RIS-Assisted 6G Wireless Communications: A Novel Statistical Framework in the Presence of Direct Channel

An RIS-assisted wireless communication system in the presence of a direct communication path between the transceiver pair is considered in this letter. The transmitter-RIS and the RIS-receiver channels follow independent Nakagami- $m$ distributions, and the direct channel between the transceiver pair follows a Rayleigh distribution. Considering this system model, the statistics of the composite channel for the RIS-assisted communication system is derived in terms of obtaining novel expressions for the probability density functions for the magnitude and the phase of the communication channel. The correctness of the analytical framework is verified via Monte Carlo simulations, and the effects of the shape parameters of the channels and the number of reflecting elements in the RIS on the randomness of the composite channel are studied via numerical results.