Mobile fronthaul transport options in C-RAN and emerging research directions: A comprehensive study

C-RAN is an architecture for future 5G cellular networks, which has the potential of combining emerging technologies from both the wireless and the Information Technology (IT) industries by incorporating cloud computing into Radio Access Networks (RANs). This paper presents a comprehensive review of the transport options for constructing mobile fronthaul, capable of supporting applications and services beyond LTE advanced. The architecture of C-RAN is first studied which comprises mobile backhaul, mobile fronthaul and the User Equipment (UE). Then, it describes the different fronthaul transport options that are capable to the drastic increase of wireless bandwidth as well as the massive deployment of small cells. It also numerically evaluated the End to End (E2E) latency, the maximum possible separation distance between Remote Radio Head (RRH) and Base Band Unit (BBU), and Packet Delay Variation (PDV) of the mobile fronthaul solutions with emphasis on Ethernet network. Moreover, the paper explains Ethernet frame format for transporting Radio over Ethernet (RoE) traffic. Finally, the paper presents a summary of emerging research directions, opportunities and challenges in optical networking in mobile fronthual networks.