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.