Adaptive Beamforming Algorithm And Implementation Based On Maximizing Output Power

In recent years,smart antenna has been attractive because of its advantages of improving spectrum utilization and expanding system capacity.Smart antenna has been used in a variety of military and civilian applications such as communications,radar,sonar,reconnaissance,and seismic exploration.As one of the core techniques of Smart antenna,adaptive beamforming technology has extremely high research value.Firstly,an adaptive beamforming algorithm is proposed for single-user beamforming problem in high SNR environment,and applied to spread spectrum communication systems under strong interference.Then,for the large-scale array antenna system,a sub-array beamforming algorithm based on the special array division method and special array layout is proposed.Finally,the hardware implementation of beamforming algorithm in spread spectrum communication systems with strong interference is given.The main research results of this thesis are as follows : 1.In the communication environment with high signal-to-noise power ratio,an adaptive beamforming algorithm basing on maximize output power(MOP)is proposed.Since this algorithm does not rely on training sequences,it can improve spectrum utilization.And the algorithm is of low computational complexity,which is easy in hardware implementation.Then,the algorithm is simulated from three aspects.In view of the shortcomings of convergence speed and steady state performance of the algorithm,three improved algorithms are proposed:(1)Aiming at the insufficiency of convergence speed and steady-state performance,a variable step size adaptive beamforming algorithm is proposed,which simultaneously improves the convergence speed and reduce the steady-state error.(2)Aiming at the problem of steady-state error in low SNR environment,a filtering beamforming algorithm is proposed,which reduces the steady-state error.(3)Combining the variable step size algorithm with the filtering algorithm,a variable step size filtering adaptive beamforming algorithm is proposed.Simulation shows that the convergence performance and steady state performance of the algorithm are better than that of the former two algorithms in the low SNR environment.2.A beamforming method combining power inversion algorithm and MOP algorithm is proposed for the spread spectrum communication system with strong interference.The simulation results show that the proposed beamforming method can achieve higher signalto-noise ratio gain than the scheme containing only the interference nulling algorithm,which improves the error performance.3.A sub-array beamforming algorithm basing on uniform cross-division and special array layout is proposed for the large-scale array antenna.The simulation results show that the proposed algorithm can reduce the hardware cost and computational complexity and ensure the beamforming gain,which is easy to implement in hardware compared with the array element adaptive beamforming algorithm.4.The hardware implementation scheme of adaptive beamforming algorithm for strong interference spread spectrum communication system is given.The FPGA design of adaptive zeroing module and adaptive beamforming module compared with MATLAB simulation results is expounded.