Ad hoc networks

An ad hoc network is a network created temporarily when it is needed, rather than being permanently installed. The devices connect directly to each other and do not rely on a central access point, router or server.

That last point matters: nothing sits in the middle passing data along, so each device talks straight to the ones next to it. The network only exists for as long as those devices stay connected.

For example, a youth theatre group rehearsing in a different community hall each Saturday needs to share rehearsal videos between tablets. There is no equipment in the hall they can use, so they connect the tablets directly to each other, swap the files, and the network disappears when they pack up.

Three common types

Three set-ups are commonly used: a personal area network (PAN), a link over open Wi-Fi, and tethering, which many people call a personal hotspot. You set each one up when you need it, and it lasts only as long as it is needed, with no cabling or fixed equipment of your own to install.

Why they are useful

• Flexible – you can set one up temporarily, at any time and in any location, so work does not have to stop because a building has no network point.
• Scalable – new devices can join as the group grows, without any extra sockets, cables or ports being installed.
• Limited setup – devices can communicate almost immediately once a connection is established, which suits short tasks such as sending a file between two people.

Because nothing controls the network from the middle, each device handles its own security, so an ad hoc network is not automatically safer than one with a central access point.