Alignment Tolerance in Multiple-Stream Transmission Using Orthogonal Directivities under Line-of-Sight Environments

Maki ARAI  Tomohiro SEKI  Ken HIRAGA  Kazumitsu SAKAMOTO  Tadao NAKAGAWA  

IEICE TRANSACTIONS on Communications   Vol.E99-B    No.6    pp.1362-1370
Publication Date: 2016/06/01
Online ISSN: 1745-1345
DOI: 10.1587/transcom.2015EBP3341
Type of Manuscript: PAPER
Category: Antennas and Propagation
MIMO,  directivity,  spatial division,  channel capacity,  

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A method for increasing alignment tolerance in simple multiple-stream transmission is described. Its use of π-shifted antenna directivity phase enables it to cancel interference even when antenna placement deviations occur. The interference cancellation by using π-shifted directivities provides higher alignment tolerance than that with conventional fixed weight methods. It also provides smaller channel gain variation than can be obtained using fixed weights even when antenna displacement occurs. An objective function is described that is determined by the alignment tolerance. The function is defined to maximize the alignment tolerance. The method's validity is confirmed by an experimental analysis of two-stream transmission in which the alignment tolerance of the proposed method is compared to that of conventional fixed weight methods.