## 5 Conclusions  
In this paper, we focused on co-channel coexistence between IEEE 802.11p and 5G NR-V2X to investigate the reciprocal interference and the impact of possible mitigation methods. In particular, we evaluated the performance of a number of mitigation methods, here called eM\({}_{\text{A}}\)-time-split, M\({}_{\text{B}}\)-E-signals, dM\({}_{\text{C}}\)-preamble, M\({}_{\text{C}}\)-preamble-no-SF, and M\({}_{\text{F}}\)-CTS-to-Self, which have been recently proposed by the ETSI with a focus on ITS-G5 and LTE-V2X. Simulations have been carried out through the open-source simulator WiLabV2 Xsim. In addition to a summary of the methods and a discussion of their applicability to NR-V2X, results were provided in highway scenarios in terms of various metrics, considering variable vehicle density, technology distribution, and data generation patterns. The main conclusions from the perspective of both NR-V2X and IEEE 802.11p are summarized in Table 5. As summarized, with a relatively low-density scenario, only eM\({}_{\text{A}}\)-time-split and dM\({}_{\text{C}}\)-preamble/M\({}_{\text{C}}\)-preamble-no-SF are able to improve the transmission range of one technology without reducing the performance of the other, which is in line with the conclusion reported for LTE-V2X and IEEE 802.11p in [4]. The results in this paper show that eM\({}_{\text{A}}\)-time-split, which requires modifications only to IEEE 802.11p, performs best in terms of the transmission range in most of the cases for both technologies; the transmission range was shown to reduce significantly only for IEEE 802.11p under high-density conditions when the technology distribution is unbalanced towards the same technology. eM\({}_{\text{A}}\)-time-split was also shown to increase the end-to-end delay of IEEE 802.11p compared with the No-method tests (no mitigation method applied), which might be a problem for the Day-2 delay-sensitive applications. Figure 15: Transmission range vs. density applying different mitigation methods with balanced distribution and non-periodic packet generation: (**a**) shows the TR of NR-V2X, (**b**) shows the TR of IEEE 802.11p. M\({}_{\text{B}}\)-E-signals and M\({}_{\text{F}}\)-CTS-to-Self, which require modifications in both the technologies, were shown to improve the transmission range of NR-V2X if there are relatively enough time resources (i.e., with the exception of unbalanced traffic with more NR-V2X stations), although they reduce the transmission range of IEEE 802.11p in most cases and also increase the delay of IEEE 802.11p compared with the No-method scenario. Finally, dM\({}_{\text{C}}\)-preamble and M\({}_{\text{C}}\)-preamble-no-SF, which require modifications only to NR-V2X (and are therefore applicable also in Europe, where vehicles equipped with ITS-G5 are already being registered) were shown to improve the transmission range of IEEE 802.11p, without negatively affecting the other metrics compared with the No-method results in either technology. Between the two, M\({}_{\text{C}}\)-preamble-no-SF provided slightly better performance than the dM\({}_{\text{C}}\)-preamble in some cases, despite its simpler implementation. When comparing these results to those obtained focusing on the coexistence between IEEE 802.11p and LTE-V2X, most of the conclusions are very similar. However, two differences can be remarked. The first one is related to the numerology; when the numerology is different from the one adopted in LTE-V2X, meaning that the subcarrier spacing is larger and the time transmission interval is shorter, there are mitigation methods where adjustments are needed before they are applicable (e.g., dM\({}_{\text{C}}\)-preamble).