  In this paper, we consider multigroup multicast transmissions with different
types of service messages in an overloaded multicarrier system, where the
number of transmitter antennas is insufficient to mitigate all inter-group
interference. We show that employing a rate-splitting based multiuser
beamforming approach enables a simultaneous delivery of the multiple service
messages over the same time-frequency resources in a non-orthogonal fashion.
Such an approach, taking into account transmission power constraints which are
inevitable in practice, outperforms classic beamforming methods as well as
current standardized multicast technologies, in terms of both spectrum
efficiency and the flexibility of radio resource allocation.
