"Bluetooth" is the formation of the background is this: in May 1998, Ericsson, Nokia, Toshiba, IBM and Intel Corporation and other five well-known manufacturers, in the joint standardization of short-range wireless communications technology activities proposed Bluetooth technology, its purpose is to provide a short-range, low-cost wireless transmission The purpose was to provide a short-range, low-cost wireless transmission technology for applications. These five vendors also established the Bluetooth Special Interest Group to enable Bluetooth technology to become the future standard for wireless communications. Chip juggernaut Intel was responsible for the development of semiconductor chips and transmission software, Ericsson was responsible for the development of wireless RF and cell phone software, and IBM and Toshiba were responsible for the development of interface specifications for notebook computers.In the second half of 1999, well-known industry giants Microsoft, Motorola, Sankon, Lucent, and the five Bluetooth Special Interest Group companies*** co-sponsored the establishment of the Bluetooth Technology Promotional Organization (BTPO), thereby creating a The world set off a wave of "Bluetooth" boom. The global industry is about to develop a large number of Bluetooth technology applications, so that Bluetooth technology presents an extremely broad market prospects, and heralds the beginning of the 21st century will usher in a magnificent wave of global wireless communications.
"Bluetooth" (Bluetooth) is a low-power, short-range wireless connection technology standard, the word "Bluetooth" from a united Denmark in the 10th century A.D. King, Harald II, (Harald) nicknamed "Bluetooth" (Bluetooth)." The original proponents of Bluetooth technology were five of the world's leading computer and communications companies: Ericsson, IBM, Intel, Nokia, and Toshiba, and in May 1998, the Bluetooth Special Interest Group (SIG) was formed. In May 1998, the Bluetooth Special Interest Group (SIG) was formed, and the organization adopted the strategy of transferring the patented technology to industry at no cost to achieve its goal of a globally harmonized standard.
The goal is to achieve the highest data transmission speed of 1Mbps (effective transmission speed of 721kbps), the maximum transmission distance of 10 meters, the user does not have to be permitted to use the 2.4GHz ISM (Industrial, Scientific, Medical) band, on which the establishment of 79 bandwidth of 1MHz channel, with a frequency of 1,600 switching per second, the hobbing () method. Hobbing) way of spectrum diffusion technology to realize the sending and receiving of radio waves. This is the origin and characteristics of Bluetooth technology. Devices that communicate using Bluetooth technology are divided into a "calling party" that decides the frequency of the hobbing mode and its communication counterpart, the "receiving party". The calling party can communicate with 7 receiving parties at the same time. Therefore, it is possible to connect the caller and seven recipients***8 devices into a subnet called Piconet (sawtooth network), and the recipients in a Piconet can be the recipients of more than two Piconets at the same time. in July 1999, Bluetooth announced the official specification of BluetoothVersion 1.0, and cell phones and notebook PCs complying with this specification will be available by the end of 1999 or 2000, and will be available in the future. laptops will be available in late 1999 or early 2000. The number of companies claiming to productize Bluetooth technology is growing, with the Bluetooth standardization group, the BluetoothSIG (Special Interest Group), now numbering more than 800 members.
"Bluetooth" technology is designed to smart cell phones and laptops, PDAs, and a variety of digitized information devices can no longer use cables, but a small, low-cost wireless communications technology to connect up; and then form a personal side of the network, so that a variety of information technology within the scope of the mobile portable devices can be seamlessly realize the resources **** enjoy. According to foreign authorities expect, a few years later, the world will have hundreds of millions of digital cell phones, PCs and a variety of information equipment will be based on Bluetooth technology wireless interface as a standard configuration. Bluetooth technology will be in a variety of areas of rapid development, its typical application environment, including wireless office environment (Wireless Office), the automotive industry, medical equipment, etc. Bluetooth will play an important role in people's daily lives and work, the market potential is huge, the technology is becoming the 21st century investment hot spot.
What is Bluetooth
One, the origin of the name of Bluetooth
Bluetooth's name comes from the 10th century Danish king Harald Blatand - English translation for Harold Bluetooth. in the preparatory stage of the industry associations, the need for a very expressive name to name this high technology. After a night of discussion amongst industry organizers about the history of Europe and the unlimited future of the technology, some felt that King Blatand was the perfect name for it. King Blatand united what is now Norway, Sweden and Denmark; and just like the technology that is to come, the technology will be defined to allow for coordinated work between different areas of the industry such as the computing, cell phone and automotive industries. automotive industries to work together. The name was thus settled.
In the Danish city of Jelling, there is a monument in the church that honors the achievements of King Blatand and his father, the first king of Denmark, "Gorm the Old". Interestingly, this particular stone was lost after a battle between Harald and his son Sven Forkbeard, and no one has seen it for almost 600 years; Sven won (and exiled his father), and because the stone with the ancient Norse inscription was an honor to Harald, Sven buried it. It wasn't until the last few years that a farmer became curious about this large mound of dirt on his farm and finally discovered the stone.
The logo was originally designed by Scandinavian when the business association was announced. The logo retains the traditional character of its name, containing the Old Norse letter "H", which looks very similar to an asterisk and a "B", both of which can be seen when looking closely at the logo.
