Indoor surveillance with multimodal wireless networks

In this paper, we propose a new family of wireless networks, the multimodal wireless networks. These networks offer multiple functionalities realized on the same infrastructure. We describe a wireless network that has two modes of operation: the communication mode, when the network is used as a traditional wireless communication network and the surveillance mode, when the network is used as a distributed sensor network that can detect illegal intrusion. The surveillance functionality is realized by analyzing the properties of the received signals and the change of the propagation environment caused by the intruder serves as the basis for intrusion detection. We also develop a general single-receiver model for detecting changes in a signal parameter of interest and derive a parameter change detector. The experimental results demonstrate that low-cost, off-the-shelf IEEE 802.11b WLAN hardware can be used as building blocks for multimodal networks.