Transparent tone-in-band (TTIB) aided GMSK/MSK modem systems

The authors propose a scheme which employs BBC (binary block code) coding to allow carrier pilot insertion in GMSK/MSK (Gaussian minimum-shift keying/minimum-shift keying) modems for tone calibration and coherent detection. They analyze the performance of the BBC-coded GMSK/MSK modem and derive a closed-form expression for its performance under Rayleigh fading. The effect of carrier phase noise on the modem´s performance in a nonfading channel is investigated. it is found that, in the absence of fading, GMSK signalling with small bandwidth-time product (BT) value is more sensitive to carrier phase jitter than that with larger BT. The authors also investigated the performance of a BBC-coded GMSK modem with tone calibration over a Rayleigh fading channel. It is found that the modem is capable of delivering good performance in a Rayleigh fading environment where the more conventional coherent detection would cease to be practical due to its relatively high error floor