Characterization of MIMO channel capacity in urban microcellular environment

OF DOCTORAL DISSERTATION HELSINKI UNIVERSITY OF TECHNOLOGY P.O. BOX 1000, FI-02015 TKK http://www.tkk. fi Author Abdulla A. Abouda Name of the dissertation Characterization of MIMO Channel Capacity in Urban Microcellular Environment Manuscript submitted 19 of December 2006 Manuscript revised 7 of March 2007 Date of the defence 24 of April 2007 Monograph Article dissertation (summary + original articles) Department Electrical and Communications Engineering Laboratory Communications Field of research Communications Engineering Opponent(s) Professor Markku Juntti Supervisor Professor Sven-Gustav Häggman Instructor Doctor Hassan M. El-Sallabi Abstract The research work in this thesis consists of several investigations of multiple-input multiple-output (MIMO) wireless channel capacity in urban microcellular environment. The investigations can be categorized into three groups, 1)modelbased investigations, 2)-measurement-based investigations, and 3)theoretical investigations. Utilizing three dimensional (3D) channel models the influence of environment physical parameters and antenna array configuration on MIMO channel capacity are investigated. In terms of environment influence, parameters such as street width, wall relative permittivity and multipath richness are considered. In terms of antenna array configuration, the effect of array geometry and uniform linear array (ULA) azimuthal orientation are considered. It is shown that the effect of these parameters on MIMO channel capacity is significant. Based on field measurements, the effect of spatial smoothing on the accuracy of a widely used stochastic narrowband MIMO radio channel model, namely, the Kronecker model, and the impact of temporal signal to noise ratio (SNR) variations on MIMO channel capacity are investigated. Results from non-line of sight (NLOS) and line of sight (LOS) propagation scenarios are analyzed. While under NLOS conditions spatial smoothing significantly enhances the applicability of the Kronecker structure, under LOS conditions spatial smoothing does not help to improve the accuracy of the Kronecker model. It is also noticed that while the temporal SNR variation has significant impact on the capacity of MIMO wireless channel in a NLOS propagation scenario, the influence is smaller under LOS conditions. Theoretical investigation of antenna mutual coupling (MC) on the capacity of MIMO wireless channels is presented with particular emphasis on the case of high SNR scenario. It is shown that the effect of MC on MIMO channel capacity can be positive or negative depending on the spatial correlation properties of the propagation environment and the characteristics of the two ends MC matrices. The impact of phase noise (PN) on the accuracy of measured MIMO channel capacity is studied by considering its effect on both the spatial multiplexing gain and the power gain. It is shown that in the case of a low rank physical channel matrix the PN impact is more pronounced on the spatial multiplexing gain than on the power gain. Based on that an eigenvalue filtering (EVF) technique is proposed to improve the accuracy of the measured MIMO channel capacity.