# 5G-NR Physical Layer-Based Solutions to Support High Mobility in 6G Non-Terrestrial Networks
## 2 Related Works
While some authors focused on independent aerial/space architectures, there has yet to be a formalization of the constraints and opportunities associated with a multi-layered network in which various non-terrestrial stations interact at different altitudes in an integrative manner [27]. Other papers, [19; 26], discussed how to improve the protocol stack design in a space-air-ground integrated network but did not comprehensively investigate the most recent technology breakthroughs to accomplish performance optimization. Furthermore, a thorough description is given for NTN supporting technological solutions, and research goals are now dispersed throughout multiple technical studies, making them difficult to grasp without the necessary background [4; 28]. All these characteristics must be considered when simulating the NR performance. The evolution of 6G-non-terrestrial networks is examined in this paper. We analyze the 5G-NR physical layer link-level performance to support high UE mobility up to 500 km/h to propose NR-based solutions for NTN. Table 1 briefly summarizes the research work conducted by the 3 GPP groups and other researchers. \begin{table}
\begin{tabular}{c c c c c} \hline
**Reference** & **Brief Description** & **Reference** & **Brief Description** \\ \hline
3 GPP TR 38.811 & Study on NR to support non-terrestrial networks & [PERSON] et al. [17] & NR supports modulation orders up to 256-QAM \\ (Release-15) [1] & Study channel model, deployment scenarios, and potential key impact areas & & \\ \hline  & Reviewed NTN research activities & & \\  & Described the features and enabling technologies of & & \\  & NTNs in the 62d landscape & & \\  & Focused on the problems in the field that remain & & \\  & open for research. For example, they examined how & & \\  & different networking configurations affect the & & \\  & performance of an NTN scenario in which & & \\  & aerial/space vehicles use millimeter wave & & \\  & (mmWave) frequencies to offer access connectivity & & \\  & to on-the-ground mobile terminals & & \\ \hline  & & & \begin{table}
\begin{tabular}{c c c c} \hline
**Reference** & **Brief Description** & **Reference** & **Brief Description** \\ \hline [PERSON] et al. [12] & Presented a novel network architecture for an integrated nanosatellite-SG system operating in the millimeter wave (mmWave) domain & [PERSON] et al. [24] & Proposed massive MIMO and beamforming-based methods that support high mobility for high-speed real broadband mobile communications \\ \hline [PERSON] et al. [13] & Identified the most promising satellite networking configurations and discussed some design & [PERSON] et al. [25] & The analysis of flexible numerologies of 5G-NR to support integrated satellite-terrestrial networks with low earth (LEC) satellites are described \\ \hline [PERSON] et al. [14] & Describe the physical layer communication research beyond 5G because of the numerous extra features provided to NR, PHY abstraction of NR-based systems is a difficult task & [PERSON] et al. [28] & Thorough description is given for NTN supporting technological solutions, and research goals are now dispersed throughout multiple technical studies, making them difficult to grasp without the necessary background \\ \hline [PERSON] et al. [15] & The variable number of resource blocks (RRb) and OFDM symbols that can be allocated to each user in NR results in a significant increase in the number of supported transport block sizes (TBSs) & Study on using satellite access in 5G \\ \hline Our Contributions & Introduces the NTN wireless system, highlights its key features based on 3 GPP TR and TS & \\ \hline \end{tabular}
\end{table} 
Table 1: _Cont._