RAN Slicing Performance Trade-offs: Timing versus Throughput Requirements

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.