# 5G Spectrum

## Summary


5G spectrum spans a wide range from 410 MHz to 52600 MHz. The high end of the spectrum falls in the millimeter range, which is novel to 5G. With its high bandwidth, it enables high-throughput, ultra-low-latency applications.

Not all frequencies in this range are used by 5G. 5G defines a number of operating bands within which 5G services can be offered. These frequencies have been selected based on suitability and availability. The bands should not overlap with non-5G systems such as military, maritime, and satellite communication systems.  

Both licensed and unlicensed spectrum can be used in 5G. 5G can share 4G's licensed spectrum and Wi-Fi's unlicensed spectrum.

Successful worldwide deployment of 5G requires that countries agree on a common set of bands. Good agreement was reached in November 2019 at WRC-19.

## Discussion

### Which are the main spectrum bands allocated for 5G?

The standard defines two **frequency ranges**: FR1 (410-7125 MHz) and FR2 (24250-52600 MHz). 

NR **operating bands** are defined within each range. While FR1 bands are either in FDD, TDD, SDL or SUL, FR2 bands can operate only in TDD. Supplementary Downlink (SDL) and Supplementary Uplink (SUL) are modes that allow only downlink or uplink in those bands. SDL and SUL are meant to provide additional capacity. 

In practice, industry looks at 5G spectrum in terms of low-band (600-700 kHz), mid-band (3-5 GHz) and high-band (26-100 GHz).  Others simply refer to FR1 as "sub-6 GHz" band and FR2 as mmWave band. 

Specifically, **n78 (3300-3800 MHz) TDD band** is globally harmonized and will be the primary 5G band. It's a subset of n77 (3300-4200 MHz). 


### How are the 5G bands and frequencies named or numbered?

Operating bands are named with prefix "n" to signify New Radio. In Release 16, FR1 has 49 different bands from n1 to n96. FR2 has 5 bands n257-n261. 

In each band, the standard gives identifying numbers to frequencies. There are two sets of numbers:

    + **NR Absolute Radio Frequency Channel Number (NR-ARFCN)**: Used in signalling to identify reference frequencies. *Channel raster* is a subset of reference frequencies used to identify RF channel position in uplink and downlink.
    + **Global Synchronization Channel Number (GSCN)**: Used for synchronization. *Synchronization raster* is specified by GSCN and indicates frequency positions of the Synchronization Signal Block (SSB). GSCN has a coarser granularity than NR-ARFCN and therefore should enable a UE do a faster cell search.

### Could you describe the 5G NR channel bandwidth?

Each operating band may have one or more **BS channel bandwidths**. Each BS channel bandwidth supports a single RF carrier in UL or DL. Multiple **UE channel bandwidths** may be supported within the same BS channel bandwidth. 

One or more resource blocks (RBs) form a UE channel bandwidth or transmission bandwidth. Each RB has 12 subcarriers. Unlike 4G where sub-carrier spacing (SCS) is fixed to 15 kHz, 5G NR allows **flexible SCS** of 15, 30 or 60 kHz (FR1); and 60 or 120 kHz (FR2). 

Guardbands exist at the edges of the BS channel bandwidth. Standard specifies the minimum guardband for each valid combination of SCS and BS channel bandwidth. 

BS channel bandwidth can take values 5, 10, 15, 20, 25, 30, 40, 50, 60, 70, 80, 90 and 100 MHz (FR1); and 50, 100, 200 and 400 MHz (FR2). However, not all values as valid for all bands. For example, 100MHz in FR1 is valid only for bands n40, n41, n77, n78, n79 and n90. 


### Could you compare FR1 and FR2 operating bands?

FR1 defines bands in the sub-6 GHz spectrum (although 7125 MHz is the maximum) and FR2 defines bands in the mmWave spectrum. Because of the higher carrier frequencies in FR2, it has a higher maximum bandwidth. Bandwidths include 5-100 MHz (FR1) and 50/100/200/400 MHz (FR2). Correspondingly, valid subcarrier spacing values are also different: 15/30/60 kHz (FR1) and 60/120 kHz (FR2). In FR2, 240 kHz subcarrier spacing is allowed for only SS/PBCH with valid bandwidths 100/200/400 MHz. 

Downlink MIMO differs: 8x8 (FR1) and 2x2 (FR2). FR1 caters for macro cells, high mobility and many users. FR1 bands also experience multipath effects. Higher-order MIMO therefore enable **spatial multiplexing** and Multi-User MIMO (MU-MIMO). On the other hand, FR2 is for small cells, low mobility and a few users. Multipath effects are less pronounced than in FR1. Lower-order MIMO therefore enables **beamforming**. These differences imply that spectral efficiency is higher in FR1 than in FR2. 


### What's the suitability of low, mid and high-bands for 5G services?

Lower frequencies have better range but offer lower data rates. At mmWave spectrum, we get high data rates but waves can't get through walls, trees or even glass. Thus, there's a tradeoff between coverage and speed. It's therefore good that 5G spans a wide spectrum to suit many different use cases and deployment scenarios. 

Low-band spectrum can offer rural coverage. Strong indoor signals could help connect to IoT devices in smart buildings and underground parking lots. 

