5G -

5G Spectrum

Background

5G is set to change the picture significantly in terms of spectrum allocation and use, and in this article, we aim to provide more clarity in terms of the many issues related to the licensing, standardisation / harmonisation, and use of spectrum as we head towards the 5G era.

Spectrum is highly sought after, primarily because it allows an operator to increase capacity on the network efficiently. The additional spectrum can be added to existing base stations which reduces the number of new base stations needed. This makes spectrum highly valuable, hence regulators will charge a fee for licensed spectrum. The cost of spectrum varies, but can be quite substantial depending on the specific frequencies being licensed.

An auction mechanism is often used in order to establish the value of the spectrum. Not only does this bring in revenue for the regulator/government, but through market forces, pretty much ensures that the spectrum will be used appropriately and as intended. Significant portions of lower frequency spectrum will generally attract higher fees than the same amount of higher frequency spectrum because of the better coverage it offers.

5G Spectrum – Big Picture

With the introduction of 5G, a much greater range of frequency spectrum can be made available to the industry. As well as the more traditional cellular frequencies (generally 450MHz to 2600MHz), spectrum between ~ 3 to 7 GHz, and in the much higher mmWave bands (initially above 24.25 GHz) can be made available. The radio propagation at these higher frequencies mean that spectrum allocation can be much more flexible (due to the isolated nature of the cell coverage and minimised interference), and unlicensed, shared, or local bands are more feasible. The way in which 5G works with 4G also introduces more flexibility - so in short 5G is set to change the picture significantly in terms of spectrum allocation. The figure below illustrates the general principle.

5G Spectrum

3GPP Standard Frequency Bands

Getting specific in terms of what may actually be licensed in any particular country, in the first 3GPP Releases of 5G (Releases 15-17), the 5G New Radio has been specified to operate in two frequency ranges.

  • Frequency range 1 (FR1) is between 410 and 7125 MHz, so it encompasses and extends the frequency range of LTE.
  • Frequency range 2 (FR2) encompasses millimetre waves, initially between 24250 and 52600 MHz.

3GPP has defined the two frequency ranges (FR) because the requirements and test conditions of the 5G analogue radio in FR1 and FR2 are somewhat different. As shown in the table below this article (Source: 3GPP TS 38.104 Release 17), bands within each range have been specified that support the 5G New Radio, and for each band, the mode of operation is defined as either FDD (Frequency Division Duplex, where there are separate uplink and downlink frequencies), or TDD (Time Division Duplex, where the same frequencies are used for both uplink and downlink). Each band is numbered, with the “n” prefix (for New Radio).

FR1 incorporates some of the bands previously used for LTE, as well as some new bands. With a few significant exceptions, below 3000 MHz, bands are mainly specified to use Frequency Division Duplex (FDD) mode, and bands above 3000 MHz are specified to use Time Division Duplex (TDD) mode. FR2 only supports TDD, and uses band numbers from n257 onwards.

Uplink and Downlink Optimisation

TDD has significant efficiency advantages over FDD at higher frequencies, where advanced antenna schemes are used. At these higher frequencies, interference is less significant, which negates some of the advantages of FDD at lower frequencies (related to interference control) – hence the move to TDD as we adopt those higher parts of the spectrum for cellular communications. However, there are also significant legacy bands that were allocated for previous generations, or for unlicensed use – and these massively complicate the picture. Essentially, this is why we have a very long list of bands in FR1, and a very short list in FR2, which is newly allocated with the introduction of 5G (without the complication of legacy bands).

In the tables, SDL stands for Supplementary Downlink. This is a feature inherited from LTE, in which a secondary cell used for Carrier Aggregation can be downlink-only. Similarly, SUL stands for Supplementary Uplink. This is a new 5G feature, in which the UE is configured with two uplink carriers (transmitting on one at a time – as directed by the base station), which both correspond to a single downlink of the same cell. The supplementary uplink is usually on a lower frequency than the normal uplink, and improves the uplink coverage for mobiles that are close to the cell edge.

Which Bands are to be Licensed?

As part of their overall spectrum planning, different regulators can choose (in theory) to license any of the 3GPP standardised bands. However, cost-effective deployment of 5G in any particular market depends on wider industry support for specific options. In this regard, the picture is becoming clearer.

