Iterative noncoherent sequence detection and decoding of serially concatenated coded MSK

Some previous research has been done on the coherent serially concatenated coded MSK (SC-MSK) (V.F. Szeto et al., Sept. 1999). We propose an iterative noncoherent sequence detection (NSD) and decoding of SC-MSK based on the soft-output (SO) NSD (G. Colavolpe et al., Sept. 2000). Here, the exponentially decaying observation window (EDW) (R. Schober et al., Dec. 1999) is applied in SO-NSD, in place of the original rectangular observation window (RW). The SO-NSD with EDW can achieve comparable performance to that of the optimal and more complex noncoherent BCJR (N-BCJR) with RW (G. Colavolpe et al., Sept. 2000) in the iterative detection. Besides its use in AWGN channel, we also extend it to flat Rayleigh fading channel and derive the decoding metric without channel state information (CSI). The noncoherent SC-MSK is robust to smaller phase change in AWGN channel, and it also performs well in slow, flat Rayleigh fading channel.