5G is the 5th generation mobile network technology, consisting of 5G Core (5GC) for the core network and NR (New Radio) for the radio access. It was standardized starting with Rel-15 (2018), enhanced in Rel-16 (2020), and extended in Rel-17 (2022).
Key Features
5G introduces revolutionary capabilities:
- 5G Core (5GC) - service-based cloud-native core network
- NR (New Radio) - new radio interface with gNB base stations
- Higher frequencies - FR1 (sub-6 GHz) + FR2 (mmWave 24-52 GHz)
- Scalable numerology - flexible subcarrier spacing (15-240 kHz)
- Massive MIMO - up to 256 antenna elements
- Network slicing - virtual networks for different services
- Ultra-low latency - <1ms target for URLLC
📋 Specifications: TS 38.300 (NR Overall), TS 23.501 (5GS Architecture)
5G Use Cases
IMT-2020 Triangle
| Use Case |
Description |
Requirements |
| eMBB |
Enhanced Mobile Broadband |
20 Gbps DL, 10 Gbps UL |
| URLLC |
Ultra-Reliable Low Latency |
<1ms, 99.999% reliability |
| mMTC |
Massive Machine Type Comm |
1M devices/km² |
Application Examples
| Category |
Applications |
| eMBB |
4K/8K video, VR/AR, cloud gaming |
| URLLC |
Industrial automation, remote surgery, autonomous driving |
| mMTC |
Smart cities, agriculture, logistics |
Network Architecture
Deployment Options
Non-Standalone (NSA)
┌─────────────┐
│ EPC (4G) │
└──────┬──────┘
│
┌───┴───┐
│ eNB │←──X2──→┌───────┐
│ (LTE) │ │ gNB │
└───┬───┘ │ (NR) │
│ └───┬───┘
└────────┬───────┘
│
┌──┴──┐
│ UE │
└─────┘
Option 3/3a/3x: LTE anchor + NR for data boost (EN-DC)
Standalone (SA)
┌─────────────┐
│ 5GC (5G) │
└──────┬──────┘
│ N2/N3
┌───┴───┐
│ gNB │
│ (NR) │
└───┬───┘
│
┌──┴──┐
│ UE │
└─────┘
Option 2: Full 5G with 5G Core
See the detailed glossary entry for evolution across releases.
| Component |
Full Name |
Function |
| AMF |
Access and Mobility Management |
MM, authentication |
| SMF |
Session Management Function |
Session management, IP |
| UPF |
User Plane Function |
Data forwarding, QoS |
| UDM |
Unified Data Management |
Subscriber data |
| PCF |
Policy Control Function |
Policies |
| AUSF |
Authentication Server |
Authentication |
| NSSF |
Network Slice Selection |
Slice selection |
| NRF |
Network Repository Function |
Service discovery |
Interfaces
| Interface |
Connection |
Protocol |
| N1 |
UE ↔ AMF |
NAS |
| N2 |
gNB ↔ AMF |
NGAP |
| N3 |
gNB ↔ UPF |
GTP-U |
| N4 |
SMF ↔ UPF |
PFCP |
| Xn |
gNB ↔ gNB |
Xn-AP |
📋 Specifications: TS 23.501 (System Architecture), TS 38.401 (NG-RAN Architecture)
NR Physical Layer
Scalable Numerology
| μ |
SCS (kHz) |
Slot (ms) |
Symbols/slot |
CP |
Use Case |
| 0 |
15 |
1.0 |
14 |
Normal |
Sub-6 GHz |
| 1 |
30 |
0.5 |
14 |
Normal |
Sub-6 GHz |
| 2 |
60 |
0.25 |
14 |
Normal/Ext |
FR1/FR2 |
| 3 |
120 |
0.125 |
14 |
Normal |
mmWave |
| 4 |
240 |
0.0625 |
14 |
Normal |
mmWave sync |
NR vs LTE Comparison
| Feature |
LTE |
NR |
| SCS |
15 kHz fixed |
15-240 kHz |
| Max BW |
20 MHz |
100/400 MHz |
| Slot length |
1 ms |
0.0625-1 ms |
| Mini-slot |
No |
2/4/7 symbols |
| Waveform DL |
OFDM |
OFDM |
| Waveform UL |
SC-FDMA |
OFDM + SC-FDMA |
| Ref signals |
CRS always-on |
DMRS on-demand |
Physical Channels
| Channel |
Direction |
