Bluetooth
In Ericsson’s laboratories in 1994, engineers set out to solve a simple problem: replacing the cables connecting electronic devices with an inexpensive, low-power radio link. This project would take on a surprising name, borrowed from Viking history. Harald Bluetooth, King of Denmark in the 10th century, had unified Denmark and Norway. The designers saw it as a perfect symbol for a technology designed to connect different devices.
Four years later, in February 1998, five electronics giants—Ericsson, IBM, Intel, Nokia, and Toshiba—created the Bluetooth Special Interest Group. This association’s mission was to define common technical specifications. The movement gained momentum: 3COM, Microsoft, Lucent, and Motorola joined the group, which already had more than 1,900 members by 2000.
The first commercial version was released in 1999. Devices from different manufacturers struggled to communicate with each other. Version 1.1, in 2002, corrected these teething problems and stabilized throughput at 1 Mbit/s. Two years later, version 2.0 tripled transmission speed thanks to Enhanced Data Rate.
The operation relies on piconets, these small networks where a master device coordinates up to seven active slaves. The 2.4 GHz frequency band serves as the operating space, with an interesting feature: the transmission frequency changes 1,600 times per second among 79 available channels. This frequency hopping limits interference.
Security was not overlooked. The designers included three levels of protection, from open mode to encrypted connection, with authentication and authorization mechanisms. But it was in 2010 that everything changed. Version 4.0 introduced Bluetooth Low Energy, a variant that consumes much less power. Smartwatches, health sensors, and home automation devices found their gateway to the wireless world.
Six years later, version 5.0 quadrupled range and doubled speed. The Internet of Things exploded, and Bluetooth adapted. Protocol layers stack up: the radio layer handles waves, the baseband controls packets, the link manager establishes connections. Above, L2CAP segments and distributes data. Protocols like RFCOMM also emulate serial ports to maintain compatibility with existing systems.
Profiles define uses: file transfer, synchronization, telephony, audio. The Generic Access Profile serves as the foundation for all others. This layered architecture enabled Bluetooth to go beyond its initial role as a simple cable replacement. Forecasts predicted 5.4 billion devices shipped in 2023.
In 2017, the addition of mesh networking opened new possibilities. Extended networks became feasible, useful for connected lighting and building automation. In hospitals, sensors monitor patients remotely. Factories collect data to anticipate breakdowns. Bluetooth beacons guide customers through stores and revolutionize proximity marketing.
This technology illustrates how a simple radio link can evolve into a complex system. From point-to-point to mesh networks, from cable replacement to the backbone of IoT, Bluetooth has managed to transform itself without breaking compatibility with previous versions. Throughput increases, range extends, energy efficiency improves. And yet, a recent device can still communicate with an old peripheral from the 2000s.