Cognitive passive estimation of available bandwidth (cPEAB) in overlapped IEEE 802.11 WiFi WLANs

Correct estimation of the available bandwidth in overlapped WiFi WLANs environments is one of the essential functions for efficient network resource management and seamless mobile service provisioning of QoS-guaranteed realtime multimedia applications in future Internet. In this paper, we propose a cognitive passive estimation of the available bandwidth (cPEAB) by correct measurements of i) the proportion of waiting and back-off delay, ii) packet collision probability, iii) acknowledgement delay, and iv) channel idle time compared to measurement period. For more accurate estimation of the available bandwidth, the information of the hidden nodes and exposed nodes are provided by the cognitive network management system. Also, the proposed scheme is using passive measurements, instead of active probe packet exchange which directly affects the available bandwidth of other mobile nodes. The proposed cPEAB scheme has been implemented on Multiband Atheros Driver for WiFi (MadWiFi), and the performance has been analyzed and compared with existing schemes, such as active bandwidth measurements with probes, adaptive admission control protocol (AAC), available bandwidth estimation (ABE), and improved available bandwidth estimation (IAB). From the experimental measurements on real WiFi environment, we found that the proposed cPEAB provides the most accurate estimation of available bandwidth on the overlapped WiFi WLAN environment where the hidden/exposed nodes are dynamically affecting the available bandwidth.