SoNIC: Classifying and Surviving Interference in 802.15.4-based Sensor Networks

Sensor networks that use 802.15.4 in the 2.45 GHz ISM band are prone to radio interference from devices such as microwave ovens, WiFi devices, and Bluetooth devices. Interference can cause packet loss and thus reduces network performance and lifetime. Online detection of interference in sensor networks is challenging, because nodes cannot decode foreign transmissions due to incompatibility between 802.15.4 and other technologies. We present SoNIC, a system that enables sensor networks to detect and classify cross-technology interference. At the core of SoNIC lies an interference classification approach that assigns individual corrupted 802.15.4 packets to different interference classes. A voting algorithm fuses the classification results to detect the presence of interferers. The output of the voting can be used to select a mitigation strategy. In contrast to other solutions, SoNIC does not require active spectrum scanning or specialized hardware. It runs on ordinary TelosB sensor nodes using Contiki. This technical report describes the core idea of SoNIC, selected system aspects of it (including three mitigation strategies), as well as initial experiments in an office environment.