Multilevel Modulation Techniques

􀂄So far we have had Bit rate = Baud Rate, where each signal element corresponded to just one bit of data, but more bits per signal element can be encoded.
􀂄Common Techniques include:
􀁺Quadraturephase shift keying (QPSK)or 4 PSK which allows 4 phase changes
􀁺QuadratureAmplitude Modulation (QAM)which changes phase and amplitude
􀂄The more bits per signal element the higher the throughput is, but the more complex the scheme is.