# 3 GPP Evolution from 5G to 6G: A 10-Year Retrospective
## 1 Introduction
\begin{table}
\begin{tabular}{|c|l|l|l|} \hline
**3 GPP Release** & \multicolumn{2}{c|}{**Enhancements to Existing Features**} & \multicolumn{2}{c|}{**New Features**} \\ \hline
**Release 15: Birth of 5G** & \(\bullet\) & N.A. & \(\bullet\) & 5G New Radio \\ \hline
**Release 16: First 5G Upgrade** & \(\bullet\) & MIMO & \(\bullet\) & Industrial Internet of Things and \\  & \(\bullet\) & Mobility enhancements & & ultra-reliable low-latency \\  & \(\bullet\) & UE power saving & & communications \\  & \(\bullet\) & Dual connectivity and & \(\bullet\) & Unlicensed operation \\  & & carrier aggregation & \(\bullet\) & Sidelink communication \\  & \(\bullet\) & Cross link interference and remote & \(\bullet\) & Positioning \\  & & interference management & \(\bullet\) & Integrated access and backhaul \\  & & & \(\bullet\) & 2-step random access \\ \hline
**Release 17: Expansion of 5G** & \(\bullet\) & MIMO & \(\bullet\) & Non-terrestrial networks \\
**Horizons** & \(\bullet\) & Coverage enhancements & \(\bullet\) & Multicast and broadcast services \\  & \(\bullet\) & Industrial Internet of Things and & \(\bullet\) & Reduced capability device support \\  & & ultra-reliable low-latency & \(\bullet\) & Operation extension to 71 GHz \\  & & communications & & \\  & \(\bullet\) & Sidelink communication & & \\  & \(\bullet\) & Positioning & & \\  & \(\bullet\) & Integrated access and backhaul & & \\  & \(\bullet\) & Others: UE power saving, dynamic & & \\  & & spectrum sharing, multi-subscriber & & \\  & & identity module support, & & \\  & & small data transmission & & \\ \hline
**Release 18: Dawn of** & \(\bullet\) & MIMO & \(\bullet\) & Network energy savings \\
**5G-Advanced** & \(\bullet\) & Coverage enhancements & \(\bullet\) & Extended reality support \\  & \(\bullet\) & Mobility enhancements & \(\bullet\) & Artificial intelligence/machine learning \\  & \(\bullet\) & Sidelink communication & & for next-generation radio \\  & \(\bullet\) & Positioning & & access network \\  & \(\bullet\) & Integrated access and backhaul & \(\bullet\) & In-device coexistence \\  & \(\bullet\) & Non-terrestrial networks & \(\bullet\) & Uncrewed aerial vehicle \\  & \(\bullet\) & Multicast and broadcast services & \(\bullet\) & Air-to-ground network \\  & \(\bullet\) & Reduced capability device support & \(\bullet\) & Support for less than 5 MHz spectrum \\  & \(\bullet\) & Others: Multi-carrier enhancements, & \(\bullet\) & Network-controlled repeater \\  & & dynamic spectrum sharing, & & \\  & multi-subscriber identity module & & & \\  & support, small data transmission & & \\ \hline \end{tabular}
\end{table} 
Table 1: A summary of 3 GPP evolution from Release 15 to Release 20 (non-exhaustive). In summary, this article makes the following contributions that distinguish it from the prior literature:  
* **Cross-release evolution mapping:** Whereas most existing surveys focus on a single release or individual technologies, this study is the first to systematically trace the technical evolution across Releases 15 through 20. By aligning each release's enhancements under common thematic pillars, this study exposes recurring design principles and feature interdependencies that have not been jointly analyzed before;
* **Forward-looking 6G development guidelines:** Building on lessons learned from 5G standardization, this study derives a concrete set of recommendations for 6G standardization justified by historical precedents and industry trajectories. The remainder of this article is organized as follows. Section 2 reviews 3 GPP Release 15, the birth of the 5G NR system, and its foundational design principles. Section 3 examines Release 16's first 5G upgrade, highlighting enhancements for industrial IoT, V2X, and spectrum efficiency. Section 4 details Release 17's expansion of 5G horizons into NTNs, RedCap devices, and advanced MIMO and coverage features. Section 5 introduces Release 18, the dawn of 5G-Advanced, with a focus on AI/ML integration, energy saving, and XR improvements.