| Ultra-high reliability and low latency(uRLLC)is a special use case of cellular mobile communication,which is mainly aimed at areas with extremely high requirements of information transmission reliability and latency,such as unmanned driving and remote surgery.It is one of the three major applications of 5G,which has received more and more attention from researchers in recent years.In order to improve the reliability and robustness of the transmission of the communication system,in Rel-16 of 5G NR,the multi-transmitting multireceiving node technology(Multi-TRP)was mainly discussed.Therefore,in this paper,the mainstream Multi-TRP transmission schemes based on FDM(Frequency Division Multiplexing)and TDM(Time Division Multiplexing)are explored,and the performance of the communication system is evaluated by designing and building a 5G NR system-level simulation platform.The main research contents of the paper are as follows:(1)Key technologies involved in multi-node transmission.The key technologies to achieve low latency and high reliability in the uRLLC scenario are studied.At the same time,the related concepts of cooperative communication and CoMP technology are explored,the classification method of CoMP technology is introduced,the Multi-TRP technology in the 5G scenario is based on time division,frequency division and space division redundant transmission methods are studied,the Multi-TRP transmission scheme based on FDM and TDM is analyzed emphatically.(2)Design and implement a 5G system-level simulation platform.Systemlevel simulation is an important means to evaluate the performance of key technologies in 5G systems.This paper proposes the design goals of modularity and high flexibility.Based on this,the overall design scheme and sub-module design of the 5G NR system-level simulation platform are introduced in detail,including parameter configuration,base station layout,scene layout,loss calculation,attribution judgment,user access,beamforming,precoding and user scheduling,and statistical calculation are 9 major functional modules,and each module is implemented in the Matlab simulation environment according to the design scheme.Combined with the simulation curve provided by 3GPP,the system-level simulation platform is calibrated,and the result proves that the built system-level simulation platform is correct and can be used for subsequent research on Multi-TRP technology.(3)The Multi-TRP technology is designed and implemented in the systemlevel simulation platform,and the system performance is evaluated.According to the difficulties of Multi-TRP technical scheme design,the design goals of flexible expansion and process optimization are formulated.Based on this design idea,the design of Multi-TRP transmission scheme based on FDM mode and TDM mode is completed.Make adjustments to related functional modules at the code level.Finally,in the system-level platform,the throughput and reliability results of the system based on FDM and TDM Multi-TRP transmission technology are obtained by simulation,and the system performance without Multi-TRP technology is used as the control group to analyze it.The experimental data shows that both the FDM-based retransmission method and the TDM-based retransmission method can improve the reliability of data transmission in the uRLLC scenario,and there is no significant difference in the occupancy rate of frequency resources.Slowly change can bring time diversity gain,and will generate a certain delay,and this adverse effect will gradually increase with the increase of traffic.The FDM-based Multi-TRP transmission method transmits the same resource blocks for users in the same time slot,and the allocation of frequency domain resources does not overlap,which can improve the reception rate without introducing additional delay,so it is a better choice. |
