When the time dispersive channel deteriarates, the excellent interference-free performance of CDMA system spread with Loosely Synchronized code (LS-CDMA) may not be guaranteed any more. The goal of our study is to improve the robustness for LS-CDMA system against channel deterioration. Based on theoretical and experimental analysis, it is found that code allocation algorithm, which is seldom mentioned for LS-CDMA before, has great impact on the interference-resist ability of the system. We define a new parameter to reflect system robustness and propose a novel code allocation algorithm aiming to maximize this parameter. Simulation results show that system employing the proposed algorithm has superior interference-resist performance compared with system based on random code allocation algorithm, especially when the system load is not very heavy.
['Jing Li', 'Aiping Huang', 'Jiangli Zhu', 'Zhaoyang Zhang']
A Novel Code Allocation Algorithm for LS-CDMA System