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.
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.
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 FUL,low – FUL,high |
Downlink (DL) operating band 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. |
|||
NR operating bands in FR2
(Source: 3GPP TS 38.104 Release 17
|
NR operating band |
Uplink (UL) and Downlink (DL) operating band 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 |