The effect of receiver antenna array horizontal orientation on MIMO channel capacity

In multiple-input multiple-output (MIMO) systems the horizontal orientation of a linear array has, in some situations a large influence on the available channel capacity. In this paper, we investigate the effect of horizontal array orientation on channel capacity, eigenvalue distribution and antenna complex correlation coefficient in such systems. We present channel measurements in an office corridor environment for a 6/spl times/6 MIMO system and compare the capacity results to those of a physical and non-physical model based on the measurements. The results show that under LOS conditions the channel capacity can vary significantly depending on the receiver array orientation in the horizontal plane

UWB channel measurements in an industrial environment

In this paper, we present the (to our knowledge) first measurement results for ultra-wideband channels in industrial environments, i.e., a factory hall. The measurements are done with virtual arrays, which allows analysis of the small-scale fading statistics, as well as a directional analysis. We find that there is dense multipath scattering due to the abundance of metallic scatterers in the considered environment. Multiple scatterer clusters can be identified both in the delay and the angular domain. Typical rms delay spreads lie between 30 ns for LOS scenarios and 40 ns for NLOS scenarios. For non-LOS scenarios at large distances, the maximum of the power delay profile is observed some 40 ns after the arrival of the first multipath components. We also draw conclusions about the behavior of typical UWB system designs in the measured channel

Statistical analysis of the UWB channel in an industrial environment

In this paper, we present a statistical model for the ultra-wideband (UWB) channel in an industrial environment. Based on a set of measurements in a factory hall, we find that the abundance of metallic scatterers causes dense multipath scattering. This can be seen to produce mostly a Rayleigh distributed small-scale fading signal, with only a few paths exhibiting Nakagami distributions. For the power delay profile, we suggest a generalization of the Saleh-Valenzuela model where clusters with different excess delays have different ray power decay constants; the decay constants follow a linear dependence on the delay. This model provides an excellent fit to the measured data. We also note that for non-line-of-sight scenarios at larger distances, several hundred multipath components need to be collected to capture 50% of the available energ

Modeling the ultra-wideband outdoor channel - measurements and parameter extraction method

This paper presents results from one of the few existing outdoor measurement campaigns for UWB. We specifically focus on scenarios applicable for "infostations," where large amounts of data can be downloaded to a user within a limited amount of time. We describe the measurement setup, and present a novel high-resolution algorithm that allows the extraction of the scatterer's positions. Measurement data is extracted using eight meter uniform linear virtual array where incoming front waves are spherical, and thus allowing for high-precision location of the scatterers. Insight is given on how these components can be tracked in the impulse response for a spatially varying terminal. We then cluster the detected components, and investigate how the angular power variations of a given scatterer are correlated with the power variations of the other scatterers belonging to the same cluster. This results in the definition of the clusters' angular radiation pattern. Further sample measurements show how obstacles obstruct the line-of-sight component; a phenomenon that we describe mathematically by "shadowing regions," and compare these measurements with the theoretical results predicted by diffraction theory

Scatterer detection by successive cancellation for UWB - method and experimental verification

We present a new high delay resolution method to detect Ultra-Wideband (UWB) scatterers when using frequency domain measurements. Our approach makes use of the impulse response envelope amplitudes and delays measured over a distance that is larger than the region of stationarity, and detects the 2-D coordinates of the channel scatterers, assuming that only single-scattering (single-interaction) processes occur. The identification methodology is based on multiple applications of interference cancellation: at every step, we detect the strongest scatterer from an array of measurements, save its information, cancel it from the channel and search for the next strongest scatterer. To precisely define the strength of each scatterer, we present a method to define its birth and death locations along the measurement array. Finally, we verify the method by applying it to measurement results in an outdoor environment; the scatterer locations identified from the measurements show excellent agreement with the physically present objects like walls and columns

Statistical evaluation of outdoor-to-indoor office MIMO measurements at 5.2 GHz

In this paper, we present a statistical evaluation of an outdoor-to-indoor multiple-input multiple-output (MIMO) measurement campaign performed at 5.2 GHz. 159 measurement locations in an office building are analyzed. Our analysis pays special attention to two key assumptions that are widely used in stochastic channel models. An assumption that is used in practically every channel model is that the channel can be represented as a sum of a line-of-sight (LOS) component plus a (possibly correlated) zero-mean complex Gaussian distribution. Our investigation shows that this model does NOT adequately represent our measurement data. Our analysis also highlights the difference between the LOS power factor and the Rician K-factor. We show that the direction-of-arrival (DOA) spectrum depends noticeably on the direction-of-departure (DOD). Therefore, the popular Kronecker model is not applicable, and the more general Weichselberger model should be use

Outdoor-to-indoor office MIMO measurements and analysis at 5.2 GHz

The outdoor-to-indoor wireless propagation channel is of interest for cellular and wireless local area network applications. This paper presents the measurement results and analysis based on our multiple-input-multiple-output (MIMO) measurement campaign, which is one of the first to characterize the outdoor-to-indoor channel. The measurements were performed at 5.2 GHz; the receiver was placed indoors at 53 different locations in an office building, and the transmitter was placed at three ”base stations ” positions on a nearby rooftop. We report on the root-mean-square (RMS) angular spread, building penetration, and other statistical parameters that characterize the channel. Our analysis is focused on three MIMO channel assumptions often used in stochastic models. 1) It is commonly assumed that the channel matrix can be represented as a sum of a line-of-sight (LOS) contribution and a zero-mean complex Gaussian distribution. Our investigation shows that this model does not adequately represent our measurement data. 2) It is often assumed that the Rician K-factor is equal to the power ratio of the LOS component and the other multipath components (MPCs). We show that this is not the case, and we highlight the difference between the Rician K-factor often associated with LOS channels and a similar power ratio for th

Outdoor to indoor office MIMO measurements at 5.2 GHz

This paper presents the results of one of the first measurement campaigns for the double-directional characterization of outdoor to indoor wireless propagation channels. Such channels play a vital role for cellular systems with multiple antenna elements at transmitter and receiver, i.e. multiple-input multiple-output (MIMO) systems. Measurements were performed at 5.2 GHz between 53 different receiver locations in an office building, and three "base station" positions on a nearby rooftop. In the paper we present results for angular-delay profiles, RMS angular spread, and other statistical parameters characterizing delay and angular dispersion

On the performance of iterative receivers for interfering MIMO-OFDM systems in measured channels

This paper investigates the gains harvested through base station cooperation in the up-link for a multi-user (MU) Multiple-Input Multiple-Output Orthogonal Frequency Division Multiplexing (MIMO-OFDM) system, operating in a real indoor environment. The base stations perform joint detection using an iterative receiver that carries out multi-user detection and channel estimation via soft information from the single-user decoders. Performance evaluation is carried out using real channels from an indoor dynamic dual MIMO link measurement campaign. The measured scenario represent a real life situation where two users communicate with two base stations, each with two antennas, in an environment resembling a shopping mall or an airport terminal. System performance is evaluated in terms of both Bit-Error Rate (BER) vs. Signal-to-Interference Ratio (SIR) and Cumulative Distribution Functions (CDF) for the instantaneous BER. Also, the impact of using soft information in the channel estimation is analyzed