Bluetooth

Bluetooth wireless technology was created by the Ericsson mobile phone company as an alternative to using wired data cables to connect devices. Today the Bluetooth standard is overseen by the Bluetooth Special Interest Group (SIG). The IEEE previously standardized Bluetooth as IEEE 802.15.1.

Bluetooth operates at frequencies between 2402 and 2480 MHz, or 2400 and 2483.5 MHz including guard bands 2 MHz wide at the bottom end and 3.5 MHz wide at the top.

Frequency Spread:

• 2.4GHZ to 2.4835GHz

Bluetooth is a packet-based protocol with a master/slave architecture. A master BR/EDR Bluetooth device can communicate with a maximum of seven devices in a piconet. The devices can switch roles, by agreement, and the slave can become the master.

Bluetooth is short range. Because the devices use a radio broadcast communications system, they do not have to be in visual line of sight of each other.

• Class 1 Bluetooth range 300ft allocated for industrial use
• Class 2 Bluetooth range 30ft allocated for consumer mobile devices
• Class 3 Bluetooth range 3ft allocated for consumer mobile devices

Most Bluetooth applications are for indoor conditions, where attenuation of walls and signal fading due to signal reflections make the range far lower. Most Bluetooth applications are battery powered Class 2 devices, with little difference in range whether the other end of the link is a Class 1 or Class 2 device as the lower powered device tends to set the range limit.

Bluetooth and Wi-Fi have some similar applications: setting up networks, printing, or transferring files. Wi-Fi is intended as a replacement for high speed cabling for general local area network access in work areas or home. Bluetooth was intended for portable equipment and its applications. Wi-Fi is usually access point-centered. Bluetooth is usually symmetrical, between two Bluetooth devices. Bluetooth serves well in simple applications where two devices need to connect with minimal configuration.