Hollow Fibre vs Starlink

You probably know about Elon Musk’s Starlink project, but have you heard about Hollow Fibre? Both of these ideas have the potential to radically reduce your international latency.

You are probably thinking: how is this possible? Surely the speed of light is constant and we just have to live with 140ms pings forever? It turns out round-trip latency as low as 75ms is possible – because light travels nearly 50% faster through air than through glass.

Starlink

If you had a large collection of interconnected low-earth orbiting satellites, you could bounce internet traffic around the earth’s outer atmosphere using lasers. You would still need to have ground stations to connect the satellites to the internet, but simulations show that you would get pings of about 80ms between Cape Town and London.

To say gamers were hot and sweaty at the mere thought of international pings this low would be an understatement, but reaching this dream is going to take a while.

Watch this simulation of Starlink’s latency on YouTube:

Starlink launched their Version 1 satellites in 2019. These satellites do not yet have the inter-satellite lasers that would allow communication above the earth’s atmosphere. Instead they bounce traffic between satellites and ground stations a few times to reach the eventual destination.

Once enough satellites are in orbit, with their laser communications enabled, we could start seeing international pings under 100ms. To date progress has been slow, but steady, with Starlink constantly changing the configuration and orbits of their satellite network.

Hollow Fibre

Progress doesn’t happen in isolation though, and you can be sure that companies that base their existence on low latency fibre services would do everything in their power to make sure they aren’t kicked to the curb.

British Telecom built a 10km hollow fibre backhaul link in 2021. More recently Comcast built a 40km backhaul link using hollow fibre. Lumenisity have plans to use hollow fibre technology in undersea cable systems.

Traditional fibre transmission networks send a laser through a very thin fibre strand protected by cladding. Light travels through a solid glass medium.

Hollow fibre changes things by making the fibre, well, hollow, or rather filled with air. This means light can travel much faster, but remains contained within a glass tube.

Currently the best round-trip latency from Cape Town to London is via the WACS Express submarine cable system at around 140ms. The same route with 47% lower latency would give you pings of around 74.2ms – if you are feeling optimistic.

The very optimistic case for Starlink is also around 75ms. Starlink will use a more direct route over Africa – where a submarine cable system needs to take a longer route around the west coast of Africa.

Our Predictions

Future versions of Starlink, with laser communications enabled, will probably be first to reach latencies as low as 75ms between Cape Town and London. This will be very good motivation for undersea cable operators to invest in hollow fibre technology.

Given that fibre offers much larger data transmission rates than satellite networks, we will probably still see fibre being the dominant internet backbone technology in the future, hopefully with much lower latency.

If Starlink can reach sub-100ms international pings, we will probably see gamers adding a Starlink connection to play on international gaming servers.

If you live in an urban area, you probably want to keep your home fibre service. Starlink receivers work inside a 22km wide hexagonal cell. Downlink bandwidth is shared by receivers in the same cell area. Similar to mobile phones connected to the same cell tower – the more users in the area, the slower the speeds.

Around 70% of content is currently downloaded from locally hosted content distribution networks and caches, where latencies are usually between 2ms and 20ms. To access this content, your best option is always going to be fibre. You simply don’t need low international latency for things like Netflix and email.

Hollow fibre should have a big impact on internet latency in future. Let’s hope scientists and engineers can speed up the rate at which this technology gets adopted and used in undersea cable systems.

🖖🏼