普适计算系统可用性度量

Measurement for the Availability of Pervasive Computing System

普适计算系统可用性度量具有典型的面向用户特点,为刻画用户行为需要引入具有非指数分布性质的用户状态,并且需要考虑用户态与系统态关联分析时的复杂情况。传统的连续时间马尔科夫链和半马尔科夫过程都不能很好地对以上情况给予分析。鉴于此,文章基于马尔科夫重生过程(MRGP)提出了普适计算系统的可用性度量方法。首先建立具有普适计算模式的用户模型,基于此构建了普适计算系统可用性度量的MRGP模型,对可用性进行了随机过程分析,给出了对应瞬态和稳态行为的度量方法,结合普适计算模式的特点定义了普适计算系统请求可用性度量。最后进行了数值分析,评价了普适计算系统可用性在MTTF和MTTR下的变化情况,据此导出来构建高可用普适计算系统需要考虑一些原则,并分析了用户和系统参数等因素对普适计算系统可用性度量的影响。

The availability of pervasive computing system has the feature of user oriented.In order to describe the behaviors of user,the non-exponential distributions and associative analysis between user states and system states need to be considered.Due to the CTMC and SMP can not be applied to the modeling of the availability of pervasive computing system,this paper presents an MRGP （Markov Regenerative Process）-based measurement for the availability of pervasive computing system.First,the user model is developed,which provides a base point for describing the availability in pervasive computing.Second,an MRGP model for availability is established,and a stochastic process-based analysis is conducted for the availability of pervasive computing system.The transient and steady availability analysis are provided for this model,and a novel availability metric,called request availability of pervasive computing system,is suggested.Finally,numerical analysis has been carried out and the results argue that the proposed approach and availability metric can give reasonable evaluation for pervasive computing system.