A comparison of trellis shaping schemes for controlling the envelope of a bandlimited PSK-signal

Compares several modulation schemes that employ trellis shaping to control the envelope fluctuations of a bandlimited 8-PSK signal. The goal is to reduce the distortions introduced by nonlinearities in the transmission path. The considered schemes differ in rate and constraint length of the convolutional encoder, which is the basis of the shaping process. Additional coding of the least significant bit compensates the shaping loss. Thus, bit error rates comparable to that of conventional QPSK are achieved. The results show that even shaping schemes with very low complexity provide the redundancy required to sufficiently influence the symbol transitions