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变步长CMA和DD-LMS双模式切换盲均衡算法

Variable step size CMA and DD-LMS dual modeswitching blind equalization algorithm
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摘要 针对经典盲均衡算法收敛速度较慢和稳态误差较大的问题,提出了一种基于变步长恒模算法(Constant Modulus Algorithm, CMA)和判决引导的最小均方(Decision Directed Least Mean Square, DD-LMS)算法的双模式切换盲均衡算法。在算法收敛初期采用CMA算法,以确保算法可以较快收敛。在收敛之后切换至DD-LMS算法,以进一步降低稳态误差。通过设定阈值来切换算法,取相邻多次迭代误差的平均值作为算法的切换值,以确保算法切换时机的合理性。另外,引入Softsign变步长函数并加入3个参数对该函数进行改进,使得Softsign变步长函数可以依据不同信道环境设定最佳参数,同时提高算法的收敛速度。仿真结果表明,在卫星通用信道条件下,所提算法的收敛迭代次数约为1 000次,稳态误差为-12 dB,在信噪比为15 dB时,误码率为1×10~(-6)。与相关算法对比,所提算法的收敛速度较高,误码率和稳态误差较低。 A dual mode switching blind equalization algorithm which includes the constant modulus algorithm(CMA)and decision directed least mean square(DD-LMS)algorithm is proposed for the problem of slow convergence and large steady-state error in classical blind equalization algorithms.In the early stage of the convergence,CMA is used to ensure fast convergence.After the convergence,it switches to the DD-LMS algorithm to further reduce steady-state errors.By setting a threshold to switch algorithms,the average of adjacent iteration errors is taken as the algorithm switching value,ensuring the rationality of the switching timing.In addition,introducing the Softsign variable step function and adding three parameters to improve the function allows the Softsign variable step function to set the optimal parameters according to different channel environments,while also improving the convergence speed of the algorithm.The simulation results show that the proposed algorithm has a convergence iteration of about 1000 times and a steady-state error of-12 dB in a satellite universal channel.When the signal-to-noise ratio is 15 dB,the error rate is 1×10-6.Compared with the relevant algorithms,the proposed algorithm has a higher convergence speed,lower error rate and steady-state error.
作者 杜慧敏 刘洋 马元中 DU Huimin;LIU Yang;MA Yuanzhong(School of Electronic Engineering,Xi’an University of Posts and Telecommunications,Xi’an 710121,China;Fiberhome Telecommunication Technologies Co.Ltd,Wuhan 430205,China)
出处 《西安邮电大学学报》 2024年第1期53-63,共11页 Journal of Xi’an University of Posts and Telecommunications
基金 国家重点研发计划项目—“宽带通信和新型网络”专项(102-202990014)。
关键词 变步长 盲均衡 误码率 均方误差 双模式算法 variable step size blind equalization error rate mean square error dual mode algorith
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