The origin of bluetooth Mesh

from the development history of bluetooth, find out the past lives of bluetooth mesh? Thinking about the soul three questions: where it comes from, where it goes, and what it wants. Prepare for learning Bluetooth mesh next.

why is bluetooth named? This comes from a short story. In the tenth century, there was a king in Denmark named Harald Blatand, who was articulate and sociable. He unified Norway, Sweden and Denmark. Because he likes to eat blueberries, his gums are often blue, so he is known as the king of Bluetooth. When determining the name, the designer felt that the name "Bluetooth" was very expressive, and King Blatand's personality was in line with the characteristics of this technology, so the name "Bluetooth" was used. Bluetooth logo design is taken from the origin letters of "H" and "B" Bluetooth logo in Harald Bluetooth name, which are represented by ancient Nordic letters. Combining the two, it becomes the Bluetooth logo.

barbaric growth stage

The core of Bluetooth is short-range radio communication, which is based on frequency hopping spread spectrum (FHSS) technology, and was put forward by Hollywood actress Hedy Lamarr and pianist George Antheil in August 1942. They are inspired by the number of keys on the piano. By using 88 different carrier frequencies to control the torpedo, the transmission frequency is constantly jumping, so they have certain confidentiality and anti-interference ability.

at first, this technology did not attract the attention of the U.S. military, and it was not used in the battlefield wireless communication system until 198s. Frequency hopping spread spectrum (FHSS) technology later played a key role in solving the problem of wireless data transmission and reception in mobile communication systems including Bluetooth, WiFi and 3G.

in the 198s and 199s, when communication technology broke out, many technology giants were studying a short-distance wireless communication technology that could connect different devices wirelessly.

in 1994, JaapHaartsen completed the core baseband part of this technology, and Sven Mattissson completed the radio frequency part. Together with link management (LMP), these three parts constitute the core protocol layer of this technology. This is the earliest Bluetooth technology, but it is not called Bluetooth at this time.

after a long period of barbaric growth, various standards have emerged one after another, and the so-called long-term integration will lead to long-term separation.

For convenience, it is impossible for every family to use their own standards, just like the charging data cable, two kinds of charging data cables on the market, Apple and Android. Even so, it makes people feel headache. Try it, if a mobile phone manufacturer uses a charging cable, what kind of scene will it be? The standard of Bluetooth mesh was born in exactly the same way as Bluetooth. Before 217, there were also various Bluetooth mesh standards at home and abroad, and it was not until the official version of Sig was released that it was unified.

The scheme created by Ericsson in 1994 aims to study the method of low-power and low-cost wireless communication connection between mobile phones and other accessories. The inventor hopes to create a set of unified rules (standardized protocols) for wireless communication between devices, so as to solve the communication problem of mobile electronic devices that are incompatible with each other among users and replace RS-232 serial communication standard.

in December 1996, Ericsson, Nokia, Intel, Toshiba and IBM decided to set up a SpecialInterestGroup to unify and maintain this wireless communication technical standard, so that it can become the future wireless communication standard. After discussion, Intel is responsible for the development of semiconductor chips and transmission software, Ericsson is responsible for the development of radio frequency and mobile phone software, and IBM and Toshiba are responsible for the development of notebook computer interface specifications.

on may 2th, 1998, Ericsson and five famous manufacturers, IBM, Intel, Nokia and Toshiba, established the "Special Interest Group" (SIG), which is the predecessor of the Bluetooth technology alliance. The goal is to develop a Bluetooth technology standard with low cost and high efficiency, which can be wirelessly connected at will in a short distance. At that time, Bluetooth introduced .7 specification, which supported two parts: Baseband and LMP(Link Manager Protocol).

in 1999, version .8, version .9 and version 1. Draft were released successively. Completed SDP(Service Discovery Protocol) and TCS (telephony control specification) protocols.

version 1.A was officially released on July 26th, 1999, and it was decided to use the 2.4GHz frequency band. Compared with the popular infrared technology at that time, Bluetooth has a higher transmission speed, and there is no need to connect interface to interface like infrared. All Bluetooth devices can be connected at any time as long as they are used within the effective communication range. Data can be exchanged at any angle and direction, which opens the prelude to the rapid development of Bluetooth technology.

