# 3 GPP Evolution from 5G to 6G: A 10-Year Retrospective
## 5 3 GPP Release 18: Dawn of 5G-Advanced
### Enhancements to Existing Features
To ensure robust positioning, Release 18 included positioning integrity frameworks, alignment with regulatory requirements, and mechanisms for collision avoidance. The Release-18 work on IAB extended Release-17 developments to support mobile IAB nodes. Mobile IAB nodes, mounted on vehicles, act as RAN nodes, providing NR access links for UEs and backhaul links to parent nodes. Mobile IAB supported integration with different IAB donors, ensuring seamless transitions during migrations. Mechanisms like collision mitigation for physical cell identity and RACH configurations were employed. Enhancements for Rel-18 UEs included RACH-less handovers during IAB-DU migrations and the prioritization of mobile IAB cells for inter-frequency reselection. The NR NTN enhancements in Release 18 improved uplink coverage, supported deployment scenarios in FR2 bands, and enabled mobility and service continuity in NTN environments. Key features included uplink enhancements, such as PUCCH repetition for HARQ and NTN-specific DMRS bundling and support for the NTN operation in 17.3-30 GHz using frequency division duplex (FDD). Mobility management was enhanced with NTN-to-TN and TN-to-NTN transitions, RACH-less handovers, and CHO for dynamic environments. A network-verified UE location with round-trip time based positioning supported regulatory needs. Additionally, a 30 MHz channel bandwidth was introduced for the FR1 bands, improving NTN operational capabilities for diverse applications. Release-18 enhancements to MBS built on the Release-17 features to support multicast reception for UEs in the RRC_INAACTIVE state enable shared processing for broadcast and unicast reception, and improve resource efficiency in RAN sharing scenarios. Multicast reception for UEs in RRC_INAACTIVE state allowed a large number of UEs to access services like mission critical services efficiently. Shared processing enabled UEs to simultaneously receive broadcast and unicast services while optimizing hardware resources. To enhance resource efficiency in RAN sharing scenarios, mechanisms were introduced to avoid duplicated resource allocation for identical MBS content provided by different operators. RedCap enhancements were introduced in Release 18 for further complexity reduction and power saving. Complexity reduction included a peak data rate limit of 10 Mbps and a baseband bandwidth reduction to 5 MHz, enabling simpler and more cost-effective devices. Enhanced power savings were achieved through further extended DRX cycles in the RRC_INAACTIVE state, matching the extended cycles in the RRC_IDLE state. These features made RedCap devices suitable for a broader range of applications. Other enhancements to existing features in Release 18 included  
* **Multi-carrier enhancements**: This work focused on improving efficiency and performance in multi-cell and multi-band scenarios. One enhancement was multi-cell PDSCH/PUSCH scheduling with a single downlink control information (DCI);
* **DSS**: Key improvements included enabling UE reception of NR PDCCH candidates overlapping with LTE cell-specific reference signal resource elements, addressing the PDCCH capacity bottleneck caused by increasing NR traffic;* **Multi-SIM support**: Release 18 improved NR support for devices managing dual active connections, by addressing temporary hardware conflicts arising when device resources are shared between two active SIMs;
* **Small data transmission**: Release 18 enhanced small data transmission by enabling downlink-triggered small data delivery for UEs in the RRC_INACTIVE state, which avoids transitions to RRC_CONNECTED for small, infrequent packets.