3GPP Glossary
Comprehensive reference of mobile network terms, components, and technologies
54 terms
Core Network (8)
Access and Mobility Management Function
The 5GC control-plane function handling registration, connection and mobility management, and NAS signaling termination for the UE.
Mobility Management Entity
The EPC control-plane node handling NAS signaling, idle-mode UE tracking, bearer activation/deactivation, and authentication for LTE.
Network Exposure Function
The 5GC function that securely exposes network capabilities and events to external third-party applications.
Network Repository Function
The 5GC function that provides service discovery, allowing network functions to register and discover each other over the service-based interface.
Policy Control Function
The 5GC function that provides policy rules for QoS, charging, and traffic steering to the SMF and other network functions.
Session Management Function
The 5GC function responsible for PDU session establishment, IP address allocation, and UPF selection and control.
Unified Data Management
The 5GC function that stores subscriber subscription data and generates authentication credentials, exposed via the UDR.
User Plane Function
The 5GC user-plane node that performs packet routing, forwarding, QoS enforcement, and traffic reporting, with control via PFCP from the SMF.
Security (1)
Physical Layer (24)
Block Error Rate
The fraction of transport blocks received in error, used as a target metric for link adaptation and MCS selection.
Bandwidth Part
A contiguous subset of the cell bandwidth that a UE is configured to operate within at a given time, enabling power-saving and mixed numerologies.
Channel Quality Indicator
UE feedback indicating the highest modulation and coding scheme the current channel conditions can support.
Channel State Information Reference Signal
A configurable downlink reference signal used for channel quality measurement, beam management, and mobility measurements.
Demodulation Reference Signal
UE- or beam-specific reference signal transmitted alongside data channels to enable coherent channel estimation for demodulation.
Modulation and Coding Scheme
An index mapping to a specific modulation order and code rate combination applied to a transport block.
Master Information Block
The broadcast system information carrying the minimal set of parameters a UE needs before it can read further scheduling information.
Physical Broadcast Channel
The physical channel that carries the MIB, allowing a UE to acquire the minimum system information needed to access a cell.
Physical Downlink Control Channel
The physical channel carrying downlink control information (DCI) that schedules PDSCH/PUSCH resources and delivers other control commands.
Physical Downlink Shared Channel
The main downlink data-bearing physical channel, carrying user-plane and higher-layer control data scheduled via PDCCH.
Physical Layer
Layer 1 of the radio protocol stack, responsible for modulation, coding, and mapping of transport channels onto physical resources.
Precoding Matrix Indicator
UE feedback recommending the precoding matrix the network should apply for closed-loop MIMO transmission.
Physical Random Access Channel
The uplink physical channel used by the UE to initiate random access, enabling uplink timing synchronization and initial access.
Physical Resource Block
The basic unit of frequency-domain resource allocation, consisting of 12 consecutive subcarriers over one slot.
Physical Sidelink Broadcast Channel
The sidelink physical channel used to broadcast synchronization and system information directly between UEs in D2D/V2X communication.
Physical Uplink Control Channel
The physical channel carrying uplink control information such as HARQ feedback, scheduling requests, and CSI reports.
Physical Uplink Shared Channel
The main uplink data-bearing physical channel, used for user-plane data and, when needed, uplink control information.
Rank Indicator
UE feedback indicating the number of spatial layers (transmission rank) that can be supported for MIMO transmission.
Reference Signal Received Power
A UE measurement of the average power of reference signal resource elements, used for cell selection, reselection, and handover decisions.
Reference Signal Received Quality
A UE measurement combining RSRP and received signal strength (RSSI) to indicate signal quality relative to total channel power.
System Information Block
Broadcast messages carrying cell configuration, neighbor cell, and access-control information beyond what the MIB provides.
Signal-to-Interference-plus-Noise Ratio
A measurement expressing the ratio of desired signal power to interference and noise power, used to estimate achievable throughput.
Synchronization Signal Block
The NR block combining PSS, SSS, and PBCH, transmitted periodically to enable cell search, synchronization, and beam management.
Transport Block Size
The number of information bits contained in a transport block, derived from the MCS, allocated resource blocks, and layer count.
Radio Access Network (6)
Carrier Aggregation
The combination of multiple component carriers to increase a UE's effective bandwidth and peak data rate.
E-UTRA New Radio Dual Connectivity
A non-standalone 5G deployment option where a UE connects simultaneously to an LTE eNodeB (master) and an NR gNodeB (secondary), sharing an EPC core.
Non-Standalone
A 5G deployment architecture where NR radio is anchored by an existing LTE/EPC control plane, most commonly realized as EN-DC.
Standalone
A 5G deployment architecture where the gNodeB connects directly to the 5G core (5GC) without relying on an LTE anchor.
Evolved Node B
The LTE radio base station, combining the functions of the UMTS Node B and RNC into a single flat-architecture element that terminates the radio interface and connects directly to the EPC.
Next Generation Node B
The 5G NR base station, capable of connecting to both 5GC (via NG) and, in non-standalone mode, acting as a secondary node alongside an eNodeB.
Identifier (2)
E-UTRA Absolute Radio Frequency Channel Number
The channel numbering scheme used to identify carrier frequencies for LTE bands.
NR Absolute Radio Frequency Channel Number
The channel numbering scheme used to identify carrier frequencies in NR across FR1 and FR2.
Interface (7)
F1 Application Protocol
The signaling protocol over the F1 interface between a gNodeB-CU and gNodeB-DU in a disaggregated RAN deployment.
N2 Interface
The 5GC reference point between the NG-RAN and the AMF, carrying NGAP signaling.
N3 Interface
The 5GC reference point carrying user-plane GTP-U traffic between the NG-RAN and the UPF.
NG Application Protocol
The signaling protocol over the N2 interface between the gNodeB and the AMF, carrying UE context and PDU session management.
S1 Application Protocol
The signaling protocol over the S1-MME interface between eNodeB and MME, carrying context setup, handover, and paging procedures.
X2 Application Protocol
The signaling protocol over the X2 interface between neighboring eNodeBs, used for handover preparation and interference coordination.
Xn Application Protocol
The signaling protocol over the Xn interface between NG-RAN nodes, supporting dual connectivity and mobility.
Protocol (6)
Hybrid Automatic Repeat reQuest
A retransmission mechanism combining forward error correction with ARQ, using soft-combining of failed and retransmitted data.
Medium Access Control
The Layer 2 sublayer responsible for scheduling, HARQ, and multiplexing of logical channels onto transport channels.
Packet Data Convergence Protocol
The Layer 2 sublayer providing header compression, ciphering, integrity protection, and in-order delivery for user and control plane data.
Radio Bearer
A logical connection between the UE and the network providing a defined QoS treatment for either signaling (SRB) or user data (DRB).
Radio Link Control
The Layer 2 sublayer providing segmentation, ARQ retransmission, and in-sequence delivery between MAC and PDCP.
Radio Resource Control
The Layer 3 protocol that manages connection establishment, mobility, and configuration of the radio interface between the UE and the network.