Serial and parallel demodulation trade-offs for QBL-MSK

The authors discuss quasi bandlimited MSK. Analytical and simulated BER performance results for both carrier phase and bit synchronization timing errors were determined for serial and parallel demodulation. For a nonlimited modulated signal and ideal demodulator (no carrier phase or timing error), a BER degradation of 0.41 dB with respect to MSK performance is achieved for both serial and parallel demodulators with the sub-optimum data filter. A limited modulation signal increases the BER degradation by no more than 0.2 dB for both demodulator architectures. Serial demodulation is shown to be less sensitive to carrier phase error, while parallel demodulation offers less sensitivity to timing error. For both carrier phase and timing errors, the serial demodulator will provide less BER degradation than the parallel, if the timing error is kept small. Serial demodulation using average zero crossing bit synchronization is shown to provide either the same or less than a 0.1 dB increase in BER degradation as compared to that obtained with maximum eye opening synchronization. This result is significant, since average zero crossing synchronization is easily implemented in hardware