  This paper investigates the radio resource management (RRM) design for
multiuser rate-splitting multiple access (RSMA), accounting for various
characteristics of practical wireless systems, such as the use of discrete
rates, the inability to serve all users, and the imperfect successive
interference cancellation (SIC). Specifically, failure to consider these
characteristics in RRM design may lead to inefficient use of radio resources.
Therefore, we formulate the RRM of RSMA as optimization problems to maximize
respectively the weighted sum rate (WSR) and weighted energy efficiency (WEE),
and jointly optimize the beamforming, user admission, discrete/continuous
rates, accounting for imperfect SIC, which result in nonconvex mixed-integer
nonlinear programs that are challenging to solve. Despite the difficulty of the
optimization problems, we develop algorithms that can find high-quality
solutions. We show via simulations that carefully accounting for the
aforementioned characteristics, can lead to significant gains. Precisely, by
considering that transmission rates are discrete, the transmit power can be
utilized more intelligently, allocating just enough power to guarantee a given
discrete rate. Additionally, we reveal that user admission plays a crucial role
in RSMA, enabling additional gains compared to random admission by facilitating
the servicing of selected users with mutually beneficial channel
characteristics. Furthermore, provisioning for possibly imperfect SIC makes
RSMA more robust and reliable.
