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An Overview of 5G Advanced Evolution in 3GPP Release 18

Xingqin Lin

arXiv:2201.01358v1cs.NI

TL;DR

3GPP Release 18 begins 5G Advanced by addressing the need to further improve 5G performance, spectrum use, device support, and deployment flexibility. This article provides an overview organized around the release’s major feature groups, including AI/ML for the NR air interface and evolved network topology. The release package is presented as advancing data-driven network solutions and broader 5G capabilities.

  • Problem

    5G requires continued evolution to improve performance, use spectrum more flexibly, support diverse devices, and accommodate different deployments.

  • Method

    The article overviews Release-18 features by organizing them into thematic groups, including performance, spectrum, network topology, and AI/ML-enabled NR air-interface work.

  • Results

    Release 18 is the first release of 5G Advanced and includes work on performance enhancement, flexible spectrum use, diverse devices, evolved topology, and data-driven intelligent network solutions.

  • Takeaways & Limitations

    The Release-18 package provides a broad foundation for 5G Advanced evolution across network performance, deployment, device, spectrum, and intelligence capabilities.

Abstract

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The 3rd generation partnership project (3GPP) radio access network (RAN) plenary recently approved a work package for its Release 18, representing a major evolution and branded as the first release of 5G Advanced. The work package includes diverse study or work items that will significantly boost 5G performance and address a wide variety of new use cases. In particular, 3GPP Release 18 will embrace artificial intelligence and machine learning technologies to provide data-driven, intelligent network solutions. This article provides an overview of the 5G Advanced evolution in 3GPP Release 18, which is anticipated to trigger a paradigm shift and have a profound impact on future wireless networks.

I. INTRODUCTION

3GPP’s Releases 15–17 established and progressively enhanced 5G, while Release 18 begins the 5G Advanced evolution. The Release-18 package contains diverse work items, including AI/ML integration, and this article organizes them into five groups for overview.

  • 5G foundation: Release 15 established 5G NR for eMBB, URLLC, and mMTC, supporting both NSA and SA operation.Key features include high-frequency operation, spectrum flexibility, low latency, and advanced antenna technologies.
  • 5G evolution: Release 16 enhanced existing capabilities and addressed IIoT, URLLC, unlicensed spectrum, V2X, positioning, and IAB use cases.Enhancements included MIMO, beamforming, DSS, latency, and UE power saving.
  • 5G evolution: Release 17 further enhanced MIMO, DSS, power saving, coverage, positioning, and URLLC while adding RedCap, beyond-52-GHz, MBS, and NTN support.It was also the first complete 3GPP release produced through electronic meetings.
  • 5G Advanced: Release 18 starts 5G Advanced after a workshop that attracted more than 500 proposals and culminated in approval of 27 study or work items.The package includes work on AI and ML technologies for 5G evolution.
  • Article scope: The article categorizes the 27 Release-18 items into five groups while noting that implementation and deployment may combine features across groups.3GPP specifies features independently of particular services or use cases.

II. FURTHER ENHANCED 5G PERFORMANCE

Release 18 extends 5G performance through work on energy savings, coverage, mobility, MIMO, multicast and broadcast services, and positioning. The planned mechanisms address deployment efficiency, service continuity, and support for demanding use cases.

  • Overview: Release 18 continues work on network energy savings, coverage, mobility support, MIMO evolution, MBS, and positioning.These areas are identified as the main performance-enhancement directions illustrated in Figure 2.
  • Coverage and power: Release 18 will enhance PRACH coverage, UE power limits for CA and DC, peak-to-average-power behavior, and uplink waveform switching.The study includes dynamic switching between CP-OFDM and DFT-S-OFDM.
  • Mobility: Release 18 will introduce L1/L2-based inter-cell mobility and further enhance conditional handover.The goals are reduced latency, signaling overhead, and interruption associated with L3-based management.
  • Multicast and broadcast: Release 18 MBS work extends multicast to RRC inactive UEs, enables simultaneous broadcast and unicast reception, and studies more efficient RAN sharing.MBS supports services such as TV broadcasting, live video, software updates, and public safety.
  • Positioning: Release 18 positioning work targets improved accuracy, integrity, and power efficiency, plus sidelink positioning and RedCap support.Release 17 had already reached 20–30 cm accuracy for factory automation use cases.

III. FLEXIBLE SPECTRUM USE

Release 18 targets more flexible and efficient spectrum use across deployments with differing allocations. Its work addresses shared LTE/NR spectrum, fragmented bands, narrow channels, and flexible carrier and duplex operation.

  • Overview: Release 18 introduces spectrum-use enhancements for diverse deployments with different spectrum allocations.The article presents the enabling features in Figure 3.
  • Narrowband deployment: NR operation below the current 5 MHz minimum channel bandwidth is motivated by deployments such as future railway communications.FRMCS is described as using a harmonized 900 MHz spectrum block with 2 × 5.6 MHz FDD allocation.
  • Dynamic spectrum sharing: Release 18 will study allowing NR PDCCH transmissions over symbols overlapping LTE CRS to increase DSS control-channel capacity.It will also extend multiple LTE CRS rate-matching patterns from multi-TRP to single-TRP scenarios for interference mitigation.
  • Multi-carrier operation: To use fragmented spectrum blocks, Release 18 will allow one DCI to schedule multiple PDSCHs or PUSCHs across carriers and study multi-carrier uplink enhancements.The work responds to spectrum refarming that may leave available blocks scattered across frequencies.
  • Duplex flexibility: Release 18 will study more flexible TDD operation because limited uplink time resources can affect coverage, capacity, and latency.

