基于排队论的CAN总线消息响应时间建模与分析

CAN总线消息响应时间是评价CAN总线系统实时性高低的重要性能指标之一，与最糟糕v向应时间分析关注极端条件下响应时间计算不同，研究了均值意义下的响应时间建模与分析．在分析CAN总线CSMA／CD协议的基础上，建立了消息响应时间的非强占优先级的M／G／1排队模型．针对CAN总线独有的位填充机制，给出了相应的填充位概率分布函数，计算了均值意义下的消息响应时间．将其用于电动汽车的CAN总线消息响应时间均值计算，印证了响应时间的均值远小于最糟糕响应时间．上述结果从排队论角度对CAN总线系统进行了建模，所提供的模型和方法不仅可用于响应时间的计算和分析，也为CAN总线通信系统的设计与优化提供了理论指导．

Modeling and Analysis of Response Time of CAN Bus Based on Queueing Theory

Response time of message of CAN is used to evaluate the real-time performance of CAN bus. Compared with the worst case response time analysis which focuses on the response time under extreme condition, analysis and modeling of mean value of response time were presented. According to the CSMA/CD protocol of CAN bus, a non- preemptive priority M/G/1 model was introduced. Because bit-stuffing was adopted in CAN bus, the probability distri- bution function was calculated. Accordingly the mean value of response time was educed and the presented method was applied to a message dataset of electric vehicle. Results show that the mean value of response time is far less than the worst case response time. The above conclusions model the CAN bus based on queueing theory, which is available for the calculation of response time and theoretically helps the design and optimization of CAN based network system.