Reconfigurable Intelligent Surface

Reconfigurable intelligent surface (RIS) is a large 2D surface of metamaterial, which is composed of passive scattering elements. Each element can be controlled to change the electromagnetic properties such as phase shift of the reflection of incident signals to make better communication channels. As millimeter wave (mmWave) communication systems are becoming the standard in 5G and future wireless communications, the role of RIS is expected to grow even more as mmWave communications suffer from high propagation path loss and blockage.

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RIS is a promising technology for future wireless communication systems due to its energy efficiency and various applications. In contrast to the conventional systems, however, RIS-assisted systems pose various implementational issues as the transmitter-RIS-receiver cascade channel complicates the system design. Research about the RIS-assisted wireless communication system includes joint active (at base stations) and passive (at RIS) beamforming, channel estimation of reflected signals, deploying multiple RISs, etc.

Recent publications

• H. Lee and J. Choi*, "Multi-Cell Multi-band Systems with RIS: Balancing Reflection Design," submitted to IEEE Wireless Communications Letters (WCL), Jan. 2024.

• H. Choi, A. L. Swindlehurst, and J. Choi*, "WMMSE-Based Rate Maximization for RIS-Assisted MU-MIMO Systems," accepted to IEEE Transactions on Communications (TCOM), Mar. 2024. [arXiv]

• H. Lee, S. Moon, Y. Lee, J. Oh, J. Chung, and J. Choi*, "Multi-Group Multicasting Systems Using Multiple RISs," accepted to IEEE Transactions on Wireless Communications (TWC), Jan. 2024.

• G. Lee, H. Lee, D. Kim, J. Chung, A. L. Swindlehurst, and J. Choi*, "Joint Downlink and Uplink Optimization for RIS-Aided FDD MIMO Communication Systems," accepted to IEEE Transactions on Wireless Communications (TWC), Jan. 2024.