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Open AccessArticle

Collision Detection Method Using Self Interference Cancelation for Random Access Multiuser MIMO

1
Faculty of Engineering, Niigata University, Ikarashi 2-nocho 8050, Nishi-ku, Niigata 950-2181, Japan
2
Faculty of Engineering, Nippon Institute of Technology, 4-1 Gakuendai, Miyashiro-machi, Minamisaitama-gun, Saitama 345-8501, Japan
*
Author to whom correspondence should be addressed.
Electronics 2018, 7(1), 1; https://doi.org/10.3390/electronics7010001
Received: 30 November 2017 / Revised: 15 December 2017 / Accepted: 20 December 2017 / Published: 22 December 2017
(This article belongs to the Special Issue Smart Antennas and MIMO Communications)
This paper proposes an interference detection method for multiuser-multiple input multiple output (MU-MIMO) transmission, which utilizes periodical preamble signals in the frequency domain and the concept of full-duplex transmission when assuming idle antennas at the access point (AP) in MU-MIMO. In the propose method, collision detection (CD) of MU-MIMO is achieved by utilizing asynchronous MU-MIMO called random access MU-MIMO. In random access MU-MIMO, several antennas that are not used for the transmission exist, due to asynchronous MU-MIMO. Hence, idle antennas at the AP can receive preamble signals while the transmit antennas at the AP transmit the preamble signals: this procedure is regarded as full-duplex transmission, which cancels the self-interference between AP antennas. The interference can be detected by subtracting the short preamble signal, which is multiplied by the estimated channel response using the received signal after the FFT processing. Moreover, we utilize dual polarization to reduce the mutual coupling between transmit and receive antennas at the AP. Through a computer simulation, it is shown that the proposed method can successfully detect collision from other user terminals (UTs) with OFDM signals when the interfering power from the interfering user terminal (IT) is greater than the noise power. In addition, the interfering power from IT at the AP and the desired user terminal (DT) is measured in an actual indoor environment, and the possibility of using the proposed method at the AP is discussed by using the measurement results. View Full-Text
Keywords: random access multiuser MIMO; collision detection; short preamble signal; short preamble signal random access multiuser MIMO; collision detection; short preamble signal; short preamble signal
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Ando, K.; Nishimori, K.; Kataoka, R.; Hiraguri, T.; Morino, Y.; Mitsui, T. Collision Detection Method Using Self Interference Cancelation for Random Access Multiuser MIMO. Electronics 2018, 7, 1.

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