# 3 GPP Evolution from 5G to 6G: A 10-Year Retrospective
## 4 3 GPP Release 17: Expansion of 5G Horizons
### Enhancements to Existing Features  
MIMO was further enhanced in Release 17 to improve spectral efficiency, latency, and reliability. Key enhancements included a unified transmission configuration indicator (TCI) framework for uplink and downlink beam management. Multi-TRP support was extended to PDCCH, PUCCH, and PUSCH. Enhanced SRS configurations enabled better uplink and downlink CSI acquisition, supporting more antennas and improving coverage. Additionally, CSI reporting enhancements leveraged angle-delay reciprocity for improving accuracy and reducing UE computation. These advancements enhanced MIMO's applicability across diverse deployment scenarios, including high-speed trains and challenging propagation environments. NR coverage was enhanced in Release 17 [59]. These enhancements included improvements to PUSCH repetition, providing better coverage with dynamic slot-based repetition and advanced PUSCH dropping rules. Transport block processing over multiple slots was another major advancement, enabling a single transport block to be transmitted across multiple slots. This approach lowered coding rates and increased energy per resource element, leading to enhanced coverage. Additionally, DMRS bundling was introduced to improve channel estimation for PUSCH and PUCCH. The dynamic PUCCH repetition factor mechanism allowed the network to adapt repetition factors based on channel conditions, improving efficiency. These features collectively strengthened NR's ability to deliver reliable connectivity in diverse scenarios. In Release 17, 3 GPP enhanced NR's support for industrial IoT and URLLC to further address stringent latency and reliability demands across verticals. Key enhancements included improved HARQ and CSI feedback mechanisms for higher reliability, prioritization of traffic with varying priorities for efficient intra-UE multiplexing, and support for URLLC in shared spectrum via semi-static channel occupancy. Time synchronization for TSN was enhanced with propagation delay compensation methods. Non-public networks were also enhanced, e.g., broadcasting network selection information enabled UEs to connect to a non-public network efficiently without impacting cell selection or mobility [60]. Release 17 introduced NR sidelink enhancements aimed at improving power efficiency, reliability, and latency. Key features included power-saving resource allocation methods such as partial sensing and random resource selection. Inter-UE coordination enabled resource optimization through information exchange between devices. Sidelink DRX supported energy-efficient operation with configurable timers for unicast, groupcast, and broadcast communication. Additionally, Uu and sidelink DRX alignment was supported to improve synchronization. Sidelink relay functionality was enhanced for single-hop UEto-network relay, allowing remote UEs to connect via relay UEs under various scenarios. These updates strengthened sidelink's role in public safety, IoT, and vehicular applications. NR positioning was further enhanced to improve accuracy, latency, and reliability. Key advancements included refined timing error mitigation for positioning measurements and multi-path mitigation. Latency was reduced through preconfigured measurement gaps, PRS processing windows, and faster sampling. On-demand PRS transmission enabled dynamic control of positioning signals, while support for RRC_INACTIVE allowed efficient, low-power positioning. These enhancements facilitated robust, precise, and efficient positioning for advanced 5G applications and beyond. Release 17 enhanced IAB by improving robustness, load balancing, spectral efficiency, and backhaul performance. Key enhancements included inter-donor migration for better topology management, reduced service interruptions during node migrations, and new mechanisms for uplink re-routing during link failures. Duplexing enhancements enabled simultaneous transmission and reception, optimizing spectrum use. Scheduling and congestion control improvements addressed end-to-end performance and efficiency.