Orthogonalized Directional MIMO Transmission Using Higher Order Mode Microstrip Antennas

Maki ARAI  Tomohiro SEKI  Ken HIRAGA  Kazumitsu SAKAMOTO  Hideki TOSHINAGA  Tadao NAKAGAWA  

IEICE TRANSACTIONS on Communications   Vol.E99-B   No.1   pp.48-57
Publication Date: 2016/01/01
Online ISSN: 1745-1345
DOI: 10.1587/transcom.2015ISP0013
Type of Manuscript: Special Section PAPER (Special Section on Recent Progress in Antennas, Propagation and Wireless Systems Related to Topics in ISAP2014)
Category: Antennas and Propagation
MIMO,  directivity,  higher order mode,  capacity,  

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Multiple-input multiple-output (MIMO) technology is a useful means of achieving the higher data rates needed in the latest wireless devices. However, weighting calculations for MIMO transmission become complicated when there are a large number of antennas. Thus, developing a simpler way to transmit and receive multiple streams is an idea worth considering. With this in mind, we propose a spatial division method using orthogonal directivities formed by using higher order modes of rectangular microstrip antennas. Each of them is formed by one antenna element so that channels are orthogonalized only by antennas. We verify antenna radiation characteristics by using higher order mode microstrip antennas and confirm that orthogonal directivities are obtained with them. Measurement of two stream transmission reveals that the method achieves almost the same channel capacity as that of an eigenmode-beamforming method because of the high multiplexing gain it achieves.