How Bluetooth Creates Wireless Networks with Unique Addresses

This 2003 patent describes how Bluetooth devices use a master device's address and clock to create a unique, hopping radio channel for communication and build a network map.

What it covers

This patent details a system for wireless devices, like early Bluetooth gadgets, to form a network. A 'master' device sends its unique address and a clock signal to 'slave' devices. This information dictates how the radio channel will 'hop' between frequencies, making it unique and secure for that specific network. The master then asks the slaves for their own addresses and who they can talk to (topology information). It uses this data to build a 'configuration tree,' which is like a map of the network, helping it figure out the best way to send messages between devices. For example, a master phone could use this to connect to headphones and a keyboard, understanding how they relate to each other in the network.

What it doesn't cover

• —Wireless networks where the hopping pattern isn't based on a master device's unique address.
• —Systems that don't use a clock signal from the master to control the timing of the frequency hops.
• —Methods for building a network map that don't involve collecting addresses and 'first order' connection lists from slave devices.
• —Forming a configuration tree that doesn't follow specific rules about how 'rings' of connections can include or exclude devices.
• —Directly controlling a device's power settings or data transmission rates.

The clever bit

The innovation lies in using the master device's unique address and clock to deterministically generate a shared, pseudo-random frequency hopping sequence. This allows devices to synchronize and communicate securely without needing a central, pre-established coordination channel for the hopping itself.

Why it matters

This patent is foundational to the early development and standardization of Bluetooth technology. It describes the core mechanism for establishing piconets (small, personal area networks) and managing device discovery and network topology, which are essential for the widespread adoption of Bluetooth in countless consumer electronics.

Real-world examples

• 1.Early Bluetooth headsets
• 2.Bluetooth keyboards and mice
• 3.Original Bluetooth-enabled mobile phones
• 4.Bluetooth connectivity in laptops