基于RFieldbus的Token-Passing协议实时性能建模  

Real-time Performance Modelling of Token-Passing based on RFieldbus

作　　者：侯维岩[1] 费敏锐[1] 汪敏[2] 陈伯时[1] 

机构地区：[1]上海大学机电工程与自动化学院,上海200072 [2]上海大学通信与信息工程学院,上海200072

出　　处：《系统仿真学报》2005年第2期296-299,共4页Journal of System Simulation

基　　金：国家自然科学基金(60274031);上海市科委重点攻关项目(025111052);上海市科委重点攻关项目(041111037);且得到欧盟5th-IST 项目(1999113162)的部分资助。

摘　　要：RFieldbus 无线现场总线的 MAC 协议 Token Passing 可看成是一个多台多队列排队系统。在分析了 TTR(令牌目的循环时间)对 RFieldbus 中 3 个优先级队列的服务时间的动态限制后,多台单队列排队模型 RF-P 被提出。对从站的轮巡交换数据任务被转化为RF-P 中的令牌内走步时间,原有的高、低级别两个队列则化成了两个具有不同 Poisson 到达率的 M/G/1/∞服务台。利用排队论中的准守恒 PCL 定律,在将服务时间限制转换为数量限制后,求出了等待响应时间的数学解析式。与试验结果的比较表明,在负载不大于 60%时其偏差度约在 10-20%间。The Token-Passing protocol in the RFieldbus (Radio-Fieldbus which comprise two heterogeneous transmission media: wireless- and wired-segment) system acts as a multi-server-multi-queue system. A multi-server-single-queue RF-P model was built after the analyzing of the dynamic boundary of Token-visiting time of Token-Passing protocol in RFieldbus. In this model, the polling-time on the slaves was transformed into an internal token walking time when TTR is large enough, and the rest two queues were transformed into two M/G/1/ infinity systems with two different Poisson-arrival rates, so that the complexities of the time properties in RFieldbus can be depicted easily by 7 different parameters. With the help of Pseudo-Conversation-Law and the K-limited scheduling an equation to evaluate the average waiting time in RF-P model was derived. The experiment results show that the error of this equation is round 10-20% when system load is lower than 60%.

关 键 词：TOKEN Passing协议 多台单队列排队模型 实时性能 准守恒PCL定律 

分 类 号：TP393.04[自动化与计算机技术—计算机应用技术]