# 5G-NR Physical Layer-Based Solutions to Support High Mobility in 6G Non-Terrestrial Networks
## 5 Simulation Results and Discussion  
The MATLAB 2022a platform is utilized to develop the link-level simulation in this paper. Table 2 lists the simulation parameters used for the 5G-NR PDSCH simulation performance analysis to support high mobility in the NR-NTN [1,9]. The performance of 5G-NR PDSCH in terms of BER and throughput versus the signal-to-noise ratio (SNR) is analyzed using link-level simulations in this paper. The simulation results illustrate how different numerologies, MCS levels, power delay profiles, MIMO, and channel estimation schemes affect the system's performance. The investigations are performing out in a multi-stream system to evaluate how the modulation order and propagation channel model influence the BER and throughput. In this analysis, different modulation schemes are simulated, including QPSK, 16-QAM, 64-QAM, and 256-QAM under NLOS, such as TDL-A and LOS, such as TDL-E for multipath fading channel model from which a single tap is simulated for analysis under single-path fading, such as Rayleigh and Rician fading distribution. Figure 5 shows the BER performance, and Figure 6 illustrates the throughput performance of the NR-PDSCH LLS under single-path (1P) Rayleigh and Rician fading and multipath TDL-A and TDL-E as NLOS and LOS channel model, where the different MCS levels for SISO and MIMO schemes at stationary UE are simulated. The observed coding gain between SISO and MIMO (2 \(\times\) 2, 2 \(\times\) 4, and 2 \(\times\) 8) at BER of \(10^{-2}\) under single-path Rayleigh fading distribution is 7, 8.5, and 11 dB in the case of the MCS level of QPSK. Under a Rician fading distribution, it is 6, 9, and 11 dB, respectively. In contrast, under NLOS (TDL-A), the coding gain between SISO and MIMO cases is 9, 11, and 13 dB and 5, 9, and 11 dB under LOS (TDL-E) channel model, respectively. Similarly, the coding gain for other MCS levels, such as 16-QAM, 64-QAM, and 256-QAM, under NLOS and LOS propagation channels from Figure 5 is observed. Figure 5: _Cont._  
achievable throughput is 30 Mbps under 3 GPP NR-NTN channel models. QPSK achieves high throughput in a low SNR, whereas 256-QAM achieves higher throughput in high SNR cases. According to Figure 6d, to obtain a maximum throughput of 30 Mbps, the 256-QAM under NLOS (TDL-A) channel model requires a minimum SNR(dB) of 18, 9, 6, and 5 dB for SISO and MIMO (2 \(\times\) 2, 2 \(\times\) 4, and 2 \(\times\) 8) cases, respectively, and with MCS of QPSK under a TDL-E channel model, whereas 13, 8, 5, and 2 dB are required. This analysis shows that when the MIMO and 3D beamforming schemes are utilized, the maximum achievable throughput increases even at low SNR values. The channel estimation provides a representation of the channel effects per resource element, and the equalizer uses that information to compensate for the distortion by the channel. In this paper, we assume channel knowledge in such a way that the pilot symbols are multiplexed with the data symbols at the transmit side within the resource grid, which represents the channel conditions between the transmit and receive antennas. The equalizer requires channel knowledge between the transmit layers and the receiving antennas that must apply precoding to the perfect channel estimation. This paper analyzes the pilot-aided perfect and non-front-loaded DM-RS-based practical channel estimation for high numerology, which is SCS 120 kHz, for various MCS levels at 500 km/h in Figure 7. The results show that the system needs to be improved to support high mobility. Hence, in Figure 8, we have examined various numerologies at 500 km/h for 64-QAM under LOS and practical channel estimation. The high numerology of 5G-NR can support the mobility of UE in high-mobility scenarios because the transmit data can obtain sufficient space in the slot to avoid inter-symbol interference (ISI). Therefore, we propose utilizing 120 kHz of SCS to support high mobility in NTN. Figure 8 shows that the numerology 120 kHz achieves high link reliability and high throughput.