  There are three generic services in 5G: enhanced mobile broadband (eMBB),
ultra-reliable low-latency communications (URLLC), and massive machine-type
communications (mMTC). To guarantee the performance of heterogeneous services,
network slicing is proposed to allocate resources to different services.
Network slicing is typically done in an orthogonal multiple access (OMA)
fashion, which means different services are allocated non-interfering
resources. However, as the number of users grows, OMA-based slicing is not
always optimal, and a non-orthogonal scheme may achieve a better performance.
This work aims to analyse the performances of different slicing schemes in
uplink, and a promising scheme based on rate-splitting multiple access (RSMA)
is studied. RSMA can provide a more flexible decoding order and theoretically
has the largest achievable rate region than OMA and non-orthogonal multiple
access (NOMA) without time-sharing. Hence, RSMA has the potential to increase
the rate of users requiring different services. In addition, it is not
necessary to decode the two split streams of one user successively, so RSMA
lets suitable users split messages and designs an appropriate decoding order
depending on the service requirements. This work shows that for network slicing
RSMA can outperform NOMA counterpart, and obtain significant gains over OMA in
some region.
