Bluetooth: what is it and how does it work?

From Bluetooth 1.0 of 1998 to Bluetooth 5.0 of 2017, you will know everything about this wireless technology that has adapted to the last 20 years.

Bluetooth is a wireless technology that everyone knows. It has existed for many years and had its first glory days in the era of Bluetooth headsets. Technology has returned to the forefront with the myriad of connected objects that have emerged in recent years. If at the beginning, we were limited to connected bracelets, watches quickly appeared with new bandwidth needs, but also in terms of autonomy. The standard has adapted to new uses as and when. A brief overview of the different Bluetooth standards and their interest for the consumer .

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Bluetooth: what is it and how does it work?

Bluetooth and Wi-Fi use the same band of frequencies, that of 2.4 GHz. The comparison stops there since the Bluetooth and the Wi-Fi do not answer at all the same uses. Wi-Fi is much more efficient, but more energy hungry and more complex so more expensive. On the contrary, Bluetooth has a lower bandwidth and is used instead to transmit light data.

Bluetooth was born 20 years ago in Swedish Ericsson labs. For the record, the term Bluetooth refers to the Danish king Harald Blåtand who had managed to unify the Viking kingdoms (Sweden, Denmark and Norway). The link with new technologies? The engineers who created the Bluetooth are Swedish and have managed to unify the communications of phones and other devices (headsets, computer, personal assistant, etc.) to each other through a common protocol . The name was thus all found. The Bluetooth Special Interest Group (SIG), which groups together numerous manufacturers, then formalized the specifications of the standard.

From Bluetooth 1.0 to 3.0: rising speeds

On May 20, 1998, the Bluetooth Special Interest Group announced the specifications of the Bluetooth 1.0 standard. Less than two months later, France became world champion in football and in December 1999, version 1.0B of the standard was born. The Ericsson T39, the first Bluetooth phone, officially supported the 1.0B standard, but in fact the future version 1.1 was in the game. Compared to version 1.0B, Bluetooth 1.1 has fixed many bugs .

Version 1.2 of the standard brings many new features, starting with the flow . While it is still theoretically limited to 721 kbps, in practice the bitrate is higher than version 1.1. The reason: higher resistance to interference (microwaves, Wi-Fi, etc.) thanks to frequencies that adapt to the environment.

In 2004, the Bluetooth 2.0 + EDR (for Enhanced Data Rate) is born . The EDR is optional (hence the use of the plus sign) and it is therefore possible to find Bluetooth 2.0 devices that do not support the EDR. Yet, the EDR is one of the biggest novelties of the new version. The EDR can increase speeds to 2.1 Mbps to pass the information in a short time, saving the battery. The Bluetooth 2.1 + EDR for its part brings some improvements as an easier and more secure pairing: the SSP for Secure Simple Pairing.

In 2009, Bluetooth SIG released a fairly revolutionary version. The version 3.0 + HS (High Speed for) now uses a standard Bluetooth for pairing, but an 802.11 connection (such as Wi-Fi) for data transfer . The bandwidth then rises to 24 Mbps. Like the EDR, the devices can support Bluetooth 3.0 without the HS, which prevents them from enjoying the higher speed.

Finally, note that each version of the standard from Bluetooh 1.0 to Bluetooth 3.0 is backward compatible . If your smartphone has a Bluetooth 3.0 chip, it will work with a Bluetooth 1.0 device. On the other hand, a device like a bracelet using the Bluetooth 3.0 will not necessarily work with a Bluetooth 2.0 phone. This will depend on the features used. For Bluetooth 4.0, it's more complicated and we'll see it just below.

The scope

Bluetooth chips do not all have the same range: they are divided into three classes according to their range and power.

Class 1 can reach about 100 meters (100 mW max) compared to 10 meters for class 2 (2.5 mW max) and 1 meter for class 3 (1 mW max).

For Bluetooth LE, manufacturers can not exceed 10 mW, which prevents long distances between devices, but limits power consumption.

