Research And Implementation On Downlink MIMO Detection In LTE-A Air Interface Monitoring Analyzer

In order to meet the increasing demand of modern wireless communication system for system capacity and transmission rate,LTE-A system introduces carrier aggregation and multi-antenna enhancement technology,which further improves the system performance and brings better business experience to users.With the development of LTE-A network construction,the deployment of new technologies also brings new challenges to the existing network testing equipment.Therefore,it is significant to develop a professional new testing instrument.Signal detection is an important part of LTE-A system receiver.Its detection performance will directly affect the quality of the whole communication system.In view of the high complexity of the existing design scheme,this thesis studies the MIMO detection link and implements it in LTE-A air interface monitoring analyzer.The main work includes:1.Based on the physical layer protocol of 3GPP,the signal detection of downlink receiver is deeply studied.Firstly,analyze the detection algorithm by performance,complexity,time efficiency and other factors,then select the appropriate algorithm according to the project requirements.In view of the existing design schemes,this thesis optimizes the combinational logic,data processing capability and module coupling,and proposes an efficient downlink multi-antenna signal detection scheme.This scheme makes full use of the advantages of DDR3 in high-speed data reading and writing,and adopts the technology based on AXI4-Stream interface encapsulation,which greatly improves the data processing efficiency of the detection link.2.According to the process design,the integrated MIMO detection module is implemented on FPGA.In detector,matrix inversion is the main bottleneck to restrict the throughput performance.After comparing the candidate schemes and considering the target matrix is Hermite positive definite,this thesis choose an inversion scheme based on Cholesky decomposition.According to the data dependence among modules,a pipeline-based design structure is adopted.For the 2×2MIMO scale,a new design scheme with low consumption and high throughput is proposed in this thesis.The scheme combines matrix decomposition module and triangular matrix inversion module in a full pipeline way,which saves the resource consumption caused by control and storage in the intermediate process.3.Accomplish the test and verification work.Firstly,simulate the function of the module in form of data interaction,then complete the whole physical layer function test of the instrument,which verifies the validity of the design scheme.In the dual-stream transmission scene,the throughput of PDSCH detection reaches 140 Mbps,and the clock frequency of the receiver reaches 187.5 MHZ,which meets the project requirements.The design of this thesis provides a solution for the baseband core processing part of LTE-A system,and has a certain reference value for the IP design of other MIMO detection products.