Feasibility of deploying wireless Internet of Things in the unlicensed European 865-868 MHz band

The European Commission has made the unlicensed 865-868 MHz band available for deployment of wireless Internet of Things. The band is mainly used by RFID systems, but the current activity levels are unknown. In this paper, the in-band power levels are measured in five areas. The measurements show that RFID interrogators emit high-power single tone-like signals in four subbands, when active. Most signals are 0.4 s long, but it differs whether the subbands are used in a coordinated way or not. In some areas the RFID systems use a single subband about 80 % of the time, while in other areas two to three subbands are occupied simultaneously 65-80 % of the time. The measurements are used to evaluate the performance of a narrowband wireless Internet of Things technology, if it were to be deployed in the 865-868 MHz band. Specfically, the measurements serve as interference input in a calculation of error rate probability. If the least interfered subband is always selected for the wireless Internet of Things transmission the error rate is 0 % for desired signals up to -115 dBm, while if the subband with highest average interference is used, the error rate is up to 7.5 % and at least 25 % at -100 dBm and -120 dBm, respectively.