An improved sequential decoder for the discriminator detection of the continuous phase modulation schemes based on noise estimation techniques

Abstract

For the limiter-discriminator detection of continuous phase modulation (CPM) signals, a sequential detector is introduced. The decoder takes into account the strong noise correlation between the successive noise samples of the received signal, and uses it in the estimation process. The algorithm has been evaluated for minimum shift keying (MSK) and duobinary MSK, both in additive white Gaussian noise and fading conditions. In comparison with the conventional symbol-by-symbol detector, the technique offers gains of 2.25 dB for the MSK and 2.8 dB for the duobinary MSK (at BER=10/sup -4/). It outperforms the conventional Viterbi decoder (applied on a duobinary MSK signal) by 1 dB. >