NR Release 18 Highlights

Release 18 marks the starting point of 5G-Advanced. If Release 17 was mainly about expanding 5G into more bands, more device types, and more deployment scenarios, Release 18 shifts the focus toward intelligence, precision, and service quality. The key idea is that the network is no longer treated as just a transport pipe. It starts to behave more like an intelligent platform that can understand context, optimize itself, and support more advanced interactions between devices, applications, and users.

One of the biggest changes in Release 18 is the stronger role of AI and machine learning. In earlier releases, optimization was mostly based on fixed rules and predefined algorithms. In Release 18, AI and ML start to become part of the system design itself. This means the network can support model transfer, model management, and more adaptive optimization methods. The practical meaning is that the network can respond more intelligently to traffic changes, radio conditions, beam behavior, and service demand. This is why Release 18 is often seen as the first real step toward a more intelligent wireless system.

Another important direction is high precision positioning and ranging. Earlier releases supported positioning, but Release 18 pushes this further toward more accurate and more power-efficient operation. The focus is not only on knowing where a device is in a broad sense, but on enabling more precise spatial awareness. This is important for industrial automation, robotics, logistics, and vehicle-related services. It also supports scenarios where devices need to estimate distance directly, even without relying only on satellite systems. In that sense, Release 18 moves positioning from a useful feature toward a critical service capability.

Release 18 also strengthens immersive and time-sensitive services. This includes tactile and multi-modal communication, which is very important for XR and other highly interactive services. The network must support not only low latency, but also tight synchronization across video, audio, and touch-related feedback. The objective is to make digital interaction feel more natural, stable, and responsive. This is a major step beyond ordinary mobile broadband because the quality of experience now depends on coordination across multiple media types, not just throughput.

The evolution of network slicing is also important in this context. Earlier slicing work focused on creating logical partitions in the network. Release 18 enhances this idea so that slices can better support demanding vertical applications such as factories, healthcare, transportation, and mission-critical services. The intuition is that one network can behave like many specialized networks at the same time, with each one tuned for a specific service requirement.

Release 18 also continues the idea of universal connectivity. NTN evolves further so that satellite-based access can support more demanding services, not just basic coverage extension. This improves the feasibility of remote monitoring, surveillance, and control in areas where terrestrial infrastructure is limited. In addition, concepts such as vehicle-mounted relays show that connectivity is becoming more dynamic. Instead of only connecting end devices directly, the system can use moving platforms as intelligent connectivity nodes. This improves service quality in transportation scenarios such as trains, buses, and other mobile environments.

Overall, the intuition for Release 18 is that it begins the transition from ordinary 5G toward 5G-Advanced. The focus moves from simple expansion toward intelligence, precision, and high quality service support. Release 17 made 5G broader. Release 18 starts making 5G smarter. It is the point where the network begins to act less like a passive communication system and more like an adaptive, context-aware digital infrastructure.

Roadmap

The timeline shows the transition from Release 17 completion into Release 18 development, highlighting how 5G-Advanced is introduced through a structured timeline of freeze milestones.

The timeline begins with the finalization of Release 17, where Stage 3 Freeze and Protocol Coding Freeze are completed around 2022. At this point, Release 17 specifications become stable, meaning vendors can implement interoperable solutions based on fixed ASN.1 and protocol definitions.

Immediately after that, Release 18 work starts with the package approval phase. This marks the official start of defining new features for 5G-Advanced. It indicates that the industry has agreed on the scope and content of Release 18.

The next major milestone is the Stage 2 Functional Freeze, which occurs around 2023. At this stage, the high-level architecture and feature set of Release 18 are finalized. This is where the key concepts of 5G-Advanced, such as AI/ML integration, enhanced positioning, and advanced service capabilities, are solidified at a system level.

Following that, the process moves to the Stage 3 Freeze, where detailed protocol behavior and signaling procedures are completed. This defines exactly how network elements and devices interact to support the new features introduced in Release 18.

Finally, the timeline reaches the Protocol Coding Freeze for Release 18 around 2024. At this stage, all ASN.1 definitions and protocol details are locked. This is the point where implementations can begin in a stable and standardized way, similar to what happened for Release 17 earlier.

