# Resilience of LTE-A/5G-NR Links Against Transient Electromagnetic Interference
## 4 Results and Discussions
### Transient EMI in 5G-NR  
A double-sided exponential signal was introduced into the primary communication link at three distinct transmit gains, mirroring the configuration used in the LTE link. All parameters were kept constant, except for the operating frequency. As indicated in the table, the signal at 2.2 GHz shows the greatest performance degradation, although its impact is still less severe compared to that of the continuous wave (CW) tone jammer. Table 5 demonstrates that the 5G-NR link's performance varies significantly across different interferer frequencies, with 2.2 GHz showing the most severe impact in terms of the BER (0.3884) and SINR (\(-\)12.67 dB), which is the lowest. This frequency likely causes the greatest disruption because of the strong spectral overlap with the desired signal, leading to higher bit errors and a reduction in the signal quality. The exceptionally high EVM values at 2.1955 GHz (EVM peak: 389223.16%) suggest extreme signal distortion, even though its BER is lower than at 2.2 GHz. This indicates that while interference at 2.1955 GHz causes significant distortion, it may not cause as much bit error rate degradation, possibly due to the frequency's reduced interaction with the signal's key components.  
A distinct peak can be observed in Figure 8, resulting from the jammer effect. This peak indicates a significant increase in energy, which consequently distorts the EVM resource grid shown in Figure 9. This effect becomes evident when the jammer's transmit gain is set to 18 dB. The presence of the jammer induces substantial interference in the communication link, leading to a higher EVM peak. A comparison can be made by referring to Figure 10, where a considerable number of OFDM symbols and subcarriers exhibit a low EVM%.  
The high EVM values indicate a degradation in signal quality, reflecting the extent of distortion caused by the interference signal. As the interference gain increases, the interference becomes more pronounced, negatively affecting the integrity of the transmitted  
Figure 8: Power spectral density due to EMI at 2.2 GHz.  
\begin{table}
\begin{tabular}{c c c c c} \hline
**Interferer** & **EVM Peak (\%)** & **EVM RMS (\%)** & **BER** & **SINR (dB)** \\ \hline
2.1955 GHz & 389,223.16 & 3201.15 & 0.3214 & 3.52 \\
2.2 GHz & 107,336.92 & 1774.27 & 0.3884 & \(-\)12.67 \\
2.2045 GHz & 285,892.70 & 2446.83 & 0.3503 & \(-\)3.64 \\ \hline \end{tabular}
\end{table}
Table 5: KPI measurements of the 5G-NR link at different RF frequencies in the presence of transient interference. The gain of the interfering USRP is set to 18 dB.  
signal. This scenario highlights the critical impact of jamming on communication systems, particularly in environments where the SNR is already compromised. The distortion in the EVM resource grid further illustrates the challenges in maintaining reliable communication under such adverse conditions, underscoring the necessity for robust interference mitigation strategies in practical implementations.  
The final EVM and BER evaluation of both communication links is summarized in Table 6. It can be observed that the BER and EVM in both communication links are high when there is interference at the centre frequency of 2.2045 GHz at an interference gain value of 18 dB.  
Figure 10: EVM resource grid without interference.  
Figure 9: EVM resource grid at 2.2 GHz under interference.