What is Bluetooth
I. Origin of Bluetooth Name
Bluetooth's name is derived from the 10th century Danish King Harald Blatand - English translation is Harold Bluetooth. in the preparatory stage of the industry associations, the need for an extremely expressive name to The industry organizers, after a night of discussion about the Industry organizers, after a night of discussion about the history of Europe and the limitless technological developments of the future, some felt that the name King Blatand would be perfect. King Blatand united what is now Norway, Sweden and Denmark; just like the technology that will soon be available, the technology will be defined in a way that allows for coordinated work between different industrial sectors, 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 commemorates the achievements of King Blatand and his father, Denmark's first king, 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.
Second, the introduction of Bluetooth technology
"Bluetooth" (Bluetooth) was originally the name of the king of the tenth century united Denmark, and now take its meaning of "unity", used to name the wireless local area network 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 established Bluetooth technology special interest organization (SIG) to be responsible for the development of the technology and the development of technical agreements, now more than 1,800 companies around the world to join the organization, the recent Microsoft Corporation also formally joined and become one of the leading members of the SIG organization.
Bluetooth is an open standard for wireless data and voice transmission, which connects various communication devices, computers and their terminals, digital data systems, and even home appliances wirelessly. Its transmission distance is 10cm ~ 10m, if you increase the power or add some peripherals can reach 100m transmission distance. 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 wired cable connections, it is highly portable and applicable to a wide range of occasions, plus the technology is easy to promote because of its low power consumption, low harm to the human body, and simple, easy-to-implement applications.
Bluetooth technology
SIG organization in July 26, 1999 launched the Bluetooth technology specification 1.0 version. The system structure of Bluetooth technology is divided into three main 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 a logical link control and adaptation protocol, a service discovery protocol, a serial port emulation protocol, and a telephony communication protocol. The logical link control and adaptation protocol has the function of completing data disassembly, controlling quality of service and multiplexing protocols, and this layer is the basis for the implementation of the other layers. 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 instructions 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 it provides a unified command interface for calling hardware such as baseband, link management, status and control registers. When Bluetooth devices communicate with each other, 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 with each other through a transport layer that is transparent to both ends.
At the top of the Bluetooth stack are various high-level application frameworks. Typical ones include dial-up networking, headset, LAN access, file transfer, etc., which correspond to one application mode each. 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 multiple devices can also realize synchronous operation. This also allows for synchronized operation of multiple devices.
In short, the entire Bluetooth protocol is simple, using the retransmission mechanism to ensure link reliability, in the baseband, link management and application layer can also be implemented in a graded variety of security mechanisms, and through the frequency-hopping technology can be eliminated in the network environment from the interference of other wireless devices.
Application Prospects
Bluetooth technology has a wide range of applications, and can be widely used in local area networks for various types of data and voice equipment, such as PCs, dial-up networks, laptops, printers, fax machines, digital cameras, cell phones and high-quality headsets, etc. Bluetooth wireless communication will be the above equipment into a micro-micro-network (Piconet), and multiple micro-micro-networks can also 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, automotive industry, information appliances, medical equipment, school education and factory automation. 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 their quality of life.
What is Bluetooth?
Bluetooth (Bluetooth) is a close-range wireless data communication technology standard proposed by Toshiba, Ericsson, IBM, Intel and Nokia in May 1998***. It can realize single-point-to-multipoint wireless data and sound transmission within a 10-meter radius, with a data transmission bandwidth of up to 1 Mbps. The communication medium is an electromagnetic wave with a frequency between 2.402 GHz and 2.480 GHz.
Bluetooth communication technology features
■ Bluetooth work in the global open 2.4GHz ISM (i.e., industrial, scientific, medical) band;
■ Use of frequency-hopping spectrum expansion technology, the frequency band is divided into a number of frequency-hopping channel (hop channel), in a connection, the radio transceiver according to a certain code sequence constantly from a channel In a connection, the radio transceiver continuously "hops" from one channel to another according to a certain code sequence;
■A Bluetooth device can simultaneously establish a connection with seven other Bluetooth devices;
■Data transfer rate up to 1Mbit/s;
■Low-power consumption, communication security is good;
■Can be connected over obstacles within the effective range,
■Can be connected without special communication viewpoints. Connection, there is no special communication perspective and direction requirements;
■Support for voice transmission;
■Simple and convenient networking
Bluetooth communication technology
Bluetooth technology is an emerging technology, has not yet been put into widespread use, many Bluetooth devices are still in the laboratory test phase. However, it is certain that most of the devices with infrared wireless data communication function, in the future as much as the use of Bluetooth technology to realize the wireless connection. At the same time, the network characteristics of Bluetooth technology and voice transmission technology so that it can also realize the infrared technology can not be achieved in some specific functions, such as wireless phones, multi-device networking and so on.
Manufacturers and consumer acceptance
Bluetooth technology has gained the response of more than two thousand enterprises, which has a huge development and production capacity. Bluetooth has already possessed a high degree of popularity, and the majority of consumers are very interested in this technology.
Implantation cost
Currently on the market Bluetooth devices are still relatively rare. USB interface Bluetooth adapter, Bluetooth PC card and Bluetooth cell phone have been market-oriented products, the price is very high. This shows that the early development stage of Bluetooth implantation costs are still relatively high. However, it is estimated that the implantation cost can be under 30 dollars after batch production. In the period of mature development of Bluetooth technology, the implantation cost should be able to control within 10 dollars.
Disadvantages
Bluetooth is a technology that has not yet fully matured, and although it is described as promising, it has yet to be rigorously tested in real-world use. Bluetooth also doesn't communicate at a very high rate, which may also have an impact on its development in today's data-explosive age.
Currently, mainstream software and hardware platforms do not provide support for Bluetooth, which makes the application of Bluetooth more costly and more difficult to popularize.
The ISM band is an open band and may be subject to interference from, for example, microwave ovens, cordless telephones, scientific research instruments, and industrial or medical equipment.
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