Research And Implementation Of Hybrid Precoding System In Millimeter Wave MIMO System

The current 5G technology and the future development trend of wireless communication put forward very high requirements on the peak rate and spectrum efficiency of the communication system.However,the existing popular wireless communication systems all work in lower frequency bands and only make use of very limited frequency resources.Video stream has the characteristics of high speed and large data throughput,which is highly suitable for researching the performance of wireless systems,meanwhile,millimeter's frequency band and its own bandwidth are also suitable for this scenario.This thesis introduces the architecture design of this system's hardware platform and resource allocation.The main functions and characteristics of each hardware module of this system based on the FPGA-based NI-PXIe platform are introduced,the operations and processing of each part was assigned to different hardware module in a more reasonable,effective and low-cost manner.It also briefly introduces the method of NI millimeter wave software system to manage and run NI-PXIe hardware platform,and specifically explains the overall transmission process in the combination of software and hardware.Then,combined with the operation complexity of the proposed low complexity algorithm and the implement requirements,we design a corresponding Field Programmable Gate Array(FPGA)implementation architecture.First of all,in accordance with the algorithm functions,we decide to partition the derived algorithm into five sub-modules,and give the fixed-point representations of the various operation signals in the sub-module,which is verified via the simulation results between the floating-point link and the fixed-point link.Then according to the time division multiplexing and pipeline design ideas,we elaborate the detail implementation structures,the data processing and time scheduling of each module.In particular,followed by reasonable arrangements for the division and matrix multiply vector computing process,the proposed algorithm achieves less resources loss without compromising performance.Finally,we provide the clock frequency,latency and the resource usage of this algorithm,which is integrated in a real-time FPGA platform and is feasible in practical systems.This thesis introduces the implementation of the communication protocol based on the hardware platform.First,it briefly introduces the TCP/IP protocol of the transport layer and the IEEE 802.11 aj protocol of the media access control layer/physical layer.On this basis,the system uses the UDP protocol frame transmission technology with redundancy protection,and also introduces a simplification sheme on the IEEE The 802.11 aj protocol under the constrain of hardware resources.In addition,the system redesigned the data frame of the system according to the idea of "hardware trade for time" so that it can be processed in parallel by hardware modules.The actual implementation of the millimeter wave wireless communication system FPGA utilizes many technics.The first is flow control,which ensures that the entire system can be perfectly synchronized in timing;the second is the baseband processing of the transceiver.Taking the receiver as an example,the main processes include: time synchronization,fast Fourier transform,channel estimation and equalization,phase correction,demodulation mapping,channel decoding and descrambling,etc.This thesis gives some important parameters and commands,as well as the core Lab VIEW code of some modules.The following thesis details the design and implementation of the key technology of ultra-high-speed video streaming,including: development of FPGA as a dedicated network card for this system,the ultra-high-speed video stream data buffer mechanism,utilization of parameter Nlen and len to do some data field filling and recognization,which the latter two respectively handles data overflow and shortage.All of these mechanism guarantees a steady operating environment for the whole system.At the end of this part,a more detailed description of the key Lab VIEW code implementation used is made.The final part is the beamforming technology and implementation of the air transmission.It introduces the codebook design process for adapting to the array antenna hardware of this system,and proposes a beam scanning algorithm based on the multi-arm gaming machine,and combines it with the exhaustive method to improve it,with which has stronger stability.