Performance Evaluation of OFDM Hybrid Number and Index Modulation for 6G Mobile System

A new advanced waveform communication system is necessary for the next 6G mobile system of higher spectrum efficiency. Since the orthogonal frequency-division multiplexing (OFDM) is a typical waveform of 4G LTE and 5G new radio (NR) for the enhanced mobile broadband (eMBB) data transmission in the multicarrier bases, the improved version of the OFDM is expected for the beyond 5G (B5G) and/or 6G mobile communication system. In OFDM, multiple closely spaced orthogonal subcarrier signals with overlapping spectra are transmitted to carry data in parallel. Demodulation is based on fast Fourier transform algorithms. Each subcarrier (signal) is modulated with a conventional modulation scheme (such as quadrature amplitude modulation or phase shift keying) at a low symbol rate. This maintains total data rates similar to conventional single-carrier modulation schemes in the same bandwidth. An improved transmission scheme is introduced for efficient data transmission by conveying additional information bits through jointly changing the index and number of active subcarriers with each OFDM sub block. The OFDM-HNIM is different from OFDM- subcarrier number modulation (OFDM SNM), OFDM- index modulation (OFDM IM). This hybrid modulation technique offers superior spectral and energy efficiency compared to other OFDM modulation schemes, specially at low modulation orders such as BPSK which can provide high reliability and low complexity. The technologies which require improved spectral and energy efficiency, high reliability, and low complexity this modulation technique is suitable for these. Comparative performance analysis is provided in terms of BER, throughput, average achievable rate, and Monte Carlo simulations are represented to prove the consistency of BER performance.