Efficient RIS Channel Estimation and Projection Using Zadoff-Chu Sequences

The millimeter wave (mmWave) communication, albeit a promising technology for wireless systems owing to its abundant frequency bandwidth, suffers from large pathloss. The reconfigurable intelligent surface (RIS) technology has recently been introduced to wireless communication systems [1] as it allows for incorporating a very large number (t-housands or even more) of reflection elements for very high array gain [2]. As a (nearly) passive device, the RIS can customize favorable wireless propagation environments with limited power consumption. Hence, it is envisioned that the combination of the mmWave and RIS technologies will be one of the keys to the beyond fifth-generation (B5G) wireless networks [3].