Wireless Mesh Networking Tests and Evaluation in the Karst Natural Caves of Southwest China

Currently, the exploration and development of the Karst natural caves (KNCs) have become hot research topics, and flexible and reliable communication in the KNC is very important. However, because of the inherent concavity and irregular limestone formations in the KNC, wireless signal propagation is sparse and unpredictable. In this article, we explore the application of wireless mesh network (WMN) in the KNC. First, by measuring the relative permittivity of the KNC using the transmission line method at 530 MHz, 670 MHz, and 1.4 GHz, we segment the channel characteristics using classical free space propagation modeling, lossy waveguide modeling, and bend modeling based on the geographical features of the KNC for reducing the complexity of channel modeling. The measured results are in good agreement with the segment model calculation. Second, we test and evaluate the network performance at 530 MHz, including multihop routings and multidata flows in static scenarios and mobile scenarios. The test results show that audio and video can be transmitted clearly below three hops, and it is feasible to deploy WMN in an irregular KNC.