The Gaussian Minimum Shift Keying (GMSK) modulation scheme is a digital modulation technique used in many mobile communication systems, including GSM. It is a type of Frequency Shift Keying (FSK) where the digital information is carried through changes in the frequency of the carrier wave. GMSK is favoured for its spectral efficiency and ability to minimise phase discontinuities, which reduces the amount of sideband power, making it less likely to interfere with neighbouring channels. This modulation scheme is also known for its constant envelope, which allows for the use of non-linear power amplifiers, reducing the overall power consumption.