The fronthaul portion of a C-RAN (Cloud Radio Access Network) telecommunications architecture comprises the intermediate links between the centralized radio controllers and the radio heads (or masts) at the "edge" of a cellular network.
It comprises dedicated fibers carrying data in the CPRI or OBSAI format.
In the UK for example BT Openreach owns a majority of the fiber network to radio masts.
There are proposals to modify Ethernet to make it more suitable for the Fronthaul network.
[4] Recently, a novel wireless fronthaul solution has been proposed for ultra-dense small cell deployment where networked flying platforms (NFPs) such UAVs, drones, tethered balloon and high-altitude/medium-altitude/low-altitude platforms carrying FSO transceivers have been introduced as aerial hubs to aggregate the small cell traffic and offer connectivity to the core network.