Low-Complexity PAPR Reduction of OFDM-IM Signals via ADMM Approaches

As a new multicarrier modulation technology, orthogonal frequency division multiplexing index modulation has more advantages than OFDM. Specifically, OFDM-IM demonstrates improved bit error rate (BER) performance at low to medium data rates and enhanced robustness against inter-carrier interference in fast time-varying channels. However, OFDM-IM also has the issue of high peak-to-average power ratio (PAPR). In this letter, by exploiting the characteristics of OFDM-IM, we first add a small dither signal to the idle subcarriers signal to reduce the PAPR of the OFDM-IM signal. Then, we develop an alternating direction method of multipliers (ADMM) to design the optimal dither signal. The simulation results demonstrate that the PAPR and computational complexity can be significantly reduced by appropriately selecting the amplitude of the small dither signal.