Survey of Commercial Wi-Fi Devices’ Energy Detection Mechanism

This paper presents an experimental survey of the capabilities of commercial IEEE 802.11 (Wi-Fi) devices to detect the state of the wireless medium. Wi-Fi devices use a Clear Channel Assessment (CCA) mechanism to determine if the wireless medium is occupied. By subjecting Wi-Fi devices to Gaussian interference signals transmitted through a Universal Software Radio Peripheral (USRP), we assess their CCA behavior. Moreover, we perform a deeper investigation of the Ericsson AP6321 Wi-Fi Access Point prompted by privileged access to its internal operations. Our findings highlight variations between different Wi-Fi devices’ CCA mechanisms and reveal floating CCA thresholds. Since CCA forms the fundamental basis for Wi-Fi operation, this study provides insights into coexistence of Wi-Fi with itself and dissimilar technologies. Because future Narrow Band Frequency Hopping (NB FH) systems are a potential technology that commercial Wi-Fi devices need to coexist with, we provide an extended survey of the capability of Wi-Fi devices to detect NB FH signals in unlicensed bands. This survey demonstrates that rapidly changing, on-off signalling does not have a disproportionate impact on Wi-Fi performance.