What is Bluetooth

Bluetooth is an open global standard for wireless data and voice communication. It is a special short-range wireless technology connection based on low-cost short-range wireless connection, which establishes communication environment for fixed and mobile devices. Originally created by Ericsson, it was later maintained and formulated by Bluetooth Special Interest Group (SIG), a non-profit Bluetooth technology alliance.

Its name comes from Harald Blåtand= Gormsen, the Nordic king who unified Denmark and Norway in the Middle Ages. It is named after the king’s surname “Blatand” and directly translated into Chinese as “Bluetooth” (BL = lan, tand = ya)., The Bluetooth logo  is a bind rune merging the Younger Futhark runes  (, Hagall) and  (, Bjarkan), Harald’s initials.

Specification

Frequency

Bluetooth operates at frequencies between 2.400 and 2.4835 GHz (ISM Band). and building personal area networks (PANs). 

Channel

Bluetooth adopts 2.4GHz frequency band, with a channel every 2MHz, with a total of 40 physical channels. Before Bluetooth 5, in which there are 3 broadcast channels and 37 data channels. Starting from Bluetooth 5, the original three broadcast channels are named as Primary broadcast channels, and the remaining 37 channels are expanded into Secondary broadcast channels to improve the broadcast speed.

Because there are other wireless communication protocols in 2.4GHz band, such as WiFi and ZigBee, it is inevitable that there will be mutual signal interference in practical work, resulting in the degradation of data transmission quality. In order to cope with the interference, Bluetooth use a technique called Adaptive Frequency Hopping (AFH), that is, automatically avoiding the interfered radio frequency channel for communication.

Mode

Bluetooth technology is divided into two types: basic rate/enhanced data rate (BR/EDR) and low energy consumption (LE). Among them, BR/EDR type is one-to-one device communication created by point-to-point network topology; LE type uses a variety of network topologies such as point-to-point (one-to-one), broadcast (one-to-many) and grid (many-to-many)

Security

At present, Bluetooth has two security modes: LE security mode 1 and LE security mode 2. In addition, there are four security levels numbered from 1 to 4, of which 4 is the safest level. Therefore, when setting Bluetooth security mode, you can mix these two security modes.

https://www.bluetooth.com/bluetooth-resources/intro-to-bluetooth-security-part1/

https://www.bluetooth.com/bluetooth-resources/intro-to-bluetooth-security-part2/

Standards

Bluetooth technology was put forward in 1989, by Nils Rydbeck, CTO at Ericsson Mobile in Lund, Sweden, but the first official specification Bluetooth 1.0 was not officially announced by Bluetooth Special Interest Group until 1998. Since then, SIG has continuously introduced new specifications to improve Bluetooth technology. The most obvious point is that it has been greatly optimized and improved for Internet of Things applications since 4.0. The latest specification is Bluetooth 5.2 introduced in January 2020, which significantly improves the transmission distance and data transmission speed.

VersionYearMax transfer speedMax range
bluetooth 5.2202048 Mbit/s300 meters
bluetooth 5.1201948 Mbit/s300 meters
bluetooth 5201648 Mbit/s300 meters
bluetooth 4.2201424 Mbit/s50 meters
bluetooth 4.1201324 Mbit/s50 meters
bluetooth 4.0201024 Mbit/s50 meters
bluetooth 3.0+HS200924 Mbit/s10 meters
bluetooth 2.1+EDR20073 Mbit/s10 meters
bluetooth 2.0+EDR20042.1 Mbit/s10 meters
bluetooth 1.220031 Mbit/s10 meters
bluetooth 1.12002810 Kbit/s10 meters
bluetooth 1.01998723.1 Kbit/s10 meters

Bluetooth Low Energy (BLE)

With the development of IOT, BLE is more and more widely used in mobile devices and smart devices

BLE is one of the subsets of Bluetooth 4.0, which is designed to reduce energy consumption, keep the communication range/speed similar to that of classic Bluetooth, and be better applied to devices powered by coin batteries, such as sensors, so that it can last for months or years.

technical/technological specification  Classic BluetoothBLE
Radio Frequency2.4 GHz2.4 GHz
Range10 meter/100 meter30 meters
Speed1-3 Mb/s1 Mb/s
Act Speed0.7-2.1 Mb/s0.2 Mb/s
node/unit7-16,777,184Undefined (theoretical maximum is 2^32)
Security64/128-bit and user-defined application layer128-bit AES and user-defined application layer
RobustnessAutomatic adaptive fast frequency hopping, FEC, fast ACKAutomatic adaptive fast frequency hopping
Latency(Unconnected state)100 ms<6 ms
Total time to send data0.625 ms3 ms
AudioyesLE audio
https://www.bluetooth.com/learn-about-bluetooth/bluetooth-technology/le-audio/
https://www.bluetooth.com/media/le-audio/le-audio-faqs/
network topology (Distributed Networks)(Star topology) (Bus topology) (Mesh topology)
Power consume1(As a reference)0.01to 0.5(Depending on the usage)
Maximum operating current<30 mA<15 mA(The maximum operating time is 15 mA )
main applicationMobile phones, game consoles, headphones, stereo audio streams, cars and PCs, etc.Mobile phones, game machines, PCs, watches, sports and fitness, health care, automobiles, home electronics, automation and industry, etc.

BLE has two different types of devices.

Bluetooth Smart Ready-This is a central device, which is powered by batteries and has high resources and can run all Bluetooth protocols. They are your laptop and mobile phone.

Bluetooth smart-they are your terminal devices, like fitness trackers, baggage trackers or smart dildos. They don’t need to run the whole stack, they need to save power and resources. They only run bluetooth LE servers. They are peripheral devices to which the central device can be connected.

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Bluetooth Qualification

Every bluetooth product needs to be certified according to the bluetooth SIG certification and declaration process. Products need to meet the requirements of Bluetooth license agreement and specification

The qualified products would have a QDID and listed on the Bluetooth Product Listing Database.

Resources

Bluetooth SIG Official website

Bluetooth on Wikipedia:

https://en.wikipedia.org/wiki/Bluetooth

Understanding Bluetooth Technology | CISA

https://us-cert.cisa.gov/ncas/tips/ST05-015#:~:text=Bluetooth%20technology%20allows%20devices%20to,is%20within%20the%20required%20distance.

http://news.eeworld.com.cn/mp/BLE5CODER/a88067.jspx

Youtube Channel

https://www.youtube.com/channel/UC9jommLf3DHXzz2Skx7UWqg