Real-Time Embedded Research Articles

Research on Real-Time Embedded Software Scheduling Model Based on EDF

Schedulability analysis is a very important part in real-time system research. Because the scenarios faced by real-time systems are very complicated, the functional characteristics must be combined with the predictability of response time. It is necessary to ensure the correctness of the calculation results and meet the real-time requirements. To solve this problem, we propose the IEDF (Improved Earliest Deadline First) algorithm, which is combined with the queuing theory model. The IEDF algorithm is based on the EDF (Earliest Deadline First) algorithm, which is more suitable for the scheduling of real-time embedded system. Scheduling of non-periodic tasks that arrive randomly. There are two types of tasks in the task set, tasks with a high static priority are executed first. In the ready queue of the same priority task, the deadline and execution time are considered. The comparison of simulation experiments shows that: the sum of waiting time in the execution of IEDF with enough deadline is much less than that of ordinary queuing algorithm; the number of errors in the execution of IEDF algorithm with deadline is much less than that of ordinary queuing algorithm. These results demonstrate the feasibility of the IEDF algorithm.

Research on Security Level Assessment Technology in Embedded Real-Time System

This paper briefly describes the main ideas and implementation of technology strategy of Embedded real-time system security level assessment which is important part of mechanism to system flexibility based on embedded real-time system, designs the embedded real-time system security level assessment system based on pattern matching for the characteristics of embedded real-time systems. By building security level assessment system and simulation testing environment based on RT-Linux real-time operating system, the impact of Embedded real-time system security level assessment strategy on performance of RT-Linux was tested.

Design Patterns for Self-Adaptive RTE Systems Specification

The development of self-adaptive real-time embedded (RTE) systems is an increasingly hard task due to the growing complexity of both hardware and software and the high variability of the execution environment. Different approaches, platforms, and middleware have been proposed in the field, from low to high abstraction level. However, there is still a lack of generic and reusable designs for self-adaptive RTE systems that fit different system domains, lighten designers’ task, and decrease development cost. In this paper, we propose five design patterns for self-adaptive RTE systems modeling resulting from the generalization of relevant existing adaptation-related works. Combined together, the patterns form the design of an adaptation loop composed of five adaptation modules. The proposed solution offers a modular, reusable, and flexible specification of these modules and enables the separation of concerns. It also permits dealing with concurrency, real-time features, and adaptation cost relative to the adaptation activities. To validate our solution, we applied it to a complex case study, a cross-layer self-adaptive object tracking system, to show patterns utilization and prove the solution benefits.

An Dynamic Control Mechanism of Interrupt Stack Overflow on Real-time Embedded Monitor REMON

An Dynamic Control Mechanism of Interrupt Stack Overflow on Real-time Embedded Monitor REMON

실시간 임베디드 시스템 상황 정보 서비스를 위한 확장된 Petri-Net 모델링

컴퓨터 환경에서 한 가지 사건으로 상황이 특징 지워지기도 하지만, 일반적 상황 인식은 공간과 시간을 포함하는 다양한 사건들에 의해서 결정되어 진다. 상황 인식 서비스 관계 설정 방법으로 임베디드 시스템 상황 인식을 시공간적으로 취급하는 것이 요구된다. 물리 공간과 연동되는 시스템의 예외적 동작은 임베디드 시스템의 운영에 심각한 위험과 피해를 초래 할 수 있다. 본 논문은 상황 인식 모델에 시공간적 특성과 예외 관리가 포함 되도록 하는 방법을 제안하고, 이를 확장된 Petri-Net을 이용하여 효과를 확인한다. 실시간 임베디드 시스템 상황 인식을 위해 기본 Petri-Net, 패턴화된 Petri-Net 및 예외 동작을 위한 시공간 Petri-Net 모델 특성을 연구한다. 이 방법을 이용하여 응급의료지원 서비스에 적용 예를 보였다. 본 연구를 통해 시공간 Petri-Net을 사용한 응용 개발 뿐 만아니라 예외 처리를 위한 시공간 상황 인식 모델링에 기여 할 것이다. Some context is characterized by a single event in computing environment, but many other contexts are determined by a lot of things which occur with a space and a time. The Realtime Embedded System context-awareness service that interacts with the physical space can have property such as time. The exceptional behaviors of the system that interact with physical space can result in critical damage and cause danger to the operation of an embedded system. we propose an approach which should include spatio-temporal property and exceptional management in the context model, and verify its effectiveness using an expanded Petri-Net. The context-awareness service modeling of an embedded system is discussed the properties of model such as basic Petri-Net, patterned Petri-Net, or Spatio-temporal Petri-Net for the exceptional behaviors of the system. The proposed methodology demonstrated using an example that is emergency medical service. The use of expanded Petri-Net will contribute not only to develop the application but also to model the spatio-temporal context awareness for the exceptional handling.

