## What is GMSK modulation technique?

The Gaussian Minimum Shift Keying (GMSK) modulation is a modified version of the Minimum Shift Keying (MSK) modulation where the phase is further filtered through a Gaussian filter to smooth the transitions from one point to the next in the constellation.

### Why GMSK modulation technique is used in GSM mobile?

GMSK is a special case of MSK modulation. The phase of the transmitted signal in GMSK scheme is continuous and smoothed by a Gaussian filter. This results in more compact spectrum than MSK and enables better utilization of the available frequency spectrum, at the expense of increased inter-symbol interference (ISI).

#### What is GMSK in mobile communication?

Gaussian Minimum Shift Keying, or to give it its full title Gaussian filtered Minimum Shift Keying, GMSK, is a form of frequency modulation that is used in radio communications systems.

What wireless technology that uses GMSK modulation?

Special forms of FSK, such as GMSK used with older GSM cell phones, are a bit better. BPSK has a spectral efficiency of 1. Table 8.1 gives the efficiencies of most of the popular digital wireless modulation schemes….Spectral Efficiency.

Modulation Method Spectral Efficiency (bps/Hz)
GMSK 1.35
BPSK 1
QPSK 2
16-QAM 4

How is GMSK different from MSK?

GMSK differs from MSK (Minimum Shift Keying) in that a Gaussian Filter of an appropriate bandwidth (defined by the BT product) is used before the modulation stage. The time-domain impulse response of the filter is described in Equation 1, where k 1 = p 2 ln 2 and B is the half-power bandwidth.

## How GMSK is better than MSK?

GMSK spectral efficiency is better than MSK as shown in figure 5. Also it has reasonably less demodulator complexity. Disadvantages- Power spectral density of MSK does not fall fast hence will not reduce interference completely between adjacent channels. Hence GMSK is designed with various BT factors.

### What does GFSK stand for?

GFSK stands for Gaussin Frequency Shift Keying modulation. In GFSK, baseband pulses (consists of -1 and 1) are first passed through the gaussian filter before modulation. This makes pulses smooth and hence limit the modulated spectrum width. This process is known as pulse shaping.

#### What is the difference between FSK and GFSK?

First of all, GFSK modulation is a much cleaner signal than FSK. This is because GFSK process filters out spurious to a much narrower transmission bandwidth than FSK. But in addition to that, we are now transmitting at 76.8Kbps which has a much wider bandwidth than 4.8Kbps we used before.