基于修正超指数迭代算法的双模式盲均衡算法仿真研究

收敛速度和剩余均方误差是评价盲均衡算法性能优劣的主要参数之一。超指数迭代盲均衡算法收敛速度快，但是，该算法对高阶QAM信号具有较大的剩余均方误差。针对数字无线电信道的盲均衡问题，提出了一种修正的超指数迭代盲均衡算法，该算法可校正无线电信道引入的载波相位旋转，并具有较快的收敛速度。在此基础上又提出了一种双模式盲均衡算法，该算法在收敛阶段采用修正的超指数迭代算法，之后根据某一切换准则，切换到判决导引算法，可有效减小超指数迭代算法对高阶信号的剩余均方误差。通过仿真证明了本算法的有效性。

A New Dual-Mode Blind Equalization Approach Based on Modified Super-Exponential Iteration Algorithm

Blind adaptive equalization plays an extremely important role in digital wireless radio communications. Convergence rate and residue mean square error (MSE) are two main parameters in evaluating the performance of blind equalization algorithms. The iteration form of the super-exponential (SEI) algorithm, which was proposed by Shalvi and Weinstein, converges fast, but its residue MSE is large when used for higher-order quadrature amplitude modulation (QAM) signals. A modified algorithm of the SEI (MSEI) was introduced for digital wireless radio channels, and it is capable of correct the phase rotation of the carrier frequency as well as has a fast convergence rate. On this condition, a kind of dual-mode blind equalization method was proposed. At the beginning of the iteration process, the MSEI algorithm was used. When the MSE level was reduced to a certain level, the iteration mode switched to the decision directed (DD) algorithm. This switch method can achieve less residue mean square error for high order QAM signals. The performance of the proposed algorithms is validated by computer simulations.