Introduction of Bluetooth
Bluetooth is a low-power,short-distance radio technology, originally developed as a cable replacement to connect devices such as mobile phone handsets,headsets and portable computers. Bluetooth uses frequency spectrum in the range of 2400 MHz to 2483.5 MHz. Bluetooth allows both time critical data communication like voice and audio,as well as high speed,time insensitive packet data communication. Data rate via Bluetooth connection can be up 723.2 kbps. Each Bluetooth device has a unique-48-bit IEEE MAC address known as the Bluetooth device address (BD-ADDR) that is used to identify a Bluetooth device. This address cannot be easily changed by the end-user.Because Bluetooth is designed for low-powered portable applications, the radio power must be minimized.
Files can be transferred between two Bluetooth devices using OBEX (Object Exchange) file transfer. OBEX is binary protocol designed to allow a variety of devices to exchange data simply and spontaneously. Briefly, OBEX defines a session protocol that is used to send request from a client to a server. The server replies with responses.When one Bluetooth device wants to download files from another Bluetooth device, it first searches if the other device is in range. On success, a Bluetooth connection will be set up between two devices.After the connection is set up, the file can be transferred from source to destination by using OBEX protocol if in both devices OBEX is implemented. The Bluetooth radio is the lowest of Bluetooth communication.
Bluetooth devices are divided into three power classes; the only difference between them is the transmission power levels used. Table 1.1 summarizes their differences among the power classes of Bluetooth. Almost all Bluetooth-enabled cell phones,headsets,laptops,and other consumer-level Bluetooth devices are class 2 devices. There are many class 1 USB devices for sale to consumers. It is the higher class that determines the properties. If a class 1 USB device communicates with a class 2 Bluetooth cell phone, the cell phone limits the range Bluetooth radio. Class 3 Bluetooth device are rare, as their limited range heavily restricts their usefulness.
Bluetooth is a low-power,short-distance radio technology, originally developed as a cable replacement to connect devices such as mobile phone handsets,headsets and portable computers. Bluetooth uses frequency spectrum in the range of 2400 MHz to 2483.5 MHz. Bluetooth allows both time critical data communication like voice and audio,as well as high speed,time insensitive packet data communication. Data rate via Bluetooth connection can be up 723.2 kbps. Each Bluetooth device has a unique-48-bit IEEE MAC address known as the Bluetooth device address (BD-ADDR) that is used to identify a Bluetooth device. This address cannot be easily changed by the end-user.Because Bluetooth is designed for low-powered portable applications, the radio power must be minimized.
Files can be transferred between two Bluetooth devices using OBEX (Object Exchange) file transfer. OBEX is binary protocol designed to allow a variety of devices to exchange data simply and spontaneously. Briefly, OBEX defines a session protocol that is used to send request from a client to a server. The server replies with responses.When one Bluetooth device wants to download files from another Bluetooth device, it first searches if the other device is in range. On success, a Bluetooth connection will be set up between two devices.After the connection is set up, the file can be transferred from source to destination by using OBEX protocol if in both devices OBEX is implemented. The Bluetooth radio is the lowest of Bluetooth communication.
Bluetooth devices are divided into three power classes; the only difference between them is the transmission power levels used. Table 1.1 summarizes their differences among the power classes of Bluetooth. Almost all Bluetooth-enabled cell phones,headsets,laptops,and other consumer-level Bluetooth devices are class 2 devices. There are many class 1 USB devices for sale to consumers. It is the higher class that determines the properties. If a class 1 USB device communicates with a class 2 Bluetooth cell phone, the cell phone limits the range Bluetooth radio. Class 3 Bluetooth device are rare, as their limited range heavily restricts their usefulness.
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