Two, Bluetooth technology
"Bluetooth" (Bluetooth) was originally the name of the king of Denmark in the tenth century united, and now take the meaning of its "unity", used to name the wireless LAN communication standards intended to unify the Bluetooth technology. Bluetooth technology. Bluetooth technology is a wireless network technology jointly launched by Ericsson, IBM and five other companies in 1998. Subsequently, the Bluetooth Special Interest Group (SIG) was established to be responsible for the development of the technology and the formulation of technical agreements, and now there are more than 1,800 companies around the world that have joined the organization, and recently Microsoft has officially joined and become one of the leading members of the SIG organization.
Bluetooth is an open standard for wireless data and voice transmission that connects a variety of communication devices, computers and their terminals, digital data systems, and even home appliances wirelessly. Its transmission distance is 10cm to 10m, and if the power is increased or some peripherals are added, the transmission distance can reach 100m. It adopts 2.4GHz ISM band and FM, frequency hopping technology, using right-to-error correction coding, ARQ, TDD and baseband protocols.TDMA is 0.625μs per time slot, and the baseband complies with the rate of 1Mb/s. Bluetooth supports real-time voice and data transmission at 64kb/s, with voice coding as CVSD, and the transmit power is 1mW, 2.5mW, and 100mW, respectively, and uses a globally standardized 48-bit device identification code. Because Bluetooth uses a wireless interface to replace the wired cable connection, it has strong portability and is suitable for a wide range of occasions, coupled with the technology's low power consumption, low harm to the human body, and the application is simple and easy to implement, so it is easy to promote.
Bluetooth technology
SIG organization in July 26, 1999 launched the Bluetooth technical specifications 1.0 version. The system structure of Bluetooth technology is divided into three major parts: the underlying hardware module, the intermediate protocol layer and the high-level application. The underlying hardware part includes radio frequency hopping (RF), baseband (BB) and link management (LM). The wireless frequency hopping (RF) layer filters and transmits data bit streams through microwaves in the 2.4GHz unauthorized ISM band. This protocol layer mainly defines the conditions that Bluetooth transceivers need to satisfy for normal operation in this band. Baseband is responsible for frequency hopping and the transmission of Bluetooth data and information frames. Link management is responsible for connecting, establishing and dismantling links and performing security controls.
Bluetooth technology combines circuit-switched and packet-switched features to enable asynchronous data communications, support for up to three simultaneous synchronous voice channels, and the ability to use a single channel to transmit both asynchronous data and synchronous voice. Each voice channel supports a synchronous voice link of 64 kb/sec. Asynchronous channels can support asymmetric links with a maximum rate of 721kb/sec at one end and 57.6kb/sec at the other, as well as symmetric links with a rate of 43.2kb/sec.
The intermediate protocol layer includes the logical link control and adaptation protocol, the service discovery protocol, the serial emulation protocol, and the telephony communication protocol. The logical link control and adaptation protocol has the function of completing data disassembly, controlling the quality of service and multiplexing protocols, and this layer of protocols is the basis for the realization of the other layers of protocols. The Service Discovery Protocol layer provides a mechanism for upper layer applications to discover the services available in the network and their characteristics. The serial port emulation protocol layer has the capability to emulate a 9-pin RS232 serial port. The telephony communication protocol layer provides call control commands for voice and data between Bluetooth devices.
The Host Control Interface (HCI) layer is the interface between hardware and software in the Bluetooth protocol, and provides a unified command interface for calling hardware such as baseband, link management, status, and control registers. When communicating between Bluetooth devices, the protocol software entities above the HCI run on the host computer, while the functions below the HCI are performed by the Bluetooth device, and the two interact through a transport layer that is transparent to both ends.
At the top of the Bluetooth stack are various high-level application frameworks. The more typical ones are dial-up networking, headset, LAN access, file transfer, etc., which correspond to an application mode. Various applications can realize wireless communication through their corresponding application modes. Dial-up network applications can access the Piconet through the emulated serial port, and data devices can also access the traditional LAN; users can realize wireless transmission of audio streams in cell phones and earbuds through the Audio layer in the protocol stack; multiple PCs or laptops can quickly and flexibly transfer files and *** enjoy information without any wires, and synchronized operation can also be realized between multiple devices. This means that you can also synchronize the operation of your PCs with other devices.
In short, the entire Bluetooth protocol is simple and uses a retransmission mechanism to ensure link reliability, and a variety of security mechanisms can be implemented in the baseband, link management, and application layers for hierarchical security, and frequency hopping technology to eliminate interference from other wireless devices in the network environment.
Application Prospects
Bluetooth technology has a wide range of applications, and can be widely used in local area networks for all types of data and voice devices, such as PCs, dial-up networks, laptops, printers, fax machines, digital cameras, cell phones, and high-quality headsets, etc. Bluetooth's wireless communication method connects the above devices to a Piconet, and multiple Piconets can be connected to each other. Multiple micro-micro-network can also be connected to each other, thus realizing the communication between various types of equipment at any time and anywhere. Typical environments where Bluetooth technology is applied include wireless office environment, automobile industry, information appliances, medical equipment, as well as school education and factory automatic control. At present, the initial products of bluetooth has come out, some chip manufacturers have begun to improve the chip with bluetooth function. At the same time, some powerful software companies or the introduction of their own protocol stack software, or with the chip manufacturers to launch a Bluetooth technology to achieve the specific program. Nevertheless, Bluetooth technology to really popularize the following problems need to be solved: first of all, to reduce costs; secondly, to achieve convenient, practical, and really bring benefits to people; thirdly, to be safe, stable and reliable work; fourthly, to introduce an authoritative international standard as soon as possible. Once the above problems are solved, Bluetooth will rapidly change the way people live and work, and greatly improve people's quality of life.