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自适应判决反馈均衡器(DFE)能跟踪信道时变响应并自动调整抽头系数,解决数字通信中因信道衰减和噪声引起的符号间干扰问题,从而大大降低通信系统误码率。针对在自适应均衡过程中均衡器阶数难以确定的问题,根据最优估计理论,分析判决反馈均衡器结构,研究DFE的抽头长度对均衡器均方误差性能的影响,在此基础上提出阈值可变动态长度算法,找出最小均方误差与滤波器阶数之间的折中。Matlab分析和仿真结果显示,当信道衰减和符号间干扰较严重时,均衡器阶数收敛在30阶左右,且误差可以收敛在较小范围内跟踪信道响应,并在瞬时累计均方误差准则下收敛到滤波器最优阶数。
The adaptive decision feedback equalizer (DFE) can track the time-varying channel response and automatically adjust the tap coefficient to solve the problem of intersymbol interference caused by channel attenuation and noise in digital communication, thus greatly reducing the bit error rate of the communication system. Aiming at the problem that the equalizer order is difficult to be determined in adaptive equalization process, the structure of decision feedback equalizer is analyzed according to the optimal estimation theory. The influence of the tap length of DFE on the mean square error performance of the equalizer is studied. Based on this, the threshold Variable dynamic length algorithm finds the trade-off between the minimum mean square error and the filter order. Matlab analysis and simulation results show that when the channel attenuation and intersymbol interference are more serious, the equalizer order converges to about 30 orders, and the error can converge in a smaller range to track the channel response, and under the instantaneous cumulative mean square error criterion Convergence to the filter optimal order.