A Novel Channel Model for Reconfigurable Intelligent Surface-assisted Wireless Networks

The reconfigurable intelligent surface (RIS) is one of the promising technology contributing to the next generation smart radio environment. A novel RIS-assisted wireless channel model is proposed. Particularly, we consider the RIS and the scattering environment as a whole by studying the signal's multipath propagation. The model suggests that the RIS-assisted wireless channel can be treated as Ricianly distributed. Analytical expressions are derived for the shape factor and the scale factor of the distribution, which depend on detailed RIS parameters, such as phase-alignment accuracy and the number of elements. Closed-form expressions for the outage probability of the proposed channel model arc derived. It is proved that a constant diversity order exists, which is independent of the number of RIS elements. Simulation results are presented to confirm that the proposed model applies effectively to the phased-array implemented RISs.