A good example is that Bands n28 (703 to 748 UL, 758 to 803 DL), n78 (3300 to 3800) and n258 (24250 to 27500) are of particular importance to 5G operators in Europe. These are the low, mid and mmWave bands harmonised by CEPT (The European Conference of Postal and Telecommunications Administrations). This approach to 5G spectrum allocation provides much-needed flexibility for the operators, and the wider emerging ecosystem. It ensures that once licensing of the bands has been achieved, all key existing or new use case requirements can be efficiently satisfied, at least in terms of the spectrum. This includes coverage, capacity, latency, small cell deployment, support for (wider area) IoT, or 5G in unlicensed / shared bands (amongst many other considerations). Many other countries are adopting similar approaches to licensing.

Other important bands include n1, n3, n7, n8, n20 and n38, which have been inherited from GSM, WCDMA and LTE. Over time, and once a sufficient number of handsets of the right type are in the various different markets (at different times across the globe), and if allowed by the regulators, these bands should see a shift towards 4G and 5G in order to maximise network efficiency. The move away from GSM/GPRS bands (still extensively used for Machine Type Communications (MTC) in many networks) may take a little longer – for reasons related to radio performance.

Spectrum for 4G vs 5G

The 4G and 5G radio interfaces share the same underlying technology and are able to work together seamlessly to provide the overall connectivity within the network. Devices are specified to use a technique called Dual Connectivity to work both types of interfaces simultaneously – allowing a device to operate seamlessly in a combined 4G/5G network (as well as interworking with previous generations).

Operators, sooner or later, and once 5G uptake accelerates, may want to migrate even 4G spectrum to 5G. This can be achieved very efficiently through a feature called Dynamic Spectrum Sharing (see below). This feature allows spectrum within the same band to be dynamically allocated, or shared, between 4G and 5G. Hence, over time, as more 5G capable handsets or devices are sold or provisioned, the network will allocate more resources to 5G than 4G.

Dynamic Spectrum Sharing

Conclusion

Overall, spectrum use for 5G is highly complex, with many considerations – some technical, others regulatory, and many associated with diverse use cases and deployment options. In addition, markets have very different positions in terms of legacy spectrum licensing, and of course, are on different trajectories in terms of the competitive 5G environment (not least in terms of time-lines, number of communications service providers, and government involvement). A clear view of the issues related to spectrum use with 5G will give telecoms organisations an advantage in their strategic decision making. We hope this short article has helped to clarify the picture!

NR operating bands in FR1
(Source: 3GPP TS 38.104 Release 17)

