  Liquid crystal (LC) technology offers a cost-effective, scalable,
energy-efficient, and continuous phase tunable realization of extremely large
reconfigurable intelligent surfaces (RISs). However, LC response time to
achieve a desired differential phase is significantly higher compared to
competing silicon-based technologies (RF switches, PIN diodes, etc). The slow
response time can be the performance bottleneck for applications where frequent
reconfiguration of the RIS (e.g., to serve different users) is needed. In this
paper, we develop an RIS phase-shift design that is aware of the transition
behavior and aims to minimize the time to switch among multiple RIS
configurations each serving a mobile user in a time-division multiple-access
(TDMA) protocol. Our simulation results confirm that the proposed algorithm
significantly reduces the time required for the users to achieve a threshold
signal quality. This leads to a considerable improvement in the achievable
throughput for applications, where the length of the TDMA time intervals is
comparable with the RIS reconfiguration time.
