连续时间完全服务与门限服务两级轮询系统性能研究

Research of continuous time two-level polling system performance of exhaustive service and gated service

在信息分组以连续时间规律到达系统的基础上,对于轮询系统中不同优先级的业务问题,提出区分优先级的两级轮询服务模型。首先,在该模型中,低优先级站点采用门限服务,高优先级站点采用完全服务;然后,在高优先级转低优先级时,将传输服务与转移查询并行处理来降低服务器在查询转换期间所耗费的时间,提高轮询系统的效率;最后,运用马尔可夫链和概率母函数的方法建立了系统的数学模型,通过对数学模型精确解析,得到了连续时间两级服务系统每个站点的平均排队队长和平均等待时间的表达式,精确解析出平均排队队长和平均等待时间的值。仿真实验结果表明:理论计算值与实验仿真值近似相等,说明理论分析正确合理。该模型既能保障低优先级站点服务质量,又能为高优先级站点提供优质服务。

For the fact that information groups arrive at the system in a continuous time,a two-level polling service model with different priorities was proposed for the business problems of different priorities in the polling system. Firstly,gated service was used in sites with low priority,and exhaustive service was used in sites with high priority. Then,when high priority turned into low priority,the transmission service and the transfer query were processed in parallel to reduce the time cost of server during query conversion,improving the efficiency of polling system. Finally,the mathematical model of system was established by using Markov chain and probabilistic parent function. By accurately analyzing the mathematical model,the expressions of average queue length and average waiting time of each station of continuous-time two-level service system were obtained. The simulation results show that the theoretical calculation value was approximately equal to the experimental simulation value,indicating that the theoretical analysis is correct and reasonable. The model provides high-quality services for high-priority sites while maintaining the quality of services in low-priority sites.