Spectral occupancy and error rate considerations of coherent GMSK

The objective of this proper is to develop an analytical method of calculating the average power spectral density (PSD) and bit error rate (BER) of Gaussian minimum shift keying (GMSK) modulation scheme. GMSK modulation has been widely used in terrestrial and satellite communication systems. No method, other than simulation is currently available to calculate GMSK PSD. In this paper we express the PSD in a compact Hermitian form suitable for numerical computation. We also analyze the BER performance of a coherent I-Q receiver. The relationship between out of band radiation attenuation and BER degradation is clearly shown. The degradation caused by the transmit and receive filters is estimated. The formulas given in this paper can be extended to arbitrary pulse shapes of finite duration.