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11.
嵌入式RTOS中任务优先级反转问题研究   总被引:1,自引:0,他引:1  
李屏  张艳军 《信息技术》2006,30(9):94-96
针对嵌入式实时系统任务调度策略的特点,任务在运行的时候可能被更高优先级的任务中断。分析了嵌入式RTOS中的最高就绪任务的查找算法,指出该调度算法存在的不同优先级的反转问题,并且针对这一问题进行研究,给出了相应的优先级继承方案。较好地解决了RTOS中任务调度中的优先级的反转问题。  相似文献   
12.
Uplink scheduling in wireless systems is gaining importance due to arising uplink intensive data services (ftp, image uploads etc.), which could be hampered by the currently in-built asymmetry in favor of the downlink. In this work, we propose and study algorithms for efficient uplink packet-data scheduling in a CDMA cell. The algorithms attempt to maximize system throughput under transmit power limitations on the mobiles assuming instantaneous knowledge of user queues and channels. However no channel statistics or traffic characterization is necessary. Apart from increasing throughput, the algorithms also improve fairness of service among users, hence reducing chances of buffer overflows for poorly located users. The major observation arising from our analysis is that it is advantageous on the uplink to schedule “strong” users one-at-a-time, and “weak” users in larger groups. This contrasts with the downlink where one-at-a-time transmission for all users has shown to be the preferred mode in much previous work. Based on the optimal schedules, we propose less complex and more practical approximate methods, both of which offer significant performance improvement compared to one-at-a-time transmission, and the widely acclaimed Proportional Fair (PF) algorithm, in simulations. When queue content cannot be fed back, we propose a simple modification of PF, Uplink PF (UPF), that offers similar improvement. Hereafter, we refer to users with low recieved power at the base even when transmitting at peak transmit power as “weak” users, and the strongly recieved users at the base as “strong” users. Krishnan Kumaran is currently a member of the Complex Systems Modeling section in the Corporate Strategic Research of ExxonMobil Corp., Clinton, NJ. Formerly, he was a Member of Technical Staff in the Mathematics of Networks and Systems Research Department at Bell Labs in Murray Hill, NJ, where his research interests were in modeling, analysis and simulation of design, resource management and scheduling issues in telecommunication networks. Lijun Qian is an assistant professor in the Department of Electrical Engineering at Prairie View A&M University. He received his B.S. from Tsinghua University in Beijing, M.S. from Technion-Israel Institute of Technology, and Ph.D. from WINLAB, Rutgers University, all in electrical engineering. Before joining PVAMU, he was a researcher at Networks and Systems Research Department of Bell Labs in Murray Hill, NJ. His major research interests are in wireless communications and networking technologies, especially in radio resource management, protocol design, TCP/RLP optimization and MPLS traffic engineering.  相似文献   
13.
Mehta  Vipin  El Zarki  Magda 《Wireless Networks》2004,10(4):401-412
Communicating with sensors has long been limited either to wired connections or to proprietary wireless communication protocols. Using a ubiquitous and inexpensive wireless communication technology to create Sensor Area Networks (SANs) will accelerate the extensive deployment of sensor technology. Bluetooth, an emerging, worldwide standard for inexpensive, local wireless communication is a viable choice for SANs because of its inherent support for some of the important requirements – low power, small form factor, low cost and sufficient communication range. In this paper we outline an approach, centered on the Bluetooth technology, to support a sensor network composed of fixed wireless sensors for health monitoring of highways, bridges and other civil infrastructures. We present a topology formation scheme that not only takes into account the traffic generated by different sensors but also the associated link strengths, buffer capacities and energy availability. The algorithm makes no particular assumptions as to the placement of nodes, and not all nodes need to be in radio proximity of each other. The output is a tree shaped scatternet rooted at the sensor hub (data logger) that is balanced in terms of traffic carried on each of the links. We also analyze the scheduling, routing and healing aspects of the resulting sensor-net topology.  相似文献   
14.
网格资源管理系统模型研究   总被引:10,自引:3,他引:7  
网格资源管理系统是网格计算系统的重要组成部分。文章分析了网格资源管理系统的功能需求,具体论述了该模型的原型系统,最后介绍了相关研究工作。  相似文献   
15.
串行口及接口板端口是计算机通信的主要途径 ,也是目前计算机工程测控中通用的基本方法。C Builder (简称CB)编程语言以其功能完备、开发效率高的特点而成为目前流行的程序开发工具 ,介绍了利用CB语言编写串行口和端口通信的程序的方法 ,并对具体的各方法编写了相应的示例。  相似文献   
16.
串行和并行接口模式是A/D转换器诸多分类中的一种,但却是应用中器件选择的一个重要指标.在同样的转换分辨率及转换速度的前提下,不同的接口方式不但影响了电路结构,更重要的是将在高速数据采集的过程中对采样周期产生较大影响.本文通过12位串行ADC ADS7822和并行ADC ADS774与AT89C51的接口电路,给出二者采样时间的差异性.  相似文献   
17.
一种计算机实时控制系统的分析及其DCS实现   总被引:2,自引:0,他引:2  
简述了计算机实时控制及分布式控制系统(DCS)的一般特点.并以某型水下机器人的控制系统为例,详细介绍了一种小型实时DCS系统的具体实现。  相似文献   
18.
Future generation wireless multimediacommunications will require efficient Medium AccessControl (MAC) protocols able to guarantee suitable Qualityof Service (QoS) levels for different traffic classes whileachieving a high utilization of radio resources. This paperproposes a new scheduling technique to be adopted at the MAClevel in wireless access systems, named Dynamic Scheduling-Time DivisionDuplexing (DS-TDD), that efficiently managesvideo, voice, Web and background traffics. A theoretical approachis proposed in this paper to evaluate the DS-TDD performance withvoice and Web traffics. Simulation results have permitted tohighlight the following promising characteristics of the DS-TDDscheme: (i) a high capacity of real-time traffics isattained with a QoS insensitive to Web and background trafficloads; (ii) a high throughput can be guaranteed whilepreserving the QoS levels of the different traffic classes;(iii) heavier downlink traffic loads do not modify the QoSof uplink traffics. Finally, extensive comparisons with differentscheduling schemes proposed in the literature have permitted tohighlight the better performanceof DS-TDD.  相似文献   
19.
研究了以集合论为基础的调度优化模型。给出了该离散型优化问题的求解算法。根据优化结果,在G2实时智能平台上开发了包含监视子系统和调度子系统的调度支持系统。在中国石化股份有限公司长岭分公司的试用结果表明,该调度系统可以提高炼油厂的生产效率,从而提高炼油厂的经济效益。  相似文献   
20.
Modular testing is an attractive approach to testing large system ICs, especially if they are built from pre-designed reusable embedded cores. This paper describes an automated modular test development approach. The basis of this approach is that a core or module test is dissected into a test protocol and a test pattern list. A test protocol describes in detail how to apply one test pattern to the core, while abstracting from the specific test pattern stimulus and response values. Subsequent automation tasks, such as the expansion from core-level tests to system-chip-level tests and test scheduling, all work on test protocols, thereby greatly reducing the amount of compute time and data involved. Finally, an SOC-level test is assembled from the expanded and scheduled test protocols and the (so far untouched) test patterns. This paper describes and formalizes the notion of test protocols and the algorithms for test protocol expansion and scheduling. A running example is featured throughout the paper. We also elaborate on the industrial usage of the concepts described.  相似文献   
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