OVSF code groups and reduction in call blocking for WCDMA systems

Abstract

Compact code assignment (CCA) scheme for wideband CDMA (WCDMA) system has been proposed using Orthogonal Variable Spreading Factor (OVSF) channelization codes. In WCDMA systems, each User Equipment (UE) is given an OVSF code tree. In CCA scheme, the codes in OVSF code tree are divided into groups and the new call is handled by most congested group. The CCA scheme assigns code to the incoming call in the most compact form such that the available capacity after code assignment is least fragmented. This increases call handling capability of the OVSF-CDMA system. Simulation results show that proposed assignment scheme provide performance improvement in terms of reducing new call blocking probability.