10 papers · 1 filter
Online Movable Antenna Repositioning Under Movement Delay and a Long-Term Energy Budget
Yunseob Tae, Jeongjae Lee, Songnam Hong
Movable antenna (MA) systems improve the channel by repositioning antennas, but each repositioning interrupts data transmission for a time set by the largest displacement and consu…
Scalable Rate-Splitting Precoding via Recurrent Structure-Preserving Graph Neural Networks
Wonseok Choi, Jeongjae Lee, Songnam Hong
Graph neural network (GNN)-based precoding has demonstrated strong potential for scalable multi-user beamforming in multi-user multiple-input single-output (MU-MISO) systems under…
Channel Estimation for Reconfigurable Intelligent Surface Assisted Upper Mid-Band MIMO Systems
Jeongjae Lee, Chanwon Kim, Songnam Hong
The upper mid-band (UMB) spectrum is a key enabler for 6G systems, yet reconfigurable intelligent surface (RIS)-assisted UMB communications face severe channel estimation challenge…
CSIT-Free Beamforming for Multi-Group Multicast in Overloaded mmWave Systems
Wonseok Choi, Jeongjae Lee, Songnam Hong
We study downlink multi-group multicast (MGM) transmission in overloaded millimeter-wave (mmWave) systems, where the number of users exceeds the number of transmit antennas. We fir…
CSIT-Free Downlink Transmission for mmWave MU-MISO Systems in High-Mobility Scenario
Jeongjae Lee, Wonseok Choi, Songnam Hong
This paper investigates the downlink (DL) transmission in millimeter-wave (mmWave) multi-user multiple-input single-output (MU-MISO) systems especially focusing on a high speed mob…
Blind Massive MIMO for Dense IoT Networks
Jeongjae Lee, Songnam Hong
In this paper, we investigate the downlink communication challenges in heavy-load Internet-of-Things (IoT) networks supported by frequency-division-duplexing (FDD) millimeter-wave…
Piecewise Beam Training and Channel Estimation for RIS-Aided Near-Field Communications
Jeongjae Lee, Songnam Hong
In this paper, we investigate the channel estimation challenge in reconfigurable intelligent surface (RIS)-aided near-field communication systems. Current channel estimation techni…
Near-Field LoS/NLoS Channel Estimation for RIS-Aided MU-MIMO Systems: Piece-Wise Low-Rank Approximation Approach
Jeongjae Lee, Songnam Hong
We study the channel estimation problem for a reconfigurable intelligent surface (RIS)-assisted millimeter-wave (mmWave) multi-user multiple-input multiple-output (MU-MIMO) system.…
Asymptotically Near-Optimal Hybrid Beamforming for mmWave IRS-Aided MIMO Systems
Jeongjae Lee, Songnam Hong
Hybrid beamforming is an emerging technology for massive multiple-input multiple-output (MIMO) systems due to the advantages of lower complexity, cost, and power consumption. Recen…
Near-Field Channel Estimation for XL-RIS Assisted Multi-User XL-MIMO Systems: Hybrid Beamforming Architectures
Jeongjae Lee, Hyeongjin Chung, Yunseong Cho +2
Channel estimation is one of the key challenges for the deployment of extremely large-scale reconfigurable intelligent surface (XL-RIS) assisted multiple-input multiple-output (MIM…