NETWORK CAPACITY TRENDS

There are three ways to address a mobile operator’s needs for increasing network capacity:

  • Spectrum
  • MIMO layers
  • Sectorization.

Spectrum

3GPP n96/n102/n104

Figure 7 3GPP 6 to 7 GHz spectrum bands. Source: EJL Wireless Research LLC ©2024.

Spectrum remains the most important resource for mobile operators developing capacity evolution strategies. However, asking what spectrum assets are still usable and wideband in the 3GPP frequency range 1 (FR1) from 410 to 7125 MHz is a valid question. The global mobile operators are focusing on the upper portion of the n96 frequency band (6 to 7 GHz) for 5G NR Advanced (5.5G) and possibly 6G services. The full bandwidth of the n96 spectrum has been allocated for unlicensed Wi-Fi 6E/7 services, primarily in the Americas. Figure 7 shows the bandwidth and the band designations for the 3GPP 6 to 7 GHz spectrum bands.

The countries that have adopted using the entire 5925 to 7125 MHz spectrum for unlicensed services are:

  • ITU Region 1: The U.S., Argentina, Brazil, Canada, Columbia, Costa Rica, Dominican Republic, El Salvador, Guatemala, Saudi Arabia and South Korea
  • ITU Region 2: Saudi Arabia
  • ITU Region 3: South Korea.

Nearly all other countries have adopted only the lower 500 MHz 3GPP n102 sub-band for unlicensed services and are considering the upper 700 MHz for licensed applications. The 3GPP n104 band is where the battle to the death between the Wi-Fi Alliance and 3GPP/GSMA will be fought for future spectrum allocations for both terrestrial and non-terrestrial mobile networks within the ITU and individual regulatory agencies worldwide. The allocation of n96 in the Americas, South Korea and Saudi Arabia puts these countries at a severe disadvantage in finding spectrum for 5G NR Advanced and 6G services, unless these countries go back and reallocate only the n102 portion of the band for unlicensed usage.

China has allocated the 3GPP n104 6425 to 7125 MHz with 700 MHz bandwidth spectrum for 5G NR Advanced services. China’s Ministry of Industry and Information Technology is expected to issue licenses to its four mobile operators in 2025, China Broadnet, China Mobile, China Telecom and China Unicom. Other countries and regions, such as those in Europe, the Middle East and Asia Pacific, could adopt the n104 spectrum for mobile and non-terrestrial 5G NR Advanced and 6G services and leave the n102 spectrum for unlicensed Wi-Fi services.

India has not yet adopted any spectrum within n96 for any services and could follow the same n102/n104 split as the rest of the countries in ITU Regions 1 and 3.

3GPP FR3/FR4/FR5

The other main chunks of the spectrum that 3GPP is focused on are:

  • FR3 7.125 to 24.25 GHz
  • FR4 71 to 114.25 GHz
  • FR5 114.25 to 275 GHz.

The FR5 band includes parts of the D-Band (110 to 170 GHz) and J-Band (220 to 330 GHz) and all of the G-Band (140 to 220 GHz) and H-Band (170 to 260 GHz).

The realistic and most likely choice is the FR3 spectrum for 5G NR Advanced and 6G. This spectrum sits between the FR1 and FR2 bands, and the ecosystem for RF components and systems can be ramped into commercial use. The belief is that this can happen more quickly than systems can be developed in the FR4 and FR5 bands.

Auctions

Now that potential spectrum has been identified across various regions and countries, is there any money available for spectrum auctions given the price per MHz/pop spent on the 5G spectrum? This is doubtful, given the current capital markets structure for debt and the cash-poor situation for many mobile operators. This could be a very significant roadblock on the path to 5G NR Advanced and 6G. Again, the reader must remember that there has been little monetary gain and return on investment in 5G technology/spectrum for most mobile operators except for the Chinese.

Evolution of MIMO

Within the frequency-division duplex (FDD) segment, there are two important issues to explore. The first is determining the benefits of modernizing the mobile network from existing 4T4R macro RUs to 16T16R/32T32R FDD AAUs at mid-band spectrum. The second is evaluating whether these benefits outweigh an evolution to FDD 8T8R. There is a much higher likelihood that 32T32R FDD will result in a capacity gain of approximately 50 percent from 4T4R FDD units. However, this comes with a power consumption penalty for single- or dual-band, mid-band 32T32R FDD systems. The argument against 8T8R FDD is that the incremental capacity gain of approximately 10 percent is not worth the replacement effort. Proponents of this argument believe that this small capacity gain will be quickly absorbed and the mobile operator will still need to upgrade to the 32T32R solution. The question then becomes, why not just use it in the first place? China has embraced the 8T8R strategy for mid-band 1.8/2.1 GHz spectrum while the U.S. is adopting the 32T32R solution instead. Europe and other regions will most likely be operator-dependent.

For the TDD segment, Chinese OEMs Huawei Technologies and ZTE Corporation have focused on the extra-large antenna array architecture to use in the 6 to 7 GHz band to extend the downlink and uplink cell radius using 128T128R and 256T256R architectures. In the current FR2 mmWave and future FR3 spectrum, very large antenna element arrays of up to 1024 or even higher are expected to extend the cell radius.

Evolution of Multi-Beam Antennas

Increasing the MIMO order and the number of layers is not the only way to increase network capacity. Sector splitting and dual-beam, 33-degree half-power beamwidth (HPBW) antennas can increase macro site capacity compared with legacy single-beam, 65-degree HPBW antenna configurations. However, these antenna solutions are typically side-by-side and there is significant sidelobe interference between the two beams, which ultimately reduces capacity. Multi-beam antennas have been used extensively in high-capacity venues that can support more than eight beams. However, these antennas are very wide and have significant wind load issues on a macro site tower or rooftop installation. There are no wind issues for an indoor arena or domed stadium. However, solutions available today in the market can create 9 to 24-sector macro sites using just 4T4R technology that outperforms current state-of-the-art massive MIMO (mMIMO) three-sector solutions. The challenge is that this goes against the industry RAN equipment giants, as they would need to license the technology and kill off the mMIMO marketing campaigns for the mobile industry.

CONCLUSION

Ultimately, the mobile operator has many technical and financial decisions to address over the next few years. These decisions will determine where their expenditures go and can push the mobile industry in different directions, depending on the international market outside of China. The mobile industry is permanently fractured between China and the rest of the world and 5G NR Advanced will only increase the size of the rift in the future until 6G network features become clearer and these systems begin deploying. The EJL Wireless view is that opportunities outside of China will be available but at a fraction of the size and without the leverage and scale of Chinese deployments to reduce global pricing. As a result, 5G NR Advanced and 6G system and network pricing will increase for the rest of the world.