Experimental Evaluation of the Deterministic Wireless Communication System Industrial LTE

Abstract

The demand for highly customized products will be met in the future by smart and flexible factories. Future factories will rise to this challenge by employing stationary and mobile Cyber Physical Systems (CPS) which need to exchange various information. With mobile systems, this should be done wirelessly. This paper evaluates a previously proposed concept for a deterministic wireless communication system based on LTE. The concept combines LTE for data transmission with GPS for time synchronization and a time-based control scheme to enable a deterministic exchange of control information. To conduct experimental evaluation, an implementation of the concept is necessary. A prototypical implementation using off-the-shelf hardware and custom software is presented. Using two exemplary test cases, the concept and implementation are evaluated with regard to the overall system latency and the quality of the time synchronization of the internal clocks. The level of synchronicity of coordinated output values after transmitting the corresponding set-point values over the communication system is evaluated in another exemplary test case using a total of three communication end devices. With a measured maximum offset of 814 µs between the synchronized output of two receivers, the concept and implementation stand validated and deemed feasible.