Description
The GSM EDGE Radio Access Network (GERAN) is the collective term for the radio network infrastructure that implements the GSM, GPRS, and EDGE radio technologies as defined by 3GPP. Architecturally, GERAN is composed of Base Station Subsystems (BSS). Each BSS consists of two main elements: the Base Transceiver Station (BTS), which houses the radio transceivers and antennas for one or more cells, and the Base Station Controller (BSC), which manages radio resources, handles handovers, and controls the BTSs. The BSC performs critical functions like frequency allocation, power control, and the management of traffic and signaling channels (e.g., SDCCH, TCH).
GERAN connects to the core network via two key interfaces. For circuit-switched (CS) voice and SMS services, it uses the A-interface to link the BSC with the Mobile Switching Center (MSC). For packet-switched (PS) data services via GPRS and EDGE, it uses the Gb-interface to connect the BSC (or a dedicated Packet Control Unit - PCU) with the Serving GPRS Support Node (SGSN). The radio interface, known as the Um interface, uses a combination of FDMA (dividing the spectrum into 200 kHz carriers) and TDMA (dividing each carrier into 8 time slots). EDGE (Enhanced Data rates for GSM Evolution) introduced advanced modulation (8-PSK alongside GMSK) and coding schemes, significantly boosting data rates within the same TDMA structure.
Within a multi-RAT (Radio Access Technology) environment, GERAN's role evolved from being the sole RAN to interworking with UMTS (UTRAN) and LTE (E-UTRAN). Specifications define mechanisms for handover and cell reselection between GERAN and these newer networks, allowing for service continuity. The BSC manages both CS and PS resources, and with the introduction of EDGE, it also handles the adaptive modulation and coding that defines EDGE's higher throughput. GERAN specifications cover everything from the physical layer (modulation, burst structures) in the 45-series specs, to layer 2 and 3 protocols (e.g., RLC/MAC, BSSGP over Gb) in the 44 and 48-series, and to performance requirements in the 51-series.
Purpose & Motivation
GERAN was formally defined as a term to encompass the evolved 2G radio access network that included both the original GSM standard and its packet-data enhancements, GPRS and EDGE. Its creation solved the problem of providing a clear architectural definition for the radio network that supported both voice-centric circuit-switched services and emerging internet-based packet-switched data services under a single umbrella. Before this consolidation, specifications often referred separately to GSM radio and GPRS radio aspects.
The historical motivation was the need to evolve the successful GSM network to handle data efficiently, leading first to GPRS (a packet overlay) and then to EDGE (a radio enhancement). GERAN represents the culmination of this evolution, maximizing the utility of the deployed 200 kHz carrier TDMA infrastructure. It addressed the limitation of slow circuit-switched data (CSD) by introducing always-on packet connectivity (GPRS) and then significantly boosting its speed (EDGE), enabling early mobile internet experiences. As 3G (UMTS) emerged, defining GERAN allowed for clearer specifications on how this legacy network would interwork and coexist with the new WCDMA-based UTRAN, ensuring a smooth transition and global roaming across multiple generations of technology.
Classification
Detected Changes Across Releases
from 3GPP Change RequestsSpecific changes extracted from the „Change history“ tables of 3GPP specifications (40 CRs across 5 releases). Complements the general historical overview above with the evidence-based evolution of this function.
In Release 15, the primary change for GERAN was the removal of references to the specifications for its Iu mode (TS 44.118 and TS 44.160), effectively deprecating that operational mode. Furthermore, a correction was made to the procedure for GERAN redirection without security. The release also defined GERAN's role in the broader 3GPP system for inter-RAT handover to E-UTRA configured with EN-DC.
- Add attribute peeParametersList to UTRAN NRM SS TS 28.653CR0018
- Update E-UTRAN SS definitions to support ng-eNB management TS 28.659CR0025
- Introduction of New Radio Access Technology in TS 36.300 TS 36.300CR0998
- Introduction of increased number of E-UTRAN data bearers TS 36.306CR1613
- Introduction of increased number of E-UTRAN data bearers TS 36.331CR3446
- Inter-RAT Handover from GERAN or UTRAN to E-UTRA configured with EN-DC (36.300) TS 36.300CR1200
+ 12 more changes
In Release 16, there were no new functional enhancements specified for the GERAN itself. The approved Change Requests for this release focused exclusively on enhancements and corrections for other radio access technologies, such as E-UTRAN mobility, UE radio capability procedures for EN-DC and IIoT, and NB-IoT/eMTC. Therefore, the GSM EDGE Radio Access Network specifications saw no updates compared to the previous release.
