摘要:
Multiple inputs multiple outputs (MIMO) systems can be designed for two operational modes: to improve bit error rate (BER) or to increase capacity without consuming additional power or bandwidth. In this paper, MIMO space-timefrequency (STF) conjugate two-path transmission orthogonal frequency division multiplexing (OFDM) systems with precoders are presented to combat inter-carrier interference (ICI) and to adaptively switch between these two modes in mobile fading channels. First, the STF architecture is developed to form a 2x1 STF-OFDM system. Second, a conjugate cancellation (CC) two-path transmission scheme is integrated with the STF-OFDM system to form a new 2x1 STFCC-OFDM system. This system improves BER without expanding power or bandwidth in comparing with the CC scheme. Third, Walsh– Hadamard (WH) transform is employed as the precoder to form the 2x1 WHSTFCC-OFDM system. Finally, a 2x2 WHSTFCCOFDM architecture is designed. It can be used to improve BER or switch to two 2x1 WHSTFCC-OFDM systems to increase capacity as needed. Simulations indicate that the 2x1 WHSTFCC-OFDM system has the best BER, the STFCC-OFDM system, and the STF-OFDM system follow in order. Similarly, the BER of the 2x2 WHSTFCC-OFDM system outperforms the 2x1 WHSTFCC-OFDM, and the 2x2 STFCC-OFDM system follow in order. All these STFCC- and WHSTFCC-OFDM schemes are simple and backward compatible with the existing OFDM system. They may serve as baseband building blocks in OFDM transceivers and can be adaptively switched between 2x1 and 2x2 architectures as required for the fourth generation (4G) and the future planned 5G MIMO systems. This adaptive MIMO system can also be applied to the regular or bad weather environment in the disaster conditions for increasing capacity or enhancing the reliability of the communication system.
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主讲人介绍：葉先覺教授：成功大學工程科學學士, 台灣 , 中国加州大學爾灣分校（University of California, Irvine）機械工程碩士, 電機工程博士。現任: 加州州大長堤分校（California State University, Long Beach）電機系系主任, 教授。葉先覺教授在1988年任法國電信巴黎大學 (Telecom Paris University) 訪問教授；在2004年任加州大学洛杉矶分校访问教授；从2004-2011年在加州理工學院（California Technology Institute）任訪問教授。
葉先覺教授的研究方向主要包括數字信號處理, 通信系統, 自適應和自動控制, 可再生能源和智能電網。
葉先覺教授在IEEE 期刊 (數字信號處理, 通信, 無線通信, 電路與系統)上发表学术论文100余篇。在从2009 - 現在是 IEEE Systems Council Chapter的主席；从2010-现在是IEEE 綠色能源與智能系統會議；IEEE 期刊電路與系統 II, 副主編, 2016 –現在；IEEE 系统期刊, 副主編, 2018 –現在
榮譽: 加州州大長堤分校全領域傑出教授（教學，研究，服務）成就獎 (2015) 加州州大長堤分校傑出教授學術研究創新獎 (2009) 諾斯羅普·格魯曼公司優秀教學獎 (2007) 波音 Welliver 教授獎 (2006) The Aerospace Corporation 發明獎 (2002) The Aerospace Corporation 表現出色獎 (2002), NASA 暑期教授研究獎 (1992, 2003) NASA 新技術獎 (1987) NASA 技術創新發展獎 (總共 4 次, 1994 - 1996)
