Differentially coherent detection of MSK

The author extends to minimum shift keying (MSK) modulation the differentially coherent reception theory established for phase shift keying (PSK) modulation. A differentially coherent detector for MSK is thus derived. He shows that performance can be improved when the delay between signals, multiplied by the differential detector, is increased from one-bit to M-bit time intervals. In order to keep the differential detector simple, M should be odd. The bit error probability of the proposed receiver is calculated. It is found that almost all potential improvement due to the delay M is obtained with M=3. For the same probability of error the required E _b/N₀ in the present case is just 1.15 dB more than for differential binary PSK. Simulations, for M =1 and M=3 confirm the theoretical analysis