On the Cost of Achieving Downlink Ultra-Reliable Low-Latency Communications in 5G Networks

We determine the cost of serving Ultra-Reliable Low-Latency Communications (URLLC) traffic (1 ms one-way latency, 99.999% reliability) in 5G New Radio (NR) Macro cellular networks. The cost is measured as the degradation of the enhanced Mobile Broadband (eMBB) downlink system capacity when serving a certain offered load of URLLC traffic on the same radio carrier. A methodology for assessing the cost of URLLC is presented, which takes into account all the aspects related to configuring a suitable resource allocation and link adaptation strategy, as well as the associated control channel overhead due to the use of mini-slots with very frequent control channel resources for monitoring downlink data assignments. When taking a holistic view on the performance, advanced system-level simulation results show that 1 Mbps of URLLC traffic results in an eMBB throughput reduction of up to 60 Mbps, i.e. URLLC traffic can be up to 60 times more costly than traditional best-effort. The presented results can be used by cellular service providers, such as operators, for understanding and dimensioning the tradeoffs and impact towards traditional network services when adding URLLC services to their portfolio.