End-to-End Delay Analysis in Disaggregated O-RAN Fronthaul Networks

During the last years we have witnessed a growing trend towards the deployment of disaggregated Radio Access Network (RAN) networks. In this context, the Open-RAN (ORAN) architecture is one of the most relevant approaches for 5G/6G networks, and it is believed to be a key element of forthcoming deployments. The performance of the so called Open - Fronthaul (<tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathrm{O}-\text{FH}$</tex>) segment is of the utmost importance to ensure an appropriate overall system performance. In this sense, the overall delay of the communication between nodes within the O-RAN fronthaul needs to be kept at very low values, to fulfill the requirements of the corresponding technologies. In this paper we propose exploiting queuing theory to model the O-FH performance, including a realistic traffic characterization. In particular, we present a theoretical framework based on Open Jackson Networks to model the one-way end-to-end delay, and we compare it with a that obtained by a realistic simulation setup. The results show that the theoretical model provides a reasonably accurate behavior under certain conditions, setting in all cases a tight upper bound for the end-to-end delay, which we identify as a key performance indicator.