2400 – 2483.5 MHz (ISM-Band)
Bluetooth is used for short distance communications between devices such as computers, peripherals, mobile phones, and PDAs. The communication method was developed in the 1990s by the Bluetooth Special Interest Group (SIG), a working group of five industrial companies, and first standardized by IEEE in 2002 (IEEE 802.15). Bluetooth version 4.1 was announced by Bluetooth SIG on December, 4th 2013.
For 1 Mbit/s: GFSK (+/-140 kHz hub)
For 2 Mbit/s: π/4-DQPSK (Bluetooth version 2.0 onwards)
For 3 Mbit/s: 8-DPSK (Bluetooth version 2.0 onwards)
Transmitting and receiving combines TDD (time division duplex) and FDD (frequency division duplex). Frequency hopping with hops of 1 or 2 MHz after every timeslot. Timeslots spaced at 625 µs. 366 µs of the timeslot are used for a burst. The last timeslot is correspondingly truncated for multislot packets.