Overall, the key idea from this diagram is that Release 18 follows the same structured evolution path as previous releases, but it represents a major shift in capability. While Release 17 focused on expanding coverage and use cases, Release 18 formalizes 5G-Advanced, where intelligence, precision, and advanced services become central to the network design.

Feature List

This feature list shows that Release 18 is no longer focused mainly on extending coverage or adding more radio options. The emphasis moves to making the 5G system more intelligent, more service-aware, and more tightly integrated with real applications and industries. In simple terms, Release 18 starts to treat the network not just as a communication pipe, but as an active platform that can support decision making, precise control, and specialized service behavior.

One major theme is intelligence inside the network. Features such as AI and ML model transfer in 5GS, subscriber-aware northbound API access, and data integrity in 5GS show that the core network is becoming more aware of context, more open to interaction with applications, and more capable of handling sensitive operational data. This means the network is evolving from a passive transport system into something that can participate more directly in optimization, automation, and service logic.

Another clear theme is support for industry and vertical applications. Items such as service exposure interfaces for industry, application layer support for factories of the future, low power high accuracy positioning for industrial IoT scenarios, and tactile and multi-modality communication services all point in the same direction. The goal is to make 5G useful not only for smartphones, but also for factories, robotics, automation, immersive systems, and other environments where timing, positioning, responsiveness, and coordination are critical. Release 18 is therefore much more aligned with real industrial operations than earlier releases.

Positioning and ranging are also important in this list. Ranging-based service and low power high accuracy positioning show that the network is moving beyond general location awareness toward more precise spatial understanding. This is very important in areas such as industrial control, safety, logistics, and proximity-based interaction. The focus is not only on knowing where something is, but on enabling systems to react accurately to distance and position in real time.

The list also shows a strong service quality and resilience direction. Features such as enhanced access to and support of network slices, 5G timing resiliency system, smart energy and infrastructure, and signal level enhanced network selection indicate that the network is being refined to behave more predictably and more efficiently under demanding conditions. The idea is that different services should get behavior that matches their needs, whether that means low latency, precise timing, better reliability, or better energy efficiency.

Mission critical communication is another major pillar. Mission critical services over 5MBS, gateway UE function for mission critical communication, ad hoc group communication support in mission critical services, and sharing administrative configuration between interconnected MCX and MCS systems all show that Release 18 is strengthening support for public safety, emergency response, and coordinated critical operations. This means the network is expected to support organized, resilient, and trusted communication structures, not just ordinary consumer traffic.

Satellite-related features also stand out. 5G system with satellite access to support control and or video surveillance, and 5G system with satellite backhaul, show that Release 18 continues the NTN direction but pushes it toward more practical and demanding services. The meaning is that non-terrestrial connectivity is no longer just for basic reachability. It is becoming part of a broader service platform that can support monitoring, control, and operational traffic in remote areas.

There is also a clear convergence and service integration trend. Features such as MPS when access to EPC or 5GC is WLAN, support for service function chaining, evolution of IMS multimedia telephony service, and 5 networks providing access to localized services show that Release 18 is trying to make different access methods, service frameworks, and core capabilities work together more smoothly. This reflects a broader view of 5G as a unified service environment rather than a standalone radio system.

Overall, this feature list shows that Release 18 is the beginning of 5G-Advanced in a very practical sense. It is less about simply adding more connectivity options and more about building a network that is intelligent, context-aware, precise, resilient, and deeply connected to application needs. In that sense, Release 17 expanded the reach of 5G, while Release 18 starts to give 5G a stronger brain, a finer sense of position and timing, and a much deeper role in real-world services.

New RRC Messages and IEs for Release 18

The high-level intuition for this file is that it contains the technical blueprint in ASN.1 form for the new Release 18 features. The earlier diagrams and feature lists describe Release 18 at a conceptual level. This file shows the actual RRC level definitions that make those ideas usable between the UE and the network. In other words, this is where the high-level Release 18 concepts become concrete signaling parameters and message structures.

One major area visible in this file is advanced multicast and broadcast support. The code defines how the network configures multicast sessions and how the UE understands which session, frequency, and configuration it should follow. Parameters such as MBS multicast configuration and interest indication are important in this context. The overall meaning is that the network can deliver one stream to many users more efficiently, and the UE can explicitly indicate which multicast or broadcast service it wants to receive. This is the signaling foundation for scalable media delivery and public content distribution.

