Study of path loss and data transmission error of IEEE 802.15.4 compliant wireless sensors in small-scale manufacturing environments

Wireless sensors emerge as a promising candidate for supporting a wide range of plant floor monitoring applications in manufacturing; nevertheless, manufacturing environments are notoriously harsh for radio propagation. Usually abundant of stationary and moving objects, manufacturing environments may cause transmission errors among wireless sensors due to blocking, scattering, and multipath effects. This study aims to experimentally investigate the nature of such transmission errors due to common stationary and moving obstacles in small-scale manufacturing environments inside a machine shop and with a moving forklift, respectively. The measurement study was performed using the commonly adopted IEEE 802.15.4-based 2.4 GHz Zigbee radio. The measurements show that the occurrence of transmission errors closely depends on the received signal strength in both stationary and moving settings, and the transmission errors can be mostly avoided by controlling the transmit power to assure the received signal strength above the radio receiving sensitivity level. It is also found that electromagnetic noise due to the typical machinery has negligible effects on the transmission error.