  The coexistence of diverse services with heterogeneous requirements is a
major component of 5G. This calls for spectrum slicing: efficient sharing of
the wireless resources among diverse users while guaranteeing the respective
requirements in terms of throughput, timing, and/or reliability. In this paper,
we set up a simple system model of a radio access network (RAN) for
investigating spectrum slicing for two user types: (1) broadband users with
throughput requirements and (2) intermittently active users with a timing
requirement, expressed as either latency-reliability or Age of Information
(AoI). We evaluate the trade-offs between between the achievable throughput of
broadband users and the timing requirement of the intermittent users under
three different access modes: Orthogonal Multiple Access (OMA), Non-Orthogonal
Multiple Access (NOMA), and Partial Non-Orthogonal Multiple Access (PNOMA).
Analysis shows that, under a pessimistic model with destructive collisions,
NOMA schemes can almost match the throughput of OMA without jeopardizing the
reliability and timeliness performance. This indicates that the capture effect
can significantly improve NOMA performance, as confirmed by the numerical
results.
