Prototyping Verification And Key Technical Research Of TDD-based Massive MIMO System

Since the beginning of the 21st century,the Internet industry and the mobile communication technology have been rapidly developing.In order to meet the explosio of terminal equipments and communication traffic in mobile Internet and the Internet of Things era,people have set off a research boom on the fifth generation mobile communication system(5G).As one of the core technologies of 5G,massive multiple-input multiple-output(MIMO)can greatly improve the spectral efficiency and energy efficiency of the system.It is worth noting that the massive MIMO technology can also bring many challenges such as the increasing cost,the increasing complexity of data processing,and the high difficulty of prototyping verification at the same time.In this thesis,we will investigate the wireless transmission technologies and prototyping verification of massive MIMO system which works in time-division duplex(TDD)mode,and the specific work arrangements are as follows:Firstly,the physical layer of the prototyping system is designed after completing the research of massive MIMO teclhnology.With the premise that the system transmission parameters,frame structure and resource grid of UEs are defined,the system model and transmission scheme according to hardware implementation,including orthogonal frequency division multiplexing(OFDM),frame synchronization,MIMO channel esti-mation and equalization,MIMO precoding,channel reciprocity calibration,are emphasized.In addition,we complete the functional link-level simulation of system by Matlab smulation platform,the theoretical ver-ification and performance evaluation of the system's transmission scheme from the aspects of bit error rate(BER)and throughput,which provide a theoretical foundation for the realization of the prototyping system.Then,the hardware and software platforms,and the hardware architecture of the prototyping system are studied in this thesis.The software platform and hardware components of the prototyping system are introduced to highlight the characteristics and performances of the core hardwares.On this basis,we design the hardware architecture of the system with the selected hardwares,including the hardware architecture of base station,the clock and trigger signal distribution architecture of base station,and the hardware architecture of users.Following the system's data processing block diagrams,the hardware architecture of the system is evaluated based on the goals of the system realization and the capability of each hardware unit,so that the current hardware configuration can meet the requirements of the prototyping system.Finally,we focus on the realization and related measurements of the prototyping system for uplink and downlink data transmission.The details of the hardware implementation for each functional unit of the proto-typing system are described following the order from the user side to the base station side,from the FPGA side to the Host side,and from one functional unit to another.Some significant modules,such as RF transceiver module,synchronization module,OFDM modulation and demodulation module,peer-to-peer(P2P)routing module,uplink channel estimation and equalization module,downlink precoding module,reciprocity cali-bration module and so on,are emphasized.In addition,combined with the consumption of FPGA resources for each functional unit of the system and the actual operating envirunent,the channel information,the u-plink and downlink data transmission for multi-users' video streams,and the performance of the calibration algorithm is tested and analyzed.The results indicate that the constructed massive MIMO prototyping system based on TDD mode in this paper can run the uplink and downlink data transmission for multi-users' real-time video streams smoothly and achieve the expected goals.