智能天线中变步长LMS自适应波束形成算法研究

Research on Variable Step Size LMS Adaptive Beam-Forming Algorithm for Smart Antenna

波束形成算法是智能天线研究的核心内容,可以使天线有效地接收期望信号并抑制干扰信号,但各种算法均存在计算量大、收敛速度慢、稳态误差大等缺点。为提高系统性能,提出了一种改进的变步长LMS自适应波束形成算法,其步长因子由上一步长因子和自相关误差共同确定。对新算法的性能进行了理论分析,并推导了确保算法收敛的参数α的取值范围。计算机仿真结果与理论分析一致,与现有的变步长算法相比,新的变步长LMS算法具有较快的收敛速度、较小的稳态误差以及较低的算法复杂度,非常适用于智能天线波束形成问题。

Beam - forming algorithm is the core of smart antenna research. It makes antenna receive desired sig- nal and suppress the interference signal effectively. But some of algorithms have the shortcomings such as high com- putational complexity, slow convergence rate and high steady- state error. For improving the system＇s performance, an improved variable step size Least Mean Square （LMS） algorithm for smart antenna was proposed, and its step size factor was determined by previous step size and auto - correlation error. First, the performance of the new LMS algo- rithm was analyzed theoretically. Secondly, the value range of parameter ct was educed to guarantee the algorithm＇s convergence. Finally, simulation results confirm the theoretical analysis and demonstrate that the proposed algorithm has faster convergence rate, lower steady - state error and less complexity than the state - of - the art algorithms, which show that the new LMS algorithm is very suitable for beam- forming in smart antenna.