Intersymbol interference reduction for differential MSK by nonredundant error correction

A theoretical analysis and experimental results for differential detection of minimum-shift keying (MSK) with nonredundant error correction are described. The proposed demodulator utilizes the output detected from the difference in phase over two or three time slot intervals along with the conventional detector output. A single error can be corrected by using two differential detectors, and a single and a double error can be corrected by using three detectors. It is shown that the error rate performance is improved, especially in the presence of intersymbol interference (ISI), without the addition to the transmitted data of redundant bits. Simulation and experimental results agree with the theoretical analysis, which shows that the degradation of differential detection relative to coherent detection is reduced from 2.2 dB without error correction to 1.2 dB with single error correction and to 0.7 dB with double error correction. The method can be applied effectively to mobile communications over a fading channel or to time-division multiple-access (TDMA) communications using burst mode transmission.<
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