Model Optimization And Performance Research Of OFDM-IM

With the rapid development of information technology and the rapid increase of communication data,people have higher and higher requirements on the speed and performance of communication.Index modulation is a new multi-dimensional modulation technology,which can achieve the tradeoff between spectrum efficiency and energy efficiency.Besides,with the advantages of high energy efficiency and low bit error rate,it grately attracts the attention and research of scholars.The orthogonal frequency division multiplexing with index modulation(OFDM-IM)system based on frequency domain dimension uses the index of the subcarrier to control the activation of the carrier,which has high energy efficiency,but the spectral efficiency is limited.The existing multi-mode OFDM-IM(MM-OFDM-IM)technology has a higher spectral efficiency than OFDM-IM,but it has lost the advantages of high energy efficiency.Moreover,MM-OFDM-IM system can achieve significant signal-to-noise ratio(SNR)gain in Rayleigh channel,but its BER performance is poor in Gaussian channel.Therefore,aiming at the above problems,the OFDM-IM system model is optimized,and the performance of the optimized system is studied.The research contents are as follows:1.To improve the spectral efficiency and energy efficiency of MM-OFDM-IM system,an extended permutation multiple mode OFDM with subcarrier index modulation(EP-MM-OFDM-SIM)system model and an in phase and quadrature(IQ)system model are proposed.The system improves the spectrum efficiency and energy efficiency by extending the number of permutations of the constellation modes and introducing zero-padding mode.An optimized ML detection algorithm is proposed to reduce the complexity of constellation pattern detection.Theoretically analyze the influence of the increased constellation permutation mode and the introduction of zero mode on the bit error rate(BER)of the system,and the multi-mode constellation with zero mode is optimized accordingly.The simulation of bit error rate shows that EP-MM-OFDM-SIM(-IQ)has better BER than MM-OFDM-IM(-IQ)in high SNR range under Rayleigh fading channel,and a small amount of SNR gain can be obtained after constellation optimization.However,the BER of EP-MM-OFDM-SIM(-IQ)and MM-OFDM-IM(-IQ)in Gaussian channel is worse than that of OFDM-IM.Besides,the simulation of anti frequency offset ability show that EP-MM-OFDM-SIM system is better than MM-OFDM-IM system.2.In order to solve the problem of high bit error rate of MM-OFDM-IM system in Gaussian channel,a dual-mode OFDM with in phase / quadrature index modulation(DM-OFDM-IM-I/Q)optimization system is proposed.The optimization model uses pulse amplitude modulation to replace the no-load in-phase / quadrature component of the OFDM-IM system to improve the system's spectral efficiency.At the same time,in order to optimize the EE of the model,only one in-phase / quadrature component with larger amplitude is used in one sub block,and the remaining in-phase / quadrature components are pulse amplitude modulated with a smaller amplitude.In addition,a minimum Euclidean distance criterion is proposed to optimize the amplitude of pulse amplitude modulation,so that the system has smaller constellation and larger minimum Euclidean distance than OFDM-IM system.Finally,in order to reduce the detection complexity of the system,a low complexity ML algorithm is proposed.The simulation results show that compared with the traditional OFDM?OFDM-IM and MM-OFDM-IM systems,the optimized system of DM-OFDM-IM-I/Q has lower bit error rate in Gaussian white noise channel and multipath fading channel.