车载自组网V2I通信中可休眠轮询接入控制策略性能分析

Performance analysis of polling access control strategy with sleeping mechanism for V2I in VANETs

在车载自组网通信协议IEEE 802.11p的基础上,提出一种车辆与路侧单元间通信的门限服务可休眠接入控制策略(GPC-S).首先,结合休眠机制,采用概率母函数和嵌入马尔可夫链的分析方法建立数学分析模型,推导了系统服务性能特性量平均查询周期、排队队长的精确解析;进而推导了站点休眠时间与特性量及网络服务参数之间定量关系的闭式表达式;最后,通过仿真实验对所提出的接入控制策略进行性能和能效测试.测试结果表明:性能特性量的理论计算精度最高可提升9%以上;相较无休眠的IEEE 802.11p,在低负载时,GPC-S能效提升97%以上.在对轮询系统进行建模时结合系统的空闲状态及由此触发的休眠,可提高理论解析精度,为系统的性能及能效评估提供一种有效的分析方法.

An access control strategy, called the gated-service polling control with sleeping mechanism(GPC-S), was proposed for communications between the vehicle and the roadside unit(RSU) based on a communication protocol for vehicular ad-hoc networks(VANETs) IEEE 802.11 p. First, a mathematical model with the sleep mechanism was established by the embedded Markov chain theory and the probability generating function. Then, the mathematical expressions of performance characteristics, mean cyclic period and queue length were deduced. Furthermore, the expressions of the quantitative relationship among the sleeping-time, performance characteristics and service parameters were derived in the closed form. Finally, the performance and the energy efficiency of the proposed strategy were tested by simulation experiments. The results demonstrate that the theoretical precision of the performance characteristics is raised more than 9% at most. Compared with unsleeping IEEE 802.11 p, the energy efficiency of GPC-S is increased by more than 97% when the load is not high. When modeling the polling system, combining with the idle state or the following sleeping state, the accuracy of theoretical calculations is increased. Thus, it provides an effective method for measuring the system performance and the energy efficiency.