Understanding the Spectrum Needs for 6G

Introduction

The transition to 6G represents a significant leap in telecommunications, promising unprecedented advancements in connectivity, speed, and integration of new technologies. As we stand on the cusp of this new era, understanding the spectrum requirements for 6G is crucial to ensure its successful deployment and operation. The recent report by the Next G Alliance, titled "Spectrum Needs for 6G," provides a detailed assessment of the spectrum requirements necessary to support the diverse applications envisioned for 6G.

Methodology for Spectrum Estimation

The report employs a data-rate-based methodology to estimate the spectrum needs for 6G. This approach is grounded in the data rate requirements of various 6G applications and their corresponding technical performance requirements (TPRs). By analyzing the expected data rates and spectral efficiency, the methodology offers a comprehensive framework for calculating the required spectrum for different deployment scenarios and application groups.

Data Rate Method

A straightforward principle underpins the data rate method: a higher data rate requirement necessitates more spectrum. For instance, an application demanding a 100 Mbits/s user data rate requires ten times more spectrum than one needing only 10 Mbits/s. This relationship is quantified through the formula:

where B is the bandwidth in Hz, n is the number of simultaneously served users, D is the required data rate, and S is the spectral efficiency in bits/s/Hz.

Deployment Scenarios and Use Cases

The report categorizes deployment scenarios into macrocells and microcells, each suitable for different environments such as rural, urban, and indoor settings. The deployment scenarios significantly influence the spectrum needs due to varying propagation characteristics, network densities, and user distribution.

Example Use Case Combinations

6G is expected to support a wide range of use cases categorized into four foundational areas: Living, Experience, Critical, and Societal. These include enhanced mobile broadband (eMBB), ultra-reliable low latency communications (URLLC), and massive machine-type communications (mMTC). Each use case is analyzed based on its environment, such as dense urban, suburban, and rural, to estimate the spectrum requirements accurately.

Numerical Results and Analysis

The report provides detailed numerical results for various frequency bands and deployment scenarios. For instance, the 5th percentile user-perceived throughput values were simulated for three frequency ranges (3.1-3.45 GHz, 7.125-8.5 GHz, and 12.7-13.25 GHz) across different environments (Rural Macrocell, Urban Macrocell, and Urban Microcell). These simulations reveal the spectral efficiencies and help estimate the spectrum needs for each scenario.

Key Findings

• Rural Macrocells: The spectrum needs are generally lower due to the wider area coverage and fewer users. For instance, the spectrum requirement for smart cities in the 3.1-3.45 GHz band is estimated at 92 MHz.
• Urban Macrocells and Microcells: Higher data rates and user densities in urban settings demand significantly more spectrum. In the 7.125-8.5 GHz band, the spectrum need for extended reality (XR) applications in an urban microcell scenario is estimated at 1,019 MHz.
• High-Frequency Bands: The higher the frequency, the more spectrum is required to maintain performance levels due to increased path loss and reduced coverage. For example, in the 12.7-13.25 GHz band, the spectrum requirement for network-enabled robotics in an urban microcell is 1,281 MHz.

Challenges and Future Considerations

The report acknowledges several challenges and limitations. Many assumptions are based on current 5G technologies due to the lack of detailed 6G specifications. Additionally, real-world variations, regulatory constraints, and the need for new methodologies to address latency and reliability requirements are significant considerations for future studies.

Conclusion

The "Spectrum Needs for 6G" report by the Next G Alliance offers a comprehensive framework for understanding and estimating the spectrum requirements for 6G. By considering various deployment scenarios, application groups, and technical performance requirements, the report lays the groundwork for data-driven policy and regulatory decisions. As 6G technology continues to evolve, ongoing research and adaptation of these methodologies will be essential to meet the growing demands of future wireless applications.