Description
The E-UTRAN Absolute Radio Frequency Channel Number (EARFCN) is a fundamental identifier within 3GPP specifications for Long-Term Evolution (LTE) and its evolution into 5G New Radio (NR). It serves as a channel number that uniquely maps to a specific center carrier frequency used for communication between User Equipment (UE) and the evolved NodeB (eNB) or gNB. The mapping is defined by a formula that converts the EARFCN value into an absolute frequency in kHz, with separate formulas defined for the uplink and downlink directions. This system abstracts the physical frequency, allowing network commands and configurations to refer to a simple number rather than a raw frequency value, simplifying software and protocol design.
The architecture of frequency identification relies on EARFCN being part of system information broadcast by the cell and used in measurement reporting and handover commands. Key components include the channel raster, which defines the set of allowed EARFCN values and their corresponding frequencies, ensuring that all UEs and base stations tune to the same precise frequency for a given EARFCN. The specifications define different ranges for EARFCN in different operating bands (e.g., Band 1, Band 3), and the value itself indicates whether it is for the uplink or downlink based on the band-specific mapping tables. Its role is central to radio resource management, enabling functions like carrier aggregation, where multiple EARFCNs can be assigned to a single UE to increase bandwidth.
In operation, when a network operator deploys a cell, they configure its operating frequency by setting the EARFCN. The UE, upon scanning or receiving system information, reads the EARFCN and uses the standardized formula to calculate the exact frequency to which it must tune its radio. For measurement reports, the UE identifies neighboring cells by their detected EARFCN. The system supports a wide range of values to cover all licensed spectrum from below 1 GHz to millimeter wave frequencies, with extensions in later releases to accommodate new spectrum allocations. The precision and unambiguous nature of EARFCN are vital for avoiding interference and ensuring seamless mobility across networks from different vendors and operators.
Purpose & Motivation
EARFCN was created to address the need for a unified, scalable, and technology-agnostic method to identify radio channels in LTE networks, replacing the earlier UMTS Absolute Radio Frequency Channel Number (UARFCN) used for 3G. Prior to LTE, different radio access technologies (GSM, UMTS) used their own channel numbering schemes, which complicated multi-mode device design and network interworking. The transition to OFDMA-based LTE required a new scheme that could efficiently represent the wider channel bandwidths and diverse spectrum allocations envisioned for 4G.
The primary problem EARFCN solves is the abstraction of physical frequency details from higher-layer protocols and network management systems. By using a simple integer, network configuration, neighbor cell lists, and handover commands become independent of the actual MHz or GHz values, simplifying software implementation and reducing errors. This abstraction is especially important for global roaming, as a device can interpret an EARFCN from any network worldwide and correctly calculate the local operating frequency based on the standardized formulas. It also future-proofs the system, as new frequency bands can be added by extending the EARFCN range without altering the core protocol mechanics.
Historically, the motivation stemmed from the increasing complexity of spectrum management with the advent of LTE, which was designed to operate in paired (FDD) and unpaired (TDD) spectrum across a continuum from traditional cellular bands to new, higher frequencies. EARFCN provides a consistent reference point that scales across all these scenarios, enabling features like carrier aggregation, where a device simultaneously uses multiple EARFCNs. Its creation was a foundational step in ensuring that LTE and subsequent 5G NR could be deployed flexibly across the globe's fragmented radio spectrum.
Classification
Detected Changes Across Releases
from 3GPP Change RequestsSpecific changes extracted from the „Change history“ tables of 3GPP specifications (76 CRs across 5 releases). Complements the general historical overview above with the evidence-based evolution of this function.
Studied in Rel-8, normative work from Rel-15.
In Release 15, specific corrections were made to the EARFCN function, including a correction to the offset of the NB-IoT channel number to EARFCN. Additionally, corrections were applied to channel spacing for specific intra-band carrier aggregation combinations and to NB-IoT TDD cell frequency information. These updates ensured accurate frequency channel numbering and parameter alignment for both LTE and NB-IoT technologies.
