Indoor Propagation Measurements with a Reconfigurable Intelligent Surface at 3.5 GHz

This paper describes an investigation of the practical impact of a reconfigurable intelligent surface on indoor radio propagation. The evaluation is based on measurements of the instantaneous channel impulse response (CIR) between a static transmitter (Tx) and moving receiver (Rx) antennas in non-line of sight (NLOS), where the reconfigurable intelligent surface (RIS) was placed to potentially improve the channel. Different configurations of the RIS were employed and a mean power gain of up to 22 dB was found when introducing the RIS, but the gain was highly dependent on the distance between the Tx antenna and the RIS as well as the polarization, where gains of only about 1 dB was found for a 5 m distance. Also the correct focus point of the RIS was found to be important for close distances. In addition, statistics of the instantaneous power level were investigated.