https://orcid.org/0000-0001-6915-6693
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Abstract
This paper presents a non-codebook based Multiple User Multiple Input Multiple Output (MU-MIMO) test-bed system for Time Division Duplex (TDD) Long Term Evolution-Advanced (LTE-A). The system was implemented for verifying the performance of a dynamic precoding procedure that selects the most appropriate precoder among a given set of precoding techniques. Using two parameters, the propagation path gain and the condition number of the channel matrix, the proposed MU-MIMO system can adaptively switch the precoding software to guarantee that the upper bound Bit Error Rate (BER) is maintained with a minimum computational burden. This paper also presents a novel procedure for accurately and simply calibrating the multiple Radio Frequency (RF) paths of the multiple antennas and RF transceivers of the MU-MIMO system. From various experimental measurements obtained from the implemented test-bed system, the upper bound BER, which was arbitrarily set to 10−3 in this paper, can be maintained with the simplest precoder, Zero Forcing (ZF), unless the propagation path gain becomes less than 0.25. It was also found in the experimental tests that, as the distance between 2 handsets becomes shorter than 1 meter, which causes the condition number of the channel matrix to be larger than 17, the precoder should be switched from Lattice Reduction (LR) to Tomlinson-Harashima Precoding (THP) when the minimum distance between base-station and each handset maintained is set to at least 6 meters.
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Notes on contributors
Sangwook Han
Sangwook Han received his BS and MS degrees from Hanyang University, Seoul, Korea, in 2011 and 2013, respectively. He is currently working towards his PhD degree in the Department of Electronics and Computer Engineering at Hanyang University in Seoul, Korea. His current research focuses on LTE-A, various MIMO technologies, and software defined radio systems. Email: [email protected]
Daejin Kim
Daejin Kim received his BS degree from Soongsil University in Seoul, Korea in 2015. He is currently working towards his PhD degree in the Department of Electronics and Computer Engineering at Hanyang University in Seoul, Korea. His current research focuses on LTE-A, various MIMO technologies, and software defined radio systems. Email: [email protected]
Heungseop Ahn
Heungseop Ahn received his BS degree from Hanyang University, Seoul, Korea, in 2013. He is currently working towards his PhD degree in Department of Electronics and Computer Engineering from Hanyang University, Seoul, Korea. His current research focuses on RAN architecture, virtualization, LTE-A, mmWave communications, cellular network planning, and various MIMO technologies. Email: [email protected]
Jaeho Lee
Jaeho Lee received his BS degree from Cheongju University in Cheongju, Korea in 2017. He is currently working towards his MS degree in the Department of Electronics and Computer Engineering at Hanyang University in Seoul, Korea. His current research focuses on LTE-A and software defined radio systems. Email: [email protected]
Yekaterina Kim
Yekaterina Kim received the BS degree from Almaty University of Power Engineering and Telecommunications in Almaty, Kazakhstan in 2010. She is currently working towards her MS degree in the Department of Electronics and Computer Engineering at Hanyang University in Seoul, Korea. Her\columnbreak current research focuses on LTE-A and filter bank multicarrier modulation. Email: [email protected]
Seungwon Choi
Seungwon Choi received the BS degree from Hanyang University in Seoul, Korea, and the MS degree from Seoul National University in Seoul, Korea, in 1980 and 1982, respectively, both in electronics engineering, the MS degree (computer engineering) in 1985, and the PhD degree (electrical engineering), in 1988, both from Syracuse University, Syracuse, NY. From 1988 to 1989 he was with the Department of Electrical and Computer Engineering at Syracuse University, Syracuse, NY, as an assistant professor. In 1989, he joined the Electronics and Telecommunications Research Institute in Daejeon, Korea. From 1990 to 1992 he was with the Communications Research Laboratory, Tokyo, Japan, as a Science and Technology agency fellow, developing adaptive antenna array systems and adaptive equalizing filters. He joined Hanyang University in Seoul, Korea, in 1992 as an assistant professor. He is currently a professor in the School of Electrical and Computer Engineering at Hanyang University. His research interests include digital communications and adaptive signal processing with a recent focus on the implementation of smart antenna systems for both mobile communication systems and wireless data systems.
Byungcho Choi
Byungcho Choi received the BS degree in electronics from Hanyang University, Seoul, Korea, in 1980, the MS and the PhD degrees in electrical engineering from Virginia Polytechnic Institute and State University, Blacksburg, in 1988, and 1992, respectively. From 1992 to 1993, he was a research scientist at the Bradley Department of Electrical Engineering, Virginia Polytechnic Institute and State University. From 1994 to 1995, he served as a Team Leader of the Power Electronics Systems Team, Samsung Electronics Company. In 1996, he joined the School of Electrical Engineering and Computer Science, Kyungpook National University, Taegu, Korea, where he is currently a professor. His research interest includes modeling and design optimization of highfrequency power converters for portable electronics, computer power systems, and distributed power systems. Email: [email protected]