Measurements for the development of an enhanced model for wireless channels in industrial environments

Novel wireless systems are often first evaluated by simulation, before prototypes are tested and the concepts are standardized. In order to ensure relevant simulation results, the wireless channel has to be modelled properly and application oriented. Currently, only few considerable industrial channel models are available. The IEEE 802.15.4a model is the most commonly used. CM 7 applies for LOS modelling and CM 8 for NLOS environments. Both are only applicable for distances up to 8m. In order to enhance the existing channel models, an extended wide band measurement campaign including seven scenarios at three different industrial locations was performed. From different LOS and NLOS measurement series in a warehouse, a manufacturing shop and a mechanical workshop, values for the path loss exponent, RMS delay spread, coherence bandwidth and fading statistics were obtained, valid for distances up to 40m. Setup, scenarios and the results of these measurements are presented in this paper. The abundance of metallic reflectors and scatterers leads to a dense multipath environment, which causes Rayleigh distributed small scale fading for both LOS and NLOS scenarios. The path loss exponent is smaller than 2 for LOS scenarios and the PDPs show very small power decay constants due to the rich scattering environment. Moreover, the RMS delay spread was found to increase proportionally to the distance. Corresponding to this, the coherence bandwidth decreases inversely proportional to the distance. The measurement results are compared to the related work and especially with the IEEE 802.15.4a channel model.