Time-sensitive networks(TSNs)support not only traditional best-effort communications but also deterministic communications,which send each packet at a deterministic time so that the data transmissions of networked con...
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Time-sensitive networks(TSNs)support not only traditional best-effort communications but also deterministic communications,which send each packet at a deterministic time so that the data transmissions of networked control systems can be precisely scheduled to guarantee hard real-time ***-wait scheduling is suitable for such TSNs and generates the schedules of deterministic communications with the minimal network resources so that all of the remaining resources can be used to improve the throughput of best-effort ***,due to inappropriate message fragmentation,the realtime performance of no-wait scheduling algorithms is ***,in this paper,joint algorithms of message fragmentation and no-wait scheduling are ***,a specification for the joint problem based on optimization modulo theories is proposed so that off-the-shelf solvers can be used to find optimal ***,to improve the scalability of our algorithm,the worst-case delay of messages is analyzed,and then,based on the analysis,a heuristic algorithm is proposed to construct low-delay ***,we conduct extensive test cases to evaluate our proposed *** evaluation results indicate that,compared to existing algorithms,the proposed joint algorithm improves schedulability by up to 50%.
Several routing schemes have been proposed for intermittently connected mobile networks. In these schemes, a node carries a message and forwards the message to another node when they meet. To increase the delivery suc...
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Several routing schemes have been proposed for intermittently connected mobile networks. In these schemes, a node carries a message and forwards the message to another node when they meet. To increase the delivery success rate and reduce the message delivery delay, the node to forward the message is selected based on such criteria as the probability that the node is likely to meet the destination. However, even if a node is suitable under such criteria, the contact duration may be too short to complete the message forwarding, which is called forwarding failure' in this paper. The risk of forwarding failure due to link disconnection during transmission has been mostly ignored in the existing routing schemes. In this paper we focus on avoiding forwarding failure. To this end, a large message is divided into smaller fragments, and we present a mathematical model to derive the optimal fragment size that minimizes message delivery delay. We then present a run-time algorithm which determines whether a current message fragment should be forwarded to a node encountered. Contact duration with the candidate node is estimated for this decision. Delayed forwarding and transmission power adjustment is incorporated into this algorithm to enhance energy efficiency of message forwarding. The benefits and feasibility of the proposed scheme are extensively evaluated by simulations and experiments. (c) 2014 Elsevier B.V. All rights reserved.
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