Ethernet fronthaul transport of an upper-physical layer functional split using time-aware shaping

Abstract

An Upper Physical layer functional Split (UPS) for an Ethernet fronthaul network is modelled, and the frame delay and Frame Delay Variation (FDV) limitations are investigated. The results show that contention in Ethernet switch ports can cause an increase in the delay and FDV beyond proposed specifications for the UPS and other time-sensitive traffic types such as I/Q-type traffic. Time Aware Shaping (TAS) can significantly reduce or even remove FDV for UPS traffic and I/Q-type traffic, but it is shown that TAS design aspects have to carefully consider the transmission pattern of the contending traffic in the Ethernet fronthaul network switches. Taking into account the transmission pattern of the UPS traffic, different time allocations within TAS window sections are proposed in conjunction with both receiver and transmitterside buffering. Further, it is proven that using TAS with higher link rates for example, 10 Gbps link rates or beyond makes it possible to transport the UPS and time sensitive traffic within its specification over fronthaul fiber spans, more than 10 km length, and/or more hops as TAS can potentially eliminate any increase in the FDV of the UPS traffic.