Performance analysis of LoRa in the 2.4 GHz ISM band: coexistence issues with Wi-Fi

摘要

Within realization of the visions of the Internet-of-Things (IoT), Low Power Wide Area Networks (LPWANs) are undoubtedly one of the fields that attract high interest from both academic and industrial fields. To ensure reliable data exchange between low power and low data rate devices across long distances, which are the main aims of LPWAs, it is necessary to utilize advanced wireless communication technologies. Emerging LPWA technologies, for instance Long-Range (LoRa) and SigFox, offer many benefits for IoT. These technologies have been primarily developed for sub-GHz frequency bands, but, in the future, their deployment is also considered in the 2.4 GHz industrial, scientific and medical (ISM) bands. However, these unlicensed ISM bands are also used by other technologies for Wireless Local Area Network (WLAN also denoted as Wi-Fi) connectivity and other services, and therefore, coexistence issues can occur here in the future. The main aim of this paper is to perform a performance analysis of the LoRa radio signals interfered by Wi-Fi, using interferers confirming to different IEEE 802.11 family standards, in the 2.4 GHz ISM band. For this purpose, an automated measurement setup and methodology on Physical (PHY) layer are proposed and used. In general, the evaluated results confirm theoretical assumptions on high robustness of LoRa against interferences. However, our results reveal that this robustness of LoRa is highly depending not only on the used LoRa system parameters, but also on the interferer properties and the assumed coexistence scenarios (co-channel, in-band and adjacent channel interferences).