Mobile fronthaul is positioned to become an important technology as mobile operators make their 5G plans and move to centralized and cloud-based radio access networks (C-RANs).

Today, Infinera and EBlink announced a partnership to combine fiber and wireless technologies to provide an end-to-end mobile fronthaul architecture, which raises the question: What the heck is fronthaul?

It's "the interface between the cellular base station’s processing elements (namely the baseband unit — BBU) and the remote radio heads (RRHs)," EBlink explains in an email to SDxCentral. "Historically, coaxial cables were used to connect the base station to the radio antennas located at the top of the tower or building."

Newer cellular architectures replace co-ax with fiber optics or, in EBlink's case, other wireless technology, so that the radios and BBU don't have to be in the same place. That's the principle behind the C-RAN: Baseband processing becomes a centralized pool for RRHs to tap.

As part of their new partnership, Infinera and EBlink tested their fronthaul technologies on Orange’s live 4G network in western France, interconnecting BBUs and RRHs from several of Orange’s RAN vendors.

Where fiber exists, the Infinera TM-Series delivers fronthaul bandwidth using wavelength division multiplexing (WDM) technology. Where there is no fiber, EBlink’s wireless fronthaul completes the connection.

The idea is that EBlink can eliminate the last few hundred meters of fiber, which can be difficult and costly to deploy.

Competitors in fronthaul include startup Altiostar, which uses Ethernet connections rather than WDM.