Channel Characterization and Delay Optimization for Industrial Wireless Control Systems
Xiaolin Jiang, Zhibo Pang, Richard Candell, Dacfey Dzung, Michele Luvisotto, Carlo Fischione
Wireless communication is gaining popularity in industry for its simple deployment, mobility and low cost. Ultra low latency and high reliability requirements of mission critical industrial applications are highly demanding for wireless communication, and the indoor industrial environment is hostile to wireless communication due to the richness of reflection and obstacles. Assessing the effect of industrial environment to the reliability and latency of wireless communication is a crucial task, yet it is challenging due to the difficulty to model accurately the wireless channel in various industrial sites. Based on the comprehensive channel measurement results from the National Institute of Standards and Technology at 2.245 GHz and 5.4 GHz, we quantify the reliability degradation of wireless communication in multi-path fading channels. A delay optimization based on the channel characterization is then proposed to minimize packet transmission times of cyclic prefix orthogonal frequency division multiplexing system under a reliability constraint at the physical layer. When the transmission bandwidth is abundant and the payload is short, the minimum transmission time is found to be restricted by the optimal cyclic prefix duration, which is correlated with the communication distance. Results further motivate that using relays may in some cases reduce end-to-end latency in industrial sites, as achievable minimum transmission time significantly decreases at short communication ranges.