Hadamard and Riemann Matrix-Based SLM for PAPR Reduction in OTFS Signal

In this letter, we study the peak-to-average power ratio (PAPR) reduction and bit error rate (BER) performances of the Hadamard and Riemann matrix-based selected mapping (SLM) technique for Orthogonal Time Frequency Space (OTFS) signals. Unlike the conventional phase sequence based on $\{\pm 1,\pm j\}$, which requires the entire sequence to extract the original signal at the receiver, the Hadamard and Riemann matrix-based SLM techniques require only the row index of the matrix, reducing the additional information necessary to extract the signal. Simulation results are presented to verify the PAPR and BER performance. The results are also compared with the existing normalized μ-law, rooting μ-law, and conventional SLM methods. The results demonstrate that the Riemann-based SLM technique shows significant performance improvement.