Extension of IEEE 802.15.4a to improve resilience for wireless automation using soft-bit combination

Ultra-Wideband Impulse Radio is a promising technology for industrial automation applications because of its inherent multipath robustness and coexistence features. In our efforts to deploy UWB-IR for industrial automation, we use an adapted version of the IEEE 802.15.4a PHY. In this paper, we present a way to improve robustness for low-latency sensor-actor networks with short cyclic packets of process data, as found in industrial control applications. Due to the low cycle times of the wireless network, which can be shorter than the application cycle, soft-bit combinations across multiple repetitions of a packet can be used to collect enough information to recover packets that would not be decodable by a single transmission. To determine if a packet is a repetition or contains different data than the last transmission, a change indicator is inserted into the packet by the sender. The findings are proven by simulation against IEEE industrial channel models and show a significant improvement.