Performance Evaluation for the Co-Existence of eMBB and URLLC Networks: Synchronized versus Unsynchronized TDD

Abstract

To ensure the high level of automation required in today's industrial applications, next-generation wireless networks must enable real-time control and automation of dynamic processes with the requirements of extreme low-latency and ultrareliable communications. In this paper, we provide a performance assessment for the co-existence of a macro (eMBB) and a local factory (URLLC) network and evaluate the network conditions under which the latency and reliability requirements of factory automation applications are met. In particular, we evaluate the coexistence of the eMBB and URLLC networks under two scenarios: (i) synchronized TDD, in which both networks follow the same TDD pattern, and (ii) unsynchronized TDD, in which the eMBB and URLLC networks follow different TDD patterns. Simulation results show that the high downlink interference from the macro base stations towards the factory results in a reduction of the downlink URLLC capacity and service availability in case of synchronized TDD and a reduction of the uplink URLLC capacity and service availability in case of unsynchronized TDD. Finally, it is shown that a promising case for co-existence is the adjacent channel allocation, for both synchronized and unsynchronized TDD deployments. Here, the required isolation to protect the URLLC network in the worst-case scenario where the factory is located next to a macro site can be handled via the factory wall penetration loss (e.g., considering high concrete or metal-coated building walls) along with other solutions such as filters, larger separation distance, and band pairing. Index Terms -5G, URLLC, eMBB, factory automation, coexistence, unsynchronized TDD.I.

On the Performance of Co-existence between Public eMBB and Non-public URLLC Networks

“…The assumed co-existence scenario between the macro and the factory network becomes very challenging, if some active eMBB users served by the overlaid public macro cells are located inside the factory. This is due to a few main differences compared to the evaluations in [12]. First and most importantly, the wall penetration loss is no longer helping to mitigate the inter-network interference from the eMBB users towards both the factory base stations and users.…”

“…The level of the inter-network interference can be reduced by increasing the level of the isolation between the networks for example by increasing the separation distance [12] and the wall loss, by applying a guard band, or by deploying the factory network on an isolated frequency. However, if the factory contains eMBB traffic, an increased isolation with the help of an increased wall loss may make the near-far problems even worse due to the increased transmission powers for the eMBB users located inside the factory.…”

“…However, none of the listed studies consider scenarios where the victim network is assumed to be offering a URLLC service with stringent latency and reliability requirements. The authors in [12] evaluate the performance of a co-existence scenario between a public 5G NR eMBB macro network and a non-public 5G NR URLLC factory network. The evaluation considers both the impact of unsynchronized TDD (uTDD) and synchronized TDD (sTDD), as well as the impact of the separation distance between the factory and the closest macro site on the network performance.…”

“…Motivated by the initial results and the identified research gaps, we substantially extend [12] to provide a more complete picture of the performance of the assumed co-existence scenario. First of all, we evaluate the service availability of the URLLC network and the average user throughput of the eMBB network when the factory contains eMBB traffic served by the overlaid macro cells.…”

URLLC and eMBB in 5G Industrial IoT: A Survey

“…Therefore, a trade-off between the two is of particular emphasis, i.e., to achieve URLLC and eMBB simultaneously with same resource efficient method to satisfy the QoS requirement defined by ITU. Thereby, the coexistence of URLLC and eMBB open the doors to new technologies and research directions [31], [36], [174]- [178].…”