The availability of sufficient spectrum—those all-important radio frequencies allocated for communication over the airwaves—is critical to the success of 5G. In its April, 2017 white paper, 5G Spectrum Recommendations, 5G Americas takes an in-depth look at global activities underway to identify spectrum suitable for a wide range of 5G applications, with roaming and economies of scale in mind. The organization’s conclusions are summarized here.
5G Americas divides spectrum into three ranges, based on physical characteristics:
- Low-range: up to ~3 GHzVery good propagation aspects; suitable for large area coverage. Limited capacity due to lack of available spectrum and component design considerations.
- Mid-range: ~3-6 GHzSuitable for urban development, with increased capacity.
- High-range: above ~6 GHzLimited coverage, but high capacity potential due to amount of unused spectrum available.
“No single band can meet every 5G requirement,” 5G Americas stresses, recommending that policymakers focus more on lower frequency bands in addition to efforts now underway around spectrum in the 24-86 GHz range.
Further, “policy makers should consider not only frequencies that can be allocated domestically, but also the possibilities provided by such global ‘tuning range’ solutions,’” referring to the concept of addressing regional and global spectrum needs.
Regional Spectrum Initiatives
Since 2015, a variety of organizations and government agencies and have been involved in identifying spectrum for 5G and making decisions around how that spectrum should be allocated. 5G Americas’ paper goes into depth on how different bands are being handled around the world.
Globally, the World Radio Conference (which last met in 2015), reviews and revises the International Telecommunications Union (ITU) treaty for radio spectrum. Its role is to designate mobile allocations for specific bands, and identify bands appropriate for use by the International Mobile Telecommunications (IMT) ITU specification.
In the U.S., the Federal Communications Commission (FCC) has “achieved significant progress toward making spectrum above 24 GHz available for 5G,” the paper notes. Its latest move: in July, 2016, the agency adopted and released a Report and Order and Final Notice of Proposed Rulemaking for availability of spectrum in certain bands above 24 GHz.
In Canada, “The Innovation, Science and Economic Development (ISED) ministry has opened a proceeding to repurpose TV spectrum in the 600 MHz band for mobile wireless use,” 5G Americas said. But, “at present, there is no specific consultation open to assign high-band spectrum for mobile services.”
5G Americas covered Latin American allocations and utilization in a separate report mostly focused on low-band spectrum; key findings from that report included a strong need for spectrum allocation and assignment. “As of April 2017, the region had allocated on average less than 27 percent of the 2015 ITU-recommended amount of spectrum to support mobile networks.”
In Asia last year, regional organization Asia-Pacific Tele-Community “approved a recommendation on frequency arrangement for implementation of IMT in the band 698-806 MHz,” 5G Americas said. “This is now being globally considered.” Twenty-six Region 3 countries have now identified this band (or portions of it) for IMT. Further 5G spectrum activities in Asia are part of the agenda for WRC-19 (planned for Oct-Nov, 2019). “Several countries in the region have started planning on making additional spectrum available for 5G in mid- and high-range bands,” among them China, Korea, and Japan.
In Europe, “studies are ongoing around the spectrum allocations for next generation IMT system (5G)… stemming from decisions made in ITU WRC-15, possibly leading to decisions in WRC-19.”
Spectrum for 5G Use Cases
5G Americas notes three major usage scenarios for 5G, based on Recommendation ITU-R M.2038:
- Enhanced mobile broadband, encompassing human-centric use cases involving multimedia content, services, and data.
- Ultra-reliable and low-latency communications, with stringent throughput, latency, and availability requirements. Examples: wireless control of industrial manufacturing and production processes, remote medical surgery, and distributed automation for smart grid and transportation safety.
- Massive machine-type communications, involving a large number of connected devices transmitting low-volume, non-delay-sensitive data.
Each of these applications “have specific technical requirements that need to be addressed through adequate design of the 5G ratio interface(s) and access to appropriate frequency ranges,” 5G Americas stresses.
Determining the appropriate spectrum frequencies for specific 5G applications involves a variety of factors, including:
- Peak data rate
- Spectral efficiency
- User-experienced data rate
- Device density
- Coverage area
- Deployment environment
- Radio system technical requirements and conditions
“Whether one does very simple, rough estimates of spectrum needs based on key performance indicators (KPIs) such as peak or user experienced data rate, or detailed calculations involving aspects such as link budget and system-level simulations, it should be recognized that for the system to support these KPIs, certain capabilities need to exist in the radio interface irrespective of geography or user demand/device projections,” 5G Americas points out.
Approaches to Identifying Above-24GHz Spectrum Needs for IMT-2020
5G Americas notes that, in preparation for WRC-19, the ITU-R Working Party 5D (WP5D) are performing studies to determine spectrum needs for IMT-2020. Another ITU-R group, Task Group 5/1, will use results from these studies as part of a larger look at bands between 24.25 GHz and 86 GHz.
WP5D’s analysis involves several methodologies:
- Application-based approach, which considers existing and future applications and their throughput requirements, combined with tele-density environments and spectral efficiency capabilities of 5G systems.
- Technical performance-based approach, looks at the amount of spectrum needed to achieve 5G radio interface targets, based on technical performance requirements.
- Country-specific information on existing or planned 5G spectrum allocations for bands above 24 GHz.
The spectrum needs of 5G are “dependent on the methodology and the target numbers used in each methodology,” concluded 5G Americas. “Various applications require different amount of spectrum to be delivered to users/devices,” and “target technical performance requirements have a direct impact on the total amount of spectrum needed.”
Harmonizing 5G Spectrum
Addressing the 5G spectrum harmonization topic, 5G Americas notes that regulators in the Americas region have already created a roadmap for spectrum policy decision, and that globally there is growing consensus around what needs to be done based on analysis of use cases and propagation characteristics.
The paper recommends more attention be paid to all three band ranges, with focus on 600 and 700 MHz for low-range, 3-4 GHz for mid-range, and “broad swaths of millimeter wave spectrum above 6 GHz.”
Regulators should also “facilitate the use of existing IMT bands for 5G usage,” 5G Americas advises. “3GPP Release 15 includes an objective to develop co-channel coexistence between LTE and New Radio. A good example of an existing IMT band that is available for New Radio deployment today is the 2.5 GHz band.”
Getting into the technical nitty-gritty of spectrum harmonization and economies of scale, 5G Americas stresses that “harmonization is not limited to a situation where all regions have identical spectrum allocations. The benefits of harmonization can also be derived from ‘tuning range’ solutions covering adjacent or nearly-adjacent bends in which equipment can be reconfigured to operate over multiple bands.” Making best use of this concept requires flexible licensing for mobile services.
All of this illustrates the very important role spectrum plays in 5G development, and the many inter-related, complex decisions regulators and operators will need to make about this finite resource.
“Spectrum is the lifeblood for mobile, which means it’s also the lifeblood for all of the mobile applications and services upon which nearly every person and business depends,” 5G Americas concluded. “New spectrum is critical for the success of fifth-generation (5G) terrestrial mobile service.”