Performance and Spectral Analysis of QPSK and CEQPSK Systems in Ideal Bandlimited Channels

The authors present theoretical performance analysis and simulation results for Quadrature-Quadrature Phase Shift Keying (QPSK), Constant Envelope (CE) QPSK, and trelliscoded 16D CEQPSK in ideal bandlimited channels of various bandwidths. The performance of receivers with and without channel estimation is reported. Spectral analysis is presented for each system, in addition to MSK and expanded uncoded 16D CEQPSK. We show that the effects of bandlimiting are most severe for QPSK. Knowledge of the channel information aids 4D CEQPSK the least. Only 6.8 dB of SNR is needed for the TCM system for a bit error rate of 10 for the narrowest channel bandwidth studied here, if the receiver has knowledge of the channel.