Performance Analysis of Downlink Dual-Frequency Index Modulation Assisted NOMA System

This paper proposes a non-orthogonal multiple access system transmission method based on dual-frequency index modulation (DFIM-NOMA), which combines the advantages of high spectrum utilization efficiency of non-orthogonal multiple access and high energy efficiency of index modulation. At the transmitter of the system, dual-frequency index modulation is used to improve the proportion of implicit signal transmission in information transmission. At the receiver, serial interference cancellation (SIC) and maximum likelihood (ML) are used to demodulate the mixed transmission signal of two users. The proposed system is simulated and verified by using various M-QAM modulation methods in multipath Rayleigh fading channels. Under the condition of using the same spectrum resources and transmitting the same signal, compared with the traditional index modulation assisted non-orthogonal multiple access ( IM-NOMA ), increasing the proportion of index modulation signal reduces the energy consumption of the transmitted signal. Under the condition of little difference in bit error rate performance, the average amplitude of the transmitted signal can be reduced by about one third, and the energy consumption can be reduced by about half.