High-band spectrum could be ideal for short-range communications in dense urban areas and within buildings. It can cater to many high-value services in retail, healthcare, entertainment, and more. They could involve AR/VR applications. Serving thousands of users in a stadium, critical IoT applications or applications that need ultra low latency are more use cases. 

Mid-band spectrum is a compromise of both low-band and high-band spectra. It could cover large neighbourhoods and even an entire city but probably can't serve rural areas. Smart city services can benefit from it, such as fleet management, transit services and vehicle communications. 


### What are some features that enhance the use of 5G spectrum?

It's possible for 5G to share 4G spectrum. Called **Dynamic Spectrum Sharing (DSS)**, this is an attractive option for operators who don't have licensed 5G spectrum yet. Instead of statically re-farming the spectrum, DSS allows operators to dynamically migrate more spectrum from 4G to 5G as more 5G users come into the system. DSS requires only a software upgrade.  

Supported since LTE Release 10, **Carrier Aggregation (CA)** is enhanced in 5G. Multiple carriers within the same band or across bands can be combined to serve a single UE. CA allows operators to achieve better capacity, throughput and coverage in mid-band and high-band spectra. For example, low band FDD with DSS can be used in uplink for better coverage and a high band TDD in downlink for higher throughput and capacity. 

Supported since LTE Release 12, **Dual Connectivity (DC)** is enhanced in 5G. DC allows a UE to connect to two different cells possibly served by different gNBs. It may be an LTE or 5G cell. Whereas user plane split happens at MAC for CA, it happens at PDCP for DC. It's also possible to combine CA and DC. 


### What's the relevance of unlicensed bands for 5G?

Cellular use of unlicensed spectrum started in LTE. It's variants include LTE Unlicensed (LTE-U), Licensed Assisted Access (LAA) and MulteFire.  

In Release 16, **5G NR-U** allowed the use of unlicensed spectrum. In particular, NR-U supports both license-assisted and standalone use of unlicensed spectrum. It supports 5 GHz unlicensed band used by Wi-Fi and LAA. It also opens up unlicensed spectrum in the 6 GHz band. Unlicensed spectrum in the mmWave band is being studied for Release 17. 

Since licensed spectrum is limited, for very high bandwidth applications, aggregating with unlicensed spectrum is an attractive approach. Shared/unlicensed spectrum can enable local/private networks and Industrial IoT applications. 

With **Anchored NR-U**, operators can employ carrier aggregation with 5G NR or dual connectivity with LTE. In urban hotspots, campuses and malls, this can deliver consistent user experience. With **Standalone NR-U**, operators will find it easier to deploy private networks. 

## Milestones

Nov  
2015

At the World Radiocommunication Conference 2015 (WRC-15), delegates agree on additional spectrum for International Mobile Telecommunications (IMT). This includes **C-band** that later becomes a globally harmonized spectrum for 5G. 

2016

Szydelko and Dryjanski publish an evolution of spectrum from LTE to 5G. Spectrum below 6 GHz and mmWave spectrum are being considered for 5G. For CA, 700 MHz is being considered for SDL. This is standardized in Release 16 (July 2020). 

Mar  
2017

In the US, FCC auctions 600 MHz spectrum currently used by TV stations. This spectrum will be used for LTE and 5G, with the transition expected to take 39 months. In July 2020, it's reported that 99% of the migration is complete. 

Sep  
2019

Ericsson claims the world's first 5G data call using **Dynamic Spectrum Sharing (DSS)** in low band FDD. In February 2020, with vendors Ericsson, Huawei and Qualcomm, Vodafone proves Dynamic Spectrum Sharing (DSS) in the low bands 700 MHz and 800 MHz on a non-standalone device. In June 2020, AT&T deploys DSS. Meanwhile, Nokia has claimed that DSS is nothing new to it. Years ago, it achieved 2G-4G DSS in which low-band GSM spectrum was used to expand LTE service. 

Nov  
2019

At the World Radiocommunication Conference 2019 (WRC-19), delegates meet and agree towards **harmonization of 5G spectrum**. In particular, 24.25-27.5, 37-43.5, 45.5-47, 47.2-48.2 and 66-71 GHz are identified. This translates to 17.25 GHz of spectrum compared to only 1.9 GHz available before this conference. Of this, 14.75 GHz of spectrum has been harmonized worldwide, reaching 85% of global harmonization. The next meeting will be WRC-23 in 2023. 

Jun  
2020

Global mobile Suppliers Association (GSA) reports that 97 operators in 17 countries have public licenses to operate 5G service in mmWave spectrum. Of these, 22 operators are already operational with 24.25–29.5 GHz being the most common band. 

Jul  
2020

3GPP finalizes **Release 16** specifications. This release adds many more bands to FR1. In FR2, n259 (39500-43500 MHz) is added.  This release also adds **NR-U** for operation in unlicensed spectrum. 

Oct  
2020

GSA reports that operators are showing most interest in n77 and n78 (mid-band); n257, n258 and n260 (mmWave); and n28 (low-band). GSA website is also the place to track the latest in 5G spectrum news.

Dec  
2020

In the US, FCC puts up for **auction** 280 MHz of spectrum in the range 3.7-3.98 GHz, known as C-band. A successful bidder will likely purchase 100 MHz of contiguous mid-band spectrum. Compared to mmWave, C-band has better propagation properties, making this an important auction for 5G operators.