Rate Splitting Multiple Access for Energy Efficient RIS-aided Multi-user Short-Packet Communications

Abstract

This paper investigates a novel framework of resource allocation design in a reconfigurable intelligent surface (RIS)-aided rate-splitting multiple access (RSMA) system for energy-efficient short-packet communications (SPC). In particular, we focus on the joint design of the precoder at the base station (BS) and passive beamforming at the RIS for energy efficiency maximization of multi-user downlink (DL) RSMA the system under given information on packet size and packet-error probability. Due to the non-convexity of the formulated resource allocation problem, we proposed a sub-optimal iterative algorithm that effectively solves the joint optimization problem using an alternating optimization algorithm, Dinkelbach algorithm, and successive convex approximation techniques. Finally, numerical results are presented to validate the effectiveness and the superiority of the proposed RIS-aided RSMA scheme for SPC over conventional non-orthogonal multiple access (NOMA) and space-division multiple access (SDMA) schemes, while maintaining low packet size and high reliability.