Research On Frequency Offset Suppression Of 5G Modulation And Multiple Access Communication

Multi-carrier communication technology,represented by Orthogonal Frequency Division Multiplexing(OFDM)technology,has become an indispensable part of future communication for its strong anti-jam capability and high spectral efficiency.In order to meet the demands of massive users and devices under different scenarios,the 5G mobile communication system is committed to improving the spectral efficiency,transmission rate and throughput.To address this issue,it is necessary to study the new multiple access and transmission technology based on OFDM.This paper respectively studies the combination of OFDM technique,such as spatial modulation(SM)technique,IGMA technique and SCM-SM technique.However,all the above incorporate transmission schemes suffer from sensitivity to frequency offset due to the adoption of OFDM technique.Worse still is that in the case of multiple users or multiple antennas,the frequency offset can not be compensated simply by single-user detection.The suppression of Multi-frequency remains to be studied and solved.Therefore,this paper studies the frequency offset suppression of SM-OFDM system,IGMA-OFDM system and SCM-SM-OFDM system.The main work and innovation are as follows:Compared with the traditional interference cancellation algorithm in SM system,an interference cancellation algorithm based on frequency offset matrix is proposed to improve the accuracy of signal detection to reduce the degree of error propagation in the iterative process,and improve the system performance.Then taking into account the influence of the peak-to-average ratio in the spatial modulation system,we derive the interference offset formula based on the clipping noise and frequency offset and propose a joint cancellation algorithm based on the clipping noise and frequency offset.In the IGMA system which is distinguished from the user using the interleaved pattern and the mesh map,First,the structure of the transmitter and receiver is analyzed and the simulation results shows that the performance of the loading user rate in IGMA system is better than that in IDMA system.Then,considering the influence of the frequency offset in the system,two algorithms are proposed for the system.The basic principle of the first algorithm is that firstly the compensation of the corresponding frequency offset to the signal is processed to reduce the interference caused by the frequency offset and then the signal is subjected to the symbol-by-symbol iterative detection;The second algorithm is to use the frequency offset matrix as part of the channel information to directly symbol-to-symbol iterative detection.In the SCM-SM system with the high transmission rate,two kinds of frequency offset suppression algorithms are proposed for the system.The basic principle of the first algorithm is that the received signal is firstly subjected to overall compensation and then an accurate compensation based on the antenna information demodulated by the Maximal-Ratio Combiner is made.The method which requires multiple time-frequency conversion leads to high complexity.So we propose the second algorithm which use the frequency offset matrix as part of the channel information to directly Multi-user iterative detection.