Introduction

Bluetooth is everywhere—you'll find it in smartphones, tablets, laptops, TVs, cars, security systems, computer peripherals (mice, keyboads, headphones), smartwatches and more. A great many manufacturers in every sector of the tech industry have adopted Bluetooth for reliable and ubiquitous short-distance communication. But while most of us can decode the intricacies of a Wi-Fi connection by the standard's nomenclature, recognition of Bluetooth capabilities usually ends with the version number.

Bluetooth is fascinating, though—not just for its technical operation, but for the multi-national conglomerate of corporations standing behind it, and the work they do behind the scenes to makes sure Bluetooth is the standard. This article is an in-depth look at everything Bluetooth: the science, the tech, the security and the standard.

What Is Bluetooth?

In a nutshell, Bluetooth is a wireless communication specification operating on the unlicensed 2.4GHz band. It could be considered a short-range sibling of Wi-Fi. Where Wi-Fi enables wireless local area networks (WLANs) and ties together devices around some venue, Bluetooth enables wireless personal area networks (PANs) to enable communication in a 10-meter range (for Class 2 and Class 3 Bluetooth devices) and more than 100-meter range for Class 1 devices, mostly used for industrial applications. Even the low-power Class 2 and Class 3 devices are capable of greater than 10-meter range with the new networking and modulation schemes introduced by the Bluetooth standard in March 2016.

Wi-Fi, microwave ovens, drones and Bluetooth all operate on the 2.4GHz band. This frequency is categorized as "unlicensed" in most areas of the world. Unlicensed, however, does not mean unregulated—there are limits on the amount of power that can be transmitted, modulation schemes and unintentional out-of-band RF interference. Fortunately, operating a transmit/receive system does not require a user license. Otherwise we'd all have to take a radio operator course before enabling the Wi-Fi or Bluetooth functions on our smartphones, or even to turn on our microwave ovens.

Like all wireless communications technologies, Bluetooth requires a transmitter and receiver (with antennas on each), and modem-like control chips to modulate and demodulate the digital signal. These functions are usually integrated into one SoC that includes a transceiver, antenna and control chip. For more complex systems like smartphones, Bluetooth is often integrated into a multi-communication SoC that handles other wireless specifications as well.

Texas Instruments CC2560/64 Bluetooth evaluation module

Current implementations of Bluetooth come in two flavors: Bluetooth Basic Rate/Enhanced Data Rate (BR/EDR) and Bluetooth low energy (LE), also called Bluetooth Smart. The former establishes short-range connections for continuous data transfer (think headsets streaming music from a smartphone). Bluetooth LE is designed for short bursts of small data packets over a longer range in order to conserve battery life. Sensors, "smart" lightbulbs and other "smart home" devices are the ideal use-case for Bluetooth LE. Finally, some laptops and smartphones require both LE modes and BR/EDR modes, and this capability is offered by so-called "dual-mode" Bluetooth solutions.



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A Short History Of Bluetooth

In the tenth century, the Viking king Harald Blåtand (Harald Bluetooth in English) united large swathes of modern-day Norway and Denmark under his rule. Fast-forward to 1994, when Ericsson's R&D teams started investigating ways to connect computers and the "smartphones" of the day without cables. In 1997, Jim Kardach proposed the name "Bluetooth" for the new technology that would unify communications protocols like King Harald had united Scandinavia.

Monument donated by Ericsson CEO Sven-Christer Nilsson in 1999 at the Ericsson R&D facility in Lund. Photograph "Ericsson Runestone" by Karl Baron (CC BY 2.0)

But Ericsson soon realized that implementing such a far-reaching, near-universal protocol would require cooperation on a vast scale. So, in 1998, along with Nokia, IBM, Intel and Toshiba, Ericsson founded the Bluetooth Special Interest Group (SIG). The first formalized Bluetooth technical specification arrived in 1999. The standard's logo is a ligature of two runes from the Younger Futhark runic alphabet: Hagall (ᚼ) and Bjarkan (ᛒ), Harald Bluetooth’s initials.

Bluetooth Special Interest Group

The Bluetooth specification was conceived as a worldwide communications specification. The founding members of the SIG, apart from being the multi-national companies with the most to gain from Bluetooth's adoption, also represented geographic regions: Ericsson and Nokia were from Europe, Toshiba hailed from Asia, and IBM and Intel represented North and South America.

The SIG's day-to-day tasks involve Bluetooth advocacy to governments, legal issues, managing test processes and compliance, and publishing the Bluetooth specification.

Microsoft, Motorola, Lucent Technologies and 3Com also jointed the SIG, and these nine companies formed the upper-level SIG administrators, the "SIG Promoters." The current list of promoters includes Apple, Ericsson, Intel, Lenovo, Microsoft, Nokia, and Toshiba.

"Associate Members" sign a legal document and pay an annual membership fee that allows them to participate in marketing and technical activities. They're also allowed to see draft documents 0.5 and above. With new Bluetooth specifications surfacing every few years, early drafts of the regulations provide Associate Members and the SIG Promoters an advantage in product design and deployment lead times. A third tier, called "Adopters," join for free, but still sign a legal memorandum of understanding. They have access to draft document versions 0.9 and above.

Bluetooth SIG membership tiers

SIG membership is mandatory if a manufacturer wants to use the Bluetooth specification in products, or use the Bluetooth logo or other intellectual property.

IEEE, FCC, CE And Other Regulatory Acronyms

In the United States, the FCC allocates frequency bands for specific uses, the transmission power of devices in various configurations (narrowband vs. spectrum spread), modulation requirements and product certification for any product that has the potential for RF interference.

Most countries require some sort of licensing or approval of low-power devices operating on the 2.4GHz band, and also set limitations on power levels, modulation and other technical specifics of operation. Industry Canada (IC) handles this in Canada, there's CE for Europe and so on. And there are also country-specific requirements. For example, France sets geographical constraints, and Lithuania requires user licenses. Each regulation may also dictate the minimum and maximum number of channels Bluetooth can operate on.

The IEEE, a governing body that develops worldwide consensus standards on electronics, incorporated Bluetooth as standard 802.15.1. Wi-Fi is 802.11, in comparison.