Purpose |
| PBCH |
DL |
Broadcast (MIB) |
| PDCCH |
DL |
Control (DCI) |
| PDSCH |
DL |
Shared data |
| PUCCH |
UL |
Control (UCI) |
| PUSCH |
UL |
Shared data |
| PRACH |
UL |
Random access |
Reference Signals
| Signal |
Purpose |
When |
| DMRS |
Demodulation |
With data |
| CSI-RS |
Channel state |
Periodic/triggered |
| PT-RS |
Phase tracking |
mmWave |
| SRS |
Sounding (UL) |
UL channel estimation |
📋 Specifications: TS 38.211 (Physical Channels), TS 38.212 (Multiplexing)
Frequency Bands
FR1 (Sub-6 GHz)
| Band |
Frequency |
Duplex |
Region |
| n1 |
2100 MHz |
FDD |
Global |
| n3 |
1800 MHz |
FDD |
Global |
| n28 |
700 MHz |
FDD |
APAC/EU |
| n41 |
2.5 GHz |
TDD |
USA/China |
| n77 |
3.3-4.2 GHz |
TDD |
Global (C-band) |
| n78 |
3.3-3.8 GHz |
TDD |
Global (C-band) |
| n79 |
4.4-5.0 GHz |
TDD |
Japan/China |
FR2 (mmWave)
| Band |
Frequency |
Max BW |
Region |
| n257 |
26.5-29.5 GHz |
400 MHz |
Global |
| n258 |
24.25-27.5 GHz |
400 MHz |
Global |
| n260 |
37-40 GHz |
400 MHz |
USA |
| n261 |
27.5-28.35 GHz |
400 MHz |
USA |
Bandwidth
| FR |
Max Channel BW |
Max Aggregated |
| FR1 |
100 MHz |
800 MHz (8 CC) |
| FR2 |
400 MHz |
1.6 GHz (4 CC) |
📋 Specifications: TS 38.101-1 (FR1 RF), TS 38.101-2 (FR2 RF)
Massive MIMO is essential for 5G NR performance. See the detailed glossary entry for evolution across releases.
Massive MIMO in NR
| Configuration |
Antennas |
Typical Use |
| 32T32R |
64 elements |
Urban macro |
| 64T64R |
128 elements |
Dense urban |
| 128T128R |
256 elements |
High capacity |
| Type |
Description |
Use Case |
| Analog |
Single beam, phase shifters |
mmWave |
| Digital |
Multiple beams, baseband |
FR1 |
| Hybrid |
Combined approach |
FR2 |
Beam Management
| Procedure |
Purpose |
| Beam sweeping |
Initial access, find best beam |
| Beam measurement |
UE reports best beam |
| Beam indication |
Network indicates active beam |
| Beam recovery |
Recover from beam failure |
SSB Beams
| FR |
Max SSB Beams |
Period |
| FR1 |
4-8 |
5-160 ms |
| FR2 |
64 |
5-160 ms |
📋 Specifications: TS 38.214 (Physical Layer Procedures)
Network Slicing
Network Slicing enables creating multiple virtual networks on shared infrastructure. See the detailed glossary entry for evolution across releases.
Slice Types (SST)
| SST |
Name |
Use Case |
| 1 |
eMBB |
Broadband |
| 2 |
URLLC |
Low latency |
| 3 |
MIoT |
Massive IoT |
| 4 |
V2X |
Vehicles |
S-NSSAI Components
| Field |
Description |
| SST |
Slice/Service Type (8 bits) |
| SD |
Slice Differentiator (24 bits, optional) |
Slice Architecture
┌─────────────────────────────────────────────┐
│ Physical Network │
├─────────────┬─────────────┬─────────────────┤
│ Slice 1 │ Slice 2 │ Slice 3 │
│ eMBB │ URLLC │ mMTC │
│ │ │ │
│ ┌───────┐ │ ┌───────┐ │ ┌───────────┐ │
│ │ AMF │ │ │ AMF │ │ │ AMF │ │
│ │ SMF │ │ │ SMF │ │ │ SMF │ │
│ │ UPF │ │ │ UPF │ │ │ UPF │ │
│ └───────┘ │ └───────┘ │ └───────────┘ │
└─────────────┴─────────────┴─────────────────┘
📋 Specifications: TS 23.501 §5.15 (Network Slicing), TS 28.531 (Slice Management)
URLLC
Ultra-Reliable Low-Latency Communications (URLLC) - mission-critical services. See the detailed glossary entry for evolution across releases.
