PIE in the sky: online passive interference estimation for enterprise WLANs

Trends in enterprise WLAN usage and deployment point to the need for tools that can capture interference in real time. A tool for interference estimation can not only enable WLAN managers to improve network performance by dynamically adjusting operating parameters like the channel of operation and transmit power of access points, but also diagnose and potentially proactively fix problems. In this paper, we present the design, implementation, and evaluation of a Passive Interference Estimator (PIE) that can dynamically generate fine-grained interference estimates across an entire WLAN. PIE introduces no measurement traffic, and yet provides an accurate estimate of WLAN interference tracking changes caused by client mobility, dynamic traffic loads, and varying channel conditions. Our experiments conducted on two different testbeds, using both controlled and real traffic patterns, show that PIE is not only able to provide high accuracy but also operate beyond the limitations of prior tools. It helps with performance diagnosis and real-time WLAN optimization, we describe its use in multiple WLAN optimization applications: channel assignment, transmit power control, and data scheduling.