Guest Editors' Introduction: Special Section on Autonomic Network Computing

IN the paper “Slicing Distributed Systems,” Gramoli et al. consider the problem of slicing—the partitioning of nodes into subsets using an one-dimensional attribute—in distributed systems. This problem arises in peer-to-peer networks and other popular distributed systems used in today’s large data centers. Slicing can help autonomic systems shift work dynamically among nodes and react dynamically to nodes dropping from the system or new nodes joining. The paper reviews existing approaches such as sorting and ranking and shows their problems in convergence, resulting in slow adaptation to changed conditions or inaccurate slice assignments in nonstatic networks. The authors introduce Sliver, a simple distributed slicing protocol that samples attribute values from the network and estimates the slice index from the sample. The theoretical results show that Sliver has provably rapid conversion, is robust under stress, and is simple to implement which they also show with simulation results of the new protocol. The paper “Cholla: A Framework for Composing and Coordinating Adaptations in Networked Systems” by Bridges et al. describes Cholla, a software architecture that separates the policy decisions of how and when adaptive components in networked systems react to their environment into separate centralized controllers that are constructed from composable rule sets. A major goal of this work is to develop a controller architecture that can be used for any collection of adaptive networking components, not a specific architecture that has to be implemented for each application-specific configuration or reimplemented each time that configuration changes. To achieve this, controllers are designed to be composable, with each adaptive component in the system contributing logic that together implements the overall functionality of the controller. This logic is implemented as rule sets that describe particular adaptation policies, and allow rule sets that implement linear, heuristic, and fuzzy control policies. Using composable control logic allows the controller to be specialized based not only on the set of adaptive components in the system, but also on the target network architecture and application requirements. This architecture consists of adaptable components, composable adaptation controllers, and a runtime system. In addition to describing the architecture of Cholla, this paper also presents a Linux-based prototype implementation of this architecture that controls and coordinates adaptation policy decisions inside network protocols and multimedia applications. An experimental evaluation of this prototype demonstrates that Cholla’s controller architecture enables component-based construction and customization of adaptation policies in networked systems, and that these policies can effectively control and coordinate adaptation. The paper “An Online Mechanism for BGP Instability Detection and Analysis” by Deshpande et al. proposes an online instability detection architecture for the border gateway protocol (BGP). BGP is one of the core building blocks of the Internet and is used to direct traffic between different subnetworks of the Internet, known as Autonomous Systems (ASs). The stability of BGP is critical to the stability of the Internet, and under stressful conditions such as worm attacks or router failures, BGP’s basic update protocol can result in severe route fluctuations and loss of connectivity for impacted networks for extended periods of time. The proposed architecture can be implemented by individual routers autonomously without the need for central control or centralized data. This allows widespread deployment without the need for modification of standards and also allows partial deployments without the need of large-scale cooperation among networks. The proposed system uses statistical techniques to detect instabilities using the time domain characteristics of BGP update message data and does not need any additional probing. The experimental evaluation using data collected from routers in Europe including data from several anomaly periods show that the system performs well various kinds of instabilities and across different topologies and policies. The paper “An Integrated Planning and Adaptive Resource Management Architecture for Distributed RealTime Embedded Systems” by Shankaran et al. looks at autonomicity issues in an open distributed embedded realtime environment. Such systems which may arise in context such as space control missions have fundamentally different characteristics than traditional embedded systems with controllable inputs. Autonomic operations require a close coordination between the resource planning needs of the IEEE TRANSACTIONS ON COMPUTERS, VOL. 58, NO. 11, NOVEMBER 2009 1441

