Advances in micro technology has led to the development of miniaturized sensor nodes with wireless communication to perform several real-time computations. These systems are deployed wherever it is not possible to maintain a wired network infrastructure and to recharge/replace batteries and the goal is then to prolong as much as possible the lifetime of the system. In our work, we aim to modify...

This paper proposes an analysis method to check the schedulability of a set of sporadic tasks under earliest deadline first (EDF) scheduler. The sporadic task model consists of subtasks with precedence constraints, arbitrary arrival times and deadlines. In order to determine the schedulability, we present an approach to find exact worst case response time (WCRT) of subtatsks. With the technique...

In a number of application domains, the volatility of the monitored environment where Wireless Sensor Networks (WSNs) operate engenders timing constraints on the generation, processing, and communication of sensory data. In this paper, we primarily focus on the use of an information theoretic approach, namely network coding, to improve the on-time delivery of messages in IEEE 802.15.4-compliant...

We consider a set of real-time periodic tasks where some tasks are preferably executed as soon as possible (ASAP) and others as late as possible (ALAP) while still meeting their deadlines. After introducing the idea of preference-oriented (PO) execution, we formally define the concept of PO-optimality. For fully-loaded systems (with 100% utilization), we first propose a PO-optimal scheduler, na...

für meinen Vater ii Summary Within this thesis time evaluated predicate/transition nets (t-pr/t-nets) have been developed for the purpose to model, simulate and verify complex real-time systems. Therefore, t-pr/t-nets integrate concepts to model timing constraints and can be analysed by the means of structural analysis such as the calculation of sand t-invariants as well as the identification o...

In the studies of real-time concurrency control protocols (RT-CCPs), it is always assumed that earliest deadline first (EDF) is employed as the CPU scheduling algorithm. However, using purely (ultimate) deadline for priority assignment may not be suitable for distributed real-time database systems (DRTDBS) in which there exist different kinds of transactions, such as global and local transactio...

Partitioned scheduling algorithms are typically based on Earliest Deadline First (EDF) or Rate-Monotonic Scheduling (RMS). Often, heuristics like First Fit are applied for task allocation to processors. The performance of the heuristics can be improved by sorting tasks in a preprocessing step. While for partitioned EDF, Decreasing Utilization is the approved sequence, there is a variety of sort...

In this paper we examine the packets’ delay performance under the temporal fairness opportunistic scheduling (TFOS) algorithm which is first introduced in [1]. We also simulate the earliest deadline-first (EDF) scheduling algorithm in the wireless environment. We find that the opportunistic scheduling algorithm biases the users who always experience the good channel condition in packets’ delay ...

The conflict resolution technique normally used in Real Time Systems is EDF(Earliest Deadline First). However ,this technique is found to be biased towards the shorter transactions. No technique has been Reported in the literature to remove this biasing. This paper presents a new technique of dynamic priority assignment in real time transactions that is based on the ratio of time left to the ti...

Highly dynamic programming environments for embedded real-time systems require a strict isolation of real-time threads from each other to achieve dependable systems. We propose a new real-time scheduling technique, called guaranteed percentage (GP) scheme that assigns each thread a specific percentage of the processor power. A hardware scheduler in conjunction with a multithreaded processor gua...