Another important area is relay and indirect path support. The file shows mechanisms for handling cases where the UE does not communicate with the network only through the direct path, but may rely on another node or relay-related path. In this context, failure reporting for indirect path behavior becomes important. The intuition is that Release 18 is expanding communication flexibility, so the network also needs detailed signaling for when those more complex paths fail or need to be changed. This helps the network diagnose the problem and recover service more intelligently.

A third major theme is small data transmission and paging efficiency. The file includes structures that support sending small amounts of data without requiring the UE to go through full connection overhead every time. This is closely related to power saving. Instead of waking the device completely for every small exchange, the system can use more lightweight procedures. Paging-related extensions also fit into this same idea. The network can notify more selectively and more efficiently, which reduces unnecessary UE activity and improves battery life. So this part of the file is not just about message definition. It is about making low-overhead and low-power operation practical.

The file also shows strong support for positioning enhancement. In particular, it includes signaling related to SRS-based positioning resources and associated configuration. The meaning is that positioning is treated as a structured radio capability, not just an external application feature. Release 18 pushes this toward higher precision and more flexible operation, including better support across different UE states. When bandwidth aggregation and richer positioning resource configuration are used, the network can estimate UE location much more accurately. So this part of the ASN.1 reflects the move from ordinary location awareness toward more advanced spatial awareness.

Overall, the best way to understand this file is to see it as the engineering-level realization of Release 18. The feature lists and roadmap slides explain what Release 18 wants to achieve. This ASN.1 file shows how those goals are translated into actual RRC messages, information elements, and protocol extensions. In that sense, the earlier material is the concept layer, and this file is the implementation layer where multicast, relay support, small data handling, paging efficiency, and high-precision positioning are formally defined for real network operation.

