On RIS-Assisted Random Access Systems with Successive Interference Cancellation

Abstract

We consider a large floor that has RIS elements assisting the transmissions from the different terminal devices towards a common access point located at the center. Showing that the near-field model is the appropriate model for this system, we provide an approach to study the improvement in performance when using RIS in a system that utilizes Successive Interference Cancellation (SIC), along with Random Access, like Slotted ALOHA. Without the use of RIS, the possible spatial region where SIC could have been used is very small, and introduction of RIS provides a promising improvement. Partial RIS sharing with SIC is seen to offer a significant further improvement in this region. By finding the optimal channel access probabilities by viewing the end-devices as individual players in a game with a common utility function, we see that the overall average system throughput performance improves with RIS assistance.