Trellis Shaping for Controlling Envelope of Single-Carrier High-Order QAM Signals

In this paper, trellis shaping (TS) is applied to dynamic range control of band-limited single-carrier high-order quadrature amplitude modulation (QAM) signals. With a newly designed shaping metric, we show that a signal with very low peak-to-average power ratio (PAR) can be achieved without significant loss of data rate. A specific example demonstrates that a band-limited transmission with spectral efficiency of 4.55 bit/s/Hz (including the redundancy due to the shaping) and PAR below 3 dB is achievable using a square 64-ary QAM constellation and a root raised-cosine filter with a roll-off factor 0.1. Furthermore, the proposed TS for high-order QAM can simultaneously reduce the average power and thus offers a shaping gain. The reduction of the PAR and average power can be flexibly controlled by adjusting a parameter associated with the shaping process.