Superposition Coding-Assisted DFT-s-OFDM: A Trade-off Between PAPR and Spectral Efficiency

Abstract

Fifth-generation (5G) communication systems employ orthogonal demodulation reference signals to eliminate pilot contamination and user interference, resulting in a significant overhead for reserving resource elements in the time-frequency grid. 5G technologies rely on orthogonal frequency division multiplexing (OFDM) and discrete Fourier transform-spread (DFT-s)-OFDM waveforms, which are unable to address the demanding requirements of next-generation systems. Conversely, next-generation (6G) systems require a spectrally efficient spread system with minimum latency. This paper proposes a novel superposition-coded (SC)-aided DFT-s-OFDM system for a cellular uplink system. The proposed method maps the SC of data and the reference signal or Zadoff-Chu sequence onto alternate subcarriers, resulting in a trade-off between peak-to-average power ratio (PAPR) and spectral efficiency. Furthermore, Monte-Carlo simulations are presented for various performance metrics, including BER, PAPR and cross-correlation. Simulation results are presented for different FFT sizes, modulation schemes, and powerallocation coefficients, and are compared with classical OFDM and DFT-s-OFDM.