Requirements
| Parameter |
URLLC Target |
| User plane latency |
<1 ms |
| Reliability |
99.999% (5 nines) |
| Jitter |
<1 ms |
| Availability |
99.9999% |
URLLC Features (Rel-15/16)
| Feature |
Description |
| Mini-slot |
2/4/7 symbol transmission |
| Grant-free UL |
Configured grant (no SR delay) |
| Preemption |
URLLC preempts eMBB |
| PDCP duplication |
Same packet on multiple paths |
| Multi-TRP |
Transmit from multiple points |
Latency Breakdown
| Component |
Target |
| Processing (UE TX) |
0.2 ms |
| Frame alignment |
0.1 ms |
| TTI |
0.125 ms (μ=3) |
| Processing (gNB) |
0.2 ms |
| Total one-way |
<0.5 ms |
📋 Specifications: TS 38.300 §8.3 (URLLC), TR 38.824 (URLLC Study)
NR-V2X
NR-based Vehicle-to-Everything - Rel-16 evolution of LTE V2X.
NR-V2X vs LTE-V2X
| Feature |
LTE-V2X (Rel-14/15) |
NR-V2X (Rel-16) |
| Latency |
20-100 ms |
3-10 ms |
| Reliability |
90% |
99.99% |
| Data rate |
10s of Mbps |
100s of Mbps |
| Range |
400 m |
1000 m (LOS) |
| Unicast |
No |
Yes |
| Groupcast |
No |
Yes |
NR Sidelink
| Feature |
Description |
| Unicast |
Point-to-point |
| Groupcast |
One-to-many |
| Broadcast |
One-to-all |
| HARQ feedback |
Unicast/groupcast |
Resource Allocation
| Mode |
Description |
| Mode 1 |
Network scheduled |
| Mode 2 |
UE autonomous (sensing) |
📋 Specifications: TS 38.300 §16 (Sidelink), TS 23.287 (5G V2X)
Rel-17 Features
RedCap (Reduced Capability)
| Feature |
NR RedCap |
vs Full NR |
| Max BW |
20 MHz FR1, 100 MHz FR2 |
100/400 MHz |
| Antennas |
1×1 or 1×2 |
2×2 or 4×4 |
| Duplex |
HD-FDD option |
FDD/TDD |
| Target devices |
Wearables, sensors, cameras |
Smartphones |
NTN (Non-Terrestrial Networks)
| Platform |
Altitude |
Latency |
| LEO |
300-1500 km |
5-25 ms |
| MEO |
7000-25000 km |
50-150 ms |
| GEO |
35786 km |
270-300 ms |
| HAPS |
20 km |
<1 ms |
NTN Adaptations:
- Extended HARQ timing
- GNSS-based timing
- Doppler pre-compensation
- Extended TA
Other Rel-17 Features
| Feature |
Description |
| NR positioning |
cm-level accuracy |
| Multi-SIM |
MUSIM support |
| DSS enhancements |
Better LTE/NR sharing |
| 52.6-71 GHz |
Extended FR2 |
| Sidelink relay |
UE-to-Network relay |
📋 Specifications: TS 38.300 (NR Overall), TR 38.811 (NTN Study)
UE Categories
NR doesn't use traditional UE categories like LTE. Instead, capability is defined by:
Capability Parameters
| Parameter |
Range |
| Max layers DL |
1-8 |
| Max layers UL |
1-4 |
| Max modulation |
256QAM/1024QAM |
| Max bandwidth |
100/200/400 MHz |
| CA support |
Band combinations |
Device Classes
| Class |
Peak DL |
Use Case |
| High-end smartphone |
>2 Gbps |
eMBB |
| Mid-range |
~1 Gbps |
General |
| RedCap |
~150 Mbps |
Wearables/IoT |
| Industrial |
Variable |
URLLC focus |
📋 Specifications: TS 38.306 (UE Radio Access Capabilities)
Timeline
- 2015 - 5G NR study started
- 2017 - NSA NR specification (Rel-15 early drop)
- 2018 - Rel-15 frozen (full NSA + SA)
- 2019 - First commercial 5G networks (Korea, USA)
- 2020 - Rel-16 frozen (URLLC, V2X, IAB)
- 2021 - 5G SA deployments expand
- 2022 - Rel-17 frozen (RedCap, NTN)