An Adaptive Beamforming Method for Phased Array Antenna with MEMS Phase Shifters

Quoc Tuan TRAN
Shinsuke HARA
Ichirou IDA
Yasuyuki OISHI

IEICE TRANSACTIONS on Communications   Vol.E89-B    No.9    pp.2503-2513
Publication Date: 2006/09/01
Online ISSN: 1745-1345
DOI: 10.1093/ietcom/e89-b.9.2503
Print ISSN: 0916-8516
Type of Manuscript: PAPER
Category: Wireless Communication Technologies
MEMS,  phase shifter,  IEEE 802.11a,  mono-resolution,  multi-resolution,  processing delay,  

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Adaptive array antennas, which control their own patterns by means of feed-back or feed-forward control, are effective tools for gain enhancement and interference suppression. However, when applying them to mobile terminals, the problems of hardware complexity and power consumption need to be taken into consideration. One solution is the use of analog device-based adaptive array antennas, such as Reactively Steered Adaptive Array (RESAA) antennas and phased array antennas, which have the attractive characteristics of low cost and power consumption. In this paper, we propose an adaptive beamforming method based on a one-dimension search algorithm for phased array antennas with Micro Electro Mechanical Systems (MEMS) phase shifters, taking into consideration their slow operating speed due to mechanical structure of the devices. Furthermore, a smoothing processing is introduced to prevent the effect of noise and a multi-resolution alogrithm is proposed to help the system form beams more quickly and stably. Numerical results based on the IEEE 802.11a Wireless Local Area Network (WLAN) standard show that the proposed method has good interference suppression and gain enhancement capabilities in multipath fading channels.