PAA:Pre-Allocation Assignment of Orthogonal Variable-Spreading-Factor Codes in W-CDMA

Abstract

This study develops a novel code assignment scheme for orthogonal-variablespreading- factor (OVSF) in wideband CDMA (W-CDMA). Specifically, a “Pre-Allocation Assignment” scheme is proposed to reduce the considerable time requirements of a code reassignment procedure. This study focuses not only on eliminating the code-blocking problem, but also on reducing the call setup delay. The concept of "pre-allocation" is applied to the reassignment procedure during the "gap" between two arriving calls. PAA thus outperforms other schemes by reducing the call setup delay. PAA dynamically pre-allocate a code with the largest available bit rate. This step enables the system to rapidly complete code assignment. By observing the simulation results, call setup delay is reduced by shifting the reassignment procedure.