Trellis-Coded Quadrature-Phase-Shift Keying (QPSK) With Variable Overlapped Raised-Cosine Pulse Shaping

This article introduces the notion of uncoded, partially overlapped, staggered quadrature raised-cosine modulation (SQORC-P) as well as that of a trellis-coded form that is implemented as a specific embodiment of the recently introduced crosscorrelated trellis-coded quadrature modulation (XTCQM). Consideration is given to the power spectral density (PSD) of the scheme over both linear and nonlinear channels as well as to its average bit-error probability (BEP) performance on an additive white Gaussian noise (AWGN) channel, the latter being characterized in terms of tight upper and lower bounds. It is shown that a continuously variable trade-off (as a function of the fractional overlap parameter, 0 ≤ α ≤ 1) between the rate of spectral roll-off and the amount of envelope fluctuation of the transmitted signal is achievable with a receiver average BEP performance that is virtually independent of the value of α and nominally equivalent to that of uncoded quadrature-phase-shift keying (QPSK).