Performance Evaluation of IEEE 802.11ah Triggered Restricted Access Window Mode in Industrial Real-Time Applications

摘要

Wireless communication has gained significant importance in industrial automation due to the ease of deployment and the low cost of components. Among the wireless standards, IEEE 802.11ah is able to provide long-range (1 km), low power communication and high degree of scalability communication, which makes it a good candidate for industrial real-time applications. Having spotted the advantages of the triggered Restricted Access Window (RAW) mode in IEEE 802.11ah, this paper intends to evaluate the real-time performance of the RAW mode. This paper first presents a detailed introduction of IEEE 802.11ah RAW mechanism, especially triggered RAW mode. Then, a simple analytical model is proposed to describe how to determine a set of proper values of RAW parameters to fulfil the requirements of a specified industrial real-time application. Additionally, we investigated the performance of the triggered RAW mechanism when adopting in industrial applications by simulation. The results show the number of the station groups, the number of the RAW slots and the duration of the RAW slots all have significant influence on the real-time performance of the network. When the number of the station groups and the number of the RAW slots keep increasing, the deadline miss ratio of the network will drop from 100% to 0%, which significantly improves the network real-time performance.