# 5G NR

5G NR (5G New Radio) is a radio access technology (RAT) developed by the 3rd Generation Partnership Project (3GPP) for the 5G (fifth generation) mobile network. It was designed to be the global standard for the air interface of 5G networks. It is based on orthogonal frequency-division multiplexing (OFDM), as is the 4G (fourth generation) long-term evolution (LTE) standard.
The 3GPP specification 38 series provides the technical details behind 5G NR, the successor of LTE.
The study of 5G NR within 3GPP started in 2015, and the first specification was made available by the end of 2017. While the 3GPP standardization process was ongoing, the industry had already begun efforts to implement infrastructure compliant with the draft standard, with the first large-scale commercial launch of 5G NR having occurred in the end of 2018. Since 2019, many operators have deployed 5G NR networks and handset manufacturers have developed 5G NR enabled handsets.

## Frequency bands

5G NR uses frequency bands in two broad frequency ranges:
* Frequency Range 1 (FR1), for bands within 410 MHz – 7,125 MHz
* Frequency Range 2 (FR2), for bands within 24,250 MHz – 71,000 MHz

## gNodeB

gNodeB or gNb (Next Generation Node B) means a 5G base station. It transmits radio data to and receives radio data from user equipment. Its coverage area is called a cell. The gNodeB may be a tower.
A "Non-Standalone" (NSA) gNodeB is built on an existing LTE (4G) base station (eNodeB or eNB).

## Network deployments

Ooredoo was the first carrier to launch a commercial 5G NR network, in May 2018 in Qatar. Other carriers around the world have been following suit.

## Development

In 2018, 3GPP published Release 15, which includes what is described as "Phase 1" Pavilash standardization for 5G NR. The timeline for Release 16, which will be "5G phase 2", follows a freeze date of March 2020 and a completion date of June 2020, Release 17 was originally scheduled for delivery in September 2021. but, because of the COVID-19 pandemic, it was rescheduled for June 2022.
Release 18 work has started in 3GPP. Rel.18 is referred to as "NR Advanced" signifying another milestone in wireless communication systems. NR Advanced will include features such as eXtended Reality (XR), AI/ML studies, and Mobility enhancements. Mobility is in the core of 3GPP technology and has so far been handled on Layer 3 (RRC), now, in Rel-18 the work on mobility is to introduce lower layer triggered mobility.

## Deployment modes

Initial 5G NR launches will depend on existing LTE infrastructure in non-standalone (NSA) mode, before maturation of the standalone (SA) mode with the 5G core network. Additionally, the spectrum can be dynamically shared between LTE and 5G NR.

### Dynamic spectrum sharing

To make better use of existing assets, carriers may opt to dynamically share it between LTE and 5G NR. The spectrum is multiplexed over time between both generations of mobile networks, while still using the LTE network for control functions, depending on user demand. Dynamic spectrum sharing (DSS) may be deployed on existing LTE equipment as long as it is compatible with 5G NR. Only the 5G NR terminal needs to be compatible with DSS.

### Non-standalone mode

The non-standalone (NSA) mode of 5G NR refers to an option of 5G NR deployment that depends on the control plane of an existing LTE network for control functions, while 5G NR is exclusively focused on the user plane. This is reported to speed up 5G adoption, however some operators and vendors have criticized prioritizing the introduction of 5G NR NSA on the grounds that it could hinder the implementation of the standalone mode of the network. It uses the same core network as a 4G network, but with upgraded radio equipment.

### Standalone mode

The standalone (SA) mode of 5G NR refers to using 5G cells for both signalling and information transfer. It includes the new 5G Packet Core architecture instead of relying on the 4G Evolved Packet Core, to allow the deployment of 5G without the LTE network. It is expected to have lower cost, better efficiency, and to assist development of new use cases. However, initial deployment might see slower speed than existing network due to the allocation of spectrum. It uses a new core network dedicated to 5G.

## Numerology (sub-carrier spacing)

5G NR supports seven subcarrier spacings:
| Sub-Carrier Spacing (kHz) | Slot duration (ms) | Frequency Bands | Notes |
| 15 | 1 | FR1 | Same as LTE |
| 30 | 0.5 | FR1 | |
| 60 | 0.25 | FR1 and FR2 | Both normal cyclic prefix (CP) and extended CP may be used with 60 kHz subcarrier spacing |
| 120 | 0.125 | FR2 | |
| 240 | 0.0625 | FR2 | This is only possible for search and measurement purposes, using the Synchronization Signal Block (SSB) |
| 480 | 0.03125 | FR2 | |
| 960 | 0.01565 | FR2 | |
The length of the cyclic prefix is inversely proportional to the subcarrier spacing. It is 4.7 μs with 15 kHz, and 4.7 / 16 = 0.29 μs for 240 kHz subcarrier spacing. Additionally, higher subcarrier spacings allow for reduced latency and increased support for high-frequency bands, essential for the ultra-reliable low-latency communications (URLLC) and enhanced mobile broadband (eMBB) applications in 5G.

## NR-Light / RedCap

In 5G NR Release 17, the 3GPP introduced NR-Light for reduced capabilities (RedCap) devices. NR-Light, also known as RedCap, is designed to support a wide range of new and emerging use cases that require lower complexity and reduced power consumption compared to traditional 5G NR devices.
NR-Light targets devices in the mid-tier performance category, striking a balance between the high-performance capabilities of standard 5G NR devices and the ultra-low complexity of LTE-M and NB-IoT devices. This makes it ideal for applications such as:
* Wearables: Including smartwatches, fitness trackers, and health monitoring devices that benefit from lower power consumption and extended battery life.
* Industrial Sensors: Devices in smart factories and industrial automation that require reliable connectivity with reduced complexity.
* Smart Home Devices: Home automation products, including security cameras and smart appliances, that need efficient and cost-effective connectivity.
Key features of NR-Light include:
* Reduced Bandwidth: NR-Light supports narrower bandwidths, reducing the overall complexity and power requirements of the device.
* Simplified Antenna Configurations: Utilizing fewer antennas compared to standard 5G NR devices, which helps in lowering the cost and power consumption.
* Lower Data Rates: Optimized for applications that do not require high data throughput, ensuring efficient use of network resources.
* Extended Battery Life: With optimizations aimed at reducing power consumption, NR-Light devices can achieve significantly longer battery life, which is crucial for wearables and sensors.
NR-Light enhances the 5G ecosystem by providing a scalable solution that caters to the needs of devices with varying performance requirements, expanding the potential applications and fostering the growth of IoT and other connected technologies.