A Trellis Shaping for Peak and Average Power Reduction of BICM-OFDM Signals

One of the major drawbacks of orthogonal frequency-division multiplexing (OFDM) systems is their high peak-to-average power ratio (PAPR) signals, and trellis shaping (TS) is a promising approach for reducing both peak power and average power of OFDM signals. In practice, OFDM should be employed with coded modulation for improving reliability, and bit-interleaved coded modulation (BICM) has been often combined with OFDM to gain robustness against severe fading channels. In this work, we propose a new BICM-OFDM system concatenated with TS for achieving good error performance. To this end, a novel soft-in-soft-out decoder for TS is developed. Optimization of the shaping convolutional code in terms of transmitter performance is also discussed. The effectiveness of our system is demonstrated through the analysis in terms of average mutual information as well as frame error rate (FER) over an additive white Gaussian noise channel. Furthermore, the FER is evaluated over a frequency-selective Rayleigh fading channel and compared with the theoretical outage probability. The simulation results reveal that our system can achieve good frequency diversity effect over such a fading channel while enjoying much lower PAPR.