Joint Scheduling and Channel Allocation for End-to-End Delay Minimization in Industrial WirelessHART Networks

WirelessHART is one of the most widely used communication standards in industrial wireless networks. In order to meet the stringent real-time requirements in industrial applications, WirelessHART incorporates many designs including the time slotted channel hopping mechanism that enables dynamic time scheduling and channel allocation. In this paper, we study the problem of joint transmission scheduling and channel allocation aiming to minimize the end-to-end delay of multiple flows in multihop WirelessHART networks. We propose a new network model based on a multidimensional scheduling space spanned by flow-link-channel-slot tuples. A multidimensional conflict graph is then established to depict the conflict relationships among the tuples. Based on this, the original delay minimization problem is formulated as an integer program, which however is difficult to solve due to its significantly large scale. To this end, we develop an iterative hop-wise scheduling algorithm by transforming the original problem into a series of maximum weighted independent set problems. We derive theoretical analysis on the schedulability and the performance bound of the proposed algorithm. In addition, we show that our results can be easily extended to accommodate more general scenarios. Finally, extensive simulation results are provided to demonstrate the effectiveness of the algorithm.