Simulation Platform Construction Based On 5G NR Protocol And Research On Related MIMO Key Technology

Multiple-input multiple-output（MIMO）system is the key technology in 5-generation new radio（5G NR）system.The major factor impacting the communication service quality is the multipath fading,whereas the MIMO technology can leverage multipath fading to increase system capacity and greatly improve system capacity without increasing the transmission power.Therefore,it has become one of the key technologies of modern mobile communication systems.Firstly,in this thesis,the physical link level simulation platform is built based on 5G NR protocol,where the data transmission function of single-user and muiti-user system is imbedded and the key technologies of MIMO are investigated and simulated based on this platform.Secondly,the link adaptive module,termed as adaptive modulation coding（AMC）is added in the above platform.The link adaptive module mainly develops adaptive modulation coding strategy at the base station according to feedback rank indicates（RI）,precoding matrix indicates（PMI）and channel quality information（CQI）signalings.Combined with the three kinds of feedback signalings,the traditional algorithm,including the maximum capacity benchmark algorithm and the maximum minimum singular value benchmark algorithm,are studied to effectively improve the system capacity.Subsequently,this thesis deploys the research on the signal detection module of 5G NR system on mobile terminal,where the traditional detection algorithm is firstly studied.Based on the research of the traditional Detection algorithms,including the zero forcing algorithm（ZF）,the maximum likehood detection（MLD）and the QR-M maximum likehood detection（QRM-MLD）algorithm,the improved QRM-MLD algorithm depending on constellation pre-ordering and dynamic tree search is proposed in this thesis.The analysis and simulation results show that the improved algorithm has greatly reduced computational complexity compared with traditional QRM-MLD algorithm,while ensure the system throughput simultaneously.Finally,the multiple user interference（MUI）suppression technique in muiti-user system is studied,where related precoding technology,as power distribution technology and user scheduling technology are analyzed and simulated.Based on traditional precoding techniques such as: ZF precoding,an improved partial zero forcing（PZF）precoding algorithm is proposed.Combined with detection at the receiver,the proposed algorithm can effectively eliminate multi-stream interference by using part of the channel information,and achieve similar performance to traditional ZF based on the bit error rate while greatly reducing the complexity of traditional ZF.PZF even preforms better than traditional ZF in some special scenarios.In addition,this paper also studies the waterpowering allocation algorithm and the minimum error rate allocation algorithm which can effectively improve the system capacity.Finally,the capacity of the whole muiti-user system is further improved by combining user scheduling pairing algorithm.