采用输出误差符号判决的变步长常数模盲均衡

Output Error Sign Based Variable Step Size CMA Blind Equalization Algorithm

针对固定步长常数模盲均衡算法在收敛速度和收敛精度上存在矛盾问题,提出了一种采用输出误差符号判决的变步长常数模盲均衡算法。在每次迭代后根据常数模准则和判决引导准则计算均衡器输出误差。如果在两种准则下输出误差符号一致,则对步长值进行修正,否则,根据自适应均衡原理利用均衡器输入信号计算最大步长值,均衡器权系数采用大步长值进行更新。与现有变步长盲均衡算法比较,无需人工设置参数,更利于工程实现。计算机仿真结果证明,采用输出误差符号判决的变步长常数模盲均衡具有良好的均衡性能。

To sovle the contradictory problem in convergence rate and precision of constant mod- ulus blind equalization algorithm with constant step size, a new variable step size method based on the sign decision of the output error is proposed. The output error can be obtained according to the constant modulus criterion and decision directed criterion respectivelly after each iteration. If the output error sign in the two criterion is consistent, the small step size is used in the algo- rithm. Otherwise, the maxmum step size calculated according to the adaptive equalization prin- ciple the input sign of the euqalizer is used for updating the equalizer coefficient. Compared with the existing variable step - size blind equalization algorithm, the proposed algorithm in the paper is without manual parameter setting, so it is more beneficial to engineering application. Comput- er simulation results show that the CMA blind equaliaztion with the variable step size based on the sign decision of the output error has a good performance.