Enhanced CDMA cellular system using interpolated uniform linear arrays

A spatial interpolation algorithm for the upsampling, beyond spatial aliasing, of uniform linear arrays (ULAs) is presented. Its usage, at the base station, to enhance the performance of a code division multiple access (CDMA) cellular antenna system is considered. The objective is to increase the user-capacity and array resolution and reduce the fading and coupling effects with a minimal receiver hardware and processing cost. The proposed base station antenna is formed by placing the real array elements farther apart than λ/2, where λ is the free space wavelength. This increase in aperture enhances the resolution, minimizes coupling, and provides a form of space diversity to combat fading. To increase the user-capacity and at the same time eliminate any spatial ambiguities, the ULA is interpolated to within the spatial Nyquist rate. This is done by placing a virtual antenna element half way in between every two real adjacent antenna elements. Numerical simulations that validate these claims are also presented