is shown that we may apply 2.45 GHz band small scale models into 5.25 GHz band. It can be also seen, as for the measured scenarios, on average, the difference in terms of path loss between 2.45 GHz and 5.25 GHz in line-of-sight indoor environment, where waveguide effect is encountered, is c.a. 8 dB, instead in rural outdoor the mentioned difference is c.a. 6 dB

Correlations of Wide-Band Channel Parameters in Street Canyon at 2.45 and 5.25 GHz

The correlation between channel parameters root mean square delay spread (DS), shadow fading, number of clusters, and Rician factors (K-factors or K) is investigated based on wide-band channel measurements. The channel measurements were performed at 2.45 and 5.25 GHz in long line-of-sight (LOS) and non-LOS (NLOS) street canyons. The relation of the channel parameters to distance is illustrated. Very high correlation between channel parameters was found in the LOS street canyon, while much lower correlation was found in the NLOS street canyon. The linear relationship between the DS and the other channel parameters is derived in the LOS case, thus allowing the use of one channel parameter (e.g., the DS) to predict the others.

On a MIMO-OTA testing based on multi-probe technology

Standardization work of the OTA test method for MIMO terminals is currently on-going. This paper discusses, mainly from the electromagnetics viewpoint, field synthesis with multi-probe technology with the emphasis on 2-D field synthesis using a circular array. Furthermore, opportunities and practical challenges of multi-probe technology for MIMO-OTA testing are discussed briefly.

A measurement-based random-cluster MIMO channel model

We present a novel geometry-based stochastic MIMO channel model based on the concept of multipath clusters. The so-called random-cluster model (RCM) represents the channel in a propagation-based stochastic way, in which the geometry enters solely by statistical means. The starting point is the recently published parametric COST 273 MIMO Channel Model. However, instead of using physical parameters (e.g. rooftop height or scatterer distance), our model requires only cluster parameters. As another major feature beyond COST 273, the model can now be parametrized directly from measurements. The model presently supports multi-user packet access, i.e. the channel changes completely from one time instant to another. Simple future extensions will incorporate smoothly time-variant channels as well.