title: First Eigenmode Transmission by High Efficient CSI Estimation for Multiuser Massive MIMO Using Millimeter Wave Bands.
abstract: Drastic improvements in transmission rate and system capacity are required towards 5th generation mobile communications (5G). One promising approach, utilizing the millimeter wave band for its rich spectrum resources, suffers area coverage shortfalls due to its large propagation loss. Fortunately, massive multiple-input multiple-output (MIMO) can offset this shortfall as well as offer high order spatial multiplexing gain. Multiuser MIMO is also effective in further enhancing system capacity by multiplexing spatially de-correlated users. However, the transmission performance of multiuser MIMO is strongly degraded by channel time variation, which causes inter-user interference since null steering must be performed at the transmitter. This paper first addresses the effectiveness of multiuser massive MIMO transmission that exploits the first eigenmode for each user. In Line-of-Sight (LoS) dominant channel environments, the first eigenmode is chiefly formed by the LoS component, which is highly correlated with user movement. Therefore, the first eigenmode provided by a large antenna array can improve the robustness against the channel time variation. In addition, we propose a simplified beamforming scheme based on high efficient channel state information (CSI) estimation that extracts the LoS component. We also show that this approximate beamforming can achieve throughput performance comparable to that of the rigorous first eigenmode transmission. Our proposed multiuser massive MIMO scheme can open the door for practical millimeter wave communication with enhanced system capacity.
authors.affiliation: NTT Access Network Service Systems Laboratories, Nippon Telegraph and Telephone Corporation, 1-1 Hikarino-oka, Yokosuka-shi, Kanagawa 239-0847, Japan. maruta.kazuki@lab.ntt.co.jp.
authors.forename: Kazuki
authors.initials: K
authors.lastname: Maruta
authors.affiliation: NTT Access Network Service Systems Laboratories, Nippon Telegraph and Telephone Corporation, 1-1 Hikarino-oka, Yokosuka-shi, Kanagawa 239-0847, Japan. iwakuni.tatsuhiko@lab.ntt.co.jp.
authors.forename: Tatsuhiko
authors.initials: T
authors.lastname: Iwakuni
authors.affiliation: NTT Access Network Service Systems Laboratories, Nippon Telegraph and Telephone Corporation, 1-1 Hikarino-oka, Yokosuka-shi, Kanagawa 239-0847, Japan. ohta.atsushi@lab.ntt.co.jp.
authors.forename: Atsushi
authors.initials: A
authors.lastname: Ohta
authors.affiliation: NTT Access Network Service Systems Laboratories, Nippon Telegraph and Telephone Corporation, 1-1 Hikarino-oka, Yokosuka-shi, Kanagawa 239-0847, Japan. arai.takuto@lab.ntt.co.jp.
authors.forename: Takuto
authors.initials: T
authors.lastname: Arai
authors.affiliation: NTT Access Network Service Systems Laboratories, Nippon Telegraph and Telephone Corporation, 1-1 Hikarino-oka, Yokosuka-shi, Kanagawa 239-0847, Japan. shirato.yushi@lab.ntt.co.jp.
authors.forename: Yushi
authors.initials: Y
authors.lastname: Shirato
authors.affiliation: NTT Access Network Service Systems Laboratories, Nippon Telegraph and Telephone Corporation, 1-1 Hikarino-oka, Yokosuka-shi, Kanagawa 239-0847, Japan. kurosaki.satoshi@lab.ntt.co.jp.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Kurosaki
authors.affiliation: NTT Access Network Service Systems Laboratories, Nippon Telegraph and Telephone Corporation, 1-1 Hikarino-oka, Yokosuka-shi, Kanagawa 239-0847, Japan. iizuka.masataka@lab.ntt.co.jp.
authors.forename: Masataka
authors.initials: M
authors.lastname: Iizuka
keywords: channel estimation; channel time variation; first eigenmode; massive MIMO; millimeter wave; multiuser MIMO