# 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. - **Patent:** US 6590928 - **Original title:** Frequency hopping piconets in an uncoordinated wireless multi-user system - **Owner:** Telefonaktiebolaget LM Ericsson AB - **Granted:** 2003 - **Status:** Public domain (expired) - **Times cited:** 131 - **Field:** consumer_electronics, telecommunications, software ## What it does 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 does NOT 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. ## Real-world examples 1. Early Bluetooth headsets 2. Bluetooth keyboards and mice 3. Original Bluetooth-enabled mobile phones 4. Bluetooth connectivity in laptops ## 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. ## Frequently asked questions ### What does How Bluetooth Creates Wireless Networks with Unique Addresses cover? 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. ### Who owns patent US 6590928? Telefonaktiebolaget LM Ericsson AB owns this patent, granted in 2003. ### When does this patent expire? This patent has expired and is now in the public domain — anyone can use the invention freely. ### What is patent US 6590928 cited by? This patent has been cited by 131 later patents that build on its ideas. ### What problem does this patent solve? 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. ### What does this patent NOT cover? Wireless networks where the hopping pattern isn't based on a master device's unique address. **Full plain-English explainer:** https://patentbrief.org/patent/us/6590928/bluetooth-frequency-hopping **Original patent:** https://patents.google.com/patent/US6590928 --- _Source: PatentBrief — https://patentbrief.org. Patent facts are from public records; the plain-English explanation is PatentBrief's._ ## Related patents Semantically similar inventions in the PatentBrief corpus: - [How Early Cell Phones Handled Calls Across Different Towers](https://patentbrief.org/patent/us/3906166/cellular-mobile-phone-radio-telephone) — This patent describes a system for early portable phones to automatically find the strongest signal from a base station and switch channels as the user moves, reducing battery drain and interference. - [CSIRO's High-Frequency Wireless Network Technology](https://patentbrief.org/patent/us/5487069/wifi-csiro-wireless-lan) — This 1996 patent from CSIRO describes a wireless local area network system that can send data reliably using radio waves above 10 GHz, even when signals bounce off walls. - [How Multiple Computers Share a Network Cable Without Crashing](https://patentbrief.org/patent/us/4063220/ethernet-packet-network) — This patent describes how multiple computers can share a single communication cable by listening for other transmissions and stopping their own if a collision occurs, then trying again later. - [Hedy Lamarr and George Antheil's Frequency Hopping Secret Communication System](https://patentbrief.org/patent/us/2292387/hedy-lamarr-frequency-hopping) — A 1942 patent for a radio-controlled torpedo guidance system that used synchronized player piano rolls to hop between frequencies, preventing enemies from jamming the signal. - [BlackBerry Device with QWERTY Keyboard and Trackball Design](https://patentbrief.org/patent/us/8219158/handheld-wireless-communication-device) — This 2012 patent describes a handheld device, like an early BlackBerry, with a QWERTY keyboard and a trackball, focusing on the physical arrangement of keys around the navigation tool.