MIMO Systems
We investigate advanced multiple-input multiple-output (MIMO) systems for millimeter-wave communications toward beyond-5G and 6G networks. Our research focuses on improving coverage, capacity, and reliability by exploiting relay-assisted architectures and advanced transmission techniques under severe propagation and blockage conditions.
Multi-user mmWave Massive Relay MIMO with User Scheduling
We propose a multi-user mmWave massive relay MIMO system that explores the potential of relay stations toward 6G. The system consists of one base station with mmWave antennas, a massive number of amplify-and-forward relay stations, and multiple users.
To improve resource utilization, a user scheduling method is introduced to group users with less mutual interference. By exploiting spatial multiplexing among multiple antennas, the proposed system enhances both coverage and system capacity.
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Fig.4 System model of the multi-user mmWave massive relay MIMO system.
Fig.5 Numerical results showing coverage and capacity enhancement achieved by massive relay MIMO and user scheduling.
Fountain Code-Based Multi-Beam Transmission for Reliable mmWave Communications
To improve reliability in blockage-prone mmWave environments, we propose a fountain code-based multi-beam transmission scheme. The system combines multi-beam communication with cross-layer coding, including packet-level loss correction and bit-level error correction.
By exploiting both line-of-sight and non-line-of-sight paths, the proposed scheme enables robust data recovery even when some beams are blocked, thereby eliminating the need for retransmissions and improving reliability.
Fig.6 Transceiver architecture of the fountain code-based multi-beam mmWave transmission system.
SAKAGUCHI & TRAN LAB
