Adaptive Array for Reducing High-Power CCI on Asynchronous TDD Systems

Kentaro NISHIMORI  Keizo CHO  Yasushi TAKATORI  Toshikazu HORI  

IEICE TRANSACTIONS on Communications   Vol.E84-B   No.7   pp.1727-1734
Publication Date: 2001/07/01
Online ISSN: 
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Issue on Adaptive Array Antenna Techniques for Advanced Wireless Communications)
Category: Adaptive Algorithms and Experiments
adaptive array,  asynchronous TDD systems,  power inversion,  MMSE,  guard time,  

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This paper proposes a novel adaptive array configuration that reduces high-power co-channel interference (CCI) by utilizing the difference in arrival times between CCI and the desired signal in asynchronous TDD systems. The proposed adaptive array extracts only the CCI and employs pre-null steering for only the CCI by utilizing the fact that only the CCI arrives during the guard time in asynchronous TDD systems. Since the proposed adaptive array enables us to apply the Minimum Mean Square Error (MMSE) algorithm through synchronization with the desired signal using the output signal obtained by pre-null steering, high quality transmission can be achieved even in the presence of high-power CCI. Moreover, based on measurements using a fading simulator and field data, an adaptive array testbed exemplifying the proposed configuration is presented to show the reduction in the high-power CCI.