Research On High Order Modulation And Demodulation Methods For Wideband Millimeter Wave Communication

Wireless mobile communication is about to enter the 6G era.The current general spectrum resources below 6GHz are very tight,and it is difficult to support the high data transmission rate and large system capacity required by next-generation communications.The millimeter wave frequency band has a large available bandwidth,which meets the high-speed transmission requirements of future wireless communications.Combining the millimeter wave frequency band with high-order modulation and demodulation,the data transmission rate can be further improved.However,the non-ideal characteristics of the millimeter wave frequency band are more serious than that of the low frequency band,especially the influence of phase noise.Academia usually considers using compensation algorithms to improve the tolerance of the communication system to phase noise,but compensation algorithms generally reduce the spectrum efficiency.The optimization of the constellation diagram can not only improve system performance,but also reduce pilot overhead and improve spectrum efficiency.Compared with the commonly used QAM modulation,APSK modulation has smaller envelope fluctuations and lower peak-to-average power ratio,which is more suitable for power-limited scenarios.Thus,this article studies the constellation diagram optimization algorithm for APSK modulation.The millimeter wave signal propagating in free space will experience obvious path loss,and the use of beamforming technology based on the establishment of a large-scale antenna array can increase the channel gain and compensate for the path loss.The millimeter wave massive MIMO communication system is essential for the large-scale commercial use of a new generation of communication networks.In the multi-antenna scenario,the influence of phase noise is more complicated,and it is necessary to study the countermeasures against phase noise in depth.This paper first introduces an APSK constellation optimization algorithm based on the maximization of the minimum Euclidean distance,and then combines the optimal detection method when phase noise exists,and proposes an APSK constellation optimization algorithm based on the maximum likelihood function.First,analyze the bit error performance of the original optimization algorithm and the optimization algorithm proposed in this paper in the Gaussian white noise channel.Then consider the tolerance of the various APSK constellations designed in this article to phase noise under different intensities of phase noise conditions.The simulation results show that based on the optimization algorithm proposed in this paper,an APSK constellation diagram with strong anti-phase noise capability under high signal-to-noise ratio can be designed,and the performance is better than QAM.Next,this article discusses the performance of the new APSK constellation optimization algorithm in broadband millimeter wave communications.First,compare the tolerance of APSK constellation and QAM to phase noise in the broadband SC-FDE system.Then expand to broadband large-scale phased array communication system,consider the frequency selectivity caused by the broadband phased array beam tilt phenomenon,and analyze the bit error performance of the new APSK constellation optimization algorithm.