Visible Light Communication Channel Models and Simulation of Coal Workface Energy Coupling

Due to their low energy consumption and small size, visible light communication systems have been widely used to eliminate communication-blind areas in coal workfaces. A workface visible light communication channel model and a mathematic model of energy coupling from the mining machine’s workspace to its footpath were established to investigate the characteristics of optical signal transmission on the workface. This paper studies the effects of coal dust (double-layer particles encapsulated by moisture) on optical signal degradation. Simulation results revealed the presence of an optimized transmitter location, which maximized the coupled energy of the two space signals due to the blocking effect of metal columns

Investigation of MIMO Channel Characteristics in a Two-Section Tunnel at 1.4725 GHz

This paper presents results from a wide band single-input–single-output (SISO) and 16 × 16 virtual multiple-input–multiple-output (MIMO) measurement campaign at a center frequency of 1.4725 GHz in a 100-meter long tunnel laboratory which is terminated by a vertical wall with a metallic door. The path loss, root-mean-square delay spread (RMS-DS) characteristics, and power delay profiles (PDPs) are described. In addition, we provide results for the MIMO channel amplitude matrix, which offers a new perspective in understanding MIMO characteristics in tunnel scenarios. Our measurement results are analyzed and compared to ray tracing simulations. The relationships among the angle spread, channel matrix singular values, and MIMO capacity at various link distances are illustrated, and these provide insights into MIMO system deployment