Spectrum Efficiency And Energy Efficiency Analysis And Optimization Of OFDM With Index Modulation

With the development of communication technology and the continuous emergence of various new services,there is a serious shortage of wireless spectrum resources,and communication energy consumption has increased sharply.OFDM-IM technology introduces index modulation technology into the OFDM communication system,and adds an index domain to the digital modulation domain.Part of the information is transmitted through the selected activated subcarriers,and the other part is transmitted through the index combination of the activated subcarriers.OFDM-IM technology improves the energy efficiency of the system and solves the problem of OFDM high PAPR,which has attracted widespread attention in the industry.However,OFDM-IM has the problem of low index utilization.Therefore,how to improve the index utilization and increase the index information and symbol information transmitted by the system so as to improve the spectrum efficiency and energy efficiency of the system has important research significance.In traditional OFDM-IM system,because the total number of index patterns does not match the number of binary digits,only some of the index patterns are selected as legal index patterns,which will reduce the amount of index information transmitted by the system.In order to improve the spectrum efficiency and energy efficiency of the OFDM-IM system,this thesis proposes to increase the system index pattern to make the total number of legal index pattern match the number of binary bits,so as to increase the information bits transmitted by the system.Furthermore,this thesis proposes OFDM-IM-SL,OFDM-IM-SM and OFDM-IM-MSC systems based on the supply index:the OFDM-IM-SL system can increase the index information of system transmission on the basis of reducing energy consumption;the OFDM-IM-SM system can not only increase the index information transmitted by the system,but also increase the symbol information transmitted by the system due to the increase in the number of active subcarriers in the supply index.;the OFDM-IM-MSC system can increase the index information transmitted by the system without increasing the energy consumption of the system,achieving a compromise between spectrum efficiency,energy efficiency and BER performance.Theoretical analysis and simulation results show that when the number of subcarriers per subblock is 4 and the number of active subcarriers is 2,compared with the traditional OFDM-IM system,the OFDM-IM-SL system improves the spectrum efficiency by about 25%and energy efficiency by about 43%;OFDM-IM-SM improves spectrum efficiency by about 50%and energy efficiency by about 33.5%;OFDM-IM-MSC improves spectrum efficiency by about 25%and energy efficiency by about 25%.In order to better adapt to the transmission environment,this thesis proposes an adaptive supply index selection algorithm.This algorithm selects the supply index with the best channel condition from the supply index candidate set as the legal index patterns of the system under the known channel conditions,and update the index mapping table in time for the next index mapping.This thesis conducts simulation verification on the adaptive supply index OFDM-IM system and concludes that,compared with the non-adaptive supply index OFDM-IM system,the adaptive supply index selection algorithm can achieve the effect of optimizing the system's BER performance.