Satoshi Kurosaki

A novel application of Massive MIMO: Massive Antenna Systems for Wireless Entrance (MAS-WE)

This paper proposes a practical application of Massive MIMO technology, Massive Antenna Systems for Wireless Entrance (MAS-WE), and its related inter-user interference (IUI) cancellation and scheduling techniques. MAS-WE, on which the entrance base station (EBS) employs a large number of antennas, can effectively provide high capacity wireless entrance links to a large number of Wi-Fi access points (APs) distributed in wide coverage area. The proposed techniques have been ultimately simplified to be less impact for their practical implementation in order to spatially multiplex more than 16 signal streams with around 100 antenna elements at EBS side. SIR performance was evaluated by system level simulation considering imperfect channel state information (CSI) and the results showed that the proposed MAS-WE with simplified techniques can achieve high spectral efficiency with high level space division multiplexing.

Experimental investigation of space division multiplexing on Massive Antenna Systems

This paper experimentally verifies the potential of higher order space division multiplexing for multiuser massive MIMO in line-of-sight (LOS) channels. We previously proposed an inter-user interference (IUI) cancellation scheme and simplified user scheduling method on Massive Antenna Systems for Wireless Entrance (MAS-WE). In order to verify the effectiveness of the proposed techniques, channel state information (CSI) for a 1×32 SIMO channel is measured in a real propagation environment with simplified test equipment. System level simulations using the measured CSI confirm that enlarging the angular gap between users reduces spatial correlation, and that the IUI cancellation proposal is effective under this condition. The degradation in SIR compared to ideal LOS channel model case is insignificant.

First Eigenmode Transmission by High Efficient CSI Estimation for Multiuser Massive MIMO Using Millimeter Wave Bands.

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.

Correlation-based user scheduling and multi-planar parallelogram array for Massive antenna systems

This paper proposes a simplified user scheduling method suitable for our proposed antenna arrangement and an antenna configuration with multi-planar antennas, for Massive MIMO. Massive MIMO has two key problems: the heavy overhead of feeding back the channel state information (CSI) for the very large number of transmission/reception antenna element pairs and the huge computation complexity imposed by the very large scale matrices. We previously proposed a parallelogram planar array (PPA) arrangement for Massive MIMO to realize channel spatial correlation reduction in LOS environments. Assuming that the proposed array is to cover omnidirectional areas, this paper proposes a user scheduling method that can easily enhance outage capacity performance in a simple manner and an antenna configuration that offers more efficient user accommodation. Simulations show that the proposed method can quadruple the system capacity over the uniform circular array antenna system.