恒模多用户检测算法在WCDMA中的应用及仿真  

Application and Simulation of Constant Modulus Multiuser Detection Algorithm in WCDMA Systems

作　　者：李少根[1] 李文元[1] 冯兴乐[2] 

机构地区：[1]西安通信学院,西安710106 [2]长安大学,西安710064

出　　处：《系统仿真学报》2011年第5期973-976,983,共5页Journal of System Simulation

基　　金：中国博士后科学基金特别资助(201003662);高等学校博士学科点专项科研基金资助课题(20090205120002);中央高校基本科研业务费专项资金(CHD2010JC023)

摘　　要：针对WCDMA两级扩频调制结构中多址干扰(MAI)的循环平稳周期等于扰码周期和扩频码周期的最小公倍数的特点,以及固定步长恒模算法收敛速度慢、稳态误差大的缺陷,提出解扰和解扩相结合的变步长恒模算法,其中权系数的迭代更新公式随扰码周期变化,迭代步长自适应调整,该算法可以抑制扩频码之间以及扰码之间的多址干扰,且能降低稳态误差。仿真结果表明,在目标误码率为10-2的20用户WCDMA系统中,变步长恒模算法所需的信噪比比固定步长恒模算法降低0.5dB。According to the two-layered spreading modulation in the WCDMA systems,the cyclo-stationary period of MAI（multiple access interference） is equal to the lease common multiple between the lengths of the spreading code and the scrambling code.A variable step size CMA（constant modulus algorithm） of adaptive multiuser detection was proposed.In the improved CMA,both the de-scrambling and the de-spreading operations are performed together and the coefficient update equation depends on the cyclo-stationary period,instead of the spreading factor in the conventional one.The iterative step is adaptive.These appropriate modifications make the improved CMA to be more suitable to the WCDMA systems.The MAIs among not only the different spreading codes,but also the different scrambling codes are eliminated by the improved algorithms.Simulation results illustrate that the improved variable step size CMA can achieve 0.5dB gain in terms of signal-to-noise ratio at the target BER of 10-2 in a 20-user system.

关 键 词：宽带码分多址 多址干扰 S(2)短扰码 恒模自适应多用户检测 

分 类 号：TN929.5[电子电信—通信与信息系统]