Efficient OVSF codes assignment strategy and management architecture in wideband CDMA

This paper presents an integrated solution to the code management and assignment problem in the UMTS system. We propose a new architecture for code management, and based upon this new architecture, a new code assignment strategy, referred to as ´crowded-group first strategy´. Our system architecture and code assignment strategy represent significant improvements in the time complexity and in the complexity of the storage operation. Moreover, the code blocking probability of the crowded-group first strategy can be as good as that of the crowded-first strategy. In order to systematically analyze the performance of the code assignment strategies, we implement a simulator to analyze the code selection behavior of each strategy, and the performance of the code blocking can be anticipated based on the analysis. We also propose a new performance metric, named ´weighted code blocking´, in order to precisely measure the performance obtained by different strategies. From the simulation results, we show that our strategy efficiently utilizes the OVSF codes with the low computation overhead.