Mid-band spectrum: strong basis for 5G in the US

The US economy will benefit from the establishment of an auction pipeline of spectrum in the 3-8 GHz range. However, new spectrum allocations should meet certain criteria to maximize the economic benefit. First, the new spectrum allocations should allow base station power limits suitable for macro coverage throughout the mid-band to ensure efficient use of spectrum for wide area use cases and indoor penetration. Second, large and contiguous spectrum allocations are needed to ensure maximum performance and global competitiveness. We must ensure new allocations do not constrain or limit 5G use case support and accomplishing the achievement of IMT-2020 performance vision.

Spectrum – fueling the growth of the mobile industry
Spectrum has been the fuel for growth of the mobile industry in the past and will continue to be so for the foreseeable future. Mobile network data traffic continues to grow at 30%-40% annually in the US driven by consumer mobile broadband demand and new use cases. In fact, average monthly data usage per smartphone in North America is forecast to grow from 15GB in 2021 to 52GB in 2027 – the highest on the globe (Ericsson Mobility Report). This growth creates capacity demand on the network that requires a pipeline of new spectrum to meet.

In addition, every generation of mobile technology improves network performance (e.g., increased bandwidth, spectral efficiency, lower latency), which also leads to new uses and in turn increased demand for spectrum. As our society transforms, humans and machines will be increasingly connected digitally to each other. Larger amounts of contiguous spectrum in a wide range of frequencies and allowing wide bandwidths, will be required to meet both the capacity and coverage needs for mobile networks.

The industry has demonstrated an ability to continue to use all the bands identified for mobile service across three major ITU-R standardization efforts: IMT-2000, IMT-Advanced, and IMT-2020. These standards defined and extended the International Mobile Telecommunication (IMT) objectives from the 3G era all the way through to the current 5G system. With each mobile generation, bandwidths have gradually increased, as have the range of frequencies required to meet the associated performance criteria.

5G was designed to operate across all frequency bands including extending into the millimeter wave (mmWave) range up to 71 GHz. 5G requires a combination of spectrum in the sub 1GHz, mid-band and mmWave spectrum to achieve its full potential. Spectrum in the mid-band range is necessary to support high capacity and broad coverage at the same time, i.e., covering city areas in a cost-effective manner.

Data demand is driven in many different ways
First is basic smartphone connectivity. This type of data has taken on greater importance as a large number of people are no longer served by wired broadband networks and use mobile phones to connect to the Internet.

This fact has placed connectivity for smartphones at the forefront of consumer demand for enhanced Mobile Broadband (eMBB) and is a major driver of demand for spectrum. Mobile phones are used by people for work, social interaction, commerce and increasingly as a means to connect other device types. While today we are using video demanding applications, in the upcoming years we expect an evolution towards the metaverse (AR/VR).

Second, the 5G standard can address a large variety of deployment conditions and use cases that go beyond traditional public telecommunications use, extending to many critical societal and industrial objectives which require stricter performance around bandwidth, reliability, and latency. Such use cases include connected cars, smart cities, smart manufacturing (including augmented and virtual reality) and many more. Many of these use cases require higher bandwidth and lower latency and are helping to fuel the need for more spectrum.

Third is demand for home internet which can increasingly be met by wireless networks. The density and diversity of devices connected at each home continues to increase, placing higher demand on home broadband connections.

In many areas Fixed Wireless Access (FWA) implementations can provide cost effective solutions that bridge gaps in digital equity and meet the higher demand of home connections. FWA users tend to consume exponentially higher volumes of data as compared to eMBB increasing the demand for spectrum.

The role of mid-band: 5G capacity and enabling diverse use cases
To enable these existing and future use cases, and the societal transformation we anticipate, large swaths of spectrum must be allocated across a diverse range of frequencies ranging from low to high band.

While low bands are the foundation for every network, they do not meet all the service requirements for more advanced use cases, including those that require higher capacity per user or higher density of users. These use cases are better supported by spectrum in the mid-band, especially in urban and densely populated suburban areas. In fact, a report by GSMA and Coleago1 estimate that an average of 2 GHz of spectrum in the mid-band range is necessary in the 2025-2030 timeframe.

To meet this demand, US operators require large contiguous blocks within the 3-8 GHz frequency range. Advancement in technologies like Advanced Antenna Systems (AAS), with state-of-the-art beamforming and MIMO (Multiple Input, Multiple Output) techniques, have proven to greatly enhance user experience in the mid-band, both in the uplink and downlink, while increasing capacity and spectral efficiency of the radio system.

However, technology is not enough to meet traffic demands. To continue to grow 5G capacity and meet end user needs, additional spectrum in the mid-band will be required. In the US, the immediate bands of interest within 3-8 GHz frequency range are the 3.3-4.2 GHz ,4.4-4.9 GHz, and the 7.125-8.5 GHz bands, which are well suited to meet the requirements both from a coverage and capacity perspective. Chairwoman Rosenworcel has noted that the Commission needs “to start planning [for 6G] now to identify spectrum in the 7-15 GHz range that can support faster speeds and wider coverage” (See remarks of Chairwoman Jessica Rosenworcel Mobile World Congress “New Frontier of partnership” Barcelona, Spain. March 1, 2022).

In light of the fragmented nature of the 3.3-4.2 GHz band, the difficulties in the range 4.4-4.9 GHz and the decision to release 6.425-7.125 GHz on an unlicensed basis, the 7.125-8.5 GHz band will be needed for commercial wireless use well before the 6G timeframe. Challenges with federal incumbents in the 7.125-8.5 GHz must be overcome. The 3.3-4.2 GHz and 4.4-4.9 GHz bands are used in a number of global 5G markets, thus offering an immediate harmonized frequency range for infrastructure and devices.

High bands also play a key role in servicing capacity demands and will indeed offload the needs from mid-band spectrum where needed. However, given limited propagation coverage from mmWave frequencies, a pipeline of mid-band to support both capacity and coverage demands is needed to support 5G’s future.

Power levels also matter
It is noteworthy that the FCC has adopted EIRP (Effective Isotropic Radiated Power) limits for public wide area coverage of 1640 W/MHz in urban and 3280 W/MHz in rural areas in both C-band and 3.45-3.55 GHz. These power levels support macro-cell environments by balancing capacity needs with cost-effective deployment and wide-area coverage footprint, including outdoor-to-indoor coverage. To ensure that these bands are used efficiently and provide a balance between coverage and capacity, regulators should allow high power macro use cases across the entire bands (3.3-4.2, 4.4-4.9 GHz and 7.125-8.5 GHz) for commercial use. When spectrum is constrained by lower power limits, this impacts the value of the spectrum. In addition, spectrum with lower power limits cannot effectively be used to deploy macro use cases and so networks would be limited to small cell deployments. Therefore, adequate power levels are required to support wide area use cases.

Needed action
To accelerate wide scale 5G and 5G-Advanced deployments that can support a myriad of use cases throughout the US, new spectrum in the frequency range 3 – 8 GHz is needed that can enable communication service providers to provide the high quality of service that is expected of these networks. Moreover, a spectrum pipeline is needed that considers the longer-term spectrum needs of the country. Identification of spectrum is a long process, and the lack of a spectrum pipeline delays access to spectrum when and where it is needed. As we move towards preliminary discussions on 6G, additional spectrum demands are anticipated where an established spectrum pipeline will be paramount to US wireless leadership.

CT Bureau