Description
An Information Element (IE) is a structured data container defined within 3GPP protocol specifications. It serves as the atomic unit of information carried within protocol messages across various interfaces, such as the radio interface (Uu), the interface between the RAN and the core network (e.g., S1, N2), or within the core network itself (e.g., N4, N11). Each IE is meticulously defined with a specific syntax, semantics, and encoding rules. The syntax defines the IE's structure, which typically includes an identifier (IEI), a length indicator, and the actual content or value. The semantics define the precise meaning and interpretation of the content, such as a Tracking Area Identity, a QoS profile, or a radio measurement report. The encoding rules specify how the IE is serialized into a bitstream for transmission, often using ASN.1 PER (Packed Encoding Rules) or other binary formats.
IEs are grouped together to form complete protocol messages. For instance, an RRC Connection Setup message contains multiple IEs that convey the new radio resource configuration to the UE. Similarly, a GTP-C Create Session Request message contains IEs for the UE's IP address, QoS parameters, and bearer context. The presence or absence of an IE, and its specific value, dictates the behavior of the receiving entity. Some IEs are mandatory (M) for a given message, while others are conditional (C) or optional (O), depending on the scenario. This flexibility allows protocols to support a vast range of functionalities and network configurations without requiring a unique message type for every possible combination of parameters.
The design and management of IEs are central to protocol evolution. New features introduced in later 3GPP releases often require the definition of new IEs or extensions to existing ones. To maintain backward compatibility, protocols are designed to allow older network nodes or UEs to ignore IEs they do not understand (unless the IE is critical for the procedure). The extensive catalog of IEs is documented across hundreds of 3GPP technical specifications, with each specification detailing the IEs relevant to a particular protocol layer or interface. Master glossaries like TS 21.905 provide a central reference for IE definitions and their associated specifications.
Purpose & Motivation
The Information Element exists to provide a standardized, modular, and extensible method for encoding information in telecommunications protocols. Before such standardization, proprietary protocols would use ad-hoc data formats, leading to severe interoperability issues between equipment from different manufacturers. The IE concept solves this by defining a common 'language' and grammar for network communication. It allows complex information—from simple integers to nested structures—to be unambiguously defined, transmitted, and interpreted by both ends of a communication link.
This modularity is crucial for supporting the immense feature set and evolutionary path of cellular networks. Instead of creating entirely new message types for every new parameter or feature, engineers can simply define a new IE or extend an existing one. This approach keeps the core protocol message set relatively stable while allowing immense flexibility. For example, the same RRC Connection Reconfiguration message can be used to set up a voice call in 3G, configure carrier aggregation in 4G, or establish a network slice in 5G, simply by including different sets of IEs. It decouples the message's purpose from its specific content, future-proofing the protocols.
Furthermore, IEs enable efficient and compact encoding. By using binary formats and carefully designed length indicators, they minimize protocol overhead, which is critical for radio interfaces where bandwidth is a precious resource. The strict typing and structure also facilitate automated code generation, testing, and validation, reducing implementation errors and accelerating development cycles for network equipment and devices.
Classification
Detected Changes Across Releases
from 3GPP Change RequestsSpecific changes extracted from the „Change history“ tables of 3GPP specifications (158 CRs across 5 releases). Complements the general historical overview above with the evidence-based evolution of this function.
In Release 15, the Information Element function was enhanced to support new capabilities including Secondary RAT information for EN-DC, the reporting of Media Bearer information, and the transfer of PSCell information to the Core Network. It also introduced specific assistance information for broadcasting and local cache, along with extensions for Data Traffic Resources and Geofencing information in CMAS. Furthermore, corrections and clarifications were applied to several existing IEs, such as those for EPS quality of service, UE assistance information, and system information acquisition.
- Correction on EPS quality of service IE name TS 24.244CR0054
- Enhance location information in trusted and untrusted WLAN TS 32.251CR0503
- Cell Site Supplemental Information Reporting-Handover Details TS 33.108CR0395
- Delivery of PTC Encryption information TS 33.108CR0400
- Introduce assistance information for local cache 36.331 CR TS 36.331CR3178
- Assistance Information Broadcasting TS 36.455CR0082
+ 54 more changes
In Release 16, the Information Element (IE) function was enhanced with new capabilities and corrections across several interfaces, including X2AP and F1-C. Key additions included specific IEs for VoLTE information, bearer-level QoS, and APN-AMBR, alongside clarifications for usage in DAPS handover and traffic containers. The release also introduced corrections for ASN.1 encoding, RF parameters, and neighbor cell information, and expanded support for features like UE assistance information for DRX preference and 5G location information retrieval.
