Towards Transmission Rate Control Considering the Effects of the Surrounding Environment

In today's logistics sites, there is a rising trend in employing advanced equipment such as stacker cranes and conveyor robots equipped with wireless LAN devices to reduce labor costs and enhance operational efficiency. However, high-rise warehouses present distinctive challenges to wireless LAN communication due to the arrangement of metal pillars in vertical, horizontal, and diagonal patterns. This structural complexity engenders convoluted radio propagation paths, resulting in unexpected signal attenuation. This paper addresses a data-driven approach to applying propagation models to such environments. Specifically, we measure the direction of arrival and received signal strength indicator (RSSI) at each polarization of a 5-GHz wireless LAN. Subsequently, we expand the propagation model based on the radio characteristics of the high-rise warehouse by analyzing the acquired data. The analysis revealed that nonlinear attenuation, which does not show linear proportionality to distance, is locally intensified by reflected waves emanating from the surrounding metal band. Furthermore, the difference from the simulation results indicates that the accuracy can be improved by considering the leakage power of cross-polarized. By using the extended model to calculate the leakage power of cross-polarized waves at the transmitting and receiving antennas, we successfully enhance the accuracy of transmission rate estimation of wireless LANs from 11% (using the original model) to 87% in the best-case scenario.