Scheduling in an Ethernet Fronthaul Network

This paper investigates and compares the performance of different scheduling techniques in an Ethernet fronthaul network in the presence of both time-sensitive/high priority and background traffic streams. A switched Ethernet architecture is used as the fronthaul section of a cloud radio access network (C-RAN) and a comparison of two scheduling schemes, strict priority scheduling and time-aware shaping, is carried out. The different streams are logically separated using virtual local area network identifiers and contend for the use of trunk links formed between aggregator/switch nodes. The scheduling schemes are applied in the access and trunk ports in the fronthaul, and need to handle the queue management and prioritization of the different streams. In such cases, contention induced latency variation has to be characterized, especially when the fronthaul transports precision time protocol traffic, as it directly leads to errors in timestamping. OPNET models for strict priority and time-aware schedulers have been built and employed, and simulation results are used to compare the performance of the two scheduling schemes.