Design of WiFi AP-RSS Monitoring System Using Sensor Nodes

Sensor localization is one of the big problems when building large scale indoor sensor networks because GPS is unavailable in indoor environments. In this paper, we propose a sensor localization system using WiFi APs as anchors. WiFi APs are largely installed in indoor environments and are managed by a network system manager. Using WiFi APs as anchors, we can localize sensor nodes with neither newly deployed anchor nodes nor user cooperation. As a first step of our sensor localization system, this paper presents a WiFi AP-RSS monitoring system using sensor nodes. Sensor nodes are equipped with ZigBee (IEEE 802.15.4) modules, which cannot demodulate WiFi (IEEE 802.11) signals. We therefore developed a cross-technology signal extraction scheme with an AP recognition scheme on sensor nodes. We herein describe the design and implementation of our AP-RSS monitoring system. The experimental evaluations demonstrated that the proposed AP-RSS monitoring system successfully recognized WiFi APs with detection errors less than 10%. We also confirmed that the proposed system monitored AP-RSS with an average error of 1.26dB.