Development of a Hybrid Index and Number Modulation Scheme for OFDM Systems

In this paper, a hybrid index and number modulation (HINM) technique is proposed for enhancing energy efficiency and spectrum efficiency of orthogonal frequency division multiplexing (OFDM) system. It transmits additional data bits by varying the number of activated subcarriers and the indices of activated subcarriers with in an OFDM sub-block. A low complexity threshold based detector is also proposed which detects the subcarrier activation pattern, decodes information bits and demodulate the pulse amplitude modulation symbols. The bit error rate and spectral efficiency of the proposed OFDM-HINM scheme are analyzed using Monte Carlo simulation study. The proposed OFDM-HINM scheme offers lower bit error rate and higher throughput in comparison to OFDM-index modulation, OFDM-subcarrier number modulation, and classical OFDM with equivalent spectral efficiency and power at mid to high signal to noise ratio.