The key engineering, legal and policy issues
5G will be able to use all the existing 4G bands like 900 MHz, 1800 MHz, 2.6 GHz and 3.5 GHz but the term “5G spectrum” is commonly used to describe frequencies far higher than those that are currently used. These are generally called the mmWave bands, such as 24 GHz, 28 GHz and 40 GHz.
One of the great achievements of 5G is opening up these higher frequencies previously thought unsuitable for mobile communications. It allows much faster data rates and better responsiveness – theoretically speeds up to 1 Gbps and a latency of 1 millisecond.
Harmonising spectrum enables economies of scale and facilitates cross-border coordination and roaming for end users. Thus, countries and industry stakeholders around the world are trying to agree on a series of bands suitable for 5G, in a bid to create a 5G global economy.
The lower bands are likely to deliver speeds marginally higher than 4G networks, but are needed for wide area coverage.
With slight differences between the three ITU regions (Europe & Africa, Americas, and Asia), 5G spectrum can be divided into two ranges: sub 6 GHz and above 6 GHz.
Communication service providers, however, will need to balance and combine both ranges for optimal coverage, capacity and quality of service.
5G spectrum: sub & above 6 GHz
Sub 6 GHz spectrum, with a spread of 450 MHz to 6,000 MHz, promises to offer both coverage and capacity. Within this range, the lower bands (under one gigahertz) are likely to be used for wide-area and indoor coverage, as well as Internet of Things (IoT).
The lower bands are likely to deliver speeds marginally higher than the current 4G networks, but are needed for wide area coverage.
Mid-band frequencies (2000 MHz to 6000 MHz) offer a compromise between the broad coverage enabled by lower frequencies and the higher capacity supplied by higher bands. Here, the C-band (3300-4200 and 4400-5000 MHz) has emerged as prime frequency.
In line with allocation plans from many countries, the 3300-3800 MHz band will be the primary 5G band with greatest potential for global harmonisation.
26 GHz is one of the most widely-supported 5G candidate bands and has been already harmonised within the EU
From an economical point of view, this band has many benefits because it allows the deployment of 5G antennas on existing macro-cellular or small-cell grids without requiring new cell sites.
Above 6 GHz the current focus is on mmWave between 24 GHz to 86 GHz. (Technically speaking mmWave is above 30 GHz but it has become a convenient shorthand!)
Typically, these mmWave bands are seen as 5G spectrum: larger the frequencies, and larger bandwidths giving the ability to support extremely high data rates required for ultra high speed broadband – know as eMBB – and use cases like manufacturing or virtual reality.
The major drawback of mmWave spectrum is very small coverage areas and poor building penetration. Propagation for these frequencies often requires line-of-sight (LOS) conditions between the base station and device.
However, many researchers now argue that these challenges can be overcome by new technologies, such as beamforming and massive MIMO.
The World Radiocommunication Conference 2015 (WRC-15) paved the way for the future development of IMT on higher frequency bands by identifying several frequencies for study within the 24.25-86 GHz range. After four years of studies, the ITU World Radiocommunication Conference (WRC-19) will be tasked later this year with establishing international agreement on 5G bands above 24 GHz.
26 GHz vs 28 GHz
In the mmWave range, 26 GHz and 28 GHz have emerged as two of the most relevant bands. The latter (27.5-29.5 GHz) is not included in the WRC-19 Agenda Item 1.13, but the global marketplace is driving the need for additional 5G spectrum.
Countries like USA, South Korea, Japan and Canada are heavily backing this band for 5G services. The 28 GHz band has also seen its first commercial rollouts, with Verizon using this frequency for Fixed Wireless Access (FWA).
Meanwhile, 26 GHz ( 24.25-27.5 GHz) is one of the most widely-supported 5G candidate bands under discussion at WRC-19 and has been already harmonised within the EU, which means that European countries must put it to effective use by the end of March 2020.
Despite this support, a major debate is taking shape for WRC-19 over concerns that mobile use of the popular 26 GHz band for 5G could cause harmful interference to earth exploration and radio astronomy services in 23.6-24 GHz.
In general, support for bands decreases as the frequencies increase
Delegates will have to decide at WRC-19 on the technical conditions of the 26 GHz. If they adopt a lenient approach, satellites used by the World Meteorological Organisation (WMO) and the body representing European space agencies (ESA) could be affected.
On the other hand, if regulators opt for more stringent conditions, 5G rollouts could be curbed. A number of stakeholders have been raising concerns about the difficulties of manufacturing chips that can operate on 26.5 GHz frequencies.
Reaching consensus on the protection conditions could be difficult. In this research note, we explain how the protection of passive services could affect the commercial prospects for 26 GHz and how this could affect operators’ decision-making as they choose between this band and 28 GHz.
Other 5G frequency bands
Of the 11 possible bands between 24-86 GHz, 26 GHz starts with a clear advantage whilst 32 GHz is the least favourite to become a 5G candidate band. There was reasonable support for 32 GHz, but this fell away in autumn 2018 when Europe and the relevant ITU study group withdrew its backing.
Support for higher bands –71-76 GHz and 81-86 GHz– is fairly limited
Three bands around 40 GHz (37-43.5 GHz), however, have as much support as 26 GHz. Different regions support different sections of the 40 GHz range but the idea is that WRC-19 would agree on a tuning range approach so it would allow adjacent bands to be supported by the same equipment.
That approach is particularly relevant in 40.5 -43.5 GHz due to complementary developments in other regions in adjacent bands. That makes approval as 5G candidate bands at WRC-19 likely.
In general, support for identification of bands for IMT decreases as the frequencies increase. The 66-71 GHz range has a reasonable chance of an IMT identification as long as there is also access for other technologies, including unlicensed services.
Support for higher bands –71-76 GHz and 81-86 GHz– is fairly limited. Only China and US regulator the FCC are pushing to get an IMT identification in those bands.
Overall, WRC processes are highly unpredictable but PolicyTracker’s guide can help you identify areas of consensus and disagreement in some of the items being discussed at the forthcoming World Radio Conference.
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