针对解调数据有无物理帧结构的检测问题,该文提出了一种基于多重分形谱的物理层帧结构检测算法.首先,在定义序列有偏性与0, 1出现概率关系的基础上,根据编码序列、扰码序列和物理帧的生成原理,通过计算相关序列中的0, 1出现概率推导出它们的有偏性关系,即物理帧、编码序列和扰码序列的有偏性逐渐减小;然后,利用上述结论并结合多重分形谱具有描述有偏性分布的特点,对待识别序列进行固定长度拆分并计算多重分形谱宽度值;最后,通过观察多重分形谱宽度值的分布实现解调数据有无物理帧结构的检测.仿真试验验证了算法的有效性,表明该算法具有一定的工程应用价值.%In order to achieve the justification of whether a frame structure detection exists or not under the condition that protocol is unknown, an algorithm for frame structure detection in physical layer based on multi-fractal spectrum is proposed. Firstly, the relationship between bias and occurrence probability of 0 and 1 bit is defined. Through analyzing the generation principle of channel code, scrambler, frame sequence and calculating the occurrence probability of 0 and 1 bit, the conclusion is that the bias of synchronization word is larger than the others. Then, due to the above conclusion and the character that bias distribution can be described by multi-fractal spectrum, the width of multi-fractal spectrum of split sequences is calculated. At last, frame structure can be detected by observing distribution of the width of multi-fractal spectrum of split sequences. Simulation results show the proposed algorithm is effective, and it has value in engineering application.
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