Description
The RAN-based Notification Area Code (RANAC) is a fundamental component of the RRC_INACTIVE state mobility management in 5G New Radio (NR). A RAN-based Notification Area (RNA) is a logical area, composed of one or multiple cells, defined by the RAN for the purpose of tracking and paging a User Equipment (UE) that is in the RRC_INACTIVE state. The RANAC is the code that uniquely identifies this RNA within the scope of a gNodeB or a set of gNodeBs. When a UE enters RRC_INACTIVE, the network assigns it an RNA, and the UE stores the corresponding RANAC.
The operation revolves around the UE's mobility within this RNA. While in RRC_INACTIVE, the UE can move freely within the cells that belong to its assigned RNA without notifying the network, thus conserving battery power and reducing signaling. The UE performs periodic RNA Updates (RNAU) or is triggered to perform one when it moves to a cell that is outside its current RNA. During this RNAU procedure, the UE provides its last stored RANAC and other context information to the new cell, allowing the RAN to retrieve the UE's context from the previous serving gNodeB and update its location.
When downlink data arrives for a UE in RRC_INACTIVE, the RAN initiates a RAN-based paging procedure within the UE's last known RNA. The gNodeBs within that RNA broadcast a paging message containing the UE's identifier and the relevant RANAC. The UE, monitoring for paging in its current cell, responds if it is within the paged area. This mechanism is more efficient than core-network-level paging (via the 5GC) for inactive UEs, as it localizes the paging traffic to a smaller RAN-defined area. The RANAC is thus a key enabler for efficient state management, balancing the trade-off between signaling overhead and UE power consumption, which is particularly important for massive Machine-Type Communication (mMTC) and general mobile broadband users.
Purpose & Motivation
RANAC was created to address the signaling and power efficiency challenges associated with managing a massive number of connected devices, especially for IoT scenarios, in 5G networks. Previous states, like RRC_IDLE in LTE, required core network (MME) involvement for tracking area updates and paging, which could generate significant signaling load. The RRC_CONNECTED state, while keeping the UE context in the RAN, consumes more UE battery as the radio connection is maintained. The new RRC_INACTIVE state, and its associated RNA concept identified by RANAC, provides a middle ground.
The primary problem RANAC solves is enabling efficient location tracking and paging for UEs that are inactive but have data sessions that may resume shortly. By defining an RNA managed solely by the RAN, location updates (RNA Updates) do not burden the 5G Core (5GC) unless the UE moves beyond a RAN-controlled area. This reduces signaling on the N2 interface between the RAN and the AMF. Furthermore, RAN-based paging using the RANAC confines paging messages to a specific set of cells, reducing unnecessary paging load across the entire tracking area and enabling faster connection resumption.
This innovation was motivated by the 5G requirement to support massive IoT deployments with billions of devices that transmit data sporadically. For such devices, minimizing signaling and power consumption is paramount. RANAC, as part of the RNA mechanism, allows these devices to remain reachable by the network with minimal energy expenditure, extending battery life for years, while also ensuring the network can efficiently deliver incoming data when needed, fulfilling the promises of 5G mMTC and enhanced mobile broadband efficiency.
Classification
Detected Changes Across Releases
from 3GPP Change RequestsSpecific changes extracted from the „Change history“ tables of 3GPP specifications (63 CRs across 5 releases). Complements the general historical overview above with the evidence-based evolution of this function.
In Release 15, the RAN-based Notification Area Code (RANAC) function was enhanced by extending the RANAC size to 8 bits. This change provided a larger coding space for notification areas managed by the Radio Access Network. The modification was introduced through a specific Change Request titled "Extend the RANAC size to 8bits."
- Introduction of DEFLATE based UDC Solution TS 36.300CR1090
- Enabling MBMS Bearer Event Notification TS 36.300CR1138
- Stage 2 Changes based on CN type indication for Redirection from ng-eNB to E-UTRA TS 36.300CR1185
- Correction for duplication based on Rel-14 TX profile TS 36.300CR1193
- Clarification on SSB-based BM, RLM and BFD TS 38.300CR0102
- Notification Control TS 38.300CR0108
+ 8 more changes
In Release 16, the RANAC function was enhanced with corrections for Area QoS Profile (AQP) notification control, ensuring more reliable notification management. Furthermore, a correction was introduced for the activation of signalling-based Minimization of Drive Tests (MDT) procedures in the NR and SON context. These updates provided more precise control and activation mechanisms for network optimization and notification area functions.