Guest Editorial: Special Issue on EUC 2007

Embedded and ubiquitous computing is an exciting new paradigm that provides computing and communication services all the time and everywhere. Its systems are now affecting every aspect of our life to the point that they are hidden inside various appliances. This emergence is a natural outcome of research and technological advances in embedded systems, pervasive computing and communications, wireless networks, mobile computing, distributed computing and agent technologies, etc. This special issue has collected best papers presented in the 2007 IFIP International Conference on Embedded and Ubiquitous Computing (EUC 2007), held in Taipei, Taiwan, ROC. These papers present state of the art in the areas of real-time and embedded software, power-aware hardware management, network security, embedded compiler techniques, mobility and security in advanced wireless networks, and data crawling. Best papers in the EUC 2007 conference were invited for submission. All the invited papers had undergone an intensive review process. The Editor-in-Chief agreed with our recommendation of the acceptance of eleven high quality papers. The first four papers focus on software techniques in embedded and ubiquitous systems. The first paper, entitled “Task Scheduling for Context Minimization in Dynamically Reconfigurable Platforms”, by Nei-Chiung Perng et al. describes a real-time approach to reducing the number of FPGA configuration contexts in dynamic reconfigurable systems. The second paper, entitled “Real-Time Embedded Software Design for Mobile and Ubiquitous Systems” by Pao-Ann Hsiung et al., describes a component-based software architecture that supports automatic synthesis and verification, aiming at high software design productivity. The third paper, entitled “SIGMA system: A Multi-OS Environment for Embedded Systems”, by Wataru Kanda et al., introduces a virtualization technique to support multiple operating systems for multi-processor embedded architectures. The fourth paper, entitled “Compiling for Reduced Bit-Width Queue Processors” by Arquimedes Canedo et al., presents a compiler technique for generating compact codes for embedded processors. The next three papers are on hardware management for embedded and ubiquitous computing. The fifth paper in this special issue, entitled “Energy-Efficient Considerations on a Variable-Bitrate PCI-Express Device”, by Jian-Jia Chen et al., presents a dynamic power management (DPM) algorithm for variable-bitrate PCI devices for power saving. The sixth paper, entitled “Design and Synthesis of An Multiprocessor System-on-Chip Architecture for Real-Time Biomedical Signal Processing in Gamma Cameras”, by Kai Sun et al., discusses communication synthesis and areacost reduction for an MPSOC Gamma Camera. The seventh paper, entitled “Variable Length Pattern Matching for Hardware Network Intrusion Detection System”, by Chun Xue et al., presents a high-performance hardware-based network intrusion detection system. The last four papers are related to wireless-network applications. The eighth paper in this special issue, entitled “A Lightweight Authentication Protocol for Low-Cost RFID” by Hung-Yu Chien et al., proposes a lightweight L.-P. Chang (*) Department of Computer Science, National Chiao-Tung University, Hsin-Chu, Taiwan, Republic of China e-mail: lpchang@cs.nctu.edu.tw

CPU Model-Based Mechatronics/Hardware/Software Co-design Technology for Real-Time Embedded Control Systems

We review practical case studies of a developing method of highly reliable real-time embedded control systems using a CPU model-based hardware/software co-simulation. We take an approach that enables us to fully simulate a virtual mechanical control system including a mechatronics plant, microcontroller hardware, and object code level software. This full virtual system approach simulates control system behavior, especially that of the microcontroller hardware and software. It enables design space exploration of microarchitecture, control design validation, robustness evaluation of the system, software optimization before components design. It also avoids potential problems. The advantage of this work is that it comprises all the components in a typical control system, enabling the designers to analyze effects from different domains, for example mechanical analysis of behavior due to differences in controller microarchitecture. To further improve system design, evaluation and analysis, we implemented an integrated behavior analyzer in the development environment. This analyzer can graphically display the processor behavior during the simulation without affecting simulation results such as task level CPU load, interrupt statistics, and the software variable transition chart. It also provides useful information on the system behavior. This virtual system analysis does not require software modification, does not change the control timing, and does not require any processing power from the target microcontroller. Therefore this method is suitable for real-time embedded control system design, in particular automotive control system design that requires a high level of reliability, robustness, quality, and safety. In this study, a Renesas SH-2A microcontroller model was developed on a CoMET™platform from VaST Systems Technology. An electronic throttle control (ETC) system and an engine control system were chosen to prove this concept. The electronic throttle body (ETB) model on the Saber® simulator from Synopsys® and the engine model on MATLAB®/Simulink®simulator from MathWorks can be simulated with the SH-2A model using a newly developed co-simulation interface between MATLAB®/Simulink® and CoMET™. Though the SH-2A chip was being developed as the project was being executed, we were able to complete the OSEK OS development, control software design, and verification of the entire system using the virtual environment. After releasing a working sample chip in a later stage of the project, we found that such software could run on both actual ETC system and engine control system without critical problem. This demonstrates that our models and simulation environment are sufficiently credible and trustworthy.

