A New Dynamic OVSF Code Allocation Method based on Adaptive Simulated Annealing Genetic Algorithm (ASAGA)

Orthogonal variable spreading factor (OVSF) codes are widely used to provide variable data rates for supporting different bandwidth requirements in wideband code division multiple access (WCDMA) systems. Many works in the literature have intensively investigated to find an optimal dynamic code assignment scheme for OVSF codes. Unlike earlier studies, which assign OVSF codes using conventional (CCA) or dynamic (DCA) code allocation schemes, in this paper, adaptive simulated annealing genetic algorithm (ASAGA) was applied which population is adaptively constructed according to existing traffic density in the OVSF code-tree. Also, the influences of the ASAGA parameters (selection, crossover and mutation techniques and cooling schedules) were examined on the dynamic OVSF code allocation problem. The simulation results show that the ASAGA provides reduced code blocking probability and improved spectral efficiency in the system when compared to the CCA and DCA schemes. ASAGA is also tested with its components SA and GA.