基于随机Petri网的车车通信可靠性建模与分析

Reliability modeling and analysis of the train-to-train communication conditions based on the stochastic Petri net

为了更好地评估基于高速铁路无线通信LTE-R的车车通信可靠性,提出了一种基于随机Petri网的车车通信可靠性评价方法。首先,根据车车通信有中继模式和无中继模式通信的特点,综合考虑通信故障引发因素后,分别建立了不同模式下的车车通信SPN可靠性评价模型;然后采用Time-Net仿真工具对有中继和无中继的车车通信可靠性、传输出错等指标进行了量化分析;最后对不同列车速度下基于中继的译码转发DF方式和放大转发AF方式可靠性进行了比较分析。结果表明,LTE-R无线通信系统的D2D通信技术能够提供高可信的车车通信服务,基于中继的车车通信可靠性高于无中继车车通信模式。

The present paper intends to propose a novel reliability evaluation method for communications based on the stochastic Petri net so as to be able to bring about the reliability of the better train-to-train communication based on the LTE-R communication technology of the high-speed railway system. To achieve the said purpose,in accordance with the characteristic features of the relay mode with no relay communications on the train-to-train communication conditions,the paper would like to establish the SPN reliability evaluation models of communication under the different modes respectively on account of the factors that may lead to the communication failure,such as the transmission errors,the link-up failure,etc. And,then,we have also made a quantitative analysis of the communication reliability and the transmission errors of the train-to-train communication conditions based on the with-relay or/and without relay models through the Time Net simulation tool for the model in the paper. From the simulation results,it can be found that the relay mode we have proposed can help to strengthen the reliability of the communications,and make up for the impact of handover on the system reliability to improve the communications link. In the relay mode of such communications,the cooperative decode and forward mode may likely come across the understandable communication errors and remain in great need to improve the quality of communication efficiency. For instance,the communication signals are to be amplified and retransmitted through amplification in the due forward mode (AF). In doing so,the noise may also be amplified and forwarded simultaneously,which may naturally lead to a higher bit error rate in the AF relay process so as to lower the reliability than that in DF relay mode. In such a situation,the communication without relay mode can be rather lower in the following 3 modes,for the poor channel quality may have a great impact on the communication reliability. And,finally,the reliability of the relay result can be compared at the different rates. Hence,the results of our study show that the overall reliability of the communications in the relay mode tends to decrease at the railway carriage high-moving speed. In addition,the reliability of DF relay mode can actually be made higher than that of AF relay mode at the same train moving speed,for the D2 D communication technology of LTE-R wireless communication system can help also to provide for higher reliable train-to-train communication services,so that the reliability of such train-to-train communication based on the relay stations can be made higher or greater than that with no relay means.