Boosting 5G Through Ethernet: How Evolved Fronthaul Can Take Next-Generation Mobile to the Next Level

Current approaches to the fronthaul for centralized- or Cloud-Radio Access Networks (C-RANs) need to be revised to meet the requirements of next-generation mobile networks. There are two major challenges: first, fronthaul signals need to be transported over public fixed access networks, such as passive optical networks (PONs), typically sharing them with other services; second, higher data rates must be catered for due to larger radio bandwidths and greater use of multi-antenna techniques, such as massive MIMO. Using Ethernet as a new transport protocol for the fronthaul allows statistical multiplexing and enables convergence between fixed and mobile services. This new approach more easily benefits from common developments being made for service level agreements, functional virtualization and software-defined networking. Higher data rates will be supported by the move to new, and possibly flexible, functional split points inside the radio access network (RAN) protocol stack of the processing located in the central and distributed units, as is being investigated by a number of bodies. However, there are technical challenges with regard to latency and packet delay variation. This article summarizes the benefits of an Ethernet-based fronthaul for the next generation of mobile networks, its main challenges and how these may be overcome.