Performance Analysis of ISA100.11a Under Interference From an IEEE 802.11b Wireless Network

Recently, the International Society of Automation (ISA) released ISA100.11a as an open standard for reliable wireless networks for industrial automation. ISA100.11a operates in the 2.4-GHz industrial, scientific, and medical (ISM) unlicensed band, and may suffer from interference from other radio technologies operating in the same band. This coexistence issue can lead to significant degradation of ISA100.11a performance. In this work, the performance of the ISA100.11a industrial wireless network under interference from an IEEE 802.11b wireless local area network (WLAN) is evaluated. An analytical model for the coexistence between ISA100.11a and IEEE 802.11b is suggested. The packet error rate (PER) and average end-to-end delay are evaluated, where the PER is obtained from the bit error probability and collision time, whereas the average end-to-end delay is investigated from the waiting time in buffer and the transmission time. Simulation results from the OPNET modeler are presented to validate the numerical analysis. It is demonstrated that ISA100.11a achieves acceptable PER and satisfies the delay requirement for industrial process control and monitoring, even under significant WLAN interference.