A software antenna: Reconfigurable adaptive arrays based on eigenvalue decomposition

Multimedia mobile communication systems are expected to be realized in the near future. In such systems, multipath fading can cause severe degradations of the quality of the communications due to its wide bandwidth, especially in urban areas. Adaptive array antennas can be attractive solution for overcoming the multipath fading. Suppression can be achieved with the adaptive array by cophasing and combining multipath signals in the space and time domain. On the other hand, the concept of software antenna has been proposed. The software antenna recognizes radiowave environments and appropriately reconfigures itself for the signal processing required by the recognized environment. Efficient implementations can be expected if these functions are realized by the software. In this paper, we propose two types of the adaptive array systems which is reconfigurable depending on the radiowave environment as a realization of the concept of the software antenna. They recognize the environment by using the eigenvalue decomposition of space domain correlation matrices and reconfigure their structures of the signal processing. The principle and performance are examined by theoretical means and through computer simulations.