Nonstationary Channel Modeling for Wireless Communications Underlaying UAV-Based Relay-Assisted IIoT Networks in the Subterahertz Band

The Industrial Internet of Things (IIoT) is a typical future application for the mobile networks. Unmanned aerial vehicle (UAV) has attracted a great deal of interest in relay assisted wireless communication systems due to its benefits of high mobility, rapid deployment and high probability of Line-of-Sight (LoS) transmissions. This article proposes the 3-D geometry-based nonstationary channel models for wireless communication underlaying UAV-based relay assisted IIoT networks in the subterahertz (sub-THz) band. In order to accurately describe the propagation characteristics of the UAV-based wireless channels in the sub-THz band, the propagation gain and atmospheric absorption gain in free space, LoS path, single UAV-based relay and double UAV-based relay propagation paths are considered in the proposed channel models. The channel impulse response (CIR) expressions of different propagation paths are derived, respectively. The statistical properties of the channel models, including path loss, channel capacity, temporal auto-correlation function (T-ACF), and Doppler power spectral density (DPSD) at 140-GHz band, are investigated and analysed, with a performance comparison at 60-GHz band.