A Component-Oriented Programming for Embedded Mobile Robot Software

Applying software reuse to many Embedded Real-Time (ERT) systems poses significant challenges to industrial software processes due to the resource-constrained and real-time requirements of the systems. Autonomous Mobile Robot (AMR) system is a class of ERT systems, hence, inherits the challenge of applying software reuse in general ERT systems. Furthermore, software reuse in AMR systems is challenged by the diversities in terms of robot physical size and shape, environmental interaction and implementation platform. Thus, it is envisioned that component-based software engineering will be the suitable way to promote software reuse in AMR systems with consideration to general requirements to be self-contained, platform-independent and real-time predictable. A framework for component-oriented programming for AMR software development using PECOS component model is proposed in this paper. The main features of this framework are: (1) use graphical representation for components definition and composition; (2) target C language for optimal code generation with resource-constrained micro-controller; and (3) minimal requirement for run-time support. Real-time implementation indicates that, the PECOS component model together with the proposed framework is suitable for resource constrained embedded AMR systems software development.

Towards a “Synchronous Reactive” UML profile?

The domain of Real-Time Embedded (RTE) systems was ackowledged as being largely influential on many feature additions to the recent UML2.0 standard [Bjorkander, M., FDL'03 Keynote address, 2003]. Work on UML1.4 Scheduling, Performance & Time (SPT) profile also goes in that direction. Still, the paradigms underlying these modeling efforts are that of software components, running on a real-time OSs with physical time constraints and middleware (e.g., RT-Corba) concerns. In other areas of Embedded System Design other paradigms are at work, owing to codesign techniques at the border between software and hardware, or discrete time mathematical engineering (MATLAB/Simulink) and digital signal processing algorithms, etc. The paradigm of Synchronous Reactive (S/R) systems [Benveniste, A., Berry, G.: The synchronous approach to reactive and real-time systems. Proc. IEEE 79(9), 1270–1282 (1991); Benveniste, A., Caspi, P., Edwards, S., Halbwachs, N., Guernic, P.L., de Simone, R.: Synchronous languages twelve years later. Proc. IEEE 91(1), 64–83 (2003)], with discrete logical time and behavior decomposition into instantaneous reactions, proved quite natural in such areas to model mixed hardware/software System-Level Design (SLD). We describe here some of the modeling paradigms needed for a true S/R model framework, and corresponding diagrammatic interpretations. The synchronous reactive domain described here should be dealt with and included in the forthcoming UML profile for “Modeling and Analysis of Real-Time and Embedded systems” (MARTE), whose request for proposal was recently voted at OMG.

RTOS modeling in SystemC for real-time embedded SW simulation: A POSIX model

SystemC is committed to support the requirements for an integrated, HW/SW co-design flow, thus allowing the development of complex, multiprocessing, Systems-on Chip (MpSoC). To make this possible, efficient modeling and simulation methodologies for Real-Time, Embedded (RT/E) SW in SystemC have to be developed, so that the designer can verify and refine the application SW together with the rest of the elements of the platform. Accurate modeling of the application SW requires an accurate model of the RTOS. Nevertheless, low-level, dynamic timing characteristics of the RTOS such as time-slicing, priority-based preemptive scheduling, interrupts and exceptions do not have a direct implementation in SystemC. In this paper, techniques are proposed to accurately model the detailed RTOS functionality on top of the SystemC execution kernel. The model allows timed-simulation and refinement of the RT/E SW code in SystemC. The simulation technology has been applied to the development of a high-level, POSIX simulation library in SystemC. The library allows the designer a fast, sufficiently accurate, timed simulation of the application SW running on top of POSIX. As most current RTOSs support this standard, the library is portable to different development frameworks. The library provides the required infrastructure for a complete, multiprocessing, HW/SW co-simulation environment at different abstraction levels using SystemC.

Service-Oriented Paradigms in Industrial Automation

This paper outlines opportunities and challenges in the development of next-generation embedded devices, applications, and services, resulting from their increasing intelligence - it plots envisioned future directions for intelligent device networking based on service-oriented high-level protocols, in particular as regards the industrial automation sector - and outlines the approach adopted by the Service Infrastructure for Real-Time Embedded Networked Applications project, as well as the business advantages this approach is expected to provide.