The so-called Bluetooth technology is actually a short-range radio technology. Bluetooth technology can effectively simplify the communication between mobile communication terminal devices such as palmtop computers, notebook computers and mobile phones, and can also successfully simplify the communication between these devices and the Internet, thus making the data transmission between these modern communication devices and the Internet faster and more efficient, and broadening the road for wireless communication. In layman's terms, it is Bluetooth technology.
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Technology enables some modern portable mobile communication devices and computer devices to be networked without cables, and can be wirelessly connected to the Internet. Its practical application can also be extended to various household appliances such as automobiles, consumer electronic products and information household appliances, forming a huge wireless communication network. Bluetooth technology is a short-distance and low-cost wireless connection technology, and it is an open scheme that can realize wireless transmission of voice and data. Therefore, the "Bluetooth" of wireless communication has just appeared, but it has attracted the close attention of the global communication industry and users.
Second, the origin of Bluetooth
Bluetooth was named after the Scandinavian king who unified Denmark and Sweden in the 10 century. It has given birth to a rather magical prospect: for mobile phones, there is no need to connect headphones; In personal computer, the host can get rid of the messy connection with keyboard, monitor and printer; In a wider range, household appliances such as refrigerators and microwave ovens can be connected with computer networks to realize intelligent operation.
The inventor of Bluetooth technology is Swedish telecom giant Ericsson. Because this technology has a very broad application prospect,1In May 1998, five top communication/computer companies in the world, Ericsson, Nokia, Toshiba, IBM and Intel, jointly established the Bluetooth Interest Group (Bluetooth SIG) through negotiation to accelerate its development, promotion and application. After the publication of this wireless communication technology, it quickly won the unanimous support of a large number of companies including Motorola, 3Com, Lucent, Compaq and Siemens. Up to now, more than 2,000 companies have joined Bluetooth SIG, including many of the world's most famous enterprises in the fields of computers, communications and consumer electronics, and even manufacturers and producers of automobiles and cameras. An open technical specification can get such extensive attention and support from the industry, which shows that products based on this Bluetooth technology will have broad application prospects and huge potential market. Bluetooth * * * The same interest group is now renamed Bluetooth Promotion Group.
Third, the technical content of Bluetooth.
Bluetooth technology products use low-energy radio communication technology to realize voice, data and video transmission. The highest transmission rate is 1mb/s per second, and full-duplex communication is carried out in time division mode. The communication distance is about 10 meter. The configuration of power amplifier can further increase the communication distance.
Bluetooth products adopt frequency hopping technology, which can resist signal fading; Adopting fast frequency hopping and short packet technology can effectively reduce co-frequency interference and improve communication security; Adopting forward error correction coding technology to reduce the interference of random noise in long-distance communication; Adopt 2.4GHz ISM (industrial, scientific and medical) frequency band, saving the trouble of applying for special license; Adopt FM modulation mode to make the equipment more simple and reliable; Bluetooth technology products send a synchronization packet with a frequency hopping, each packet occupies a time slot, which can also be increased to five time slots; Bluetooth technology supports asynchronous data channels, or three synchronous voice channels, or channels that simultaneously transmit asynchronous data and synchronous voice. Bluetooth supports synchronous voice at 64Kbps in each voice channel, asymmetric connection at the maximum rate of 72 1Kbps in asynchronous channel, and symmetric connection at the reverse response rate of 57.6Kbps or 432.6Kbps.
The communication between Bluetooth technology products and the Internet enables home and office equipment to be interconnected without cables, which greatly improves the efficiency of office and communication. Therefore, "Bluetooth" will become the new favorite in the field of wireless communication, which will provide great convenience for users and be favored.
Four, Bluetooth technical indicators and system parameters
See table 1 for the published Bluetooth technical parameters. (200 1.5)
Table 1 Bluetooth technical parameters
Working band ISM band, 2.402～2.480 GHz
Duplex mode full duplex, TDD time division duplex
The service type supports circuit-switched and packet-switched services.
Data rate 1Mb/ sec
The asynchronous channel rate of asymmetric connection is 72 1/57.6kb/s, and that of symmetric connection is 432.6 kb/s.
Synchronous channel rate 64Kb/s
The power required by the FCC in the United States is less than 0 DBM (1 MW), and other countries can extend it to 100mW.
The frequency of frequency hopping is 79 frequency points /MHz.
Frequency hopping rate 1600 times/second
Working Mode Stay/Hold/Sniff
The data connection mode is oriented to the connection service SCO, and there is no connection service ACL.
Error correction mode 1/3FEC, 2/3FEC, ARQ.
The authentication adopts reactive logic algorithm.
Channel encryption uses 0-bit, 40-bit and 60-bit keys.
Continuous variable slope modulation CVSD in speech coding mode
Generally, the transmitting distance can reach 10~ 10cm, and it can reach 100m with the increase of power.
Verb (abbreviation of verb) Bluetooth technical term
A piconet is a network composed of devices that use Bluetooth technology in a specific way. The establishment of a piconet starts with the connection of two devices (such as a portable computer and a cellular phone) and consists of at most eight devices. All Bluetooth devices are peer-to-peer and work in the same way. However, when a piconet is established, only one is the master device, and the others are all slaves, and this situation will remain during the existence of the piconet.
The decentralized network consists of several independent asynchronous piconets.
Master device refers to a piconet. If a device's clock and frequency hopping sequence are used to synchronize other devices, it is called a master device. Slave means that all devices that are not master devices are slaves.
The MAC address is an address represented by 3 bits, which is used to distinguish devices in a piconet. A resident unit is a device that only participates in synchronization in a piconet, but has no MAC address. Sniffing and holding modes refer to two low-power working modes of slave devices in piconet.