“Fronthaul” is one of the “in” topics at the moment in mobile networks, so I thought it would be good to explore what it all means, and especially how it affects synchronization, because we all like to keep in sync.

So what is fronthaul, anyway? Well to understand that, we have to understand what “backhaul” is. “Backhaul” was a term originally coined by the trucking industry, and referred to a truck carrying a load from remote location back to a central distribution centre. The term then got applied in all sorts of contexts to refer to links connecting a remote site to a central site.

In mobile telecoms, it was applied to the link from the radio basestation back into the core network, “hauling” the data back from the basestation to the core. Of course, these links are bi-directional, so it also carries data from the core out to the basestation.

Where does fronthaul fit into this? Typically, the basestation sat in a cabinet, connected by a co-ax running up the tower to the antenna. Someone then had the bright idea that since the co-ax had issues with power loss, why not site the actual RF transceiver at the top of the tower by the antenna, and connect the transceiver via optical fibre to the basestation below.

This fibre connection between the basestation and the RF transceiver became known as “fronthaul”.

For more details check out my previous blogs covering the topics below.

• Getting into the hotel business.

• Networking the fronthaul.

• Synchronization requirements for fronthaul.

• Synchronization methods in fronthaul.

• Testing synchronization in fronthaul.

Tim Frost
Strategic Technology Manager, Calnex Solutions.