Research On Index Modulation Orthogonal Frequency Division Multiplexing

Orthogonal Frequency Division Multiplexing with Index Modulation(OFDM-IM)has attracted much attention in recent years.Compared with traditional multi-carrier systems,it has better bit performance,lower peak-to-average ratio,and stronger anti-frequency offset performance,making it one of the key technologies for the research of wireless transmission systems in the future.Based on the system structure of OFDM-IM,this paper porposes a new BER analysis method,and studies the transmission performance of OFDM-IM under the conditions of carrier frequency offset and pilot superposition.In addition,a subcarrier allocation algorithm based on optimal matching and adaptive modulation algorithm based on machine learning are proposed.The specific work can be summarized as follows:Firstly,the research status of OFDM-IM system is introduced,the disadvantages of the current research are pointed out,the research direction of this paper is clarified.Then two theoretical BER analysis methods are introduced based on OFDM-IM moddel.Based on the idea of nearest neighbors,a tighter OFDM-IM BER analysis method is proposed.Then the OFDM-IM system under carrier frequency offset conditions is modeled.And based on the segmented boundedness theory,the influence of carrier frequency offset under any block method on the bit error rate of OFDM-IM is analyzed.Finally,consider the three-dimensional index modulation multi-carrier system model in the frequency domain,space domain and time domain,gives the bits error rate and bounded results under ideal conditions,verify the correctness of the results through simulation.In practical applications,the channel information received by the receiver often has errors.Therefore,the BER of OFDM-IM system based on pilot superposition is further analyzed in this paper.Here we first introduce an OFDM-IM system model based on pilot superposition.Secondly the theoretical expression of BER of OFDM-IM system under channel estimation error is analyzed.The specific analysis is mainly divided into three parts: Firstly theoretically analysis the probability of the pilot position error of the received signal under the energy decision and the maximum likelihood decision method.Secondly,based on the error probability of pilot position,the estimation error of several channel estimation methods are analyzed.Finally accroding to the channel estimation error,the BER in the presence of channel estimation noise is theoretically analyzed,and the correctness of the theoretical derivation is verified through simulation.In addition,this paper also studies the adaptive subcarrier allocation algorithm and adaptive modulation algorithm of OFDM-IM.Firstly based on the theoretical expression of the OFDM-IM bit error rate,a weighted bipartite graph is established using each subcarrier as a point set and the minimum Euclidean distance as the weight,and the subcarrier allocation of OFDM-IM is completed by the optimal matching algorithm.In addition to this chapter,an auto-encoder network for signal transmission over analog communication networks is also introduced.This network is used to implement OFDM-IM signal transmission.Finally,a multi-layer perceptron network is used to solve the adaptive modulation problem of OFDM-IM.The last part of this article summarizes the contribution of this paper in OFDM-IM research,analyzes the defects in the research,and discusses future research directions.