Bluetooth 4.0 and 5: the rise of low-power connected objects

Bluetooth 4.0

The Bluetooth 4.0 standard is a small revolution, since it splits the standard into two branches. It integrates on the one hand the Classic Bluetooth standards (versions 1.0 to 3.0), High Speed ​​(version 3.0) and on the other hand the new standard Bluetooth low energy (LE) .

The real novelty comes from the Bluetooth LE which greatly reduces the consumption of the Bluetooth chip with a really different protocol . Manufacturers may decide to implement Bluetooth Low Energy alone (single mode) or Classic Bluetooth (dual mode) to maintain compatibility with older versions of Bluetooth. It is the Bluetooth LE that has allowed the growth of connected objects because the consumption it generates is extremely reduced. Similarly, latency for connection and data transfer is reduced. The disadvantage is a bitrate that is lower than the first version of Bluetooth, but connected objects type watches or bracelets do not require a very high bandwidth.

Bluetooth 5

Bluetooth 4.2 succeeds not Bluetooth 4.3, or even Bluetooth 5.0, but Bluetooth 5 , ratified early 2017. If the numbering suggests that it is a revolution, it is actually only an iterative update. Bluetooth SIG, in turn, adopts this trend, initiated by Google with Chrome, which consists of using only whole numbers.

The Bluetooth 5 is still a major update that, to begin, doubles the range and quadruple the flow of low-power transmissions Bluetooth Low Energy , which opens the way, among other things, the lossless distribution of music.

Moreover, since the advent of Bluetooth Low Energy, Bluetooth is used in retail for advertising purposes . The businesses install tags that detect phones, track their movements and stops. Customers with the merchant application can receive promotions or targeted advertising. And with this in mind, the Bluetooth 5 allows beacons to broadcast a set of information "eight times richer" .

The role of profiles

To connect to each other, Bluetooth devices use profiles. The profiles contain information on the data to be transmitted and the mode of operation of the device . For example, the famous Bluetooth headsets all use the HSP profile (Headset Profile) which imposes audio quality (64 kbps), but also the operation of buttons to pick up or adjust the volume. The profiles allow to release products that will necessarily be compatible with all Bluetooth chips, without the need to download special software on his phone .

With Bluetooth Low Energy, the operating mode of the profiles has changed a little. It is now much easier to create a profile and implement it . However, it must always go through the Bluetooh SIG for validation, but it seems that it is much shorter. And that's a good thing, because manufacturers can not always predict certain uses, so it saves time for consumers and builders alike. This novelty contributes to the effort of unifying the different connected objects. Bluetooth looks to the future and it is a good idea to be able to move quickly in the field of connected objects.

The interest of Bluetooth and connected objects

As we have just seen, Bluetooth has evolved to stick to new uses. According to all experts, the market for connected objects should explode by 2020. Connected fridges, connected watches, connected toothbrush, everything is possible . The devices that communicate with our smartphones already exist and the human imagination should succeed in creating new uses. According to Cisco, by 2020, it is expected to sell 50 billion connected objects. Do we really need it? Not really, no. Just as we did not need a smartphone a few years ago. But you quickly get used to book train tickets directly on your phone or use it as a GPS to go on vacation, so why not for connected objects?

Connected objects are not essential, but will become very useful everyday . You are in the supermarket and you can not remember if you have eggs in the fridge? It will be enough to interrogate it from a distance. It suddenly rains and your windows are wide open? Do you love receiving statistics about your life? You want to have a nice curve in 3D representing your oral hygiene? Connected objects may become your best friends. For others, connected objects should not become a necessity in the medium term and some even see them as enemies .

Of course, connected objects do not just have advantages. Because they use an operating system and a wireless connection, they can be hacked . There is therefore a risk for the security of personal data and intrusion into privacy. The Bluetooth protocol may be secure, hackers can easily hack to access the data of a connected object. There is also the risk of failure higher since the devices will ship more electronics with parts less easily repairable. Finally, concerning the harmfulness of Bluetooth for health , one can wonder, even if the power of emission is largely weaker than that of Wi-Fi.

For connected objects, Bluetooth is essential . It allows to transmit information between several devices without excessive data consumption and especially with almost perfect interoperability. Bluetooth has not finished talking about him.