Industrial wireless sensor network (IWSN) is an application area of WSN used in industrial process monitoring and control with strict time and reliability requirement. WirelessHART standard is the first international standard for IWSN approved by International Electrotechnical Commission (IEC). This is worthwhile to implement this standard on simulator platform. Based on the study of WirelessHART standard, this thesis set up a primary implementation of the MAC layer of WirelessHART standard. To our best knowledge, this is the first comprehensive implementation of WirelessHART using OPNET simulator. The implementation has been evaluated rational. And some improvement of current implementation and standard have also been proposed and implemented. Flexible dedicated slot assignment has also been proposed to reduce the packet loss rate caused by influences of the physical channel.
Gao, J.L., Hu, J., Min, Geyong, Xu, L.
No / Supported by the IEEE 802.15.4 standard, embedded sensor networks have become popular and been widely deployed in recent years. The IEEE 802.15.4 medium access control (MAC) protocol is uniquely designed to meet the desirable requirements of the low end-to-end delay, low packet loss, and low power consumption in the low rate wireless personal areas networks (LR-WPANs). This paper develops an analytical model to quantify the key performance metrics of the MAC protocol in LR-WPANs with bursty ONOFF traffic. This study fills the gap in the literature by removing the assumptions of saturated traffic or nonbursty unsaturated traffic conditions, which are unable to capture the characteristics of bursty multimedia traffic in sensor networks. This analytical model can be used to derive the QoS performance metrics in terms of throughput and total delay. The accuracy of the model is verified through NS-2 (http://www.isi.edu/nsnam/ns/) simulation experiments. This model is adopted to investigate the performance of the MAC protocol in LR-WPANs under various traffic patterns, different loads, and various numbers of stations. Numerical results show that the traffic patterns and traffic burstiness have a significant impact on the delay performance of LR-WPANs.
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