Glossary of Mobile Network Terms

3GPP 3rd Generation Partnership Project

The standards body that produces the technical specifications behind GSM, UMTS, LTE, and 5G NR. Its work is organised into numbered "Releases" (e.g. Rel-15 for 5G NR Phase 1).

AMF Access & Mobility Management Function

A 5G core network function responsible for device authentication, registration, and mobility tracking. Replaces part of 4G's MME in the service-based 5G core.

Carrier Aggregation

A technique introduced in LTE-Advanced that combines multiple separate spectrum blocks into one logical connection, multiplying peak throughput without needing new contiguous spectrum.

CUPS Control and User Plane Separation

An architectural principle, introduced in later LTE releases and central to 5G, that lets the control plane (signalling) and user plane (actual data) be deployed and scaled independently — enabling things like edge computing.

EDGE Enhanced Data rates for GSM Evolution

A 2G radio upgrade (sometimes called 2.75G) that introduced 8PSK modulation, tripling GPRS throughput to a theoretical 384 Kbps.

eNodeB / eNB Evolved Node B

The LTE base station. It absorbed radio-control functions that were previously handled by a separate controller (the RNC in 3G), flattening the radio access network.

EPC Evolved Packet Core

LTE's all-IP core network. It eliminated the circuit-switched voice domain entirely — even voice calls (VoLTE) run as data over the EPC.

GGSN Gateway GPRS Support Node

The 3G-era network element that allocated IP addresses and acted as the gateway to the public internet, the rough equivalent of 4G's PGW.

gNodeB / gNB Next Generation Node B

The 5G base station, typically equipped with Massive MIMO antenna arrays for beamforming.

GPRS General Packet Radio Service

The 2.5G upgrade to GSM that introduced always-on packet data, enabling WAP browsing and early mobile email alongside voice calls.

HARQ Hybrid Automatic Repeat reQuest

A fast error-correction technique that combines forward error correction with retransmission, letting a device request just the missing part of a corrupted transmission rather than the whole thing again.

HLR Home Location Register

The 2G/3G subscriber database that stores user profiles and permissions. Evolved into the HSS in 4G and the UDM in 5G.

HSPA / HSPA+ High Speed Packet Access

3G radio upgrades (HSDPA for downlink, HSUPA for uplink) that used adaptive modulation and fast retransmission to push theoretical speeds toward 42 Mbps by the end of the 3G era.

HSS Home Subscriber Server

The 4G subscriber database, an evolution of 3G's HLR, storing authentication data and service profiles.

IMS IP Multimedia Subsystem

A framework introduced in 3G for delivering voice and multimedia over IP rather than a traditional circuit-switched network — the technology that made VoLTE possible in 4G.

IMT International Mobile Telecommunications

The ITU-R's classification framework for mobile network generations — e.g. IMT-2000 (3G), IMT-Advanced (4G), IMT-2020 (5G), and the upcoming IMT-2030 (6G).

ISAC Integrated Sensing and Communication

A 6G research concept where base stations simultaneously communicate and sense their physical environment, effectively acting as distributed radar using the same signal used for data.

ITU-R ITU Radiocommunication Sector

The United Nations body that coordinates global radio spectrum and defines the IMT requirements each mobile generation must meet to carry that generation's name.

Latency

The round-trip time for a signal to travel from device to network and back. Distinct from bandwidth — a high-bandwidth connection can still have high latency, which is why video calls or cloud gaming can lag even on a fast connection.

LTE Long Term Evolution

The 4G radio standard. "LTE-Advanced" refers to later releases that added carrier aggregation and other enhancements pushing peak speeds toward 1 Gbps.

Massive MIMO

5G's evolution of MIMO using 64 to 256 antenna elements per base station to form precise, individually steered beams toward each user, dramatically improving spectral efficiency.

MIMO Multiple Input Multiple Output

A technique using multiple antennas at both ends of a radio link to transmit multiple data streams simultaneously over the same spectrum, multiplying throughput.

mMTC massive Machine-Type Communications

One of 5G's three core service families, designed to connect very large numbers of low-power devices per square kilometre — the basis for smart-city sensors and industrial IoT at scale.

mmWave Millimetre Wave

Spectrum in the 24-100 GHz range, opened up by 5G. Offers huge bandwidth for multi-gigabit speeds but has short range and poor building penetration.

MME Mobility Management Entity

The 4G control-plane function that handles authentication, handoff between towers, and paging. Part of the EPC.

MSC Mobile Switching Centre

The 2G/3G core network element that switched voice calls and managed handoffs between cells — the anchor of the circuit-switched domain that 4G later eliminated.

Network Slicing

A 5G capability that partitions one physical network into multiple isolated virtual networks, each with its own performance profile — for example, one slice for consumer broadband and another for ultra-reliable industrial control.

NR New Radio

The official 3GPP name for the 5G radio interface.

NRF Network Repository Function

A 5G core function acting as a service registry — every other network function registers with it and discovers other functions through it, enabling the modular service-based architecture.

OFDMA Orthogonal Frequency Division Multiple Access

The multiple-access scheme used by 4G and 5G. It divides the channel into many narrow, non-interfering subcarriers, allowing efficient multi-user scheduling and strong resistance to interference.

PCF Policy Control Function

The 5G core function that enforces quality-of-service policies and network slicing rules.

PGW PDN Gateway

The 4G network element that allocates IP addresses to devices and acts as the gateway to the public internet.

RNC Radio Network Controller

The 3G element that managed radio resources across multiple base stations (Node Bs) — the rough equivalent of 2G's BSC.

SBA Service-Based Architecture

The architectural model of the 5G core, where each network function (AMF, SMF, UPF, etc.) is an independently deployable, independently scalable microservice communicating over HTTP/2 APIs — replacing the monolithic nodes of the 4G EPC.

SGW Serving Gateway

The 4G element that routes user data traffic and manages handoffs as a device moves between base stations.

SGSN Serving GPRS Support Node

The 2G/3G element responsible for routing packet (data) traffic, as distinct from the circuit-switched voice path.

SIM Subscriber Identity Module

The portable smart card (or, increasingly, eSIM profile) that authenticates a subscriber to the network, introduced with GSM and still fundamentally unchanged in purpose today.

Spectrum

The range of radio frequencies a network operates in. Lower frequencies travel further and penetrate buildings better; higher frequencies (like mmWave or THz) offer more bandwidth but much shorter range.

THz Terahertz

The 0.1-10 THz frequency range targeted by 6G research, offering hundreds of GHz of bandwidth per carrier — orders of magnitude more than mmWave — at the cost of very short range.

UDM Unified Data Management

The 5G subscriber database function, an evolution of 4G's HSS and 2G/3G's HLR.

UPF User Plane Function

The 5G core function that handles actual packet routing and forwarding — the user-plane counterpart to the AMF and SMF's control-plane roles. Can be deployed at the network edge for low-latency applications.

URLLC Ultra-Reliable Low-Latency Communication

One of 5G's three core service families, targeting around 1ms latency and 99.9999% reliability — the basis for use cases like remote robotics and industrial automation.

VoLTE Voice over LTE

Voice calls carried as data packets over the 4G network, rather than over a separate circuit-switched voice channel. Offers better audio quality and faster call setup than legacy voice.

WCDMA Wideband Code Division Multiple Access

The radio interface used by 3G UMTS. Gives each user a unique spreading code rather than a time slot, improving spectral efficiency and capacity over 2G's TDMA.