- Introduction of even further mobility enhancement in E-UTRAN TS 36.300CR1270
- UE radio access capabilities introduction for IIOT WI (CR for 36.306) TS 36.306CR1758
- Introduction of Even further Mobility enhancement in E-UTRAN TS 36.331CR4205
- Corrections to even further mobility enhancement in E-UTRAN TS 36.300CR1284
- Introducing UE Radio Capability Mapping procedure for EN-DC TS 36.300CR1314
- Incorrect restriction for RLC UM radio bearers TS 36.331CR4385
+ 2 more changes
In Release 17, the GERAN-related updates focused on enhancements for Evolved Packet System (EPS) integration, specifically concerning UE security capabilities signaling for E-UTRAN access. The changes worked to avoid an unnecessary linkage between a UE's security functions and its radio access capabilities within the 3GPP system architecture. This refinement was part of the ongoing work for General Packet Radio Service (GPRS) enhancements supporting E-UTRAN access.
In Release 18, the GERAN-related work focused on enhancing network reliability and signaling integrity, specifically introducing protections against improper UE reselection to GERAN and UTRAN. This included corrections to the redirection procedure to GERAN, ensuring more robust mobility from newer radio access technologies. These updates aimed to prevent unintended campings and improve the handling of legacy network transitions.
- Protection against improper reselection to GERAN/UTRAN [RESELECTION_TO GSM_AND_UTRAN] TS 36.304CR0866
- Protection against improper reselection to GERAN/UTRAN [RESELECTION_TO GSM_AND_UTRAN] TS 36.306CR1874
- Protection against improper reselection to GERAN/UTRAN [RESELECTION_TO GSM_AND_UTRAN] TS 36.331CR4971
- Correction on redirection to GERAN [Redirect_to_GERAN] TS 36.331CR5000
- Handling of radio and RLC bearers at LTM cell switch execution in NR-DC TS 38.331CR5383
In Release 19, GERAN introduced no new features or changes for the GSM EDGE Radio Access Network itself. The listed Change Requests exclusively concerned enhancements for Non-Terrestrial Networks (NTN) and mobility procedures between E-UTRAN and NB-IoT NTN, which are outside the scope of GERAN's A/Gb mode operation and its defined interfaces like Abis.
- Introduction of NB-IoT satellite information in E-UTRAN [EUTRAN-to-NBIoTNTN] TS 36.300CR1427
- Introduction of E-UTRAN to NB-IoT NTN Mobility UE Capability [EUTRAN-to-NBIoTNTN] TS 36.306CR1917
- Introduction of NB-IoT satellite information in E-UTRAN [EUTRAN-to-NBIoTNTN] TS 36.331CR5140
- Correction for the redirection from E-UTRAN TN to NB-IoT NTN [IoT_TN_NTN_redir] TS 36.306CR1933
- Indication of supported NB-IoT NTN band list in E-UTRAN [IoT_TN_NTN_redir] TS 36.306CR1937
- Correction for the redirection from E-UTRAN TN to NB-IoT NTN [IoT_TN_NTN_redir] TS 36.331CR5173
+ 1 more changes
Explore further
Broader topics and technologies where GERAN plays a role.
Defining Specifications
3GPP specifications that define or reference GERAN, with the latest known release. Sourced from the 3GPP document catalog — see methodology.
