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Profinet IO IRT Message Scheduling
"... Abstract—This paper presents an algorithm that allows one to create a static schedule of the Profinet IO IRT communication, which is an industrial Ethernet protocol standardised in IEC 61158. This algorithm offers an alternative to the available commercial tool, providing comparable results regardin ..."
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Abstract—This paper presents an algorithm that allows one to create a static schedule of the Profinet IO IRT communication, which is an industrial Ethernet protocol standardised in IEC 61158. This algorithm offers an alternative to the available commercial tool, providing comparable results regarding the resulting time schedule length. Furthermore, we extend the problem by useful time constraints providing a greater flexibility with respect to the individual messages. Due to this flexibility, it is possible to place the selected messages in various parts of the communication cycle, to define end-to-end delays, or to increase the computational time available for the maincontroller application, for example. The solution is based on a formulation of the Profinet IO IRT scheduling problem in terms
Exact Analysis of TDMA with Slot Skipping
- 13th IEEE International Conference on Embedded and Real-Time Computing Systems and Applications (RTCSA 2007). IEEE Computer Society
, 2007
"... All in-text references underlined in blue are linked to publications on ResearchGate, letting you access and read them immediately. ..."
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All in-text references underlined in blue are linked to publications on ResearchGate, letting you access and read them immediately.
Open Access
"... (m,k)-firm pattern spinning to improve the GTS allocation of periodic messages in IEEE 802.15.4 networks Tiago Semprebom 1 *,CarlosMontez 2 and Francisco Vasques 3 The IEEE 802.15.4 standard provides a flexible communication support for low-rate wireless personal area networks) applications. When ac ..."
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(m,k)-firm pattern spinning to improve the GTS allocation of periodic messages in IEEE 802.15.4 networks Tiago Semprebom 1 *,CarlosMontez 2 and Francisco Vasques 3 The IEEE 802.15.4 standard provides a flexible communication support for low-rate wireless personal area networks) applications. When active, the beacon-enabled mode provides a real-time communication to the supported application by adopting a guaranteed time slot (GTS) mechanism. However, this mechanism permits only up to seven real-time communicating devices. One way to deal with this limitation is to share the communication opportunities among the periodic tasks, by skipping some of the task activations in a controlled way. One of the widely accepted periodic task models that allows skips in periodic activations is the (m,k)-firm model. Motivated by this problem, this paper proposes the use of a dynamic GTS scheduling approach based on the (m,k)-firm task model, to deal with the GTS starvation problem. The proposed scheduling approach is based on pre-defined spins of the originally defined (m,k)-firm pattern. The use of an exact schedulability analysis test ensures that for each admitted message stream, at least m messages will be transmitted within each window of k consecutive deadlines. The schedulability analysis may be executed in polynomial time and therefore can be used as an online admission test for GTS requests. The effectiveness of the approach has been assessed both by a set of simulations and an experimental evaluation. 1
BuST: Budget Sharing Token Protocol for Hard Real-Time Communication
"... Timed-token networks, such as FDDI, support both synchronous real-time traffic and non real-time traffic (asynchronous messages). The medium access scheme of FDDI guarantees up to one half of the total network bandwidth for synchronous communication. Further enhancements, such as FDDI-M, improve the ..."
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Timed-token networks, such as FDDI, support both synchronous real-time traffic and non real-time traffic (asynchronous messages). The medium access scheme of FDDI guarantees up to one half of the total network bandwidth for synchronous communication. Further enhancements, such as FDDI-M, improve the bandwidth dedicated to real-time messages. However, the ability of timed-token protocols to guarantee synchronous message deadlines highly depends on specific Synchronous Budget Allocation (SBA) schemes. This paper introduces BuST, the Budget Sharing Token protocol which improves the management of periodic real-time traffic, while guaranteeing a minimum throughput for non real-time messages, with respect to existing techniques. We evaluate the performance of BuST, in comparison with FDDI and FDDI-M, considering a Synchronous Budget Allocation (SBA) scheme proposed in the literature, using the Worst-Case Achievable Utilization (WCAU) as performance metrics. We demonstrate that the performance achieved by BuST is better or, in a few cases, equal to FDDI and FDDI-M. 1
TA2I: Time Slot Access with Acknowledge Insertion
"... This paper introduces a new medium access scheme for ring-based,real-time local area networks which is called Time Slot Access with Acknowledge Insertion (TA2I). It is a variant of Time Division Multiple Access (TDMA) together with a temporarily insertion of short acknowledges based on Register Inse ..."
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This paper introduces a new medium access scheme for ring-based,real-time local area networks which is called Time Slot Access with Acknowledge Insertion (TA2I). It is a variant of Time Division Multiple Access (TDMA) together with a temporarily insertion of short acknowledges based on Register Insertion. TA2I implements synchronous time slots in the form of circulating transport frames. The proposed medium access scheme tries to solve the problem of poor performance due to unbalanced network traffic with extension algorithms that allow the reallocation of unused time slots. Simulation results are presented that show the real-time capability even under overload conditions and the better performance of the extension algorithms.
Time Properties of the BuST Protocol under the NPA Budget Allocation Scheme
"... Token passing is a channel access technique used in several communication networks. Among them, one of the most effective solution for supporting both real-time trafc (synchronous messages) and non real-time traf-c (asynchronous messages), is the so-called timed-token protocol. Recently, a new token ..."
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Token passing is a channel access technique used in several communication networks. Among them, one of the most effective solution for supporting both real-time trafc (synchronous messages) and non real-time traf-c (asynchronous messages), is the so-called timed-token protocol. Recently, a new token passing protocol, called Budget Sharing Token protocol (BuST), was proposed to improve the existing timed-token approaches in terms of synchronous bandwidth guarantee, while guaranteeing a minimum throughput for the asynchronous trafc. This paper analyzes the ability of BuST to manage real-time and non real-time trafc in comparison with the clas-sic timed-token protocol and its modied version, under the Normalized Proportional Allocation (NPA) scheme. We will show that BuST achieves higher guaranteed real-time bandwidth than the original timed-token protocol, and improves the service for the non real-time trafc re-spect to its modied version. 1
