智能天线中新的波束形成方法

提出了智能天线中三种利用估计得到的信号导向向量直接形成波束的新方法.根据CDMA信号模型和多径信道模型,用码滤波法估计得到用户最强信号(主径)的导向向量,利用这些导向向量形成恢复期望信号,抑制干扰的制约条件.根据制约条件可直接得到最小二乘(LS)波束形成方法;按照制约条件使输出能量最小得到广义最小方差无失真响应(GMVDR)波束形成方法;在GMVDR方法的基础上引入虚拟信号来进一步抑制旁瓣得到扩展最小方差无失真响应(EMVDR)波束形成方法.模拟表明这三种方法都能很好的恢复期望信号、抑制干扰和噪声,但通过比较看出EMVDR方法形成的波束最好.

New Beamforming Methods in Smart Antenna

Three beamforming methods using estimated steering vectors of coming signals in smart antenna are proposed.Based upon the signal model and the multipath channel model of CDMA,the steering vectors of mainpaths of users are estimated by using code filtering method.Then restrictive conditions of recovering desired signal and constraining interferences are formed by using these estimated steering vectors.Least square(LS) beamforming method is proposed directly from these restrictive conditions.Generalized minimum variance distortionless response(GMVDR) method is proposed by minimizing the output power based upon the restrictive conditions.Extended minimum variance distortionless response(EMVDR) method is also proposed by introducing dummy signals for constraining side lobes based upon GMVDR method.Simulation results show desired signal is recovered and interferences and noise are constrained perfectly in these methods.By comparison,it is proved that the beamform in EMVDR method is the best.