  This paper investigates the resource management problem in multi-carrier
rate-splitting multiple access (MC-RSMA) systems with imperfect channel state
information (CSI) and successive interference cancellation (SIC) for
ultra-reliable and low-latency communications (URLLC) applications. To explore
the trade-off between the decoding error probability and achievable rate,
effective throughput (ET) is adopted as the utility function in this study.
Then, a mixed-integer non-convex problem is formulated, where power allocation,
rate control, and user grouping are jointly taken into consideration. To tackle
this problem, we approximate the achievable ET using a lower bound and then
develop a decomposition method to decouple optimization variables.
Specifically, for a given user grouping scheme, an iteration-based
concave-convex programming (CCCP) method and an iteration-free lower-bound
approximation (LBA) method are proposed for power allocation and rate control.
Next, a greedy search-based scheme and a heuristic grouping scheme are
developed for the user-grouping problem. The simulation results verify the
effectiveness of the CCCP and LBA methods in power allocation and rate control
and the greedy search-based and heuristic grouping methods in user grouping.
Besides, the superiority of RSMA for URLLC services is demonstrated when
compared to spatial division multiple access.
