Experiment and Simulation Results of Adaptive Antenna Array System at Base and Mobile Stations in Mobile Environment

Kenta OKINO  Chiharu YAMAZAKI  Masanori KATO  Fangwei TONG  Tohru SUNAGA  Shigeru KIMURA  

IEICE TRANSACTIONS on Communications   Vol.E90-B    No.9    pp.2330-2337
Publication Date: 2007/09/01
Online ISSN: 1745-1345
DOI: 10.1093/ietcom/e90-b.9.2330
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Section on 2006 International Symposium on Antennas and Propagation)
Category: Smart Antennas
AAA,  SDMA,  TDD,  mobility,  i-Burst,  

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In a time division duplex (TDD) based adaptive antenna array (AAA) and space division multiple access (SDMA) systems, array weights determined from the up-link signals can be applied to the down-link signal transmission because of the channel reciprocity. However, under time-varying fading conditions, for example that created by a rapidly moving mobile station (MS), the channel change between the array weight determination time in the up-link and the down-link signal transmission degrades the accuracy of the array weight. Thus, the spectral efficiency of the system degrades in the down-link. In this paper, we introduce a prototype of an MS with a 2-element antenna array and present the down-link mobility performance results of computer simulations and field experiments in a field trial system of i-Burst, which is a TDD based wireless broadband system employing the AAA/SDMA techniques at the base station. Both results show that adaptive antenna processing at an MS is effective in improving the down-link mobility performance of TDD-AAA/SDMA systems.