Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành hóa học dành cho các bạn yêu hóa học tham khảo đề tài: Research Article Space-Time-Frequency Characterization of 3D Nonisotropic MIMO Multicarrier Propagation Channels Employing Directional Antennas | Hindawi Publishing Corporation EURASIP Journal on Wireless Communications and Networking Volume 2008 Article ID 893705 14 pages doi 2008 893705 Research Article Space-Time-Frequency Characterization of 3D Nonisotropic MIMO Multicarrier Propagation Channels Employing Directional Antennas Hamidreza Saligheh Rad1 and Saeed Gazor2 1 School of Engineering and Applied Sciences Harvard University Cambridge MA 02138 USA 2 Department of Electrical and Computer Engineering Queen s University Kingston oN Canada K7L 3N6 Correspondence should be addressed to Hamidreza Saligheh Rad hamid@ Received 21 November 2007 Revised 9 April 2008 Accepted 25 July 2008 Recommended by David Laurenson Channel models for outdoor wireless systems usually assume two-dimensional 2D random scattering media. In the practical outdoor wireless channels the impact of the wave propagation in the third-dimension is definitely important especially when the communication system efficiently exploits potentials of multiple antennas. In this paper we propose a new model for multipleinput multiple-output MIMO multicarrier propagation channels in a three-dimensional 3D environment. Specifically the proposed model describes the cross-correlation function CCF between two subchannels of an outdoor MIMO channel employing directional antennas and in the presence of nonisotropic wave propagation in 3D space. The derived CCF consists of some correlation terms. Each correlation term is in the form of a linear series expansion of averaged Bessel functions of the first kind with different orders. In practice each correlation term has a limited number of Bessel components. Our numerical evaluations show the impact of different parameters of the propagation environment as well as the employed antennas on the resulting CCF. Using the proposed CCF we also establish simple formulas to approximate the coherence time the coherence bandwidth and the spatial coherence of such channels. The numerical curve
