Exploiting temporal and spatial variation for WiFi interference avoidance in ZigBee networks

In the Internet of Things (IoT), different wireless technologies will be used to build various micro-systems, which result mutual interference among these micro-systems. Specifically, ZigBee networks share the 2.4GHz ISM band with WiFi but have much lower transmission power. Therefore, the ZigBee networks inevitably suffer the interference from WiFi Networks. Unlike previous approaches that focused on minimizing effect on link level, this paper focuses on utilizing the temporal and spatial feature of WiFi interference to adjust Zigbee channel over the whole networks. In this paper, we first experimentally examine the spatio-temporal variation. Then we present a novel interference assessing method. This proposed method jointly considers the intensity and density of WiFi interference in order to better characterize the relation between interference and link quality. Further focusing on the interference locality, we propose MuZi (Multi-channel ZigBee) as an interference avoiding approach for ZigBee networks. MuZi consists of three components: interference assessment, channel switch, and connectivity maintenance. It aims to determine a better working channel for each node while taking network connectivity into consideration. Our extensive experiments on a testbed of 802.11 embedded nodes and 802.15.4 TelosB motes show that, under the existence of WiFi interference, MuZi can achieve 3.3 times throughput than the traditional single-channel method.