In the second half of 1999, Apple, Microsoft, Motorola, Samsung, Lucent and the Bluetooth Task Force jointly established a Bluetooth technology promotion organization, which set off a worldwide "Bluetooth" craze.

by April, 2, the number of SIG members had exceeded 1,5, which was faster than any other wireless alliance. Up to now, * * more than 36, companies have become members of special interest groups. The latest version of Bluetooth protocol also reached 5.2, which was released on January 7, 22. There is no news about Bluetooth 5.3 yet.

the first generation of Bluetooth: an early exploration of short-distance communication

1999: Bluetooth 1.

There were many problems in the early versions of Bluetooth 1. A and 1.B, and many manufacturers pointed out that their products were incompatible with each other. At the same time, in the process of "Handshaking" between two devices, the address of Bluetooth hardware (BD_ADDR) will be sent out, which cannot be anonymous at the protocol level, resulting in the danger of data leakage.

therefore, when version 1. was released, Bluetooth was not widely used immediately. In addition to the few types of electronic devices corresponding to Bluetooth function at that time, Bluetooth devices were also very expensive.

21: Bluetooth 1.1

Bluetooth version 1.1 was officially listed in the IEEE 82.15.1 standard, which defined the physical layer (PHY) and media access control (MAC) specifications, and was used for wireless connection between devices, with a transmission rate of 748 ~ 81 KB/s. But because it is an early design, it is easy to be interfered by products of the same frequency, which affects the communication quality.

23: Bluetooth 1.2

Bluetooth version 1.2 also has a transmission rate of only 748~81kb/s, but in view of the security problems exposed by version 1.1, the anonymity mode was improved, and the hardware address (BD_ADDR) function of shielding devices was added to protect users from identity sniffing attacks and tracking. At the same time, backwards compatibility version 1.1, In addition, four new functions have been added:

AFH(Adaptive Frequency Hopping) technology reduces the interference between Bluetooth products and other wireless communication devices;

esco (extended synchronous connection-oriented links) extends synchronous link-oriented channel technology, which is used to provide audio transmission of QoS, further meeting the needs of high-end voice and audio products;

the fast connection function of Faster Connection can shorten the time of searching again and reconnecting, and make the connection process more stable and fast;

supports the transmission requirements of Stereo sound effects, but can only work in simplex mode.

the second generation of bluetooth: EDR of transmission rate

24: bluetooth 2.

bluetooth 2. is an improved version of version 1.2, and the newly added EDR(Enhanced Data Rate) technology makes the transmission rate of bluetooth devices about 1.8M/s ~ 2.1M/s by improving the ability of multitasking and simultaneous operation of various bluetooth devices.

bluetooth 2. supports duplex mode: you can transmit documents/high-quality pictures while carrying out voice communication. At the same time, EDR technology reduces power consumption by reducing workload cycle. Due to the increase of bandwidth, Bluetooth 2. increases the number of connected devices.

the most widely used standard is bluetooth 2.+EDR, which was launched in 24, and a large number of products supporting bluetooth 2.+EDR also appeared in 26. Although the Bluetooth 2.+EDR standard has made a lot of technical improvements, the problems of complicated configuration process and high power consumption of equipment that have been inherited from the 1.X standard still exist.

