Research And Implementation Of Beamforming Algorithm For Array Antenna

Satellite communication has the characteristics of wide coverage,long communication distance and not easily restricted by geographical conditions.It is widely used in TV live broadcast,audio broadcasting,satellite broadband and other services.However,in practical applications,satellite mobile communication is often affected by these adverse factors due to the complexity and variability of the uplink/downlinks and landforms.Adaptive beamformer in smart antenna system is a common anti-interference technology in satellite mobile communication,which can adaptively optimize the array weight vector along with the variation of external environment to realize the effective reception of useful signals.In this thesis,the adaptive beamforming receiver prototype is designed,and the array weight updating methods of different adaptive beamforming algorithms are researched.Then,the data structure in the calculation of array weight is optimized and the precision of the calculation is improved.Finally,based on FPGA hardware platform,the adaptive beamforming algorithm with strong anti-interference capability is realized on different array structures through the optimization of logical sequence design.Firstly,the overall structure and design scheme of the receiver prototype are discussed,and the chip selection and peripheral circuit design of the RF receiver front-end module,ADC sampling module and FPGA module were described in details.The correlative PCB layout is designed,and the functions of the receiver prototype are verified through simulation tests.Secondly,the sample matrix inverse of rectangular array is implemented in FPGA.In the algorithm framework,the LVDS interface module and asynchronous FIFO module in the data acquisition modules are designed,and then the covariance matrix calculation module,matrix inversion module,steering vector module and array weight calculation module in the beamforming modules are designed.The results of the joint simulation of the Modelsim simulation software and the MATLAB simulation software for each module are compared to verify the correctness of the design of the module.The resource consumption of the algorithm is analyzed.Improvements of the algorithm module are proposed,the calculation accuracy is improved and the interference suppress ability is enhanced.The beamforming algorithm is tested on the FPGA board and the correctness of the algorithm design is verified.Then,in view of the problem of how to improve the adaptive beamforming interference suppression capacity under a certain number of array elements,this thesis researched the adaptive beamforming algorithm based on nested arrays.A FPGA framework,which includes Toeplitz matrix module,Toeplitz matrix inversion module and weight calculation module,is designed for nested arrays and the correlative algorithm flow chart was given.The performance of the nested array beamforming algorithm and the uniform linear array beamforming algorithm under different numbers of interference sources is compared with pratical tests.The results show that the nested array beamforming algorithm can suppress more interference sources.Finally,the works in this thesis are summarized and the possible further improvements are analyzed.