Improved base station circular antenna array receiver for wireless CDMA systems

A Spatial interpolation technique for the upsampling of uniform circular arrays (UCAs), beyond spatial aliasing, is considered. The UCA interpolation algorithm is used as a preprocessing procedure in the reverse link to improve the performance of a cellular code division multiple access (CDMA) system. The motivation is to enhance the system's capacity and array resolution and reduce the fading and coupling effects with minimal receiver hardware and cost. At the base station, we propose to place the antenna elements uniformly on an imaginary circumference farther apart than/2, where is the free-space wavelength. The resulting UCA possesses superior resolution, less coupling effects than a corresponding UCA with the same number of elements and circumferential spacing less than or equal to/2, and possibly higher diversity gain. In order to increase the system's capacity and eliminate any spatial aliasing, we propose to interpolate the UCA to within the spatial Nyquist rate. This is achieved by placing a virtual antenna element halfway on the circumference between every two adjacent antenna elements. Simulations results are provided to support our claims.