# On Vulnerability of Selected IoT Systems to Radio Jamming--A Proposal of Deployment Practices
## 8 Conclusions  
### Practical Recommendations  
The paper presents results of a measurement campaign on two leading IoT systems representing different families of the LTN group, i.e., Weightless and SigFox. Measurements were conducted in a laboratory of electromagnetic compatibility that allowed to create a controlled propagation environment to precisely control the amount and type of interference to which a measured system was exposed. Firstly, results of measurements performed in electromagnetically isolated conditions of an anechoic chamber were shown to demonstrate CNIR profiles vs. PER. A threshold PER of 50% was set to be indicative of the boundary reception quality, above which communication was deemed to have failed. The values for which PER = 50% was achieved, individually determined by means of measuring each of the Weightless eight operational modes and for SigFox uplink channel, were then transformed into an interference margin \(M_{int}\), a measure providing information on the system immunity to interference. Assuming a jammer radiating at a legal EIRP of 14 dBm, it was moved towards the BS location (at the  
Figure 8: Interference margin (\(M_{int}\)) plot for all operational modes vs. normalized distance between the jammer and the IoT base station.  
\begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline  & & & \multicolumn{4}{c}{_Weightless_} & & \multicolumn{2}{c}{_SigFox_} \\  & & \multicolumn{2}{c}{_OQPSK_} & & \multicolumn{2}{c}{_GMSK_} & & \multicolumn{2}{c}{_DBPSK_} \\ \(\frac{d}{CR}\) & NB & & \multicolumn{2}{c}{_WB_} & NB & & \multicolumn{2}{c}{_WB_} & \\  & & \multicolumn{2}{c}{_Data Rate Mode, R\({}_{b}\) [kb/s]_} & & & & & & \\  & **0.625** & **1.25** & **6.25** & **12.5** & **5** & **10** & **50** & **100** & **0.1** \\ \hline
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cell center) at regular steps, each time recalculating \(M_{int}\) to show how different operational modes respond to these changes. Some of the most important practical takeaways include:  
* the \"slowest\" Weightless modes that use OQPSK modulation, particularly narrowband (0.625/1.25 kb/s) are at the same time the most robust in terms of resistance to jamming. Thus, these two data rate settings can be recommended for use in networks for their immunity to \"legal-jamming\", as one particularly problematic to detect since the jammer's signal does not exceed lawful limits, which makes it practically untraceable, as opposed to strong jammers;
* on the far end of immunity lie the two fastest Weightless modes, i.e., 50/100 kb/s, experiencing disruption in communication, expressed by negative \(M_{int}\), with the jammer placed at the at distances between 0.1 and 0.3 _d_/_CR_ with respect to BS;
* in SigFox there exists a sufficient safety margin for jamming even at proximity between the jammer and the BS, which leaves some space for additional attenuation, e.g., due to vegetation or buildings;
* the idea of low throughput has proved correct for use in the Internet of Things systems. Not only because it provides low receiver noise (due to narrow channels, here: 12.5 kHz in Weightless, and 100 Hz in SigFox) but also due to increased immunity to EM cyberattacks. Their appearance is recognized to be a growing threat as the massive machine-type traffic becomes more and more prevalent in the years to come and as it conveys increasingly more crucial data concerning our living environment.