Bluetooth 2. can be regarded as ill-timed: although Bluetooth 2. has appeared, most mobile phones still have integrated transmitters below Bluetooth 2., which leads to compatibility problems, so there is no large-scale popularization; In addition, this is also the reason why Bluetooth is not easy to match.

in 27: Bluetooth 2.1

Bluetooth 2.1 added the power saving function of Sniff Subrating, which extended the sending time interval of mutual confirmation signals between devices from the old version of .1 seconds to about .5 seconds, thus greatly reducing the workload of Bluetooth chips. In addition, the simple and secure pairing function of SSP is added, which improves the pairing experience of Bluetooth devices and enhances the use and security intensity. Support NFC near-field communication. As long as two Bluetooth devices with built-in NFC chips are close to each other, the pairing password will be transmitted through NFC without manual input.

On August 2nd, 27, the Bluetooth Technology Alliance officially approved the Bluetooth version 2.1 specification, namely "Bluetooth 2.1+EDR", which can be freely used by future devices. At present, this version still occupies a large share of the Bluetooth market. Compared with version 2., the standby time is mainly increased by more than 2 times, and the technical standards have not changed fundamentally.

This version of the standard is used for many Bluetooth speakers in the market, and for voice broadcasting after payment by mobile phones in streets and alleys. Commonly called audio Bluetooth, it supports SSP simple and secure pairing in Android, and requires MFI authentication in iOS.

the third generation bluetooth: High Speed, with a transmission rate as high as 24Mbps

29: bluetooth 3.

on April 21st, 29, the bluetooth technology alliance officially promulgated the bluetooth core specification version 3.. Bluetooth 3. adds an optional technology, High Speed, which enables Bluetooth to call 82.11 WiFi for high-speed data transmission. The transmission rate is as high as 24Mbps, which is 8 times that of Bluetooth 2.. It is easy to realize data transmission between video recorder and HDTV, PC to PMP and UMPC to printer (both parties need to meet this standard to realize the function).

the core of bluetooth 3. is AMP(Generic Alternate MAC/PHY), which is a brand-new alternating radio frequency technology, allowing the bluetooth protocol stack to dynamically select the correct radio frequency for any task.

In terms of power consumption, Bluetooth 3. introduced EPC enhanced power control technology, supplemented by 82.11, and the actual idle power consumption was significantly reduced.

the fourth generation of bluetooth: low power consumption

21: bluetooth 4.

the specification of bluetooth 4. was officially released on July 7, 21. the biggest significance of the new version lies in low power consumption, and at the same time, it strengthens the compatibility of devices among different manufacturers and reduces the delay. The theoretical maximum transmission speed is still 24Mbps (that is, 3MB/s), which effectively covers. It has a faster response speed, and can complete the connection setting and start data transmission within 3 milliseconds at the shortest. More secure technology, using AES-128 CCM encryption algorithm for packet encryption and authentication.

bluetooth 4. is the first bluetooth integrated protocol specification so far, which integrates three specifications. The most important change is the low-power function of BLE(Bluetooth Low Energy), and three modes of low-power Bluetooth, traditional Bluetooth and high-speed Bluetooth are put forward:

BLE, formerly a Wibree technology developed by NOKIA, was originally a very low-power mobile wireless communication technology specially developed for mobile devices, and was renamed Bluetooth Low Energy (hereinafter referred to as low-power Bluetooth) after being accepted and standardized by SIG. These three protocol specifications can also be combined and matched with each other, thus realizing a wider application mode.

the chip modes of bluetooth 4. are divided into Single mode and Dual mode. Single mode can only be transmitted with Bluetooth 4., and cannot be backward compatible with version 3./2.1/2.; Dual mode can be backwards compatibility version 3./2.1/2.. The former is applied to sensor devices using button cell, such as heart rate detectors and thermometers that require high power consumption; The latter is applied to traditional Bluetooth devices, while taking into account the demand of low power consumption.

213: Bluetooth 4.1

Bluetooth 4.1 was released on December 6, 213. If data is transmitted between Bluetooth 4.1 and LTE radio signals at the same time, Bluetooth 4.1 can automatically coordinate the transmission information between them, which can theoretically reduce the interference of other signals to Bluetooth 4.1. The improvement is to improve the connection speed and be more intelligent, such as reducing the reconnection between devices.