A comparison of tracking-beam arrays and switching-beam arrays operating in a CDMA mobile communication channel

This paper presents an overview of two different types of smart antenna sys tems: the tracking-beam array (TBA) and the switching-beam array (SBA) syst ems. A conceptual description of each system is given, to analyze the inher ent advantages and disadvantages of the two systems. The array systems show n in this paper are aimed at Code-Division Multiple-Access (CDMA) mobile co mmunications. The desired beam pattern can be obtained from the weight vect or through the scalar product between the weight vector and the signals, be cause the in-phase and quadrature components of the baseband signal preserv e the magnitude and phase of the signal at each antenna element. Since the weight vector of the TEA system is computed from the solution of the eigenv ector corresponding to the largest-magnitude eigenvalue, the TEA system out performs the switching-beam array system when the desired signal is suffici ently larger than each of the interfering signals, because of the high proc essing gain. As the ratio of the power of the desired signals to the power of the interfering signals becomes lower, the superiority in the performanc e of the two systems is reversed.