Paper published in IEEE Transactions on Wireless Communications

The paper "Optimization of Rate-Splitting Multiple Access in Beyond Diagonal RIS-assisted URLLC Systems" co-authored by M. Soleymani, I. Santamaria, E. Jorswieck and B. Clerckx, has been published in IEEE Transactions on Wireless Communications and is already available under the "Early Access" area on IEEE Xplore.

Abstract.- This paper proposes a general optimization framework for rate splitting multiple access (RSMA) in beyond diagonal (BD) reconfigurable intelligent surface (RIS) assisted ultrareliable low-latency communications (URLLC) systems. This framework can provide a suboptimal solution for a large family of optimization problems in which the objective and/or constraints are linear functions of the rates and/or energy efficiency (EE) of users. Using this framework, we show that RSMA and RIS can be mutually beneficial tools when the system is overloaded, i.e., when the number of users per cell is higher than the number of base station (BS) antennas. Additionally, we show that the benefits of RSMA increase when the packets are shorter and/or the reliability constraint is more stringent. Furthermore, we show that the RSMA benefits increase with the number of users per cell and decrease with the number of BS antennas. Finally, we show that RIS (either diagonal or BD) can highly improve the system performance, and BD-RIS outperforms regular RIS.