Abstract: A simplified model equivalent to Gaussian minimum shift keying (GMSK) signal with BT equaling 0.3 was expressed. In other words, the signal could be approximately equivalent to a four-state recursively convolutional code concatenated with quadrature phase shift keying (QPSK) modulation at sampling time. So that an iterative detection with joint demodulation was proposed for coded GMSK. The decoded soft information was then fed back to the demodulation for iterations. A comparison between joint demodulation and non-joint demodulation under additive white Gaussian noise (AWGN) channel was given by computer simulations. The simulation shows that an obvious improvement is obtained by joint demodulation.

Key words: coded Gaussian minimum shift keying, serial concatenated convolu-tional code, continuous phase modulation