Research On OFDM-IM Technology Based On High-dimensional Modulatio

In recent years,the performance of communication systems has been continuously improved,but at the same time,problems such as excessive energy loss have also occurred.For this reason,researchers have proposed IM technology.At present,more research is on OFDM-IM technology.Its basic idea is to divide the sub-carriers into two parts.One part of the sub-carriers is valid and is used to transmit constellation point information,and the other part of the sub-carriers does not transmit signals,so the peak-to-average ratio of the signal can be effectively reduced.This thesis conducts related research on OFDM-IM technology based on high-dimensional modulation.The specific research work is as follows:（1）In order to further improve the performance of OFDM-IM system,this thesis proposes an OFDM-IM system architecture using high-dimensional modulation.The high-dimensional modulation signal is transmitted through multiple sub-carriers.High-dimensional modulation can increase the Euclidean distance between each constellation point,so the performance of the OFDM-IM system is effectively improved.The simulation results show that in the case of ideal channel estimation,when the BER is10^-3,the proposed scheme has a gain of about 2d B compared with the traditional OFDM-IM system.In addition,this paper also studies the effect of channel estimation error on the proposed scheme.（2）Under the condition of Gaussian additive white noise channel,the SER and BER of the high-dimensional modulation OFDM-IM system using the maximum likelihood detection algorithm are deduced.The theoretical analysis is consistent with the simulation results.At the same time,the constellation point mapping algorithm and receiving algorithm of OFDM-IM system based on high-dimensional modulation are studied,and a high-dimensional constellation point mapping scheme that can reduce BER is proposed.（3）In order to reduce the detection complexity caused by high-dimensional modulation,an OFDM-IM receiver scheme based on DNN network is proposed.By adopting partially connected network and fully connected network,a neural network with two hidden layers is constructed for demodulation of OFDM-IM system.Simulation results show that the BER performance of the receiver based on DNN network is close to the classical ML algorithm while reducing the detection complexity.