MLSE based detection for GFSK signals with arbitrary modulation index

Due to its widespread use in cordless indoor systems like DECT, Bluetooth etc., Gaussian frequency-shift keying (GFSK) is an important modulation method. In this paper we present an approach to apply maximum likelihood sequence estimation (MLSE) to GFSK modulated signals. Using a linearized model of the modulation, we develop a pseudo-coherent detection scheme based on the estimation of the transmitter state. With this approach a joint detection and estimation scheme can be realized that allows the application of a Viterbi type equalizer to GFSK signals with arbitrary modulation indices. Simulation results show a gain of up to 7 dB with respect to conventional approaches.