Differential Detection of Correlative Encoded Continuous Phase Modulation Sche1\1es Using Decision Feedback

In this paper, we generalize a differential detection technique, which was introduced in [1] for a Gaussian Minimum Shift Keying (GMSK) scheme, to include any Correlative Encoded Continous Phase Modulated (CECPM) signalling format. Similarly to [1], the proposed symbol-by-symbol receivers employ decision feedback to partially remove the effects of the destructive Inter-Symbol-Interference (lSI) which corrupts the differentially detected CECPM signal. After achieving wider eye-opening with the decision feedback, the output of the two or more differential detectors are jointly utilized to further improve the performance. As a typical example of the CECPM family of signals and because of its excellent spectral characteristics, the new receiver configurations employing up to 3-bit differential detectors have been applied to a Tamed Frequency Modulation (TFM) signal. Bit Error Rate (BER) performance evaluation results have indicated that performance improvements of more than 5 dB (at BER=10-4) over conventionally differential detected TFM scheme are possible. As compared to a limiter/discriminator receiver employing Maximum Likelihood Sequence Estimation (MLSE) [8], the proposed receivers offer gains of more than 2 dB (at BER=1O-4 ).