- X2AP CR for support of NR Multiple frequency band in EN-DC TS 36.423CR1125
- Correction of NB-IoT TDD Cell Frequency info TS 36.423CR1341
- CR to TS 37.145-2: OTA Adjacent Channel Leakage Ratio (6.7.3) and OTA Operating band unwanted emissions (6.7.5) - corrections to text and tables TS 37.145CR0055
- CR to TS 37.145-2: mirror of operating band and frequency range declaration from NR, Rel-15 TS 37.145CR0133
- Correction of channel spacing for band 46 intraband CA band combinations with 10 MHz bandwidth TS 36.104CR4737
- Correction on Offset of NB-IoT Channel Number to EARFCN TS 36.423CR1093
In Release 16, the primary updates to the EARFCN function were not direct modifications to the EARFCN definition itself, but rather related enhancements in frequency and carrier configuration. These included the finalized introduction of channel spacing specifications between E-UTRA and NR carriers for tighter integration, as well as corrections and clarifications on frequency offsets for specific operations like TDD NB-IoT standalone. The release also provided corrections on frequency information for dual-connectivity scenarios, ensuring accurate carrier alignment.
- Add new general abbreviations MCC Note: CR cover sheet wrongly shows CR number as "1118". TS 21.905CR0118
- Provisioning of manufacturer-assigned UE radio capability ID to the UE TS 24.368CR0044
- X2AP support for Radio Capability Signaling Optimization (The CR is not implemented. The CR was marked agreed by mistake while the WI is not yet complete) TS 36.423CR1468
- X2AP support for Radio Capability Signaling Optimization TS 36.423CR1468
- Introducing UE Radio Capability ID Mapping procedure TS 36.423CR1532
- Finalizing provisioning of manufacturer-assigned UE radio capability IDs at the UE TS 24.368CR0045
+ 18 more changes
In Release 17, the EARFCN function was updated to support new channel bandwidths of 35 MHz and 45 MHz, as introduced in the updated requirements for Base Station (BS) conformance testing. This expansion of supported channel bandwidths required corresponding modifications to RF requirements, including spurious emissions limits for Active Antenna System (AAS) Base Stations to ensure coexistence. These changes were implemented across several technical specifications governing BS radio transmission and reception.
- Satellite E-UTRAN in PLMN selector TS 31.102CR0956
- CR to 37.104: Introduction of requirements for 35 and 45MHz channel bandwidths TS 37.104CR0949
- CR for TS 37.141: introduction of channel bandwidths 35MHz and 45MHz TS 37.141CR0990
- CR for TS 37.145-2: introduction of channel bandwidths 35MHz and 45MHz TS 37.145CR0314
- Support of enhanced 5G-AKA sequence number re-synchronization TS 31.102CR0952
- CR to 37.145-2 to modify AAS BS OTA Spurious emissions limits for co-existence with systems operating in other frequency bands in R17 TS 37.145CR0302
In Release 18, the primary update to the EARFCN function was the correction of the E-UTRAN Absolute Radio Frequency Channel Numbers specifically for bands 107 and 108, as detailed in a Change Request to TS 36.104. This correction ensures the channel numbering aligns accurately with the defined operating bands for LTE. No other modifications to the EARFCN definition or its underlying procedures were introduced in this release.
- Add EF of IMS Data Channel configuration to the USIM TS 31.102CR1006
- Introducing Report Amount for M4, M5, M6, M7 measurements for E-UTRAN [ReportAmount_MDT_E-UTRAN] TS 36.423CR1688
- CR to TS 37.141 - Consideration of NR 3 MHz channel bandwidth TS 37.141CR1068
- CR to TS36.102 Addition of downlink physical channels for connection set-up for Cat NB1 and NB2 TS 36.102CR0025
- (LTE_NBIOT_eMTC_NTN_req-Core) CR to TS 36.102 on variable TX-RX frequency separation TS 36.102CR0059
- (IoT_NTN_FDD_LS_band-Core) Clarification for the PSD limits for a UE operating in 1610-1626.5 MHz frequency range TS 36.102CR0063
+ 22 more changes
In Release 19, the primary update related to EARFCN and channel arrangements was the introduction of a new 7 MHz channel bandwidth for NR FR1, requiring corresponding updates to RF and performance specifications. Additionally, a new IoT NTN operating band (band 252) was added to the standard for non-terrestrial networks. These changes necessitated clarifications and corrections in adjacent channel leakage ratio (ACLR) requirements and performance test criteria to accommodate the new bandwidth.
