Periodic Data Flows Research Articles

Multilevel CLOS data stream exchange algorithm based on smoothed round-robin fair scheduling

ABSTRACT The traditional scheduling algorithm has the problems of reducing the success rate of data stream exchange, increasing the exchange time, and increasing the number of required priorities. Therefore, a multi-level CLOS data stream exchange algorithm based on smooth polling fair scheduling is proposed. A multi-level CLOS network data flow scheduling model based on dynamic priority is established, and the value attribute is used as the priority parameter. Design time attribute evaluation criteria to schedule data streams in the best order to ensure that most data streams can be exchanged within the optimal scheduling time. By adjusting the two parameters of data stream value and execution urgency, you can change the degree of influence on the priority of data stream exchange. A smooth cyclic fair scheduling algorithm is used to implement data flow exchange in a multi-stage Clos network system composed of periodic data flows. Experimental results show that the algorithm improves the success rate of data stream exchange, reduces the number of exchanges, reduces the number of exchanges, and reaches the number of priorities required by the system.

Adaptive Channel Access Control Solving Compound Problem of Hidden Nodes and Continuous Collisions among Periodic Data Flows

Adaptive Channel Access Control Solving Compound Problem of Hidden Nodes and Continuous Collisions among Periodic Data Flows

Distributed Real Time TDMA Scheduling Algorithm for Tree Topology WSNs

In this paper, we address the problem of developing TDMA scheduling algorithm for tree topology WSNs. The data transmissions are organized into periodic data flows that may have opposite directions since they are carrying sensor and actuator values for feedback control. It is required to determine a periodic and collision-free allocation of the time-slots to the sensor nodes such that the end-to-end deadline of each data flow, as given in time units, is satisfied. The objective is to maximize the lifetime of the network by maximizing the time when the nodes are in the sleep mode. However, the longer the time at which the nodes stay in the sleep mode, the harder is to meet the timeliness requirements of the data flows. To solve the TDMA scheduling problem, we have found an elegant approach to express the end-to-end deadline as an integer number of the length of the schedule period. Moreover, since the distributed algorithms, in compassion with the centralized algorithms, well-suit the scarce resources of the WSNs, we focus on the distributed methods that allow each node in the network to come up with its allocated time-slots in the schedule. The proposed algorithm is based on the graph theory algorithms, namely the distributed shortest path and the distributed topological ordering. Furthermore, it falls into the category of the exact algorithms for tree topology with single-collision domain and in the category of the heuristic algorithms for multiple-collision domains tree topology.

End-to-End Communication Delay Analysis in Industrial Wireless Networks

WirelessHART is a new standard specifically designed for real-time and reliable communication between sensor and actuator devices for industrial process monitoring and control applications. End-to-end communication delay analysis for WirelessHART networks is required to determine the schedulability of real-time data flows from sensors to actuators for the purpose of acceptance test or workload adjustment in response to network dynamics. In this paper, we consider a network model based on WirelessHART, and map the scheduling of real-time periodic data flows in the network to real-time multiprocessor scheduling. We then exploit the response time analysis for multiprocessor scheduling and propose a novel method for the delay analysis that establishes an upper bound of the end-to-end communication delay of each real-time flow in the network. Simulation studies based on both random topologies and real network topologies of a <inline-formula><tex-math>$74$</tex-math></inline-formula> -node physical wireless sensor network testbed demonstrate that our analysis provides safe and reasonably tight upper bounds of the end-to-end delays of real-time flows, and hence enables effective schedulability tests for WirelessHART networks.