Bluetooth is an open standard for wireless data and voice transmission, which wirelessly connects various communication devices, computers and their terminal devices, various digital data systems and even household appliances. Its transmission distance is 10 cm ~ 10 m, and it can reach 100m if the power is increased or some peripherals are added. It adopts 2.4GHz ISM band, frequency modulation and frequency hopping technology, and uses directional error correction coding, ARQ, TDD and baseband protocols. TDMA is 0.625μs per time slot, baseband coincidence rate is 1mb/s, and bluetooth supports 64kb/s real-time voice transmission and data transmission. The speech coding is CVSD, and the transmission power is 1mW, 2.5mW and 100mW respectively, using the globally unified 48-bit equipment identification code. Because Bluetooth uses wireless interface instead of wired cable connection, it is portable and suitable for many occasions. In addition, the technology has the advantages of low power consumption, little harm to human body, simple application, easy realization and easy popularization. On July 26th, 1999, the Bluetooth technical standard 1.0 was released by SIG. The architecture of Bluetooth technology is divided into three parts: the bottom hardware module, the middle protocol layer and the high-level application. The underlying hardware includes radio frequency hopping (RF), baseband (BB) and link management (LM). The wireless frequency hopping layer filters and transmits the data bit stream through the 2.4GHz unauthorized ISM band microwave. This layer protocol mainly defines the conditions that Bluetooth transceiver needs to meet in this frequency band. Baseband is responsible for frequency hopping and transmission of Bluetooth data and information frames. Link management is responsible for connecting, establishing and dismantling links, and carrying out security control. Bluetooth technology combines the characteristics of circuit switching and packet switching, which can carry out asynchronous data communication, support at most three simultaneous voice channels, and can also transmit asynchronous data and synchronous voice simultaneously with one channel. Each voice channel supports 64kb/ s synchronous voice link. Asynchronous channel can support asymmetric connection with the maximum rate of 72 1kb/ s at one end and 57.6kb/ s at the other end, and can also support symmetric connection with the rate of 43.2 kb/s. The intermediate protocol layer includes logical link control and adaptation protocol, service discovery protocol, serial port simulation protocol and telephone communication protocol. Logical link control and adaptation protocol has the functions of completing data disassembly, controlling service quality and multiplexing protocol, and is the basis of other protocols. The service discovery protocol layer provides a mechanism for the upper application to discover the available services and their characteristics in the network. The serial port simulation protocol layer has the function of simulating a 9-pin RS232 serial port. The telephone communication protocol layer provides call control instructions for voice and data between Bluetooth devices. Host Control Interface Layer (HCI) is the interface between hardware and software in Bluetooth protocol, which 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 HCI run on the host, while the functions below HCI are completed by Bluetooth devices, and they interact through the transport layer transparent to both ends. At the top of the Bluetooth protocol stack are various advanced application frameworks. Among them, dial-up network, earphone, LAN access, file transfer and so on are typical, corresponding to an application mode respectively. Various applications can realize wireless communication through their corresponding application modes. Dial-up network applications can access piconets through analog serial ports, and data devices can also access traditional local area networks. Users can realize the wireless transmission of audio streams in mobile phones and earplugs through the audio layer in the protocol stack. You can transfer files and enjoy information quickly and flexibly without any connection between multiple PCs or laptops, and you can synchronize multiple devices.