| Specification | Title | Release |
|---|---|---|
| TR 21.905 vj00 | 3GPP Technical Terms and Definitions | Rel-19 |
| TS 22.034 vj00 | High Speed Circuit Switched Data (HSCSD) Stage 1 | Rel-19 |
| TS 22.240 vj00 | 3GPP Generic User Profile Requirements | Rel-19 |
| TS 23.009 vj00 | Handover Procedures in PLMNs | Rel-19 |
| TS 23.034 vj00 | HSCSD Stage 2 Service Description | Rel-19 |
| TS 23.060 vj00 | GPRS Service Description Stage 2 | Rel-19 |
| TS 23.107 vj00 | UMTS QoS Framework | Rel-19 |
| TS 23.205 vj00 | Bearer Independent CS Core Network Stage 2 | Rel-19 |
| TS 23.207 vj00 | End-to-End QoS Framework for GPRS | Rel-19 |
| TS 23.221 vj00 | 3GPP System Architectural Requirements | Rel-19 |
| TS 23.231 vj00 | SIP-I based CS core network stage 2 | Rel-19 |
| TS 23.251 vj00 | Network Sharing Stage 2 Specification | Rel-19 |
| TS 23.271 vj00 | LCS Stage 2 Specification | Rel-19 |
| TS 23.802 v1700 | Enhanced End-to-End QoS Architecture | Rel-7 |
| TR 23.976 vj00 | Push Service Requirements Analysis | Rel-19 |
| TR 23.979 vj00 | PoC over 3GPP Systems Architectural Requirements | Rel-19 |
| TS 24.161 vj00 | Network-Based IP Flow Mobility (NBIFOM) | Rel-19 |
| TS 24.206 v1700 | Voice Call Continuity Between CS and IMS | Rel-7 |
| TS 24.312 vj00 | ANDSF Management Objects Specification | Rel-19 |
| TS 25.123 vj00 | Radio Resource Management for TDD | Rel-19 |
| TS 25.133 vj00 | UTRAN RRM Requirements for FDD | Rel-19 |
| TS 25.331 vj00 | UTRAN RRC Protocol Specification | Rel-19 |
| TS 25.401 vj00 | UTRAN Overall Architecture | Rel-19 |
| TS 25.413 vj00 | Radio Access Network Application Part (RANAP) | Rel-19 |
| TS 25.420 vj00 | Iur Interface Introduction for UTRAN | Rel-19 |
| TS 25.423 vj00 | UTRAN RNSAP Specification | Rel-19 |
| TR 25.912 vj00 | Evolved UTRA and UTRAN Technical Report | Rel-19 |
| TR 26.937 vj00 | 3GPP PSS Characterization | Rel-19 |
| TR 26.952 vj00 | EVS Codec Selection, Verification & Characterization | Rel-19 |
| TR 26.976 vj00 | AMR-WB Codec Characterization & Verification | Rel-19 |
| TS 28.606 vc10 | CN and non-3GPP interworking NRM IRP Solution Sets | Rel-12 |
| TS 28.616 vj00 | EPC and non-3GPP access NRM IRP SS definitions | Rel-19 |
| TS 28.626 vj00 | State Management Data Definition IRP Solution Set | Rel-19 |
| TS 28.653 vj00 | UTRAN NRM IRP Solution Set Definition | Rel-19 |
| TS 28.654 vj00 | GERAN NRM IRP Requirements | Rel-19 |
| TS 28.655 vj00 | GERAN NRM IRP Information Service | Rel-19 |
| TS 28.656 vj00 | GERAN NRM IRP Solution Set Definitions | Rel-19 |
| TS 28.659 vj00 | E-UTRAN NRM IRP Solution Set Definitions | Rel-19 |
| TS 28.703 vj00 | Core Network NRM IRP Solution Set Definitions | Rel-19 |
| TS 28.706 vj00 | IMS NRM IRP Solution Set definitions | Rel-19 |
| TS 28.707 vj00 | EPC NRM IRP Requirements | Rel-19 |
| TS 28.733 vj00 | TN NRM IRP Solution Set Definitions | Rel-19 |
| TR 31.900 vj00 | 3GPP TS 31.900: Security Interworking Guidance | Rel-19 |
| TS 32.152 ve10 | IRP Information Service UML Repertoire | Rel-14 |
| TS 32.251 vj00 | PS Domain Charging Management | Rel-19 |
| TS 32.271 vj20 | 3GPP LCS Charging Management Spec | Rel-19 |
| TS 32.272 vj00 | Charging for Push-to-Talk over Cellular (PoC) | Rel-19 |
| TS 32.410 vj00 | 3GPP TS 32.410: Key Performance Indicators (KPI) | Rel-19 |
