Performance modeling and comparison of URLLC and eMBB coexistence strategies in 5G new radio systems

Industrial deployments of 5G New Radio (NR) communications are expected to be the first ones, where time- critical communications implemented via ultra-reliable low-latency service (URLLC) will coexist with enhanced mobile broadband (eMBB) service on the same radio interface. However, owing to the demanding nature of the former service and principally different traffic patterns, the conventional coexistence techniques based on a complete reservation or complete sharing either result in inefficient usage of radio resources or inability to deliver the required service level. Motivated by the lack of comparison-based studies for URLLC and eMBB coexistence at the air interface that does not affect the current 5G NR multiple access scheme, in this paper, we compare several resource allocation strategies for URLLC and eMBB traffic. To this aim, by utilizing directional antenna array and propagation models, we formulate a general performance assessment framework for a partial sharing coexistence strategy with preemptive and non-preemptive priorities. As this strategy includes several coexistence schemes as its special cases, we then proceed to assess their performance utilizing user- and operator-centric key performance indicators including the session drop and preemption probabilities, and system resource utilization. Our numerical results indicate that utilizing preemption service is vital for efficient coexistence between URLLC and eMBB traffic. Out of all the considered schemes, one of the simplest ones - preemptive priority without resource reservation is characterized by the minimum resource requirements. This scheme allows to achieve 50% gain in terms of the amount of required resources as compared to the strategies without preemption or with complete reservations.