Research On Key Technologies For Multidomain Index Modulation

Multidomain index modulation(MIM)is a novel transmission scheme that has high performance with low energy consumption by using indexes in multiple of domains to convey information.Based on the MIM system using spatial and frequency resources,this dissertation theoretically analyzes the MIM performances and proposes optimization designs in terms of diversity gain,channel estimation error and inter-subcarrier interfer-ence for various link configurations and scenarios in future mobile communications.Firstly,to address the challenge that MIM has low diversity gain by utilizing spatial and frequency resources,the relationship between the diversity gain and the modulation patterns is derived by exploiting union bound and moment generation function(MGF)methods.From the theoretical results,it is concluded that diversity gain is determined by the number of incorrectly detected subcarriers with different frequency indexes in pairwise pattern errors.According to this conclusion,novel pattern designs to enhance diversity gain are proposed.Different from the traditional MIM that maps different symbols to different resources,the proposed schemes combine multiple subcarriers into virtual blocks and use them as basic units of indexing and symbol mapping.From the simulation results,the proposed schemes can obtain significant signal to noise ratio(SNR)gains compared to the conventional one.Secondly,this dissertation studies MIM under the influence of channel estimation er-ror and clipping noise.On the one hand,based on the error model for least square channel estimation,the theoretical upper bound for MIM under channel estimation error is derived.On the other hand,a low-complexity signal detection method based on clipping noise can-cellation is proposed for the MIM system using clipping operation to reduce the peak to average power ratio(PAPR).By comparison of bit error rate(BER),the performance of the proposed detection method is close to the ideal system without clipping noise.Thirdly,with respect to inter-subcarrier interference in high-speed mobile scenario,the theoretical approximation of the upper bound of MIM error performance is obtained and the anti-interference design for modulation patterns is proposed.In the theoretical analysis,the interferences are divided into two types,intra-block and inter-block inter-ferences.Moreover,the inter-block interferences are approximated as a Gaussian ran-dom variable according to the center limit theorem to avoid the high dimensional inte-gration.According to the theoretical conclusion that the inter-subcarrier interferences are decreased exponentially as the subcarrier distance increases,a novel modulation pattern generating scheme is proposed,which reduces the interferences by avoiding activating ad-jacent subcarriers simultaneously.The simulation results show that the proposed method can obtain SNR gains for various speeds and spectral efficiency.Finally,for the spatial correlation caused by dense antenna array in future mobile communication,the relationship between the correlation coefficient and the BER upper bound is derived by incorporating the model of correlated channel.The results prove that the MIM system is robust over correlated channel.In addition,based on the high-frequency channel model,the theoretical approximation of the mutual information of in-dex modulation system using beamforming over millimeter-wave band is derived and the optimized power allocation scheme is proposed as well.The simulation results show that the proposed scheme can increase the system capacity significantly compared to the uni-form power allocation.