Abstract
WirelessHART is a wireless sensor network that is widely used in real-time demand analyses. A key challenge faced by WirelessHART is to ensure the character of real-time data transmission in the network. Identifying a priority assignment strategy that reduces the delay in flow transmission is crucial in ensuring real-time network performance and the schedulability of real-time network flows. We study the priority assignment of real-time flows in WirelessHART on the basis of the multi-channel time division multiple access (TDMA) protocol to reduce the delay and improve the ratio of scheduled. We provide three kinds of methods: (1) worst fit, (2) best fit, and (3) first fit and choose the most suitable one, namely the worst-fit method for allocating flows to each channel. More importantly, we propose two heuristic algorithms—a priority assignment algorithm based on the greedy strategy for C (WF-C) and a priority assignment algorithm based on the greedy strategy for U(WF-U)—for assigning priorities to the flows in each channel, whose time complexity is . We then build a new simulation model to simulate the transmission of real-time flows in WirelessHART. Finally, we compare our two algorithms with WF-D and HLS algorithms in terms of the average value of the total end-to-end delay of flow sets, the ratio of schedulable flow sets, and the calculation time of the schedulability analysis. The optimal algorithm WF-C reduces the delay by up to and increases the schedulability ratio by up to , and it reduces the calculation time compared with the HLS algorithm.
Highlights
With the introduction of the Industry 4.0 concept, IoT devices face many challenges such as sustainability and security, among which one of the most important is real-time performance [1,2].In this paper, we propose two heuristic algorithms to assign priority to real-time flows in WirelessHART networks, and focus on the real-time performance of these two algorithms
(2) We show that the problem of priority assignment in a single channel makes the set of flows acceptable, which is an NP-complete (NPC) problem
We propose two heuristic algorithms, namely, a priority assignment algorithm based on the greedy strategy for C (WF-C) and a priority assignment algorithm based on the greedy strategy for U(WF-U)
Summary
With the introduction of the Industry 4.0 concept, IoT devices face many challenges such as sustainability and security, among which one of the most important is real-time performance [1,2]. The TDMA protocol allows a source node to send many of the same packages to the destination node through different routes. This guarantees the accuracy of data transmission by increasing redundancy. If a source node sends the same packets through k routes, we think of them as k-independent flows with the same period and deadline. The TDMA protocol allows nodes that do not send or receive data to enter sleep mode and meet the power requirement of the WirelessHART network. Real-time flow: The information collected by the source node in the WirelessHART network is transmitted as a packet. (4) We compare our two algorithms with WF-D and HLS algorithms in terms of the average value of the total end-to-end delay of flow sets, ratio of schedulable flow sets, and calculation time of the schedulability analysis
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