  The 5G systems will feature three generic services: enhanced Mobile BroadBand
(eMBB), massive Machine-Type Communications (mMTC) and Ultra-Reliable and
Low-Latency Communications (URLLC). The diverse requirements of these services
in terms of data-rates, number of connected devices, latency and reliability
can lead to a sub-optimal use of the 5G network, thus network slicing is
proposed as a solution that creates customized slices of the network
specifically designed to meet the requirements of each service. Under the
network slicing, the radio resources can be shared in orthogonal and
non-orthogonal schemes. Motivated by Industrial Internet of Things (IIoT)
scenarios where a large number of sensors may require connectivity with
stringent requirements of latency and reliability, we propose the use of
Non-Orthogonal Multiple Access (NOMA) to improve the number of URLLC users that
are connected in the uplink to the same base station (BS), for both orthogonal
and non-orthogonal network slicing with eMBB users. The multiple URLLC users
transmit simultaneously and across multiple frequency channels. We set the
reliability requirements for the two services and analyze their pair of sum
rates. We show that, even with overlapping transmissions from multiple eMBB and
URLLC users, the use of NOMA techniques allows us to guarantee the reliability
requirements for both services.