| TS 32.615 v1920 | Bulk CM XML File Format Definition | Rel-9 |
| TS 32.616 vj00 | Bulk CM IRP Solution Set Definitions | Rel-19 |
| TS 32.625 v1900 | Bulk CM XML File Format Definition | Rel-9 |
| TS 32.626 vb20 | Generic Network Resources IRP Solution Set Definitions | Rel-11 |
| TS 32.635 v1910 | Core Network Resources IRP XML Schema | Rel-9 |
| TS 32.636 vb00 | CM Core Network Resources IRP Solution Set | Rel-11 |
| TS 32.641 vb00 | UTRAN Network Resources IRP Requirements | Rel-11 |
| TS 32.645 v930 | UTRAN Bulk CM XML File Format | Rel-9 |
| TS 32.646 vc00 | UTRAN NRM IRP Solution Set Definitions | Rel-12 |
| TS 32.651 vb00 | GERAN Network Resources CM IRP Requirements | Rel-11 |
| TS 32.652 vc00 | GERAN Network Resources NRM for Configuration Management | Rel-12 |
| TS 32.655 v920 | GERAN NRM Bulk CM XML File Format | Rel-9 |
| TS 32.656 vc00 | GERAN NRM IRP Solution Set Definitions | Rel-12 |
| TS 32.675 v1900 | State Management IRP Bulk CM XML Format | Rel-9 |
| TS 32.676 vc00 | 3GPP TS 32.676: State Management IRP Solution Set | Rel-12 |
| TS 32.715 v900 | TN interface NRM IRP XML file format definition | Rel-9 |
| TS 32.716 vb00 | TN NRM IRP Solution Set Definitions | Rel-11 |
| TS 32.725 v1900 | Repeater Network Resources IRP Bulk CM XML | Rel-9 |
| TS 32.726 vb00 | Repeater NRM IRP Solution Set Definitions | Rel-11 |
| TS 32.735 v1910 | IMS NRM IRP Bulk CM XML Format | Rel-9 |
| TS 32.736 vb00 | IMS NRM IRP Solution Set Definitions | Rel-11 |
| TS 32.751 vb00 | EPC NRM IRP Requirements | Rel-11 |
| TS 32.765 v960 | E-UTRAN NRM IRP XML Definitions | Rel-9 |
| TS 32.766 vb90 | E-UTRAN NRM IRP Solution Set Definitions | Rel-11 |
| TS 32.808 v1800 | Common User Profile Storage Framework | Rel-8 |
| TS 33.102 vj10 | 3G Security Architecture Specification | Rel-19 |
| TS 33.401 vj10 | EPS Security Architecture | Rel-19 |
| TS 33.859 vb10 | UTRAN Key Hierarchy Enhancement Study | Rel-11 |
| TS 33.863 ve20 | Security for Battery-Efficient IoT Device to Enterprise | Rel-14 |
| TS 36.133 vj20 | E-UTRA RRM Requirements | Rel-19 |
| TS 36.300 vj00 | E-UTRAN Radio Interface Protocol Architecture Overview | Rel-19 |
| TS 36.302 vj00 | E-UTRA Physical Layer Services | Rel-19 |
| TS 36.304 vj00 | UE Idle Mode Procedures in E-UTRA | Rel-19 |
| TS 36.306 vj00 | E-UTRA UE Radio Access Capability Parameters | Rel-19 |
| TS 36.331 vj00 | LTE RRC Protocol Specification | Rel-19 |
| TS 37.320 vj00 | Minimization of Drive Tests (MDT) Overview | Rel-19 |
| TS 38.331 vj00 | NR Radio Resource Control (RRC) Protocol Specification | Rel-19 |
| TS 43.051 vj00 | GERAN Stage 2 Service Description | Rel-19 |
| TS 43.129 vj00 | PS Handover in GERAN A/Gb and GAN Modes | Rel-19 |
| TS 43.130 vj00 | Iur-g Interface Overview | Rel-19 |
| TS 43.318 vj00 | Generic Access Network (GAN) Stage 2 | Rel-19 |
| TR 43.901 vj00 | Generic Access to A/Gb Interface Feasibility Study | Rel-19 |
| TR 43.902 vj00 | GAN Enhancements Feasibility Study | Rel-19 |
| TS 44.060 vj00 | GERAN RLC/MAC Protocol Specification | Rel-19 |
| TS 44.318 vj00 | Generic Access Network (GAN) Interface Procedures | Rel-19 |
| TR 44.901 vj00 | Extended NACC for External Cell Change | Rel-19 |
| TR 45.902 vj00 | Flexible Layer One (FLO) for GERAN | Rel-19 |