- Add VoLTE information TS 32.251CR0516
- IEIs assignment for Bearer level QoS IE and APN-AMBR IE TS 24.244CR0057
- Extension of alarm-information OCTET String Size TS 33.108CR0425
- Correction regarding placement of cell specific SSB QCL information TS 36.331CR4393
- Miscellaneous corrections on overheating assistance information for NR SCG TS 36.331CR4489
- PSCell information report for EN-DC TS 36.413CR1745
+ 18 more changes
In Release 17, the Information Element (IE) function was enhanced with new elements for reporting height information in LTE MDT reports and for conveying neighbour cell CSI-RS configuration information over the X2 interface. It also introduced clarifications and corrections for IEs related to multiplePositioningProtocolPDUs, Routing information, and the Security Indication IE in the Source eNB to Target eNB Transparent Container. Furthermore, new serving PLMN information was added for IoT NTN in the User Location Information (ULI).
- Introduction of 5G ProSe converged charging information TS 32.277CR0044
- On introducing height information reporting in MDT reports [LTE-Height-MDT] TS 36.331CR4756
- Correction of LTE MDT on Sensor information[LTE-Height-MDT] TS 36.413CR1901
- Signalling of Neighbour cell CSI-RS configuration information over X2 [CSIRSX2] TS 36.423CR1614
- Clarification on multiplePositioningProtocolPDUs IE TS 24.571CR0008
- Clarification on Routing information TS 24.571CR0010
+ 21 more changes
In Release 18, the Information Element function was updated with new elements including a GTP-U Extension Header for the PDU Set Information Container, converged charging information for 5G ProSe, and GNSS LOS/NLOS positioning assistance data for broadcast. The release also introduced corrections and clarifications to existing IEs, such as those for the RSPP supplementary information transport procedure, the X2AP Conditional Handover Time Based Information IE, and UE location information in various reports.
- New GTP-U Extension Header for the PDU Set Information Container TS 29.281CR0128
- Addition of converged charging information TS 32.270CR0034
- GNSS LOS/NLOS posSIB broadcast assistance information [GNSS LOS/NLOS] TS 36.331CR4931
- GNSS LOS/NLOS posSIB broadcast assistance information [GNSS LOS/NLOS] TS 38.331CR4109
- Correction to the IE's name and the correlation NOTE TS 24.571CR0030
- Payload container information IE related to PRU TS 24.571CR0054
+ 21 more changes
In Release 19, the Information Element function was expanded to support new satellite and relay communication capabilities, including the addition of satellite E-UTRAN and NG-RAN in PLMN-specific RAT restriction information and new information elements for Layer-3 ProSe UE-to-UE relay communication. It also introduced new charging-related information for store-and-forward satellite operations for SMS and UP CIoT, as well as for ProSe Multi-Hop UE-to-Network communication. Furthermore, new IEs were added for Time Reference Distribution Information in S1AP and for UE assistance information related to cell DTX/DRX.
- Add Time Reference Information Distribution Indication TS 29.272CR0862
- Addition of satellite E-UTRAN and satellite NG-RAN in the PLMN specific RAT restriction information TS 29.272CR0868
- Rel-19 CR 32.240 Support the energy related information per network slice TS 32.240CR0498
- Add charging information for store and forward satellite operation of SMS service TS 32.251CR0521
- Add charging information for store and forward satellite operation with UP CIoT TS 32.251CR0523
- Introduction of converged charging information for Ranging and Sidelink Positioning TS 32.271CR0026
+ 14 more changes
Explore further
Broader topics and technologies where IE plays a role.