- CR to TS37.104 Introduction of 7 MHz NR FR1 channel bandwidth TS 37.104CR1028
- CR to TS 37113 - Introduction of 7 MHz channel BW TS 37.113CR0142
- CR to TS37.141 Introduction of 7 MHz NR FR1 channel bandwidth TS 37.141CR1098
- CR to TS 37.145-2: 7MHz channel bandwidth introduction TS 37.145CR0398
- CR to TS 36.108: Clarification on channel bandwidth applicability in ACLR requirement TS 36.108CR0052
- Addition of IoT NTN band 252 in Operating bands and channel arrangement TS 36.521CR0111
+ 6 more changes
Explore further
Broader topics and technologies where EARFCN plays a role.
Defining Specifications
3GPP specifications that define or reference EARFCN, 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 24.368 vj40 | NAS Configuration Management Object | Rel-19 |
| TS 31.102 vj40 | USIM Application Specification | Rel-19 |
| TS 36.101 vj30 | LTE UE Radio Transmission & Reception Requirements | Rel-19 |
| TS 36.102 vj10 | E-UTRA UE Satellite Access RF Requirements | Rel-19 |
| TS 36.104 vj10 | Base Station (BS) radio transmission and reception | Rel-19 |
| TS 36.106 vj00 | E-UTRA FDD Repeater RF Requirements | Rel-19 |
| TS 36.108 vj10 | Satellite Access Node RF Requirements | Rel-19 |
| TS 36.112 vj00 | E-UTRAN LMU Conformance Requirements | Rel-19 |
| TS 36.116 vj00 | E-UTRA Relay RF Requirements | Rel-19 |
| TS 36.117 vj00 | E-UTRA Relay RF Test Methods & Requirements | Rel-19 |
| TS 36.141 vj00 | E-UTRA BS Conformance Testing | Rel-19 |
| TS 36.143 vj00 | E-UTRA FDD Repeater RF Testing | Rel-19 |
| TS 36.181 vj30 | E-UTRA RF Test Methods for Satellite Access Node | Rel-19 |
| TS 36.423 vj10 | X2 Application Protocol (X2AP) Specification | Rel-19 |
| TS 36.521 vj00 | E-UTRA UE Conformance ICS Proforma | Rel-19 |
| TS 36.744 ve00 | CBRS 3.5GHz Band Specification for US | Rel-14 |
| TS 36.755 vf00 | US 600 MHz LTE Band 71 Technical Report | Rel-15 |
| TS 36.761 vf00 | Extended-Band 12 Study Report | Rel-15 |
| TS 36.790 vf00 | LAA/eLAA for CBRS 3.5GHz Band in US | Rel-15 |
| TR 36.791 vg00 | E-UTRA 2.4 GHz TDD Band for US | Rel-16 |
| TS 36.858 ve00 | LTE 2.6 GHz SDL Band Technical Report | Rel-14 |
| TS 37.104 vj10 | MSR Base Station RF Characteristics | Rel-19 |
| TS 37.113 vj00 | EMC Requirements for Multi-Standard Radio Base Stations | Rel-19 |
| TS 37.141 vj10 | RF Test Methods for Multi-Standard Radio Base Stations | Rel-19 |
| TS 37.145 vj10 | AAS Base Station Conducted Conformance Testing | Rel-19 |
| TS 37.802 va10 | MSR BS RF Requirements for Non-Contiguous Spectrum | Rel-10 |
| TS 37.812 vb30 | Multi-band Multi-standard Radio BS Requirements | Rel-11 |
| TS 37.814 vc00 | L-band Supplemental Downlink for UTRA/E-UTRA | Rel-12 |
| TR 37.900 vj00 | Multi-Standard Radio (MSR) Base Station Requirements | Rel-19 |
| TR 38.860 vh00 | NR; Study on Extended 600 MHz NR band | Rel-17 |
| TR 38.892 vi00 | Technical Report | Rel-18 |