Performance of Adaptive Antenna Array Based Dynamic OVSF Code Assignment for Multipath Propagation and Multicell Environment

Abstract

An OVSF code assignment method using adaptive antenna (AAA) array in WCDMA network has been previously proposed [10] and it has been shown that AAA based dynamic code assignment (AAA-DCA) significantly reduces call blocking probability and increases spectral efficiency in the system when compared to conventional code assignment (CCA) and widely known dynamic code assignment (DCA). In AAA-DCA, OVSF code of an existing user can be reused for the new user as long as downlink weight vector of the existing user and channel vector of the new user have the smallest spatial correlation, and estimated SINR of the new user remains above threshold. However, ideal propagation conditions having a single cell with no multipath propagation were considered in [10]. In this work, performance of the AAA-DCA is investigated under more realistic wireless scenario where there is multicell environment and multipath propagation exists. Signal model and interference analysis to obtain SINR have been presented for this multicell and multipath conditions. Results show that AAA-DCA under these conditions still performs considerably better than CCA and DCA, but causes some degradation in the performance, i.e., 25 % decrease in spectral efficiency, when compared to ideal conditions.