NR operating band

Uplink (UL) operating band
BS receive / UE transmit

FUL,low   –  FUL,high

Downlink (DL) operating band
BS transmit / UE receive

FDL,low   –  FDL,high

Duplex mode

n1

1920 MHz – 1980 MHz

2110 MHz – 2170 MHz

FDD

n2

1850 MHz – 1910 MHz

1930 MHz – 1990 MHz

FDD

n3

1710 MHz – 1785 MHz

1805 MHz – 1880 MHz

FDD

n5

824 MHz – 849 MHz

869 MHz – 894 MHz

FDD

n7

2500 MHz – 2570 MHz

2620 MHz – 2690 MHz

FDD

n8

880 MHz – 915 MHz

925 MHz – 960 MHz

FDD

n12

699 MHz – 716 MHz

729 MHz – 746 MHz

FDD

n13

777 MHz – 787 MHz

746 MHz – 756 MHz

FDD

n14

788 MHz – 798 MHz

758 MHz – 768 MHz

FDD

n18

815 MHz – 830 MHz

860 MHz – 875 MHz

FDD

n20

832 MHz – 862 MHz

791 MHz – 821 MHz

FDD

n247

1626.5 MHz – 1660.5 MHz

1525 MHz – 1559 MHz

FDD

n25

1850 MHz – 1915 MHz

1930 MHz – 1995 MHz

FDD

n26

814 MHz – 849 MHz

859 MHz – 894 MHz

FDD

n28

703 MHz – 748 MHz

758 MHz – 803 MHz

FDD

n29

N/A

717 MHz – 728 MHz

SDL

n30

2305 MHz – 2315 MHz

2350 MHz – 2360 MHz

FDD

n34

2010 MHz – 2025 MHz

2010 MHz – 2025 MHz

TDD

n38

2570 MHz – 2620 MHz

2570 MHz – 2620 MHz

TDD

n39

1880 MHz – 1920 MHz

1880 MHz – 1920 MHz

TDD

n40

2300 MHz – 2400 MHz

2300 MHz – 2400 MHz

TDD

n41

2496 MHz – 2690 MHz

2496 MHz – 2690 MHz

TDD

n46

5150 MHz – 5925 MHz

5150 MHz – 5925 MHz

TDD3

n48

3550 MHz – 3700 MHz

3550 MHz – 3700 MHz

TDD

n50

1432 MHz – 1517 MHz

1432 MHz – 1517 MHz

TDD

n51

1427 MHz – 1432 MHz

1427 MHz – 1432 MHz

TDD

n53

2483.5 MHz – 2495 MHz

2483.5 MHz – 2495 MHz

TDD

n65

1920 MHz – 2010 MHz

2110 MHz – 2200 MHz

FDD

n66

1710 MHz – 1780 MHz

2110 MHz – 2200 MHz

FDD

n67

N/A

738 MHz – 758 MHz

SDL

n70

1695 MHz – 1710 MHz

1995 MHz – 2020 MHz

FDD

n71

663 MHz – 698 MHz

617 MHz – 652 MHz

FDD

n74

1427 MHz – 1470 MHz

1475 MHz – 1518 MHz

FDD

n75

N/A

1432 MHz – 1517 MHz

SDL

n76

N/A

1427 MHz – 1432 MHz

SDL

n77

3300 MHz – 4200 MHz

3300 MHz – 4200 MHz

TDD

n78

3300 MHz – 3800 MHz

3300 MHz – 3800 MHz

TDD

n79

4400 MHz – 5000 MHz

4400 MHz – 5000 MHz

TDD

n80

1710 MHz – 1785 MHz

N/A

SUL

n81

880 MHz – 915 MHz

N/A

SUL

n82

832 MHz – 862 MHz

N/A

SUL

n83

703 MHz – 748 MHz

N/A

SUL

n84

1920 MHz – 1980 MHz

N/A

SUL

n85

698 MHz – 716 MHz

728 MHz – 746 MHz

FDD

n86

1710 MHz – 1780 MHz

N/A

SUL

n89

824 MHz – 849 MHz

N/A

SUL

n90

2496 MHz – 2690 MHz

2496 MHz – 2690 MHz

TDD

n91

832 MHz – 862 MHz

1427 MHz – 1432 MHz

FDD2

n92

832 MHz – 862 MHz

1432 MHz – 1517 MHz

FDD2

n93

880 MHz – 915 MHz

1427 MHz – 1432 MHz

FDD2

n94

880 MHz – 915 MHz

1432 MHz – 1517 MHz

FDD2

n951

2010 MHz – 2025 MHz

N/A

SUL

n964

5925 MHz – 7125 MHz

5925 MHz – 7125 MHz

TDD3

n975

2300 MHz – 2400 MHz

N/A

SUL

n985

1880 MHz – 1920 MHz

N/A

SUL

n996

1626.5 MHz -1660.5 MHz

N/A

SUL

NOTE 1: This band is applicable in China only.
NOTE 2: Variable duplex operation does not enable dynamic variable duplex configuration by the network, and is used such that DL and UL frequency ranges are supported independently in any valid frequency range for the band.
NOTE 3 This band is restricted to operation with shared spectrum channel access as defined in [20].
NOTE 4: This band is applicable in the USA only subject to FCC Report and Order [FCC 20-51].
NOTE 5: The requirements for this band are applicable only where no other NR or E-UTRA TDD operating band(s) are used within the frequency range of this band in the same geographical area. For scenarios where other NR or E-UTRA TDD operating band(s) are used within the frequency range of this band in the same geographical area, special co-existence requirements may apply that are not covered by the 3GPP specifications.
NOTE 6: UL operation is restricted to 1627.5 – 1637.5 MHz and 1646.5 – 1656.5 MHz per FCC Order DA 20-48.
NOTE 7: DL operation is restricted to 1526-1536 MHz frequency range. UL operation is restricted to 1627.5 – 1637.5 MHz and 1646.5 – 1656.5 MHz per FCC Order DA 20-48.

 

NR operating bands in FR2
(Source: 3GPP TS 38.104 Release 17

NR operating band

Uplink (UL) and Downlink (DL) operating band
BS transmit/receive
UE transmit/receive

FUL,low   –  FUL,high

FDL,low   –  FDL,high

Duplex mode

n257

26500 MHz – 29500 MHz

TDD

n258

24250 MHz – 27500 MHz

TDD

n259

39500 MHz – 43500 MHz

TDD

n260

37000 MHz – 40000 MHz

TDD

n261

27500 MHz – 28350 MHz

TDD

n262

47200 MHz – 48200 MHz

TDD

 

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