Followings are the bulletized summary of Release 18 RRC

• Advanced multicast and broadcast support
  • The file defines multicast control signaling such as MulticastMCCH-Message-r18, MBSMulticastConfiguration-r18, and MBSInterestIndication-v1800.
  • This means the network can configure broadcast or multicast sessions, and the UE can indicate which MBS services it is interested in.
• Relay and indirect path handling
  • The file includes IndirectPathFailureInformation-r18 and FailureReportIndirectPath-r18.
  • This shows that Release 18 supports more complex relay or indirect communication paths and also provides detailed failure reporting when such paths break.
• Application-aware reporting
  • MeasurementReportAppLayerList-v1800 and MeasReportAppLayer-v1800 show that the UE can report more than radio quality.
  • The signaling now includes application-related reporting behavior, which supports QoE-aware network optimization.
• Paging and small data efficiency
  • PagingRecord-v1800 adds mt-SDT, and GroupPaging-r18 adds inactiveReceptionAllowed-r18.
  • This indicates support for mobile-terminated small data transmission and more selective paging behavior, both of which help reduce UE power consumption.
• Positioning enhancement
  • The file adds many Release 18 positioning structures such as SRS-PosResourceSetAggBW-CombinationList-r18, SRS-PosRRC-InactiveEnhanced-r18, and SRS-PosRRC-InactiveEnhancedConfig-r18.
  • This shows that Release 18 strengthens SRS-based positioning, including enhanced operation in RRC inactive state.
• Aggregated bandwidth for positioning
  • SRS-PosRRC-InactiveAggBW-AdditionalCarriers-r18 and SRS-PosConfigPerULCarrier-r18 show multi-carrier positioning-related configuration.
  • The high level meaning is that Release 18 uses richer carrier combinations to improve positioning flexibility and potential accuracy.
• Validity area based positioning control
  • SRS-PosRRC-InactiveValidityAreaConfig-r18 and AreaValidityTA-Config-r18 show that inactive-state positioning can be controlled based on area validity, timing alignment, and RSRP conditions.
  • This means positioning resources can remain valid in a smarter and more location-aware manner.
• Extended paging cycle support
  • ExtendedPagingCycleConfig-r18 introduces long paging cycles and paging PTW length configuration.
  • This reflects deeper power saving support for devices that do not need frequent wakeup.
• Inactive-state multicast handling
  • MulticastConfigInactive-r18 shows that multicast related configuration can also be prepared for inactive operation.
  • This means multicast service continuity is being extended beyond only active connected mode.
• eRedCap and MT-SDT support
  • ERedCap-ConfigCommonSIB-r18 and MT-SDT-ConfigCommonSIB-r18 show Release 18 support for enhanced reduced capability devices and mobile-terminated small data.
  • This means the system is being optimized for simpler devices and low-overhead traffic patterns.
• Sidelink expansion
  • Structures such as SL-PosTxResourceReqList-r18, SL-TxResourceReqL2-U2U-r18, SL-U2U-Info-r18, and SL-PRS-QoS-Info-r18 show richer sidelink support.
  • The high level meaning is that Release 18 expands sidelink toward positioning, QoS-aware relay, and richer U2U communication.
• Multi-SIM and coexistence refinement
  • MUSIM-Assistance-v1800, MUSIM-CapRestriction-r18, IDC-FDM-Assistance-r18, and IDC-TDM-Assistance-r18 show more advanced multi-SIM coordination and coexistence assistance.
  • This means the UE can describe more precise capability limits, band restrictions, and timing preferences to the network.
• Traffic-awareness in uplink
  • UL-TrafficInfo-r18 and QOS-FlowUL-TrafficInfo-r18 add traffic descriptors such as jitter range, burst arrival time, and periodicity.
  • This indicates that Release 18 wants the network to understand traffic pattern details, not just raw data presence.
• Aerial and flight-path related support
  • FlightPathInfoReportConfig-r18, FlightPathInfoReport-r18, and WayPoint-r18 show support for reporting path-related information.
  • This points to aerial or mobility scenarios where location trajectory matters, not only current position.
• Random access and feature reporting refinement
  • ReportedFeatureCombination-r18, PerRAInfoList-v1800, PerRASSBInfo-v1800, and PerRACSI-RSInfo-v1800 show more detailed feature reporting and RA visibility.
  • This means the network can better understand what advanced feature set the UE is using and what happened during access attempts.
• Mobility success reporting
  • SuccessPSCell-Report-r18 adds more detailed successful PSCell change reporting, including source, target, measurements, and cause.
  • This shows that Release 18 is interested not only in failures but also in understanding successful mobility outcomes.
• NTN, ATG, and coverage-area support
  • NTN-CovEnh-r18, SatSwitchWithReSync-r18, SIB22-r18, ATG-Config-r18, SIB25-r18, and CoverageAreaInfo-r18 show expansion into NTN, air-to-ground, and area-aware service definitions.
  • This means Release 18 broadens 5G-Advanced into more diverse mobility and non-terrestrial environments.
• Multicast system information expansion
  • SIB24-r18 adds multicast MCCH and multicast-related control configuration.
  • This reinforces that multicast and broadcast are now treated as first-class system information features.
• PHY refinement and advanced radio control
  • AdvancedReceiver-MU-MIMO-r18, TCI-InDCI-r18, CandidateTCI-State-r18, CellDTX-DRX-Config-r18, RACH-LessHO-r18, and UplinkTxSwitchingMoreBands-r18 show many Release 18 radio refinements.
  • The overall meaning is better receiver sophistication, more flexible beam and TCI handling, refined DRX/DTX behavior, handover simplification, and broader uplink switching support.
• CSI and codebook evolution
  • CodebookConfig-r18, TD-DD-Config-r18, CSI-ReportSubConfig-r18, and related structures show more advanced CSI feedback and codebook behavior.
  • This supports more intelligent MIMO operation and more advanced feedback strategies in 5G-Advanced.
• Overall meaning
  • The file is best understood as the engineering schematic for Release 18 RRC.
  • The brochure-level ideas of multicast, relay support, small data efficiency, positioning enhancement, sidelink growth, multi-SIM coordination, NTN expansion, and advanced radio intelligence are all translated here into precise ASN.1 message and IE definitions.

Release 18 RRC ASN.1 definitions

The complete Release 18 ASN.1 material is shown below in specification order.

Open the complete Release 18 RRC ASN.1 listing in a separate page

Reference :

• 3GPP - Release 18