THE CONTROL OF STARVATION

A generalized discussion of the anomaly of starvation is presented. Starvation is defined to be an infinite or unbounded delay, and classified in terms of its cause and the methods used for its control. A model and a set of control mechanisms are developed. The model, appropriate for various buffered and unbuffered resource systems, allows an ordering of requests by time and by stages of their lifetimes. We investigate the behavior and control of requests during starvation and during various anomalies of conflict.     

A channel reservation and preemption model using overlapping regions in sector‐based cellular networks

This paper presents a channel reservation and preemption (CRP) model using overlapping regions in a cellular network with multiple sectors. To fully exploit and reuse the frequencies, directional antennas are installed on base stations (BSs) to divide the coverage into a number of equal‐sized sectors. When traffic is unevenly distributed across the sectors in a BS, channel utilization in every sector may become very different; low‐traffic sectors may be underutilized while high‐traffic sectors may be overutilized. A CRP scheme is thus proposed to more efficiently utilize free channels among sectors. CRP aims at reducing the dropping probabilities of handoff calls. Specifically, when free channels in a sector are not available, a handoff call, instead of being dropped, is allowed to preempt an ongoing call residing in the overlapping region of two adjacent sectors or two neighbor cells. Under CRP, the preempted ongoing call will not be disconnected, because it can switch over its service to the BS of a neighbor cell or to another directional antenna of an adjacent sector. For the purpose of evaluation, we build an analytical model for the proposed CRP using six‐tuple Markov chains. Analytical results show that the proposed CRP can significantly reduce the dropping probabilities of inter‐sector handoff calls, particularly when traffic between two sectors is not evenly distributed. Copyright © 2013 John Wiley & Sons, Ltd.     

民机CNS系统动态重构技术

动态重构是一项充分利用软硬件资源的技术。在介绍民机CNS系统和动态重构基本原理基础上,给出了一种动态重构的通用功能模块的设计方案,描述了利用有限状态机和排列组合原理计算系统配置的方法,并根据系统资源状况和应用的优先级对资源进行初次分配及再分配,设计出了一种动态重构算法,该算法能很好地兼顾资源备份式重构和资源抢占式重构。同时,指出对动态重构的品质设计需从可用性、可靠性、维护性方面考虑。最后,使用Simulink对动态重构算法的正确性进行了仿真验证。     

WDM光网络的多优先级业务疏导机制

IP over WDM网络中,业务疏导能有效提高波长带宽利用率.然而,单一化的业务疏导机制难以满足不同业务的QoS要求,也很难做到经济合理地使用光路.提出了一种支持多优先级业务的疏导机制,该机制根据光路传输的时延和丢包特性来选择恰当的疏导路径,同时,该机制结合了抢占和流量分割技术,能有效地实现流量分割和多路抢占,降低了业务的阻塞概率.仿真结果显示,该疏导机制在保证业务QoS的同时,降低了高优先级业务的阻塞概率;在业务负载低时,能有效减少抢占.     

一种WiMAX接纳控制算法研究

为了使WiMAX系统能够更好的接纳新业务,该文提出了一种基于博弈论的抢占式接纳控制算法。该算法认为新连接与基站之间存在一个非合作二人博弈过程,可以依据纳什均衡决定是否接纳新连接。该算法可以在系统负载很大时保证高优先级业务接纳率,同时避免盲目抢占非实时业务带宽造成系统公平性严重下降。仿真结果表明,与传统截止优先级算法比较,该算法在系统负载很大时能更好的保证新业务接纳率和不同业务的QoS。     

Spartan6芯片μC/OS-Ⅱ的可抢占式嵌套中断控制方法

介绍了Spartan6芯片搭载MicroBlaze软核的硬件平台,以及集成了μC/OS-Ⅱ操作系统的软件平台;给出了在此软硬件平台上的可抢占、可嵌套的中断机制的实现方法;灵活地运用面向底层硬件代码与操作系统代码之间的参数传递,协调了中断处理与任务调度之间的关系。阐述了方案的原理,给出了程序流程图;通过试验,验证了可抢占、可嵌套的中断机制的正确性与可行性。     

避免抢占的多协议标记交换路由算法

目前流量工程的主要算法大多不能克服对不同类型业务流顺序的影响以及对各流类型带宽比例的影响,且很少在为业务请求计算路由时便考虑避免LSP抢占的问题。为此,提出一种避免抢占的MPLS DS-TE路由算法PA-DTE(Preempting Algorithm-DiffServ aware Traffic Engineer-ing).新算法综合考虑各类业务流的带宽比例,优先选择相对空闲的链路,从而减少了被抢占的LSP数目。为验证新算法的性能,在NS2仿真平台上实现了该算法的仿真,仿真结果表明,与在为业务请求计算路由时未考虑避免LSP抢占问题的算法相比,新算法在负载均衡、维持链路各CT(Class Type)流量比例、保证业务QoS和避免抢占等方面表现出了一定的优势。     

A hybrid particle swarm optimisation for scheduling just-in-time single machine with preemption,machine idle time and unequal release times

This paper addresses preemption in just-in-time (JIT) single–machine-scheduling problem with unequal release times and allowable unforced machine idle time as realistic assumptions occur in the manufacturing environments aiming to minimise the total weighted earliness and tardiness costs. Delay in production systems is a vital item to be focussed to counteract lost sale and back order. Thus, JIT concept is targeted including the elements required such as machine preemption, machine idle time and unequal release times. We proposed a new mathematical model and as the problem is proven to be NP-hard, three meta-heuristic approaches namely hybrid particle swarm optimisation (HPSO), genetic algorithm and imperialist competitive algorithm are employed to solve the problem in larger sizes. In HPSO, cloud theory-based simulated annealing is employed with a certain probability to avoid being trapped in a local optimum. Taguchi method is applied to calibrate the parameters of the proposed algorithms. A number of numerical examples are solved to demonstrate the effectiveness of the proposed approach. The performance of the proposed algorithms is evaluated in terms of relative percent deviation and computational time where the computational results clarify better performance of HPSO than other algorithms in quality of solutions and computational time.     

一个面向嵌入式系统实时性能优化的抢占模型

通过对采用RM调度策略的实时嵌入式系统抢占行为的分析，建立了一个周期性实时任务集的抢占模型，从数学上定量地刻画了因抢占而导致的额外开销与系统中各实时任务属性的关系，以及与整个实时任务集的可调度性的关系。依据该模型并借鉴生物学领域的寄生思想，提出了一个基于进化规划的性能优化方法，通过调整任务启动时间，以减少抢占次数或改变抢占关系，降低系统额外开销，提高系统实时性能；最后通过实验验证了建立在抢占模犁基础上的嵌入式系统件能优化方法的有效件。     

安全关键系统的栈空间分析研究

由于存储空间异常引起的系统故障,系统开发或维护人员很难从失效特征直接判断到根原因。另外,存储空间异常通常会引起整个系统崩溃,对于安全关键系统,如航空电子系统,系统的失效往往会引起坠机或人员伤亡,因此,对安全关键系统的空间分析显得尤为重要。由于系统栈空间的分析涉及系统动态运行状态,在程序的任意点都有可能被中断服务程序或实时操作系统的其它任务中断。此外系统的栈分析需要基于目标码等特性,再次增加了对于系统栈空间分析的难度。本文从栈空间分析的必要性出发,提出一种综合中断抢占图的栈分析理论和方法,并就安全关键系统如何保证栈空间使用的确定性进行论述。最后,就安全关键软件系统FCOS的栈空间分析过程进行详细的阐述。