Performance of Conventional and DBD (Direct Bit Detection) Receivers for MFSK/QPSK Modulation When Operating in the Presence of Noise and Rayleigh Fading

摘要

This thesis devoted to studying the properties of a digital M-ary signaling scheme called MFSK/QPSK combines the features of M-ary FSK and QPSK modulation. This scheme is shown to be a form of biorthogonal signaling, and a receiver that is optimum in error rate sense is introduced and analyzed in order to obtain its bit error rate (BER) performance when signal interference can be modeled as additive white Gaussian noise. The bandwidth of the MFSK/QPSK signaling scheme is derived and compared with that of M-ary PSK and M-ary FSK signaling. MFSK/QPSK signaling results in receivers that provide error rates much lower than corresponding receivers for M-ary PSK and slightly lower than those for M-ary FSK, while maintaining a bandwidth efficiency at least three times greater than that of M-ary FSK though not as great as that of M-ary PSK signaling. A significant effort has been devoted to examining a detection method known as direct bit detection (DBD) which has been applied to M-ary PSK and MFSK/QPSK signaling, DBD receivers are introduced, and the BER of the MFSK/QPSK DBD receiver is derived and compared with that of the optimum (symbol discrimination) receiver. Lastly, the effects on performance due to Rayleigh fading are analyzed and evaluated for M-ary PSK DBD receivers as well as for MFSK/QPSK optimum (symbol discrimination) and DBD receiver. (RH)