Non-Orthogonal Multiple Access Technology In Future Mobile Communications

Multi-access technology is the basis of wireless communication networks,and is also one of the signs of wireless communication system update.Among them,Non-Orthogonal Multiple Access(NOMA)technology and new modulation technology have received deep and extensive attention.This paper focuses on Interleave-Division Multiple Access(IDMA)and Interleave-Grid Multiple Access(IGMA)in new modulation technology and NOMA systems in the Fifth Generation Communications System(5G).IDMA technology inherits most of the advantages of Code Division Multiple Access technology and can resist the interference between symbols.The IGMA technology is more capable of resisting multiple access interference,so it can also load more users.This paper mainly studies NOMA technology represented by IDMA and IGMA.The specific research contents are as follows:The first chapter introduces several typical multiple access technologies in wireless communication systems,including Frequency Division Multiple Access,Time Division Multiple Access,Code Division Multiple Access and Orthogonal Frequency Division Multiplexing Access.The advantages and disadvantages of Code Division Multiple Access technology and Orthogonal Frequency Division Multiplexing Access technology are introduced in detail.Then the IDMA technology and IGMA technology which inherit the advantages of Code Division Multiple Access technology and the receiver complexity is lower than that of Code Division Multiple Access technology are introduced.The research background and the current situation of IDMA and IGMA technology are introduced.The second chapter first introduces the principle of the IDMA system,including transmitter structure and receiver structure,and gives an iterative detection algorithm based on Elementary Signal Estimator(ESE)in simple cases and more complicated cases.This traditional detection algorithm can make multi-user system performance tend to single-user system performance under high SNR,which means,it can suppress multiple access interference.Finally,a new iterative detection algorithm based on Approximate Message Passing(AMP)is proposed,and it is verified that in the case of multiple receiving antennas,this new iterative detection algorithm can achieve better than traditional iteration with slightly lower complexity of traditional iterative detection algorithms.The system performance of the detection algorithm.The third chapter introduces the principle of the IDMA system based on OFDM,including transmitter structure and receiver structure.In addition,the performance of the detection algorithm based on ESE and AMP is compared and evaluated in the IDMA-OFDM system.And the conclusion is drawn that the detection algorithm based on approximate message passing proposed in this paper can still maintain its performance advantage in the IDMA-OFDM system.Then,the performance impact of the carrier frequency offset(CFO)on the IDMA-OFDM system is introduced,and the frequency offset suppression is performed using two frequency offset detection algorithms based on the ESE and the AMP algorithm.Finally,it is verified by simulation that the IDMA-OFDM-CFO system using these two frequency offset detection algorithms can achieve a large performance improvement and achieve a good frequency offset suppression effect.The fourth chapter first introduces the principle of the IGMA system,including transmitter structure and receiver structure,and gives two iterative detection algorithms based on ESE and Message Passing Algorithm(MPA).The simulation proves that the IGMA-OFDM and IDMA-OFDM non-orthogonal transmission technologies using MPA receiver are better than the OFDMA system performance under the same spectral efficiency.Therefore,NOMA technology is a valuable future technology that can become the core of 5G.Then some disadvantages of the interleaver in IGMA are pointed out,and a scheme of replacing the interleaver with a random sequence is proposed.The fifth chapter summarizes the full text,and on this basis gives the future research direction and work plan.