Conference Paper

An Algorithm for Estimation and Tracking of Distributed Diffuse Scattering in Mobile Radio Channels

Signal Process. Lab., Helsinki Univ. of Technol., Espoo
DOI: 10.1109/SPAWC.2006.346497 Conference: Signal Processing Advances in Wireless Communications, 2006. SPAWC '06. IEEE 7th Workshop on
Source: IEEE Xplore

ABSTRACT Future wireless communication systems will exploit the rich spatial and temporal dispersion of the radio propagation environment. This requires new advanced channel models, which need to be verified by real-world channel sounding measurements. In this context the reliable estimation and tracking of the model parameters from measurement data is of particular interest. In this paper, we build a state-space model, and track the parameters of the distributed diffuse scattering component of the mobile radio channel using the extended Kalman Filter. The extended Kalman Filter is applied to capture the dynamics of the channel parameters in time and to reduce the computational complexity of the estimator compared to existing estimators. The proposed estimator can be combined with existing techniques for the estimation of specular/concentrated propagation paths, which are based on the maximum likelihood approach (SAGE/RIMAX) or the Kalman Filter. The performance of the algorithm is demonstrated using both simulated and measured data

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    • "Equation (14) can be modified to account for the limited bandwidth of the system and the discrete sampling of the measurement equipment [13] [14]. In that case, the parameters for the sampled bandwidth-limited exponential decaying power profile can be estimated with a non-linear least square parameter estimator (see in Figure 7): ξ d = arg min ξd M −1 m=0 ψ (k) meas,XY (m∆τ ) − ψ (k) d,XY (m∆τ, ξ d ) 2 (15) Fig. 6. "
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    ABSTRACT: Multiple-input-multiple-output (MIMO) technologies allow high data rates to be obtained, but they suffer from interantenna correlation caused by the limits in interantenna spacing. Polarized MIMO systems resolve this problem by using colocated perpendicularly polarized antennas that have low interantenna correlation. In this paper, a polarized single-directional channel model for 2× N MIMO systems at 3.6 GHz in an indoor environment is presented. The wireless channel is modeled as a sum of clusters, where each cluster has specular and diffuse components. The polarization of the specular component of the clusters is included by considering a per-path polarization. The diffuse component of the clusters is modeled with a Fisher-Bingham (FB5) spectrum in the azimuth-coelevation domain and with an exponential power delay profile. Polarization is analyzed by introducing the cross-polar discrimination of the exponential power delay profile parameters. All of the parameters in the model are extracted from an experimental measurement campaign performed in an indoor environment at 3.6 GHz. Individual paths are extracted from the measurements with the space-alternating generalized expectation-maximization (SAGE) algorithm. These paths are grouped in clusters within the azimuth of arrival-elevation of arrival-delay domains at the receiver side using automatic clustering algorithms. The specular component properties of the clusters are then determined. Finally, the diffuse components of the clusters are investigated and parameterized by applying a beamforming algorithm on the diffuse part of the impulse response.
    IEEE Transactions on Vehicular Technology 11/2010; 59(8-59):3685 - 3693. DOI:10.1109/TVT.2010.2064795 · 1.98 Impact Factor
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    • "The residual power is usually referred to as the diffuse multipath component (DMC), and it supposed to be due to a lot of small propagation paths with equivalent power, that cannot be resolved by highresolution algorithms. In [8] [9], the DMC was modeled with an exponential power profile, whose parameters were estimated with a non-linear MMSE estimator. "
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    ABSTRACT: Stochastic geometry-based models have been widely adopted for modeling wireless channels. These models are parametrized based on extensive measurement campaigns, where individual propagation paths are extracted with algorithms like SAGE or RiMax. It has been observed that when extracting individual propagation paths, part of the power is not captured. This residual power is referred to as the diffuse multipath component (DMC). In this paper, the spatio-temporal characteristics of the DMC are extracted from an extensive measurement campaign. It is observed that the angular power spectrum of the DMC is not angular-white, and that the angular properties of the DMC are significantly correlated with the angular properties of the specular part of the channel. A scheme is proposed to model the diffuse part of the channel by adding diffuse properties to each cluster corresponding to the specular part of the channel. The angular properties of the diffuse part of the clusters are modeled with Von-Mises distributions, whereas the delay properties of the clusters are modeled with an exponential decaying power profiles. Finally, the polarization properties of the diffuse part of the clusters are investigated.
    Antennas and Propagation (EuCAP), 2010 Proceedings of the Fourth European Conference on; 05/2010
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    • "In [3] recursive expectationmaximization (EM) and recursive space-alternating generalized EM (SAGE)-inspired algorithms have been proposed for tracking of the azimuths of arrival (AoAs) of paths. In [4] and [5], the extended Kalman filter (EKF) is derived for tracking of the delays, DoAs, DoDs and complex amplitudes of timevariant paths. These algorithms are applicable in the case where the linear approximation of the non-linear observation model is accurate. "
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    ABSTRACT: In this contribution a low-complexity particle filtering algorithm is proposed to track the parameters of time-variant propagation paths in multiple-input multiple-output (MIMO) radio channels. A state-space model is used to describe the path evolution in delay, azimuth of arrival, azimuth of departure, Doppler frequency and complex amplitude dimensions. The proposed particle filter (PF) has an additional resampling step specifically designed for wideband MIMO channel sounding, where the posterior probability density functions of the path states is usually highly concentrated in the multi-dimensional state space. Preliminary investigations using measurement data show that the proposed PF can track paths stably with a small number of particles, e.g. 5 per path, even in the case where the paths are undetected by the conventional SAGE algorithm.
    Proceedings of IEEE International Conference on Communications, ICC 2008, Beijing, China, 19-23 May 2008; 01/2008
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