Susceptibility of LoRa Communications to Intentional Electromagnetic Interference with Different Sweep Periods

Abstract

This work presents a detailed analysis of the susceptibility of LoRa communications in the presence of intentional jamming signals. The analysis is performed with a periodic frequency-sweeping intentional electromagnetic interference, corresponding to the most common jamming signals. Such a waveform faithfully represents the signals emitted by commercial jammers. As the sweep period of the jamming signals may vary from one such device to another, the analyses are conducted with different sweep period values, from 1 μs to 50 μs. The experimental results indicate that the impact varies significantly according to the sweep period of the jamming signal. The detailed analysis allows us to identify the jamming signals to which LoRa communications can be resilient or not as well as to identify which LoRa channels are less affected during an attack.

A simulation tool to interpret error rates in LoRa systems under frequency-sweeping jamming

“…The simulation results are presented here together with the experimental results from [4]. These experiments were run in conducted mode, meaning the connection between the LoRa devices is established with cables instead of antennas.…”

“…In both cases, the error rates are evaluated within a range of signal-to-interference ratios (SIR). The SIR calculation follows the methodology described in [4]. All simulations were run with a fixed SNR of 20 dB.…”

“…On the other hand, jamming STs can change from one device to another. Commercial values typically vary from 1 µs to 50 µs [4]. In this work, we consider a LoRa symbol time of 1.025 ms (SF = 7), while the impacts of several jamming STs are evaluated.…”

“…We do that to take into account the fact that the IEMI frequency components seen by a LoRa receiver are equally spaced by 1/ST Hz and they will only "invade" LoRa channels whose central frequencies are multiples of this value. For more details, please refer to [4]. Finally, we use a down-sampler with a factor of 1000 to convert the original IEMI sampling frequency of 250 MS s −1 into 250 kS s −1 , which is the sampling rate used to generate the LoRa signal and the noise.…”

“…In this context, long-range wide area network (LoRaWAN) has been showing to be an efficient remote maintenance solution [3]. However, to operate in harsh electromagnetic (EM) environments such as railways, it is necessary to ensure the robustness of LoRaWANs face to intentional electromagnetic interference (IEMI) [4]. Indeed, IEMI is increasingly widespread nowadays due to the low prices and the easy manipulation of jammers.…”