5G New Radio Fronthaul Network Design for eCPRI-IEEE 802.1CM and Extreme Latency Percentiles

Abstract

Packet-switched fronthaul networks are often designed following the rule that the worst-case network delay must be below a given target end-to-end network latency budget. However, the theoretical maximum delay can be too pessimistic in particular scenarios, where the latency budget needs to be a very small or there is a need to stretch the distance between the radio heads and the baseband units. In this paper, we propose to use a very high packet delay percentiles as an alternative to the maximum theoretical delay in order to stretch the range of the fronthaul links at the expense of a higher frame loss ratio (FLR), within the limits established by eCPRI and the IEEE 802.1 CM. Several methods to estimate the percentiles for the \mathbf {I}-{U}~/~\mathbf {II}-{D} eCPRI functional splits are analyzed. Namely, G/G/1 and N∗D/D/1 queueing models are tested and compared with simulation as dimensioning tools. The results support that the N∗D/D/1 queue is able to model the behavior of a packet-switch fronthaul aggregator using the eCPRI standard for 5g New Radio (NR) Fronthaul streams and can be used as a tool to dimension the length of the links. The experiments show that the fronthaul links' lengths can be increased by 60% and 10% for 50- and 100-MHz NR channels, respectively, while keeping the latency budget and frame loss ratio within the IEEE 802.1 CM limits.