What is Bluetooth and how does it work?

Bluetooth, we cannot say that the term is recent, but we hear it more and more in our daily lives. Suddenly, we thought that it could be a lot to redo a little topo! Because finally, what is Bluetooth? All the answers in this little folder. If you are interested to learn what’s the Best Bluetooth Audio Transmitter is and want to get one for your home, I advise you to read all the reviews before buying it.

Where does it come from, Bluetooth?

In the eighties, the electronics industry became aware of the need to invent a wireless communication standard quite economical and easy to deploy for the general public. So that Michel does not need to get up to zap during the PSG-OM pub for example. Suddenly, infra-red technology (IrDA) arrives in the home of Michel in the form of a remote control. The principle is simple: the information is transmitted by an invisible light flow between Michel’s remote control and his TV. Problem: when Jacques gets up for a beer, impossible for Michel to change channels, the luminous flux being interrupted by the imposing overweight Jacques. Moreover, if the amount of data transmitted by this stream is sufficient for a remote control, it is very small, and new uses are developing rapidly which require transmitting more information at the same time.

In 1994, Ericsson created the Bluetooth, quickly joined in a few years by large companies like IBM, Intel, Microsoft or Nokia to form the Bluetooth Special Interest Group (Bluetooth SIG). A new standard is born, all the big companies working together on the standard. It has evolved a lot and is used by your smartphone, your computer, your watch, your PlayStation controllers, your speakers … And soon a lot more with the advent of connected objects, but it will be the subject of an upcoming file!

Minute Culture!

Since you really want to know – and Wikipedia tells you – the name “Bluetooth” comes from a Danish king who unified all the tribes of his country long before the birth of your great-grandfather. He called himself “Blue Tooth”. The marketing team loved it.

Principle of operation

Bluetooth, like WiFi, uses radio waves to transmit information. For this reason, placing an object or even a wall between the transmitter and the receiver does not prevent the proper transmission of data. Bluetooth uses the 2.4 GHz band, like WiFi again. This band is part of the frequency bands called ISM (Industrial, Scientific, and Medical), it does not require a license to operate.

However, the similarities with WiFi stop there and the differences are numerous. By scope and power first. Bluetooth has mainly been designed for mobile devices, not necessarily having a power supply. Its energy consumption is therefore much lower, for a much narrower range. Most Bluetooth transmitters sold on the market, called “class II”, are sold for a maximum range of 15 to 20 meters.  which is limited in practice often a few meters.

Throughput also: the most efficient Bluetooth connections reach 24 Mb / s , using the 802.11 standards as its big brother, while the best “classic” WiFi connections easily exceed 1 Gb / s (1024 Mb / s, 1000 more what..)

And above all, they differ in their mode of operation. Bluetooth uses the principle of piconets for the connection: a master device, and up to seven slave devices, which cannot communicate with each other. In reality, the master device can maintain the connection with only one of the devices, and therefore alternates the sending / receiving of data to each of them. Thus dividing the total available flow by the number of connected devices. Security is also fundamentally different from that of WiFi. Search for available devices in the range is automatic and permanent. When a device is found the connection is made by the first pairing of both devices requiring only basic authentication by PIN. Fortunately, the range is low … Bluetooth is absolutely unsuited to the transfer of sensitive information.

Still a little technique?

The problem with Bluetooth is that it is easy to get lost in the meanders of different standards used during the evolution of the protocol. The Bluetooth SIG, at the origin of the commercial name of the standard, has stamped a number the different versions of it. Meanwhile, the IEEE in charge of the “official” standardization of the various protocols, has normalized some of its sides… but not all! Finally, several additional and optional protocols can accompany some versions of Bluetooth.

We gave you a little recap, as clear as possible:

  • Bluetooth 1.0: The base. It did not work yet terrible, many problems of interoperability between different manufacturers … Max Rate: 1 Mb / s!
  • Bluetooth 1.1: Always the same maximum speed, but a lot of problems solved. Standardized by the IEEE under the sweet nickname of IEEE 802.15.1-2002.
  • Bluetooth 1.2: If the theoretical flow remains the same, in practice we already accelerated a little! IEEE will call it 802.15.1-2002
  • Bluetooth 2.0 / 2.1 + EDR:

    This is where additional protocols come into play (yes, otherwise it was too easy). The EDR, for Enhanced Data Rate, allows a very sharp increase in bit rates to 3 Mb / s, but is optional. Thus a Bluetooth 2.0 device may not support the EDR. But as it is rare, we will remember especially that it goes much faster! There will also be a 2.1 version. It’s exactly the same, but the pairing has finally been simplified and secured.

  • Bluetooth 3.0 + HS:

    We get to the heart of the matter. As for the EDR, the HS (for High Speed) is optional. On the other hand for the peripherals which support it, it is a true revolution. Forgot 802.15, we go to 802.11 for data transfer. A cousin of WiFi in short, with speeds of up to 24 Mb / s!

  • Bluetooth 4.0 + LE:

    Here we are, that’s what the current Bluetooth looks like. Always backward compatible with all previous versions, it can support EDR or HS. The LE standard, for Low Energy, certifies for appliances that support extremely low energy consumption, giving them greater autonomy. It is intended only for “watch connected” devices because the bit rates are however very low. For LE devices, the bit rates and latency have been further improved!

  • Bluetooth 4.1 / 4.2 /:

    The standard continues to evolve today to adapt to new connected objects that arrive in all sectors of the market. Version 4.1 brings Bluetooth cooperation with 4G mobile, version 4.2 improves security. In short, it’s not over!

To finish on the technical aspect, we could not really let you go without having told you about the profile system, which still slightly spice things up. Profiles are still a type of standard, built into Bluetooth devices. To summarize, using these profiles the device informs the transmitting device of the services it supports: rendering and transmitting its low bit rate for headphones (HSP – Headset Profile), made only its high speed for the speakers (A2DP)

They are the guarantors of the proper functioning of your Bluetooth hardware with the transmitting device. More than twenty standard profiles already exist, and many will be added to the appearance of new types of connected objects.


That’s it, this time you know everything about Bluetooth. It is a protocol that has evolved and adapted to changes in uses and needs, successfully because it still meets today perfectly.

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