Defining Specifications
3GPP specifications that define or reference IE, 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 23.066 vj00 | Mobile Number Portability Technical Realization | Rel-19 |
| TS 23.078 vj00 | CAMEL Phase 4 Stage 2 Specification | Rel-19 |
| TS 23.146 vj00 | 3G Facsimile Group 3 Technical Realization | Rel-19 |
| TS 23.172 vj00 | Service Change and UDI Fallback (SCUDIF) | Rel-19 |
| TS 23.218 vj00 | IMS Call Model Specification | Rel-19 |
| TS 23.278 vj00 | CAMEL for IMS Stage 2 Specification | Rel-19 |
| TR 23.910 v1400 | UMTS Circuit Switched Bearer Services Overview | Rel-5 |
| 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 24.171 vj00 | NAS Protocol for LCS in E-UTRAN | Rel-19 |
| TS 24.244 vj00 | Wireless LAN Control Plane Protocol | Rel-19 |
| TS 24.259 vj00 | Personal Network Management (PNM) Protocol Details | Rel-19 |
| TS 24.571 vj20 | Control Plane LCS Procedures | Rel-19 |
| TS 25.104 vj00 | UTRA FDD Base Station RF Characteristics | Rel-19 |
| TS 25.324 vj00 | Broadcast/Multicast Control Protocol | Rel-19 |
| TS 25.331 vj00 | UTRAN RRC Protocol Specification | Rel-19 |
| TS 25.413 vj00 | Radio Access Network Application Part (RANAP) | Rel-19 |
| TS 25.423 vj00 | UTRAN RNSAP Specification | Rel-19 |
| TR 25.931 vj00 | UTRAN Signalling Procedures Examples | Rel-19 |
| TR 25.967 vj00 | Home NodeB RF Requirements Technical Report | Rel-19 |
| TS 29.060 vj00 | GPRS Tunnelling Protocol (GTP) version 1 | Rel-19 |
| TS 29.228 vj20 | Cx and Dx Interface Signaling Flows | Rel-19 |
| TS 29.272 vj40 | Diameter Interfaces for MME/SGSN | Rel-19 |
| TS 29.281 vj20 | GTPv1-U Protocol Specification | Rel-19 |
| TS 29.328 vj20 | Sh and Dh Interfaces: HSS-AS Interactions | Rel-19 |
| TS 32.240 vj40 | Charging Management Architecture & Principles | Rel-19 |
| TS 32.251 vj00 | PS Domain Charging Management | Rel-19 |
| TS 32.253 vj00 | Charging for Control Plane Data Transfer | Rel-19 |
| TS 32.254 vj21 | Charging for Northbound APIs | Rel-19 |
| TS 32.270 vj00 | MMS Charging Management Specification | 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 32.277 vj20 | Charging Management for Proximity Services (ProSe) | Rel-19 |
| TS 32.295 vj00 | 3GPP Charging: CDR Transfer via GTP' Protocol | Rel-19 |
| TS 32.816 v800 | UMTS Management Reuse for E-UTRAN/EPC | Rel-8 |
| TS 32.869 vf00 | Diameter Overload Control for Charging Interfaces | Rel-15 |
| TS 32.870 vf00 | Study on 3GPP Charging Forward Compatibility | Rel-15 |
| TS 33.108 vj00 | LI Handover Interface Specification | Rel-19 |
| TS 33.859 vb10 | UTRAN Key Hierarchy Enhancement Study | Rel-11 |
| TS 36.331 vj00 | LTE RRC Protocol Specification | Rel-19 |
| TS 36.413 vj10 | S1 Application Protocol (S1AP) | Rel-19 |
| TS 36.423 vj10 | X2 Application Protocol (X2AP) Specification | Rel-19 |
| TS 36.444 vj00 | M3AP Protocol Specification for M3 Interface | Rel-19 |
| TS 36.455 vj00 | LTE Positioning Protocol Annex (LPPa) | Rel-19 |
| TS 36.463 vj00 | XwAP Protocol Specification | Rel-19 |
| TS 36.887 vc00 | Energy Saving Enhancement for E-UTRAN Study | Rel-12 |
| TS 37.857 vd10 | Study on Indoor Positioning Enhancements | Rel-13 |
| TS 38.211 vj10 | NR Physical Channels and Modulation | Rel-19 |
| TS 38.331 vj00 | NR Radio Resource Control (RRC) Protocol Specification | Rel-19 |
| TR 38.889 vg00 | NR-based access to unlicensed spectrum study | Rel-16 |
| TR 45.903 vj00 | SAIC Feasibility Study for GSM Networks | Rel-19 |