Bøger af Lynda Alkama

In wireless sensor networks, each device is able to monitor its environment and send the collected information via a wireless connection. However, to monitor the critical infrastructure, critical messages must be transmitted with minimal delay to deal with failures that may occur. In order to allow this monitoring, the use of the 802.15.4 standard becomes limited. Thus, in 2013, the IEEE organization proposed the new version IEEE 802.15.4k. This amendment proposes new priority channel access mechanisms, namely CSMA/CA with PCA backoff and ALOHA PCA. To evaluate the performance of this amendment, we have modeled its two mechanisms by a Markov chain. The resolution of the systems induced by our models, allowed us to calculate some performance metrics. Non ideal and ideal channel, saturated and non-saturated traffic conditions are considered. In addition, the effect of varying some parameters on our performance metrics is proposed. The results obtained are satisfactory, because the size of the data packets and network size are the most important parameters in industrial applications, especially in critical infrastructure monitoring systems. By varying them, good results are observed.