Written by Nick Wood
BT’s networks arm Openreach is making progress with its new-ish approach to getting fibre into hard-to-reach areas.
The Openreach press release calls the tech it’s using a ‘subtended headend’, but beyond saying that they are installed in street cabinets, pretty much leaves it at that when it comes to explaining what they actually are.
However, the name also crops up in an ISPreview article from 2019, which explains that it’s another name for a shrunken optical line terminal (OLT) – the box that connects the fibre coming from the modems installed in the user’s premises (also known as the optical network terminal (ONT)) to the backbone network.
Due to their size, a typical OLT tends to be deployed in a local exchange. This is fine under most circumstances because the premises they serve are close enough to not cause any issues. But their performance is limited once you get beyond a certain distance, and that can become a problem in sparsely-populated areas where multiple rural communities are served by a single exchange.
Enter the subtended headend (SHE). It is small enough to fit into a street cabinet – which is deployed much closer to the customer and being part of the fibre-to-the-cabinet (FTTC) network is already connected by fibre to the local exchange. Using a SHE therefore doesn’t require Openreach to extend its backbone network or build new exchanges.
