NL-Locate: An Inaudible Multi-Targets Indoor Localization for IoT Devices via Microphone Nonlinearity

Ubiquitous connection applications have become unprecedentedly attractive recently, and increasing demand for real-time multiple targets localization is proposed. Traditional methods face challenges on efficient localization simultaneously due to signal conflict. In this paper, a real-time multiple-object localization mechanism NL-Locate is proposed. By utilizing the nonlinearity of the microphone modules, we design a modulated ultrasound signal for each target device, which enables the receiver to identify each device simultaneously. Such a method does not require any channel negotiation or preallocation, and we implement the prototype of the localization system and evaluate the system performance in both simulations and real systems. The experiment results demonstrate that NL-Locate can achieve a decimeter-level localization accuracy for multiple targets efficiently.