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为解决时变多径信道中调制分类问题,提出对数字通信信号先分段盲均衡,后星座图匹配的识别策略,保证了每段信号对应的信道环境近似静态以及降低码元速率和载波频率的估计误差对均衡的影响。选取与信号星座图形状无关的分数阶盲均衡算法,以满足调制识别过程中均衡算法对调制类型盲的要求。信道时变使得各段序列均衡效果表现很大差异,采用极大似然比方法挑选最佳均衡段。对最佳均衡段通过星座图匹配实现调制类型判别。仿真结果表明:在典型城市和恶劣城市模型下,信噪比大于5 dB时,平均正确率在90%以上,该算法对时变多径信道非常有针对性。
In order to solve the problem of modulation classification in time-varying multipath channels, an identification strategy of segmentally blind equalization and rear constellation matching for digital communication signals is proposed to ensure that the channel environment corresponding to each signal is approximately static and the symbol rate and carrier frequency are reduced The impact of estimation error on the equilibrium. The fractional blind equalization algorithm, which has nothing to do with the shape of the signal constellation, is selected to meet the blind requirement of the modulation type during the process of modulation identification. Time-varying channel makes each segment of the sequence of equalization shows great differences, using the maximum likelihood ratio method to select the best balanced segment. Modulation type discrimination based on constellation matching for the best equalization section. The simulation results show that the average correct rate is above 90% when the signal to noise ratio is more than 5 dB in the typical city and the bad city model. The algorithm is very specific to time-varying multipath channels.