Bluetooth is a wireless communication technology that uses GFSK (Gaussian Frequency Shift Keying) modulation. In GFSK modulation, the frequency of the carrier is shifted to carry the modulation. By doing this, Bluetooth achieves a bandwidth of 1 MHz with stringent filter requirements to prevent interference on other channels. DQPSK (Differential Quadrature Phase Shift Keying), BPSK (Binary Phase Shift Keying), and MSK (Minimum Shift Keying) are also modulation schemes used in wireless communication technologies.