ACE-QPSK: a new method of coding QPSK for the nonlinear transmitter

摘要: Band-limited QPSK signals are prone to a high degree of spectral regrowth when nonlinearity is present in the transmitter amplifier. In multi-carrier application with close adjacent channels (such as an FDMA satellite system), can result severe interference desired carrier. This may lead substantial BER performance degradation or make necessary increase spacing between carriers. The transmitted carrier suffer levels spurious RF emission which exceed system specifications mask regulations. paper proposes new 4-dimensional trellis coding technique be applied conventional modulation, and leads substantially reduced regrowth. When applied, modulated signal exhibits envelope fluctuation, hence it less affected by amplitude nonlinearity. scheme termed Almost-Constant-Envelope (ACE-QPSK).