Spatial Division Transmission without Signal Processing for MIMO Detection Utilizing Two-Ray Fading

Ken HIRAGA  Kazumitsu SAKAMOTO  Maki ARAI  Tomohiro SEKI  Tadao NAKAGAWA  Kazuhiro UEHARA  

IEICE TRANSACTIONS on Communications   Vol.E97-B    No.11    pp.2491-2501
Publication Date: 2014/11/01
Online ISSN: 1745-1345
DOI: 10.1587/transcom.E97.B.2491
Type of Manuscript: PAPER
Category: Wireless Communication Technologies
spatial division transmission,  array a ntennas,  parallel transmission,  line-of-sight (LOS),  two-ray ground reflection model,  reflection coefficient,  polarization,  

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This paper presents a spatial division (SD) transmission method based on two-ray fading that dispenses with the high signal processing cost of multiple-input and multiple-output (MIMO) detection and antennas with narrow beamwidth. We show the optimum array geometries as functions of the transmission distance for providing a concrete array design method. Moreover, we clarify achievable channel capacity considering reflection coefficients that depend on the polarization, incident angle, and dielectric constant. When the ground surface is conductive, for two- and three-element arrays, channel capacity is doubled and tripled, respectively, over that of free space propagation. We also clarify the application limit of this method for a dielectric ground by analyzing the channel capacity's dependency on the dielectric constant. With this method, increased channel capacity by SD transmission can be obtained merely by placing antennas of wireless transceiver sets that have only SISO (single-input and single-output) capability in a two-ray propagation environment. By using formulations presented in this paper for the first time and adding discussions on the adoption of polarization multiplexing, we clarify antenna geometries of SD transmission systems using polarization multiplexing for up to six streams.