Research on Measurement and Statistical Characteristics of Air-to-Ground Bidirectional Links Channels

The development of UAV communication systems has underscored the complexity of analyzing wireless channel characteristics for air-to-ground bidirectional links. In order to better assess the performance of UAV communication systems, this paper introduces a scheme for measuring and analyzing the multipath characteristics of air-to-ground bidirectional links. A method for capturing the channel impulse response is presented, employing constant false alarm rate detection for multipath extraction and channel feature analysis. Particularly, an arrival angle estimation algorithm based on a backpropagation neural network is proposed, which is aimed at enhancing the precision of the angle parameter estimation. To validate the reliability of the methods presented in this paper, field measurements are conducted, where the channel characteristics of air-to-ground bidirectional links, including multipath distribution, delay spread, and angle spread, are analyzed and compared. The comparison of simulation and field results demonstrates that the proposed method enables high-precision channel characteristic analysis for air-to-ground bidirectional links. The validity and limitations of the channel reciprocity theorem have been verified.