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 systems: the tracking-beam array (TBA) and the switching-beam array (SBA) systems. A conceptual description of each system is given, to analyze the inherent advantages and disadvantages of the two systems. The array systems shown in this paper are aimed at Code-Division Multiple-Access (CDMA) mobile communications. The desired beam pattern can be obtained from the weight vector through the scalar product between the weight vector and the signals, because the in-phase and quadrature components of the baseband signal preserve the magnitude and phase of the signal at each antenna element. Since the weight vector of the TBA system is computed from the solution of the eigenvector corresponding to the largest-magnitude eigenvalue, the TBA system outperforms the switching-beam array system when the desired signal is sufficiently larger than each of the interfering signals, because of the high processing gain. As the ratio of the power of the desired signals to the power of the interfering signals becomes lower, the superiority in the performance of the two systems is reversed.