Wavefront shaping for Wireless Communications in complex media with tunable metasurfaces

Abstract

In this talk, I will show how the work performed at Langevin Institute on wave control have led to the seminal concept behind large reconfigurable intelligent surfaces (RIS) that is currently a topic of great interest in the wireless communication community and that is proposed as a new paradigm for the sixth generation (6G) of communication networks. Starting with the first demonstrations of “time-reversal mirrors” that are connected to the concept of active focusing with multiple antenna (MIMO communications), I will compare this classical approach to a new approach using tunable metasurfaces to obtain the best communication performance. The main idea is to replace the numerous transmitting antennas in MIMO communications by a smart modification of the wireless environment by physically shaping the propagation medium to achieve optimal focusing and channel diversity. I will show how the optimization of these metasurfaces results from the generalization of the “time reversal mirror” concept to the one of the products of different time-reversal mirrors associated with each transmitter and receiver. I will discuss the way to simplify these reconfigurable metasurfaces to increase significantly the Shannon capacity et the energy efficiency in complex environment.