IV. DIVERSE 5G DEVICES

Release 18 expands tailored 5G functionality beyond smartphones to support diverse devices and usage scenarios. The targeted device classes include XR, cloud gaming, low-complexity, vehicular, and UAV devices.

  • Device diversity: Release 18 will enhance 5G capabilities for XR, cloud gaming, low-complexity, vehicular, and uncrewed aerial vehicle devices.The work spans eMBB, URLLC, and mMTC usage scenarios.

A. 5G Consumer Devices

Release 18 extends 5G support for diverse consumer devices by improving in-device coexistence and studying enhancements for XR and cloud gaming.

  • In-device coexistence: Release 18 will refine in-device coexistence by letting UEs report affected frequencies with finer granularity and their preferred TDD pattern.The serving gNB can use this information to restrict radio-resource usage and help resolve internal coexistence issues.
  • XR and cloud gaming: 5G-connected XR and cloud-gaming devices require high data rates and bounded latency for quasi-periodic traffic.Release 18 will study NR enhancements to better support these devices.

B. 5G Devices for Verticals

Release 18 develops tailored support for vertical devices, spanning lower-complexity and lower-power UEs, small-data traffic, vehicular sidelinks, and UAV connectivity.

  • Low-complexity devices: Release 18 will study enhancements for RedCap devices requiring even lower complexity and power consumption than the Release 17 framework supports.Relevant use cases include industrial sensors, video surveillance, and wearables.
  • Low-power operation: Release 18 will study low-power wake-up receivers, wake-up signals, and supporting procedures so devices can activate their main radio when triggered.The wake-up receiver can monitor signals while the main communication radio is off or in deep sleep.
  • Small-data transmission: Release 18 will add mobile-terminated small-data transmission in RRC inactive mode to reduce signaling overhead and latency.This complements Release 17 support for mobile-originated small-data transmission in the same mode.
  • Vehicular devices: Release 18 will enhance sidelink V2X by adding carrier aggregation, extending operation to unlicensed spectrum, and improving FR2 support.It will also study coexistence of LTE V2X and NR V2X devices in the same frequency channel.
  • Aerial devices: Release 18 will introduce 5G NR support for UAVs, building on earlier LTE features for aerial devices.Release 15 LTE support included enhanced measurements, UAV height, location, speed, flight-path reporting, and subscription-based identification.

V. EVOLVED NETWORK TOPOLOGY

Release 18 evolves network topology to improve coverage and resilience through failure analysis, mobile IAB, network-controlled repeaters, sidelink relays, and enhanced NTN integration.

  • Topology evolution: Release 18 addresses coverage limitations where full-stack base stations are infeasible by exploiting IAB nodes, RF repeaters, relays, and NTNs.These approaches support a more flexible and resilient split NG-RAN topology.
  • NG-RAN resilience: Release 18 will study gNB-CU-CP failure scenarios because such failures may disrupt connected gNB-CU-UPs and gNB-DUs and impact served UEs.The failure analysis targets resilience in the split NG-RAN architecture.
  • Mobile IAB: Release 18 will enhance NR-based IAB for vehicle-mounted mobile nodes through topology adaptation, mobility improvements, and interference mitigation.IAB provides wireless NR backhaul as an alternative to fiber and can support multi-hop connectivity.
  • Network-controlled repeaters: Release 18 will study network-controlled repeaters that receive gNB side-control information in addition to amplifying and forwarding signals.The study covers necessary control information, L1/L2 signaling, and repeater identification and authorization.
  • Sidelink relays: Release 18 will expand sidelink relay support with enhanced UE-to-network relay, UE-to-UE relay, and multipath connections.Multipath combines a direct gNB path with an indirect path through a sidelink relay.
  • Non-terrestrial networks: Release 18 will enhance NR operation over NTNs for handheld coverage, deployments above 10 GHz, verified UE location, and mobility between terrestrial and non-terrestrial networks.It also addresses service continuity between different NTNs.

VI. DATA DRIVEN AND AI-POWERED 5G

Release 18 advances data-driven and AI-powered 5G through enhanced measurement collection, QoE support, and studies of AI/ML for network and air-interface functions.

  • AI-enabled NG-RAN: Release 18 will specify data collection enhancements and signaling support for AI-based network energy saving, load balancing, and mobility optimization.
  • Data collection: Release 18 enhances NR data collection through SON/MDT, including collection for random access channel optimization.SON automates RAN planning, configuration, management, optimization, and healing, while MDT uses ordinary UEs to collect measurement data.
  • QoE management: Release 18 expands NR QoE management beyond radio measurements to support services including XR, cloud gaming, and MBS.QoE reports collect application-layer metrics such as frame rate, jitter duration, round-trip time, and average codec bit rate.
  • AI/ML for the air interface: Release 18 studies AI/ML for NR air-interface functions to improve performance or reduce complexity and overhead, focusing on CSI feedback, beam management, and positioning.The study will establish a common framework, characterize models, evaluate gains and complexity, and assess standardization impact.

VII. CONCLUSIONS

Release 18 is presented as the first release of 5G Advanced and the next major evolution of 5G technologies. The article anticipates that work such as AI and ML adoption will influence future wireless-network and 6G design.

  • Conclusions: Release 18 is the first release of 5G Advanced and represents the next major evolution after Releases 15, 16, and 17.
  • Conclusions: The Release-18 evolution enhances performance, enables more flexible and efficient spectrum use, supports diverse devices, evolves network topology, and provides data-driven network solutions.
  • Conclusions: The article anticipates that 5G Advanced innovations, including AI and ML, will lay a foundation for 6G design and affect future wireless networks.The passage states that 6G standardization is expected to start in 3GPP around 2025.
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