- Introduction of Inter-gNB CSI-RS Based Mobility TS 38.300CR0249
- Correction on CSI-RS Based Intra-frequency and Inter-frequency Measurement Definition TS 38.300CR0265
- Corrections on AQP for notification control TS 38.300CR0328
- Correction on Signalling based MDT Activation [NR_SON_MDT-Core] TS 38.401CR0172
- Correction for UL Data Notification over E1 TS 38.463CR0622
- Correction on UL BH information configuration for DRBs support CA based duplication TS 38.473CR0772
In Release 17, specific clarifications and corrections were made to the RAN-based Notification Area Code (RANAC) function, particularly regarding its application in slice-based RACH configuration procedures. The enhancements also included corrections to ensure proper management-based MDT user consent and PLMN modification list handling in relation to RANAC. These updates provided more precise operational rules for the RANAC function within the overall system architecture.
- Introduction of new bands and bandwidth allocation for LTE-based 5G terrestrial broadcast TS 36.300CR1360
- CP-based Congestion Indication for IAB Networks TS 38.473CR0737
- Support of RACH-based SDT TS 38.473CR0834
- Correction on update management based MDT user consent TS 37.483CR0016
- Clarification on BFD-RS set based BFR TS 38.300CR0596
- Clarification on the application of slice-based RACH configuration TS 38.300CR0666
+ 7 more changes
In Release 18, specific enhancements were made to the RAN-based Notification Area Code (RANAC) function to improve its operation for Non-Terrestrial Networks (NTN). These included corrections for timer-based conditional handover procedures specifically for IoT NTN and NR NTN, ensuring more reliable mobility management. Additionally, the release introduced corrections for location-based measurements within the NR NTN context to support accurate RANAC updates and paging area management.
- Correction of timer-based conditional handover for IoT NTN TS 36.300CR1399
- Corrections to location-based measurement TS 36.300CR1417
- Correction on PSI based discard TS 37.483CR0113
- Correction of timer-based conditional handover for NR NTN TS 38.300CR0822
- Correction on DL PSI based discard TS 38.300CR0874
- Correction on priority-based QoE measurements in TS 38.300 TS 38.300CR0919
+ 11 more changes
In Release 19, the RAN-based Notification Area Code (RANAC) function saw specific enhancements focused on improving notification control and interaction procedures. The release introduced a correction on the Notification Control Indication to refine its operation. Furthermore, it defined the interaction between Handover Success procedures and Cell Switch Notification mechanisms to ensure more reliable area-based paging and mobility management.
- Introduction of LTE-based 5G Broadcast Phase 2 TS 36.300CR1428
- Support of Sample-based measurement (case 3b) TS 38.473CR1575
- Support for Continuous Management-based MDT TS 38.300CR1068
- Support for Continuous Management-based MDT in split architecture TS 38.401CR0484
- Stage 2 corrections for AI/ML based CCO TS 38.401CR0511
- Correction on LTM Cell Switch Notification TS 38.423CR1582
+ 7 more changes
Explore further
Broader topics and technologies where RANAC plays a role.
Defining Specifications
3GPP specifications that define or reference RANAC, with the latest known release. Sourced from the 3GPP document catalog — see methodology.
| Specification | Title | Release |
|---|---|---|
| TS 36.300 vj00 | E-UTRAN Radio Interface Protocol Architecture Overview | Rel-19 |
| TS 37.473 vj00 | W1 Application Protocol (W1AP) Specification | Rel-19 |
| TS 37.483 vj10 | E1 Application Protocol (E1AP) | Rel-19 |
| TS 38.300 vj00 | NG-RAN Overall Description | Rel-19 |
| TS 38.401 vj10 | NG-RAN Architecture Specification | Rel-19 |
| TS 38.423 vj10 | Xn Application Protocol (XnAP) specification | Rel-19 |
| TS 38.463 vj00 | E1 Application Protocol (E1AP) | Rel-19 |
| TS 38.473 vj10 | 5G F1 Application Protocol (F1AP) | Rel-19 |