Investigating the WSSUS Assumption in 300 GHz Time-Variant Channels in Industrial Environments

This paper present an initial approach to the analysis of the stationarity of time-variant channels in industrial environments, focusing on three distinct scenarios: 1) communication between a static access point (AP) and a sensor node (SN) mounted on a moving machine within a comprehensive industrial workspace, 2) communication between two static sensor node (SN) with a moving metal plate object between them, and 3) communication between two static robotic manipulators with a moving obstacle with varying movement speeds between them. The assumptions of the wide-sense stationary (WSS) and uncorrelated scatering (US), fundamental to channel modeling, are examined using local scattering function (LSF) collinearity metrics in both time and frequency domains. In blockage scenarios, where we compared the effects of two different types of obstacles – a metal plate and a robotic arm – the channel behavior can be divided into three distinct regions: fully stationary before and after the blockage, non-stationary during the transition periods, and either conditionally stationary or fully non-stationary during partial or full blockage, respectively. These distinctions were influenced by the type of blockage object and whether the scenario involved non-line-of-sight (NLOS) or obstructed-line-of-sight (OLOS) conditions. Notably, the speed of moving obstacles affects the duration and nature of non-stationary regions, with higher speeds leading to shorter and less distinct transition periods. The US assumption was found to be generally valid in the blockage scenarios but not in the AP scenario.