Performance Study of a New CSMA/CA Access Method with QoS Based on 802.11b and Comparison with 802.15.4/ZigBee

Wireless Network Controlled Systems (WNCSs) are a new area of research which concerns the implementation of control strategy over wireless networks. Therefore, many potential applications of Wireless Sensor Networks (WSNs) span a wide spectrum in various domains. The dependability of the WNCSs becomes a strong requirement due to real-time requirements of control. The Quality of Control (QoC) is performed through optimally allocating the network resources to ensure the Quality of Service (QoS) and optimally designing controller to compensate for time delays in the control feedback loop. The IEEE 802.11b standard is a really widespread wireless network. However, some QoS properties are missing, compared to more specific protocols, such as 802.15.4. In this paper, the authors present the implementation of an extended model of the IEEE 802.11b standard in order to add more QoS properties through the use of CSMA/CA with the combination of the frame selection sort and the First Come First Served (FCFS) scheduling methods. The control performances of the new model are compared to those of IEEE 802.15.4 with QoS. Several improvements are achieved including a reduction in the number of collisions and priority-based flow control.