Reconfigurable intelligent surfaces for wireless communications

Reconfigurable intelligent surfaces (RIS) allow significant throughput enhancement as all reflections have the same phase at the receiver. In this paper, we suggest to optimize packet length for wireless communications using RIS. Two techniques are suggested in order to maximize average or instantaneous throughput. Average throughput maximization requires only the average signal to noise ratio to determine the optimal packet length. The Gradient algorithm is used to maximize the average throughput. Instantaneous throughput maximization requires the instantaneous SNR in order to adapt packet length to channel conditions. We derive in closed form the expression of optimal packet length, maximizing the instantaneous throughput. Our results are valid for any number of reflecting meta-surfaces N of the RIS.