Evaluation of Multi-Connectivity Schemes for URLLC Traffic over WiFi and LTE

Abstract

Emerging applications such as wireless industrial control or robotics raise strict requirements in terms of latency and reliability on wireless communication systems. It is still an open issue which wireless communication system can be used to enable industrial applications such as closed-loop control. A promising approach to improve latency and reliability of wireless communications is multi-connectivity (MC), i.e. using multiple communication paths simultaneously. Different scheduling schemes can be used to distribute the traffic over multiple links. The characteristics of these schemes and which one is best suited to enable reliable low-latency communications in different scenarios needs to be investigated. In this paper, we evaluate the latency and reliability performance of a local Wi-Fi and a private LTE network for traffic patterns as envisioned for industrial applications. Moreover, we assess the performance of different MC scheduling schemes operating on Application Layer over these two wireless links with focus on reliability and latency metrics. For the evaluated single-user scenario, WiFi provides a lower mean latency than LTE. The evaluation of MC scheduling schemes shows that packet duplication (PD) stabilizes the latency by mitigating outliers, while load balancing (LB) reduces the latency of nearly 50 percent of packets in a scenario with bad radio conditions. Our results suggest that using links with similar mean latency would be beneficial for all scheduling schemes.