Modulation identification, a major task of intelligent receivers, is of vital importance for applications in military and civilian fields. In this work, we develop and analyze a blind modulation identification algorithm for two-path successive relaying systems. Analytical expressions for the correlation functions adopted as the basis of the proposed algorithm are derived, and the computational cost of the algorithm is addressed. By taking advantage of the space-time redundancy, we mathematically prove that a group of modulation types exhibits peaks for specific correlation functions while the other group does not. Exploiting this feature, we propose a binary tree hypothesis test for decision-making. A packet length estimator is also introduced as an auxiliary task for the proposed algorithm. The proposed algorithm does not require information about channel coefficients and noise power. The identification performance of the proposed algorithm is evaluated through Monte Carlo simulations under different conditions. Results show that the performance of the proposed algorithm is remarkably better than the traditional algorithms.

中文翻译：

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两路连续中继系统的盲调制识别算法


调制识别是智能接收机的主要任务，对于军事和民用领域的应用至关重要。在这项工作中，我们开发并分析了双路径连续中继系统的盲调制识别算法。推导了作为所提出算法基础的相关函数的解析表达式，并解决了该算法的计算成本。通过利用时空冗余，我们在数学上证明一组调制类型表现出特定相关函数的峰值，而另一组则没有。利用这一特征，我们提出了用于决策的二叉树假设检验。还引入了数据包长度估计器作为所提出算法的辅助任务。所提出的算法不需要有关信道系数和噪声功率的信息。通过不同条件下的蒙特卡罗模拟评估了所提算法的识别性能。结果表明，该算法的性能明显优于传统算法。