On-Line Data Link Layer Scheduling in Wireless Networked Control Systems

Wireless networked control systems (WNCSs) are widely used in many applications. A key challenge in WNCSs is to develop efficient data link layer (DLL) scheduling algorithms to achieve reliable end-to-end real-time communication. Previous research typically assumes that the network communication schedule of WNCS, once constructed and distributed, stays unchanged, thus cannot handle dynamic variations which are unavoidable in many WNCSs. This paper considers the DLL scheduling problem in WNCSs, where external disturbances occur sporadically. An on-line framework, employing a rhythmic task model, is introduced to adjust the static schedule to respond to external disturbances. The approach determines the time duration to apply a dynamic schedule and generates the schedule for that time duration to minimize the impact of network dynamics on existing network flows. The effectiveness and efficiency of the proposed algorithm are validated by extensive simulation. Results indicate that the proposed approach outperforms existing work both in terms of the number of feasible task sets (between 11% and 41% increase on average) and the number of feasible periodic packets (between 122% and 128% increase on average).