Unique-Word-Aided Linearized GMSK System with Frequency-Domain Decision Feedback Equalizer

A novel linearized Gaussian minimum shift keying (LGMSK) system is proposed for block data transmission. In each block, a known unique-word (UW) is inserted as guard interval, and a phase state return bit (PSRB) is also added to maintain LGMSK phase trellis consistency. It is shown that the transmit signal has near constant-envelope property. At the receiver, a frequency-domain decision-feedback-equalizer (FD-DFE) is designed to combat the joint effect of partial response signaling and the channel dispersion. With only a few feedback taps, the receiver can significantly outperform the FD linear equalizer. Compared with the Viterbi receiver, it has only 0.4-dB degradation at BER=10^-6 over AWGN channel. Hence, the proposed system has the great merits of transmit power saving, high performance, and low receiver complexity, especially for high-rate application through long dispersion channel