Multiple‐input multiple‐output system design of multidimensional orthogonal frequency division multiplexing system with coded direct index modulation

Abstract In this paper, two kinds of design methods of combining the multidimensional (MD) orthogonal frequency division multiplexing (OFDM) with coded direct index modulation (CDIM) system and multiple‐input multiple‐output (MIMO) technology are proposed to increase the spectrum efficiency more. These systems can be called as dimension‐dependent system and dimension‐independent system, respectively. MD‐OFDM‐CDIM was proposed to overcome the limitations of the spectral efficiency of MD‐OFDM. It has some advantages in terms of spectral efficiency and the performance is comparable to OFDM. However, there is a lack of compatibility studies with MIMO to increase the spectral efficiency. Therefore, in this paper, the compatibility of MD‐OFDM‐CDIM with MIMO is shown and the performance of the combined MIMO MD‐OFDM‐CDIM systems is evaluated. The simulation results show that the performance of the two proposed systems are similar under the conditions for the same spectral efficiency. However, the dimension‐independent system is better than the dimension‐dependent system because the reception processing complexity of the dimension‐dependent system increases significantly as the numbers of transmission and reception antennas go to higher.